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Sample records for quantum dissipative systems

  1. Quantum Dissipative Systems

    CERN Document Server

    Weiss, Ulrich

    2008-01-01

    Major advances in the quantum theory of macroscopic systems, in combination with stunning experimental achievements, have brightened the field and brought it to the attention of the general community in natural sciences. Today, working knowledge of dissipative quantum mechanics is an essential tool for many physicists. This book - originally published in 1990 and republished in 1999 as an enlarged second edition - delves much deeper than ever before into the fundamental concepts, methods, and applications of quantum dissipative systems, including the most recent developments. In this third edi

  2. Quantum dissipative systems

    CERN Document Server

    Weiss, Ulrich

    1993-01-01

    This book deals with the statistical mechanics and dynamics of open quantum systems moving irreversibly under the influence of a dissipative environment. The basic concepts and methods are described on the basis of a microscopic description with emphasis on the functional integral approach. The general theory for the time evolution of the density matrix of the damped system is developed. Many of the sophisticated ideas in the field are explained with simple models. The discussion includes, among others, the interplay between thermal and quantum fluctuations, quantum statistical decay, macrosco

  3. Quantum dissipation in unbounded systems.

    Science.gov (United States)

    Maddox, Jeremy B; Bittner, Eric R

    2002-02-01

    In recent years trajectory based methodologies have become increasingly popular for evaluating the time evolution of quantum systems. A revival of the de Broglie--Bohm interpretation of quantum mechanics has spawned several such techniques for examining quantum dynamics from a hydrodynamic perspective. Using techniques similar to those found in computational fluid dynamics one can construct the wave function of a quantum system at any time from the trajectories of a discrete ensemble of hydrodynamic fluid elements (Bohm particles) which evolve according to nonclassical equations of motion. Until very recently these schemes have been limited to conservative systems. In this paper, we present our methodology for including the effects of a thermal environment into the hydrodynamic formulation of quantum dynamics. We derive hydrodynamic equations of motion from the Caldeira-Leggett master equation for the reduced density matrix and give a brief overview of our computational scheme that incorporates an adaptive Lagrangian mesh. Our applications focus upon the dissipative dynamics of open unbounded quantum systems. Using both the Wigner phase space representation and the linear entropy, we probe the breakdown of the Markov approximation of the bath dynamics at low temperatures. We suggest a criteria for rationalizing the validity of the Markov approximation in open unbound systems and discuss decoherence, energy relaxation, and quantum/classical correspondence in the context of the Bohmian paths.

  4. Dissipative properties of quantum systems.

    Science.gov (United States)

    Grecos, A P; Prigogine, I

    1972-06-01

    We consider the dissipative properties of large quantum systems from the point of view of kinetic theory. The existence of a nontrivial collision operator imposes restrictions on the possible collisional invariants of the system. We consider a model in which a discrete level is coupled to a set of quantum states and which, in the limit of a large "volume," becomes the Friedrichs model. Because of its simplicity this model allows a direct calculation of the collision operator as well as of related operators and the constants of the motion. For a degenerate spectrum the calculations become more involved but the conclusions remain simple. The special role played by the invariants that are functions of the Hamiltonion is shown to be a direct consequence of the existence of a nonvanishing collision operator. For a class of observables we obtain ergodic behavior, and this reformulation of the ergodic problem may be used in statistical mechanics to study the ergodicity of large quantum systems containing a small physical parameter such as the coupling constant or the concentration.

  5. Quantum ratchets in dissipative chaotic systems.

    Science.gov (United States)

    Carlo, Gabriel G; Benenti, Giuliano; Casati, Giulio; Shepelyansky, Dima L

    2005-04-29

    Using the method of quantum trajectories, we study a quantum chaotic dissipative ratchet appearing for particles in a pulsed asymmetric potential in the presence of a dissipative environment. The system is characterized by directed transport emerging from a quantum strange attractor. This model exhibits, in the limit of small effective Planck constant, a transition from quantum to classical behavior, in agreement with the correspondence principle. We also discuss parameter values suitable for the implementation of the quantum ratchet effect with cold atoms in optical lattices.

  6. Quantum chaotic attractor in a dissipative system

    CERN Document Server

    Liu, W V; Schieve, William C.

    1997-01-01

    A dissipative quantum system is treated here by coupling it with a heat bath of harmonic oscillators. Through quantum Langevin equations and Ehrenfest's theorem, we establish explicitly the quantum Duffing equations with a double-well potential chosen. A quantum noise term appears the only driving force in dynamics. Numerical studies show that the chaotic attractor exists in this system while chaos is certainly forbidden in the classical counterpart.

  7. Quons in a Quantum Dissipative System

    CERN Document Server

    Lee, Taejin

    2015-01-01

    String theory proves to be an imperative tool to explore the critical behavior of the quantum dissipative system. We discuss the quantum particles moving in two dimensions, in the presence of a uniform magnetic field, subject to a periodic potential and a dissipative force, which are described by the dissipative Wannier-Azbel-Hofstadter (DWAH) model. Using string theory formulation of the model, we find that the elementary excitations of the system at the generic points of the off-critical regions, in the zero temperature limit are quons, which satisfy q-deformed statistics.

  8. Dynamical algebra of observables in dissipative quantum systems

    Science.gov (United States)

    Alipour, Sahar; Chruściński, Dariusz; Facchi, Paolo; Marmo, Giuseppe; Pascazio, Saverio; Rezakhani, Ali T.

    2017-02-01

    Dynamics and features of quantum systems can be drastically different from classical systems. Dissipation is understood as a general mechanism through which quantum systems may lose part or all of their quantum aspects. Here we discuss a method to analyze behaviors of dissipative quantum systems in an algebraic sense. This method employs a time-dependent product between system’s observables which is induced by the underlying dissipative dynamics. We argue that the long-time limit of the algebra of observables defined with this product yields a contractive algebra which reflects the loss of some quantum features of the dissipative system, and it bears relevant information about irreversibility. We illustrate this result through several examples of dissipation in various Markovian and non-Markovian systems.

  9. Nanoscale thermal imaging of dissipation in quantum systems

    CERN Document Server

    Halbertal, Dorri; Shalom, Moshe Ben; Embon, Lior; Shadmi, Nitzan; Anahory, Yonathan; Naren, HR; Sarkar, Jayanta; Uri, Aviram; Ronen, Yuval; Myasoedov, Yury; Levitov, Leonid; Joselevich, Ernesto; Geim, Andre Konstantin; Zeldov, Eli

    2016-01-01

    Energy dissipation is a fundamental process governing the dynamics of physical, chemical, and biological systems. It is also one of the main characteristics distinguishing quantum and classical phenomena. In condensed matter physics, in particular, scattering mechanisms, loss of quantum information, or breakdown of topological protection are deeply rooted in the intricate details of how and where the dissipation occurs. Despite its vital importance the microscopic behavior of a system is usually not formulated in terms of dissipation because the latter is not a readily measureable quantity on the microscale. Although nanoscale thermometry is gaining much recent interest, the existing thermal imaging methods lack the necessary sensitivity and are unsuitable for low temperature operation required for study of quantum systems. Here we report a superconducting quantum interference nano-thermometer device with sub 50 nm diameter that resides at the apex of a sharp pipette and provides scanning cryogenic thermal se...

  10. Nanoscale thermal imaging of dissipation in quantum systems

    Science.gov (United States)

    Halbertal, D.; Cuppens, J.; Shalom, M. Ben; Embon, L.; Shadmi, N.; Anahory, Y.; Naren, H. R.; Sarkar, J.; Uri, A.; Ronen, Y.; Myasoedov, Y.; Levitov, L. S.; Joselevich, E.; Geim, A. K.; Zeldov, E.

    2016-11-01

    Energy dissipation is a fundamental process governing the dynamics of physical, chemical and biological systems. It is also one of the main characteristics that distinguish quantum from classical phenomena. In particular, in condensed matter physics, scattering mechanisms, loss of quantum information or breakdown of topological protection are deeply rooted in the intricate details of how and where the dissipation occurs. Yet the microscopic behaviour of a system is usually not formulated in terms of dissipation because energy dissipation is not a readily measurable quantity on the micrometre scale. Although nanoscale thermometry has gained much recent interest, existing thermal imaging methods are not sensitive enough for the study of quantum systems and are also unsuitable for the low-temperature operation that is required. Here we report a nano-thermometer based on a superconducting quantum interference device with a diameter of less than 50 nanometres that resides at the apex of a sharp pipette: it provides scanning cryogenic thermal sensing that is four orders of magnitude more sensitive than previous devices—below 1 μK Hz-1/2. This non-contact, non-invasive thermometry allows thermal imaging of very low intensity, nanoscale energy dissipation down to the fundamental Landauer limit of 40 femtowatts for continuous readout of a single qubit at one gigahertz at 4.2 kelvin. These advances enable the observation of changes in dissipation due to single-electron charging of individual quantum dots in carbon nanotubes. They also reveal a dissipation mechanism attributable to resonant localized states in graphene encapsulated within hexagonal boron nitride, opening the door to direct thermal imaging of nanoscale dissipation processes in quantum matter.

  11. Nanoscale thermal imaging of dissipation in quantum systems.

    Science.gov (United States)

    Halbertal, D; Cuppens, J; Shalom, M Ben; Embon, L; Shadmi, N; Anahory, Y; Naren, H R; Sarkar, J; Uri, A; Ronen, Y; Myasoedov, Y; Levitov, L S; Joselevich, E; Geim, A K; Zeldov, E

    2016-11-17

    Energy dissipation is a fundamental process governing the dynamics of physical, chemical and biological systems. It is also one of the main characteristics that distinguish quantum from classical phenomena. In particular, in condensed matter physics, scattering mechanisms, loss of quantum information or breakdown of topological protection are deeply rooted in the intricate details of how and where the dissipation occurs. Yet the microscopic behaviour of a system is usually not formulated in terms of dissipation because energy dissipation is not a readily measurable quantity on the micrometre scale. Although nanoscale thermometry has gained much recent interest, existing thermal imaging methods are not sensitive enough for the study of quantum systems and are also unsuitable for the low-temperature operation that is required. Here we report a nano-thermometer based on a superconducting quantum interference device with a diameter of less than 50 nanometres that resides at the apex of a sharp pipette: it provides scanning cryogenic thermal sensing that is four orders of magnitude more sensitive than previous devices-below 1 μK Hz(-1/2). This non-contact, non-invasive thermometry allows thermal imaging of very low intensity, nanoscale energy dissipation down to the fundamental Landauer limit of 40 femtowatts for continuous readout of a single qubit at one gigahertz at 4.2 kelvin. These advances enable the observation of changes in dissipation due to single-electron charging of individual quantum dots in carbon nanotubes. They also reveal a dissipation mechanism attributable to resonant localized states in graphene encapsulated within hexagonal boron nitride, opening the door to direct thermal imaging of nanoscale dissipation processes in quantum matter.

  12. Dissipation-driven quantum phase transitions in collective spin systems

    Energy Technology Data Exchange (ETDEWEB)

    Morrison, S [Institute for Theoretical Physics, University of Innsbruck, A-6020 Innsbruck (Austria); Parkins, A S [Department of Physics, University of Auckland, Private Bag 92019, Auckland (New Zealand)], E-mail: smor161@aucklanduni.ac.nz

    2008-10-14

    We consider two different collective spin systems subjected to strong dissipation-on the same scale as interaction strengths and external fields-and show that either continuous or discontinuous dissipative quantum phase transitions can occur as the dissipation strength is varied. First, we consider a well-known model of cooperative resonance fluorescence that can exhibit a second-order quantum phase transition, and analyse the entanglement properties near the critical point. Next, we examine a dissipative version of the Lipkin-Meshkov-Glick interacting collective spin model, where we find that either first- or second-order quantum phase transitions can occur, depending only on the ratio of the interaction and external field parameters. We give detailed results and interpretation for the steady-state entanglement in the vicinity of the critical point, where it reaches a maximum. For the first-order transition we find that the semiclassical steady states exhibit a region of bistability. (fast track communication)

  13. Quantum bouncer with dissipation

    Energy Technology Data Exchange (ETDEWEB)

    Lopez, G.; Gonzalez, G. [Departamento de Fisica de la Universidad de Guadalajara, AP 4-137, 44410 Guadalajara, Jalisco (Mexico)

    2006-07-01

    Effects on the spectra of the quantum bouncer due to dissipation are given when a linear o quadratic dissipation in the velocity of the particle is taken into account. Classical constants of motion and Hamiltonians are deduced for these systems and their quantized eigenvalues are estimated through perturbation theory. Differences were found comparing the eigenvalues of the constants of motion and the eigenvalues of the Hamiltonians. The cases when the dissipation parameters go to zero are compared with the non dissipative cases. (Author)

  14. Quantum Gravity as a Dissipative Deterministic System

    NARCIS (Netherlands)

    Hooft, G. 't

    1999-01-01

    It is argued that the so-called holographic principle will obstruct attempts to produce physically realistic models for the unification of general relativity with quantum mechanics, unless determinism in the latter is restored. The notion of time in GR is so different from the usual one in elementar

  15. Quantum Gravity as a Dissipative Deterministic System

    NARCIS (Netherlands)

    Hooft, G. 't

    1999-01-01

    It is argued that the so-called holographic principle will obstruct attempts to produce physically realistic models for the unification of general relativity with quantum mechanics, unless determinism in the latter is restored. The notion of time in GR is so different from the usual one in elementar

  16. Non-Markovian expansion in quantum dissipative systems

    CERN Document Server

    Fraga, E S; Palhares, L F

    2009-01-01

    We consider the non-Markovian Langevin evolution of a dissipative dynamical system in quantum mechanics in the path integral formalism. After discussing the role of the frequency cutoff for the interaction of the system with the heat bath and the kernel and noise correlator that follow from the most common choices, we derive an analytic expansion for the exact non-Markovian dissipation kernel and the corresponding colored noise in the general case that is consistent with the fluctuation-dissipation theorem and incorporates systematically non-local corrections. We illustrate the modifications to results obtained using the traditional (Markovian) Langevin approach in the case of the exponential kernel and analyze the case of the non-Markovian Brownian motion.

  17. Stable classical structures in dissipative quantum chaotic systems

    CERN Document Server

    Raviola, Lisandro A; Rivas, Alejandro M F

    2009-01-01

    We study the stability of classical structures in chaotic systems when a dissipative quantum evolution takes place. We consider a paradigmatic model, the quantum baker map in contact with a heat bath at finite temperature. We analyze the behavior of the purity, fidelity and Husimi distributions corresponding to initial states localized on short periodic orbits (scar functions) and map eigenstates. Scar functions, that have a fundamental role in the semiclassical description of chaotic systems, emerge as very robust against environmental perturbations. This is confirmed by the study of other states localized on classical structures. Also, purity and fidelity show a complementary behavior as decoherence measures.

  18. Interplay between dissipation and driving in nonlinear quantum systems

    Energy Technology Data Exchange (ETDEWEB)

    Vierheilig, Carmen

    2011-07-01

    In this thesis we investigate the interplay between dissipation and driving in nonlinear quantum systems for a special setup: a flux qubit read out by a DC-SQUID - a nonlinear quantum oscillator. The latter is embedded in a harmonic bath, thereby mediating dissipation to the qubit. Two different approaches are elaborated: First we consider a composite qubit-SQUID system and add the bath afterwards. We derive analytical expressions for its eigenstates beyond rotating wave approximation (RWA), by applying Van Vleck perturbation theory (VVPT) in the qubit-oscillator coupling. The second approach is an effective bath approach based on a mapping procedure, where SQUID and bath form an effective bath seen by the qubit. Here the qubit dynamics is obtained by applying standard procedures established for the spin-boson problem. This approach requires the knowledge of the steady-state response of the dissipative Duffing oscillator, which is studied within a resonant and an offresonant approach: The first is applicable near and at an N-photon resonance using VVPT beyond a RWA. The second is based on the exact Floquet states of the nonlinear driven oscillator. The dissipative qubit dynamics is described analytically for weak system-bath coupling and agrees well for both approaches. We derive the effect of the nonlinearity on the qubit dynamics, on the Bloch-Siegert shift and on the vacuum Rabi splitting. (orig.)

  19. An information theory model for dissipation in open quantum systems

    Science.gov (United States)

    Rogers, David M.

    2017-08-01

    This work presents a general model for open quantum systems using an information game along the lines of Jaynes’ original work. It is shown how an energy based reweighting of propagators provides a novel moment generating function at each time point in the process. Derivatives of the generating function give moments of the time derivatives of observables. Aside from the mathematically helpful properties, the ansatz reproduces key physics of stochastic quantum processes. At high temperature, the average density matrix follows the Caldeira-Leggett equation. Its associated Langevin equation clearly demonstrates the emergence of dissipation and decoherence time scales, as well as an additional diffusion due to quantum confinement. A consistent interpretation of these results is that decoherence and wavefunction collapse during measurement are directly related to the degree of environmental noise, and thus occur because of subjective uncertainty of an observer.

  20. Quantum dissipative chaos

    CERN Document Server

    Brun, T A

    1993-01-01

    Using the decoherence formalism of Gell-Mann and Hartle, a quantum system is found which is the equivalent of the classical chaotic Duffing oscillator. The similarities and the differences from the classical oscillator are examined; in particular, a new concept of quantum maps is introduced, and alterations in the classical strange attractor due to the presence of scale- dependent quantum effects are studied. Classical quantities such as the Lyapunov exponents and fractal dimension are examined, and quantum analogs are suggested. These results are generalized into a framework for quantum dissipative chaos, and there is a brief discussion of other work in this area.

  1. Quantum mechanics of non-Hamiltonian and dissipative systems

    CERN Document Server

    Tarasov, Vasily

    2008-01-01

    Quantum Mechanics of Non-Hamiltonian and Dissipative Systems is self-contained and can be used by students without a previous course in modern mathematics and physics. The book describes the modern structure of the theory, and covers the fundamental results of last 15 years. The book has been recommended by Russian Ministry of Education as the textbook for graduate students and has been used for graduate student lectures from 1998 to 2006. Requires no preliminary knowledge of graduate and advanced mathematics Discusses the fundamental results of last 15 years in this theory Suitable for cours

  2. Quantum dissipation theory and applications to quantum transport and quantum measurement in mesoscopic systems

    Science.gov (United States)

    Cui, Ping

    The thesis comprises two major themes of quantum statistical dynamics. One is the development of quantum dissipation theory (QDT). It covers the establishment of some basic relations of quantum statistical dynamics, the construction of several nonequivalent complete second-order formulations, and the development of exact QDT. Another is related to the applications of quantum statistical dynamics to a variety of research fields. In particular, unconventional but novel theories of the electron transfer in Debye solvents, quantum transport, and quantum measurement are developed on the basis of QDT formulations. The thesis is organized as follows. In Chapter 1, we present some background knowledge in relation to the aforementioned two themes of this thesis. The key quantity in QDT is the reduced density operator rho(t) ≡ trBrho T(t); i.e., the partial trace of the total system and bath composite rhoT(t) over the bath degrees of freedom. QDT governs the evolution of reduced density operator, where the effects of bath are treated in a quantum statistical manner. In principle, the reduced density operator contains all dynamics information of interest. However, the conventional quantum transport theory is formulated in terms of nonequilibrium Green's function. The newly emerging field of quantum measurement in relation to quantum information and quantum computing does exploit a sort of QDT formalism. Besides the background of the relevant theoretical development, some representative experiments on molecular nanojunctions are also briefly discussed. In chapter 2, we outline some basic (including new) relations that highlight several important issues on QDT. The content includes the background of nonequilibrium quantum statistical mechanics, the general description of the total composite Hamiltonian with stochastic system-bath interaction, a novel parameterization scheme for bath correlation functions, a newly developed exact theory of driven Brownian oscillator (DBO

  3. Population equations for quantum systems in contact with dissipation mechanisms

    Science.gov (United States)

    Huang, X. Y.; Narducci, L. M.; Yuan, J. M.

    1981-06-01

    We discuss the construction of population equations for driven quantum systems in contact with dissipation mechanisms in the limit where the strength of the driving force is sufficiently weak that a suitable Born expansion can be carried out in powers of the coupling constant of the coherent interaction. The Zwanzig projector technique and the application of an appropriate eigenfunction-expansion method due to Weidlich lead to an elegant derivation of population equations. If the decay rates of the irreversible processes allow the application of the Markoff approximation, ordinary first-order differential equations for the level populations can be derived. The transition rates are constructed explicitly in terms of the coherent Liouville operator and the Weidlich eigenfunctions.

  4. Dissipation, dephasing and quantum Darwinism in qubit systems with random unitary interactions

    Science.gov (United States)

    Balaneskovic, Nenad; Mendler, Marc

    2016-09-01

    We investigate the influence of dissipation and decoherence on quantum Darwinism by generalizing Zurek's original qubit model of decoherence and the establishment of pointer states [W.H. Zurek, Nat. Phys. 5, 181 (2009); see also arXiv: quant-ph/0707.2832v1, pp. 14-19.]. Our model allows for repeated multiple qubit-qubit couplings between system and environment which are described by randomly applied two-qubit quantum operations inducing entanglement, dissipation and dephasing. The resulting stationary qubit states of system and environment are investigated. They exhibit the intricate influence of entanglement generation, dissipation and dephasing on this characteristic quantum phenomenon.

  5. Constructing quantum dissipations and their reversible states from classical interacting spin systems

    Energy Technology Data Exchange (ETDEWEB)

    Goderis, D.; Maes, C. (Liege Univ. (BE))

    1991-01-01

    The relation between certain quantum systems and classical stochastic processes - e.g. in the method of functional integration - is formulated on the level of the dynamics for both quantum and classical dissipative time evolutions. An essentially unique quantum dissipation is constructed from a classical interacting spin system, preserving the notion of detailed balance. Translation invariant and reversible infinite volume quantum dynamics are found in this way and the Hamiltonian is recovered from the action of the generator in the GNS-representation of the corresponding groundstate for which a Feynmann-Kac formula holds. Local reversibility of quantum dissipations is shown to give rise to an almost classical characterization of the corresponding quantum states.

  6. Mathematical Models of Dissipative Systems in Quantum Engineering

    Directory of Open Access Journals (Sweden)

    Andreea Sterian

    2012-01-01

    Full Text Available The paper shows the results of theoretical research concerning the modeling and characterization of the dissipative structures generally, the dissipation being an essential property of the system with self-organization which include the laser-type systems also. The most important results presented are new formulae which relate the coupling parameters from Lindblad equation with environment operators Γ; microscopic quantitative expressions for the dissipative coefficients of the master equations; explicit expressions which describe the changes of the environment density operator during the system evolution for fermion systems coupled with free electromagnetic field; the generalized Bloch-Feynman equations for -level systems with microscopic coefficients in agreement with generally accepted physical interpretations. Based on Maxwell-Bloch equations with consideration of the interactions between nearing atomic dipoles, for the dense optical media we have shown that in the presence of the short optical pulses, the population inversion oscillates between two extreme values, depending on the strength of the interaction and the optical pulse energy.

  7. Quantum chaos, thermalization and dissipation in nuclear systems

    Indian Academy of Sciences (India)

    Sudhir R Jain

    2001-08-01

    Nuclei have complex energy-level sequence with statistical properties in agreement with canonical random matrix theory. This agreement appears when the one-particle one-hole states are mixed completely with two-particle two-hole states. In the transition, there is a new universality which we present here, bringing about a relation between dynamics and statistics. We summarize also the role of chaos in thermalization and dissipation in isolated systems like nuclei. The methods used to bring forth this understanding emerge from random matrix theory, semiclassical physics, and the theory of dynamical systems.

  8. Real-time simulation of dissipation-driven quantum systems

    CERN Document Server

    Banerjee, Debasish; Jiang, Fu-Jiun; Kon, Mark; Wiese, Uwe-Jens

    2015-01-01

    We set up a real-time path integral to study the evolution of quantum systems driven in real-time completely by the coupling of the system to the environment. For specifically chosen interactions, this can be interpreted as measurements being performed on the system. For a spin-1/2 system, in particular, when the measurement results are averaged over, the resulting sign problem completely disappears, and the system can be simulated with an efficient cluster algorithm.

  9. Time-evolution of quantum systems via a complex nonlinear Riccati equation. II. Dissipative systems

    Science.gov (United States)

    Cruz, Hans; Schuch, Dieter; Castaños, Octavio; Rosas-Ortiz, Oscar

    2016-10-01

    In our former contribution (Cruz et al., 2015), we have shown the sensitivity to the choice of initial conditions in the evolution of Gaussian wave packets via the nonlinear Riccati equation. The formalism developed in the previous work is extended to effective approaches for the description of dissipative quantum systems. By means of simple examples we show the effects of the environment on the quantum uncertainties, correlation function, quantum energy contribution and tunnelling currents. We prove that the environmental parameter γ is strongly related with the sensitivity to the choice of initial conditions.

  10. Dissipative dynamics of a quantum two-state system in presence of nonequilibrium quantum noise

    Science.gov (United States)

    Mann, Niklas; Brüggemann, Jochen; Thorwart, Michael

    2016-12-01

    We analyze the real-time dynamics of a quantum two-state system in the presence of nonequilibrium quantum fluctuations. The latter are generated by a coupling of the two-state system to a single electronic level of a quantum dot which carries a nonequilibrium tunneling current. We restrict to the sequential tunneling regime and calculate the dynamics of the two-state system, of the dot population, and of the nonequilibrium charge current on the basis of a diagrammatic perturbative method valid for a weak tunneling coupling. We find a nontrivial dependence of the relaxation and dephasing rates of the two-state system due to the nonequilibrium fluctuations which is directly linked to the structure of the unperturbed central system. In addition, a Heisenberg-Langevin-equation of motion allows us to calculate the correlation function of the nonequilibrium fluctuations. By this, we obtain a generalized nonequilibrium fluctuation relation which includes the equilibrium fluctuation-dissipation theorem in the limit of zero transport voltage. A straightforward extension to the case with a time-periodic ac voltage is shown.

  11. Signatures of classical structures in the leading eigenstates of quantum dissipative systems

    Science.gov (United States)

    Carlo, Gabriel G.; Ermann, Leonardo; Rivas, Alejandro M. F.; Spina, María E.

    2017-09-01

    By analyzing a paradigmatic example of the theory of dissipative systems—the classical and quantum dissipative standard map—we are able to explain the main features of the decay to the quantum equilibrium state. The classical isoperiodic stable structures typically present in the parameter space of these kinds of systems play a fundamental role. In fact, we have found that the period of stable structures that are near in this space determines the phase of the leading eigenstates of the corresponding quantum superoperator. Moreover, the eigenvectors show a strong localization on the corresponding periodic orbits (limit cycles). We show that this sort of scarring phenomenon (an established property of Hamiltonian and projectively open systems) is present in the dissipative case and it is of extreme simplicity.

  12. Deconstructing non-dissipative non-Dirac-hermitian relativistic quantum systems

    CERN Document Server

    Ghosh, Pijush K

    2011-01-01

    A method to construct non-dissipative non-Dirac-hermitian relativistic quantum system that is isospectral with a Dirac-hermitian Hamiltonian is presented. The general technique involves a realization of the basic canonical (anti-)commutation relations involving the Dirac matrices and the bosonic degrees of freedom in terms of non-Dirac-hermitian operators, which are hermitian in a Hilbert space that is endowed with a pre-determined positive-definite metric. Several examples of exactly solvable non-dissipative non-Dirac-hermitian relativistic quantum systems are presented by establishing/employing a connection between Dirac equation and supersymmetry

  13. Deconstructing non-dissipative non-Dirac-Hermitian relativistic quantum systems

    Science.gov (United States)

    Ghosh, Pijush K.

    2011-08-01

    A method to construct non-dissipative non-Dirac-Hermitian relativistic quantum system that is isospectral with a Dirac-Hermitian Hamiltonian is presented. The general technique involves a realization of the basic canonical (anti-)commutation relations involving the Dirac matrices and the bosonic degrees of freedom in terms of non-Dirac-Hermitian operators, which are Hermitian in a Hilbert space that is endowed with a pre-determined positive-definite metric. Several examples of exactly solvable non-dissipative non-Dirac-Hermitian relativistic quantum systems are presented by establishing/employing a connection between Dirac equation and supersymmetry.

  14. Time-Minimal Control of Dissipative Two-level Quantum Systems: the Generic Case

    CERN Document Server

    Bonnard, B; Sugny, D

    2008-01-01

    The objective of this article is to complete preliminary results concerning the time-minimal control of dissipative two-level quantum systems whose dynamics is governed by Lindblad equations. The extremal system is described by a 3D-Hamiltonian depending upon three parameters. We combine geometric techniques with numerical simulations to deduce the optimal solutions.

  15. Area law for fixed points of rapidly mixing dissipative quantum systems

    Energy Technology Data Exchange (ETDEWEB)

    Brandão, Fernando G. S. L. [Quantum Architectures and Computation Group, Microsoft Research, Redmond, Washington 98052 (United States); Department of Computer Science, University College London, Gower Street, London WC1E 6BT (United Kingdom); Cubitt, Toby S. [Department of Computer Science, University College London, Gower Street, London WC1E 6BT (United Kingdom); DAMTP, University of Cambridge, Cambridge (United Kingdom); Lucia, Angelo, E-mail: anlucia@ucm.es [Departamento de Análisis Matemático, Universidad Complutense de Madrid, Madrid (Spain); Michalakis, Spyridon [Institute for Quantum Information and Matter, Caltech, California 91125 (United States); Perez-Garcia, David [Departamento de Análisis Matemático, Universidad Complutense de Madrid, Madrid (Spain); IMI, Universidad Complutense de Madrid, Madrid (Spain); ICMAT, C/Nicolás Cabrera, Campus de Cantoblanco, 28049 Madrid (Spain)

    2015-10-15

    We prove an area law with a logarithmic correction for the mutual information for fixed points of local dissipative quantum system satisfying a rapid mixing condition, under either of the following assumptions: the fixed point is pure or the system is frustration free.

  16. Dissipative preparation of entanglement in quantum optical and solid state systems

    DEFF Research Database (Denmark)

    Reiter, Florentin

    Quantum mechanics is an immensely successful theory which is essential for the explanation of numerous phenomena in atomic physics, solid state physics, nuclear physics and elementary particle physics. Quantum theory also involves effects which have no analogy in the classical world. In particular....... Entangled states are, however, sensitive to interactions with the environment, which are present in any open system. Here, in particular decoherence, i.e. loss of coherence, and dissipation, i.e. loss of energy, destroy the desired correlations. The novel approach of “dissipative quantum computing......-particle entangled states in several concrete physical systems such as optical cavities, trapped ions, and superconducting qubits. To study the dynamics of open quantum systems, we first develop an operator formalism which allows us to identify the effective interactions. Eliminating the decaying states from...

  17. Quantum bouncer with quadratic dissipation

    Energy Technology Data Exchange (ETDEWEB)

    Gonzalez, G. [NanoScience Technology Center, University of Central Florida, Orlando, FL 32826 (United States)]. e-mail: ggonzalez@physics.ucf.edu

    2008-07-01

    The energy loss due to a quadratic velocity-dependent force on a quantum particle bouncing off a perfectly reflecting surface is obtained for a full cycle of motion. We approach this problem by means of a new, effective, phenomenological Hamiltonian which corresponds to the actual energy of the system and obtain the correction to the eigenvalues of the energy in first-order quantum perturbation theory for the case of weak dissipation. (Author)

  18. Quantum bouncer with quadratic dissipation

    Science.gov (United States)

    González, G.

    2008-02-01

    The energy loss due to a quadratic velocity dependent force on a quantum particle bouncing on a perfectly reflecting surface is obtained for a full cycle of motion. We approach this problem by means of a new effective phenomenological Hamiltonian which corresponds to the actual energy of the system and obtained the correction to the eigenvalues of the energy in first order quantum perturbation theory for the case of weak dissipation.

  19. Dissipative tunneling in structures with quantum dots and quantum molecules

    OpenAIRE

    Dahnovsky, Yu. I.; Krevchik, V. D.; Semenov, M. B.; Yamamoto, K.; Zhukovsky, V. Ch.; Aringazin, A. K.; Kudryashov, E. I.; Mayorov, V. G.

    2005-01-01

    The problem of tunneling control in systems "quantum dot - quantum well" (as well as "quantum dot - quantum dot" or quantum molecule) and "quantum dot - bulk contact" is studied as a quantum tunneling with dissipation process in the semiclassical (instanton) approximation. For these systems temperature and correlation between a quantum dot radius and a quantum well width (or another quantum dot radius) are considered to be control parameters. The condition for a single electron blockade is fo...

  20. Time-minimal control of dissipative two-level quantum systems: The Integrable case

    CERN Document Server

    Bonnard, B

    2008-01-01

    The objective of this article is to apply recent developments in geometric optimal control to analyze the time minimum control problem of dissipative two-level quantum systems whose dynamics is governed by the Lindblad equation. We focus our analysis on the case where the extremal Hamiltonian is integrable.

  1. Effective Floquet-Gibbs states for dissipative quantum systems

    Science.gov (United States)

    Shirai, Tatsuhiko; Thingna, Juzar; Mori, Takashi; Denisov, Sergey; Hänggi, Peter; Miyashita, Seiji

    2016-05-01

    A periodically driven quantum system, when coupled to a heat bath, relaxes to a non-equilibrium asymptotic state. In the general situation, the retrieval of this asymptotic state presents a rather non-trivial task. It was recently shown that in the limit of an infinitesimal coupling, using the so-called rotating wave approximation (RWA), and under strict conditions imposed on the time-dependent system Hamiltonian, the asymptotic state can attain the Gibbs form. A Floquet-Gibbs state is characterized by a density matrix which is diagonal in the Floquet basis of the system Hamiltonian with the diagonal elements obeying a Gibbs distribution, being parametrized by the corresponding Floquet quasi-energies. Addressing the non-adiabatic driving regime, upon using the Magnus expansion, we employ the concept of a corresponding effective Floquet Hamiltonian. In doing so we go beyond the conventionally used RWA and demonstrate that the idea of Floquet-Gibbs states can be extended to the realistic case of a weak, although finite system-bath coupling, herein termed effective Floquet-Gibbs states.

  2. Dissipative effects in dipolar, quantum many-body systems

    Science.gov (United States)

    Safavi-Naini, Arghavan; Capogrosso-Sansone, Barbara; Rey, Ana Maria

    2015-03-01

    We use Quantum Monte Carlo simulations, by the Worm algorithm, to study the ground state phase diagram of two-dimensional, dipolar lattice bosons where each site is coupled, via density operators, to an external reservoir. A recent related study of the XXZ model with ohmic coupling to an external reservoir reported the existence of a bath-induced Bose metal phase in the ground state phase diagram away from half filling, and a Luttinger liquid and a charge density wave at half-filling. Our work extends this methodology to higher dimensional systems with long-range interactions. In the case of hard-core bosons, our method can be applied to experimental systems featuring dipolar fermionic molecules in the presence of losses. This work utilized the Janus supercomputer, which is supported by the NSF (award number CNS-0821794) and the University of Colorado Boulder, and is a joint effort with the University of Colorado Denver and the National Center for Atmospheric Research, as well as OU Supercomputing Center for Education and Research (OSCER) at the University of Oklahoma. NIST, JILA-NSF-PFC-1125844, NSF-PIF-1211914, NSF-PHY11-25915, ARO, ARO-DARPA-OLE, AFOSR, AFOSR-MURI.

  3. Quantum dissipative Higgs model

    Energy Technology Data Exchange (ETDEWEB)

    Amooghorban, Ehsan, E-mail: Ehsan.amooghorban@sci.sku.ac.ir; Mahdifar, Ali, E-mail: mahdifar_a@sci.sku.ac.ir

    2015-09-15

    By using a continuum of oscillators as a reservoir, we present a classical and a quantum-mechanical treatment for the Higgs model in the presence of dissipation. In this base, a fully canonical approach is used to quantize the damped particle on a spherical surface under the action of a conservative central force, the conjugate momentum is defined and the Hamiltonian is derived. The equations of motion for the canonical variables and in turn the Langevin equation are obtained. It is shown that the dynamics of the dissipative Higgs model is not only determined by a projected susceptibility tensor that obeys the Kramers–Kronig relations and a noise operator but also the curvature of the spherical space. Due to the gnomonic projection from the spherical space to the tangent plane, the projected susceptibility displays anisotropic character in the tangent plane. To illuminate the effect of dissipation on the Higgs model, the transition rate between energy levels of the particle on the sphere is calculated. It is seen that appreciable probabilities for transition are possible only if the transition and reservoir’s oscillators frequencies to be nearly on resonance.

  4. Modular quantum-information processing by dissipation

    Science.gov (United States)

    Marshall, Jeffrey; Campos Venuti, Lorenzo; Zanardi, Paolo

    2016-11-01

    Dissipation can be used as a resource to control and simulate quantum systems. We discuss a modular model based on fast dissipation capable of performing universal quantum computation, and simulating arbitrary Lindbladian dynamics. The model consists of a network of elementary dissipation-generated modules and it is in principle scalable. In particular, we demonstrate the ability to dissipatively prepare all single-qubit gates, and the controlled-not gate; prerequisites for universal quantum computing. We also show a way to implement a type of quantum memory in a dissipative environment, whereby we can arbitrarily control the loss in both coherence, and concurrence, over the evolution. Moreover, our dissipation-assisted modular construction exhibits a degree of inbuilt robustness to Hamiltonian and, indeed, Lindbladian errors, and as such is of potential practical relevance.

  5. Functional methods and mappings of dissipative quantum systems; Funktionalmethoden und Abbildungen dissipativer Quantensysteme

    Energy Technology Data Exchange (ETDEWEB)

    Baur, H.

    2006-07-01

    In the first part of this work we extract the algebraic structure behind the method of the influence functional in the context of dissipative quantum mechanics. Special emphasis was put on the transition from a quantum mechanical description to a classical one, since it allows a deeper understanding of the measurement-process. This is tightly connected with the transition from a microscopic to a macroscopic world where the former one is described by the rules of quantum mechanics whereas the latter follows the rules of classical mechanics. In addition we show how the results of the influence functional method can be interpreted as a stochastical process, which in turn allows an easy comparison with the well known time development of a quantum mechanical system by use of the Schroedinger equation. In the following we examine the tight-binding approximation of models of which their hamiltionian shows discrete eigenstates in position space and where transitions between those states are suppressed so that propagation either is described by tunneling or by thermal activation. In the framework of dissipative quantum mechanics this leads to a tremendous simplification of the effective description of the system since instead of looking at the full history of all paths in the path integral description, we only have to look at all possible jump times and the possible corresponding set of weights for the jump direction, which is much easier to handle both analytically and numerically. In addition we deal with the mapping and the connection of dissipative quantum mechanical models with ones in quantum field theory and in particular models in statistical field theory. As an example we mention conformal invariance in two dimensions which always becomes relevant if a statistical system only has local interaction and is invariant under scaling. (orig.)

  6. Ordered Dissipative Structures in Exciton Systems in Semiconductor Quantum Wells

    Directory of Open Access Journals (Sweden)

    Andrey A. Chernyuk

    2006-02-01

    Full Text Available A phenomenological theory of exciton condensation in conditions of inhomogeneous excitation is proposed. The theory is applied to the study of the development of an exciton luminescence ring and the ring fragmentation at macroscopical distances from the central excitation spot in coupled quantum wells. The transition between the fragmented and the continuous ring is considered. With assumption of a defect in the structure, a possibility of a localized island of the condensed phase in a fixed position is shown. Exciton density distribution is also analyzed in the case of two spatially separated spots of the laser excitation.

  7. Exact dynamics of dissipative electronic systems and quantum transport: Hierarchical equations of motion approach.

    Science.gov (United States)

    Jin, Jinshuang; Zheng, Xiao; Yan, YiJing

    2008-06-21

    A generalized quantum master equation theory that governs the exact, nonperturbative quantum dissipation and quantum transport is formulated in terms of hierarchically coupled equations of motion for an arbitrary electronic system in contact with electrodes under either a stationary or a nonstationary electrochemical potential bias. The theoretical construction starts with the influence functional in path integral, in which the electron creation and annihilation operators are Grassmann variables. Time derivatives on the influence functionals are then performed in a hierarchical manner. Both the multiple-frequency dispersion and the non-Markovian reservoir parametrization schemes are considered for the desired hierarchy construction. The resulting hierarchical equations of motion formalism is in principle exact and applicable to arbitrary electronic systems, including Coulomb interactions, under the influence of arbitrary time-dependent applied bias voltage and external fields. Both the conventional quantum master equation and the real-time diagrammatic formalism of Schon and co-workers can be readily obtained at well defined limits of the present theory. We also show that for a noninteracting electron system, the present hierarchical equations of motion formalism terminates at the second tier exactly, and the Landuer-Buttiker transport current expression is recovered. The present theory renders an exact and numerically tractable tool to evaluate various transient and stationary quantum transport properties of many-electron systems, together with the involving nonperturbative dissipative dynamics.

  8. Deconstructing non-dissipative non-Dirac-hermitian relativistic quantum systems

    OpenAIRE

    2011-01-01

    A method to construct non-dissipative non-Dirac-hermitian relativistic quantum system that is isospectral with a Dirac-hermitian Hamiltonian is presented. The general technique involves a realization of the basic canonical (anti-)commutation relations involving the Dirac matrices and the bosonic degrees of freedom in terms of non-Dirac-hermitian operators, which are hermitian in a Hilbert space that is endowed with a pre-determined positive-definite metric. Several examples of exactly solvabl...

  9. Microscopic description for the emergence of collective dissipation in extended quantum systems

    Science.gov (United States)

    Galve, Fernando; Mandarino, Antonio; Paris, Matteo G. A.; Benedetti, Claudia; Zambrini, Roberta

    2017-02-01

    Practical implementations of quantum technology are limited by unavoidable effects of decoherence and dissipation. With achieved experimental control for individual atoms and photons, more complex platforms composed by several units can be assembled enabling distinctive forms of dissipation and decoherence, in independent heat baths or collectively into a common bath, with dramatic consequences for the preservation of quantum coherence. The cross-over between these two regimes has been widely attributed in the literature to the system units being farther apart than the bath’s correlation length. Starting from a microscopic model of a structured environment (a crystal) sensed by two bosonic probes, here we show the failure of such conceptual relation, and identify the exact physical mechanism underlying this cross-over, displaying a sharp contrast between dephasing and dissipative baths. Depending on the frequency of the system and, crucially, on its orientation with respect to the crystal axes, collective dissipation becomes possible for very large distances between probes, opening new avenues to deal with decoherence in phononic baths.

  10. Microscopic description for the emergence of collective dissipation in extended quantum systems

    Science.gov (United States)

    Galve, Fernando; Mandarino, Antonio; Paris, Matteo G. A.; Benedetti, Claudia; Zambrini, Roberta

    2017-01-01

    Practical implementations of quantum technology are limited by unavoidable effects of decoherence and dissipation. With achieved experimental control for individual atoms and photons, more complex platforms composed by several units can be assembled enabling distinctive forms of dissipation and decoherence, in independent heat baths or collectively into a common bath, with dramatic consequences for the preservation of quantum coherence. The cross-over between these two regimes has been widely attributed in the literature to the system units being farther apart than the bath’s correlation length. Starting from a microscopic model of a structured environment (a crystal) sensed by two bosonic probes, here we show the failure of such conceptual relation, and identify the exact physical mechanism underlying this cross-over, displaying a sharp contrast between dephasing and dissipative baths. Depending on the frequency of the system and, crucially, on its orientation with respect to the crystal axes, collective dissipation becomes possible for very large distances between probes, opening new avenues to deal with decoherence in phononic baths. PMID:28176835

  11. Dissipative Dynamics of Quantum Fluctuations

    CERN Document Server

    Benatti, F; Floreanini, R

    2015-01-01

    One way to look for complex behaviours in many-body quantum systems is to let the number $N$ of degrees of freedom become large and focus upon collective observables. Mean-field quantities scaling as $1/N$ tend to commute, whence complexity at the quantum level can only be inherited from complexity at the classical level. Instead, fluctuations of microscopic observables scale as $1/\\sqrt{N}$ and exhibit collective Bosonic features, typical of a mesoscopic regime half-way between the quantum one at the microscopic level and the classical one at the level of macroscopic averages. Here, we consider the mesoscopic behaviour emerging from an infinite quantum spin chain undergoing a microscopic dissipative, irreversible dynamics and from global states without long-range correlations and invariant under lattice translations and dynamics. We show that, from the fluctuations of one site spin observables whose linear span is mapped into itself by the dynamics, there emerge bosonic operators obeying a mesoscopic dissipa...

  12. Quantum Dissipation and CP Violation in MINOS

    CERN Document Server

    de Oliveira, R L N; de Holanda, P C

    2014-01-01

    We use the open quantum systems framework to analyze the MINOS data and perform this analysis considering two different dissipative models. In the first model, the dissipative parameter describes decoherence effect and in the second, the dissipative parameter describes other dissipative effects including decoherence. With the second model it is possible to study CP violation since we consider Majorana neutrinos. The analysis from the muon neutrino and antineutrino beam assigns different values to all the parameters of the models, but consistent with each other. Assuming that neutrinos are equivalent to antineutrinos, the global analysis presents nonvanishing Majorana CP phase depending on the energetic parameterization of the dissipative parameter.

  13. Path-integral description of combined Hamiltonian and non-Hamiltonian dynamics in quantum dissipative systems

    Science.gov (United States)

    Barth, A. M.; Vagov, A.; Axt, V. M.

    2016-09-01

    We present a numerical path-integral iteration scheme for the low-dimensional reduced density matrix of a time-dependent quantum dissipative system. Our approach simultaneously accounts for the combined action of a microscopically modeled pure-dephasing-type coupling to a continuum of harmonic oscillators representing, e.g., phonons, and further environmental interactions inducing non-Hamiltonian dynamics in the inner system represented, e.g., by Lindblad-type dissipation or relaxation. Our formulation of the path-integral method allows for a numerically exact treatment of the coupling to the oscillator modes and moreover is general enough to provide a natural way to include Markovian processes that are sufficiently described by rate equations. We apply this new formalism to a model of a single semiconductor quantum dot which includes the coupling to longitudinal acoustic phonons for two cases: (a) external laser excitation taking into account a phenomenological radiative decay of the excited dot state and (b) a coupling of the quantum dot to a single mode of an optical cavity taking into account cavity photon losses.

  14. Dissipation-driven quantum phase transition in superconductor-graphene systems.

    Science.gov (United States)

    Lutchyn, Roman M; Galitski, Victor; Refael, Gil; Das Sarma, S

    2008-09-05

    We show that a system of Josephson junctions coupled via low-resistance tunneling contacts to graphene substrate(s) may effectively operate as a current switching device. The effect is based on the dissipation-driven superconductor-to-insulator quantum phase transition, which happens due to the interplay of the Josephson effect and Coulomb blockade. Coupling to a graphene substrate with gapless excitations further enhances charge fluctuations favoring superconductivity. The effect is shown to scale exponentially with the Fermi energy in graphene, which can be controlled by the gate voltage. We develop a theory that quantitatively describes the quantum phase transition in a two-dimensional Josephson junction array, but it is expected to provide a reliable qualitative description for one-dimensional systems as well.

  15. Fluctuation-dissipation theorem and quantum tunneling with dissipation

    CERN Document Server

    Fujikawa, K

    1998-01-01

    We suggest to take the fluctuation-dissipation theorem of Callen and Welton as a basis to study quantum dissipative phenomena (such as macroscopic quantum tunneling) in a manner analogous to the Nambu-Goldstone theorem for spontaneous symmetry breakdown. It is shown that the essential physical contents of the Caldeira-Leggett model such as the suppression of quantum coherence by Ohmic dissipation are derived from general principles only, namely, the fluctuation-dissipation theorem and unitarity and causality (i.e., dispersion relations), without referring to an explicit form of the Lagrangian. An interesting connection between quantum tunneling with Ohmic dissipation and the Anderson's orthogonality theorem is also noted.

  16. Real-time simulation of nonequilibrium transport of magnetization in large open quantum spin systems driven by dissipation

    Science.gov (United States)

    Banerjee, D.; Hebenstreit, F.; Jiang, F.-J.; Wiese, U.-J.

    2015-09-01

    Using quantum Monte Carlo, we study the nonequilibrium transport of magnetization in large open strongly correlated quantum spin-1/2 systems driven by purely dissipative processes that conserve the uniform or staggered magnetization, disregarding unitary Hamiltonian dynamics. We prepare both a low-temperature Heisenberg ferromagnet and an antiferromagnet in two parts of the system that are initially isolated from each other. We then bring the two subsystems in contact and study their real-time dissipative dynamics for different geometries. The flow of the uniform or staggered magnetization from one part of the system to the other is described by a diffusion equation that can be derived analytically.

  17. Dissipative preparation of entanglement in quantum optical and solid state systems

    DEFF Research Database (Denmark)

    Reiter, Florentin

    Quantum mechanics is an immensely successful theory which is essential for the explanation of numerous phenomena in atomic physics, solid state physics, nuclear physics and elementary particle physics. Quantum theory also involves effects which have no analogy in the classical world. In particular...... superconducting qubits in a circuit QED setup. Combining resonator photon loss, a dissipative process already present in the setup, with an effective two-photon microwave drive, we engineer an effective decay mechanism which prepares a maximally entangled state of two qubits. We find that high fidelities......, quantum entanglement is a correlation predicted by quantum mechanics, but not by classical physics. As an observable property it is indispensable for our understanding of nature. In addition, entangled states are important in quantum computation, quantum communication and quantum measurement protocols...

  18. Quantum Markov Chain Mixing and Dissipative Engineering

    DEFF Research Database (Denmark)

    Kastoryano, Michael James

    2012-01-01

    This thesis is the fruit of investigations on the extension of ideas of Markov chain mixing to the quantum setting, and its application to problems of dissipative engineering. A Markov chain describes a statistical process where the probability of future events depends only on the state of the sy......This thesis is the fruit of investigations on the extension of ideas of Markov chain mixing to the quantum setting, and its application to problems of dissipative engineering. A Markov chain describes a statistical process where the probability of future events depends only on the state...... of the system at the present point in time, but not on the history of events. Very many important processes in nature are of this type, therefore a good understanding of their behaviour has turned out to be very fruitful for science. Markov chains always have a non-empty set of limiting distributions....... Finally, we consider three independent tasks of dissipative engineering: dissipatively preparing a maximally entangled state of two atoms trapped in an optical cavity, dissipative preparation of graph states, and dissipative quantum computing construction....

  19. EDITORIAL: Focus on Quantum Dissipation in Unconventional Environments FOCUS ON QUANTUM DISSIPATION IN UNCONVENTIONAL ENVIRONMENTS

    Science.gov (United States)

    Grifoni, Milena; Paladino, Elisabetta

    2008-11-01

    Quantum dissipation has been the object of study within the physics and chemistry communities for many years. Despite this, the field is in constant evolution, largely due to the fact that novel systems where the understanding of dissipation and dephasing processes is of crucial importance have become experimentally accessible in recent years. Among the ongoing research themes, we mention the defeat of decoherence in solid state-based quantum bits (qubits) (e.g. superconducting qubits or quantum dot based qubits), or dissipation due to non-equilibrium Fermi reservoirs, as is the case for quantum transport through meso- and nanoscale structures. A close inspection of dissipation in such systems reveals that one has to deal with 'unconventional' environments, where common assumptions of, for example, linearity of the bath and/or equilibrium reservoir have to be abandoned. Even for linear baths at equilibrium it might occur that the bath presents some internal structure, due, for example, to the presence of localized bath modes. A large part of this focus issue is devoted to topics related to the rapidly developing fields of quantum computation and information with solid state nanodevices. In these implementations, single and two-qubit gates as well as quantum information transmission takes place in the presence of broadband noise that is typically non-Markovian and nonlinear. On both the experimental and theory side, understanding and defeating such noise sources has become a crucial step towards the implementation of efficient nanodevices. On a more fundamental level, electron and spin transport through quantum dot nanostructures may suffer from 'unconventional' dissipation mechanisms such as the simultaneous presence of spin relaxation and fermionic dissipation, or may represent themselves out of equilibrium baths for nearby mesoscopic systems. Finally, although not expected from the outset, the present collection of articles has revealed that different

  20. Relaxation dynamics in quantum dissipative systems: The microscopic effect of intramolecular vibrational energy redistribution

    Energy Technology Data Exchange (ETDEWEB)

    Uranga-Piña, L. [Facultad de Física, Universidad de la Habana, San Lázaro y L, Vedado, 10400 Havana (Cuba); Institute for Chemistry and Biochemistry, Freie Universität Berlin, Takustr. 3, D-14195 Berlin (Germany); Tremblay, J. C., E-mail: jean.c.tremblay@gmail.com [Institute for Chemistry and Biochemistry, Freie Universität Berlin, Takustr. 3, D-14195 Berlin (Germany)

    2014-08-21

    We investigate the effect of inter-mode coupling on the vibrational relaxation dynamics of molecules in weak dissipative environments. The simulations are performed within the reduced density matrix formalism in the Markovian regime, assuming a Lindblad form for the system-bath interaction. The prototypical two-dimensional model system representing two CO molecules approaching a Cu(100) surface is adapted from an ab initio potential, while the diatom-diatom vibrational coupling strength is systematically varied. In the weak system-bath coupling limit and at low temperatures, only first order non-adiabatic uni-modal coupling terms contribute to surface-mediated vibrational relaxation. Since dissipative dynamics is non-unitary, the choice of representation will affect the evolution of the reduced density matrix. Two alternative representations for computing the relaxation rates and the associated operators are thus compared: the fully coupled spectral basis, and a factorizable ansatz. The former is well-established and serves as a benchmark for the solution of Liouville-von Neumann equation. In the latter, a contracted grid basis of potential-optimized discrete variable representation is tailored to incorporate most of the inter-mode coupling, while the Lindblad operators are represented as tensor products of one-dimensional operators, for consistency. This procedure results in a marked reduction of the grid size and in a much more advantageous scaling of the computational cost with respect to the increase of the dimensionality of the system. The factorizable method is found to provide an accurate description of the dissipative quantum dynamics of the model system, specifically of the time evolution of the state populations and of the probability density distribution of the molecular wave packet. The influence of intra-molecular vibrational energy redistribution appears to be properly taken into account by the new model on the whole range of coupling strengths. It

  1. Relaxation dynamics in quantum dissipative systems: the microscopic effect of intramolecular vibrational energy redistribution.

    Science.gov (United States)

    Uranga-Piña, L; Tremblay, J C

    2014-08-21

    We investigate the effect of inter-mode coupling on the vibrational relaxation dynamics of molecules in weak dissipative environments. The simulations are performed within the reduced density matrix formalism in the Markovian regime, assuming a Lindblad form for the system-bath interaction. The prototypical two-dimensional model system representing two CO molecules approaching a Cu(100) surface is adapted from an ab initio potential, while the diatom-diatom vibrational coupling strength is systematically varied. In the weak system-bath coupling limit and at low temperatures, only first order non-adiabatic uni-modal coupling terms contribute to surface-mediated vibrational relaxation. Since dissipative dynamics is non-unitary, the choice of representation will affect the evolution of the reduced density matrix. Two alternative representations for computing the relaxation rates and the associated operators are thus compared: the fully coupled spectral basis, and a factorizable ansatz. The former is well-established and serves as a benchmark for the solution of Liouville-von Neumann equation. In the latter, a contracted grid basis of potential-optimized discrete variable representation is tailored to incorporate most of the inter-mode coupling, while the Lindblad operators are represented as tensor products of one-dimensional operators, for consistency. This procedure results in a marked reduction of the grid size and in a much more advantageous scaling of the computational cost with respect to the increase of the dimensionality of the system. The factorizable method is found to provide an accurate description of the dissipative quantum dynamics of the model system, specifically of the time evolution of the state populations and of the probability density distribution of the molecular wave packet. The influence of intra-molecular vibrational energy redistribution appears to be properly taken into account by the new model on the whole range of coupling strengths. It

  2. Tailored jump operators for purely dissipative quantum magnetism

    Science.gov (United States)

    Weimer, Hendrik

    2017-01-01

    I propose an architecture for the realization of dissipative quantum many-body spin models. The dissipative processes are mediated by interactions with auxiliary particles and lead to a widely tunable class of correlated quantum jump operators. These findings enable the investigation of purely dissipative spin models, where coherent dynamics is entirely absent. I provide a detailed review of a recently introduced variational method to analyze such dissipative quantum many-body systems, and I discuss a specific example in terms of a purely dissipative Heisenberg model, for which I find an additional disordered phase that is not present in the corresponding ground state phase diagram.

  3. Tailored jump operators for purely dissipative quantum magnetism

    CERN Document Server

    Weimer, Hendrik

    2016-01-01

    I propose an archtitecture for the realization of dissipative quantum many-body spin models. The dissipative processes are mediated by interactions with auxiliary particles and lead to a widely tunable class of correlated quantum jump operators. These findings enable the investigation of purely dissipative spin models, where coherent dynamics is entirely absent. I provide a detailed review of a recently introduced variational method to analyze such dissipative quantum many-body systems, and I discuss a specific example in terms of a purely dissipative Heisenberg model, for which I find an additional disordered phase that is not present in the corresponding ground state phase diagram.

  4. Dispersive and dissipative effects in quantum field theory in curved space-time to model condensed matter systems

    CERN Document Server

    Busch, Xavier

    2014-01-01

    The two main predictions of quantum field theory in curved space-time, namely Hawking radiation and cosmological pair production, have not been directly tested and involve ultra high energy configurations. As a consequence, they should be considered with caution. Using the analogy with condensed matter systems, their analogue versions could be tested in the lab. Moreover, the high energy behavior of these systems is known and involves dispersion and dissipation, which regulate the theory at short distances. When considering experiments which aim to test the above predictions, there will also be a competition between the stimulated emission from thermal noise and the spontaneous emission out of vacuum. In order to measure these effects, one should thus compute the consequences of UV dispersion and dissipation, and identify observables able to establish that the spontaneous emission took place. In this thesis, we first analyze the effects of dispersion and dissipation on both Hawking radiation and pair particle...

  5. Dissipative quantum trajectories in complex space: Damped harmonic oscillator

    Science.gov (United States)

    Chou, Chia-Chun

    2016-10-01

    Dissipative quantum trajectories in complex space are investigated in the framework of the logarithmic nonlinear Schrödinger equation. The logarithmic nonlinear Schrödinger equation provides a phenomenological description for dissipative quantum systems. Substituting the wave function expressed in terms of the complex action into the complex-extended logarithmic nonlinear Schrödinger equation, we derive the complex quantum Hamilton-Jacobi equation including the dissipative potential. It is shown that dissipative quantum trajectories satisfy a quantum Newtonian equation of motion in complex space with a friction force. Exact dissipative complex quantum trajectories are analyzed for the wave and solitonlike solutions to the logarithmic nonlinear Schrödinger equation for the damped harmonic oscillator. These trajectories converge to the equilibrium position as time evolves. It is indicated that dissipative complex quantum trajectories for the wave and solitonlike solutions are identical to dissipative complex classical trajectories for the damped harmonic oscillator. This study develops a theoretical framework for dissipative quantum trajectories in complex space.

  6. Quantum metrology in open systems: dissipative Cramér-Rao bound.

    Science.gov (United States)

    Alipour, S; Mehboudi, M; Rezakhani, A T

    2014-03-28

    Estimation of parameters is a pivotal task throughout science and technology. The quantum Cramér-Rao bound provides a fundamental limit of precision allowed to be achieved under quantum theory. For closed quantum systems, it has been shown how the estimation precision depends on the underlying dynamics. Here, we propose a general formulation for metrology scenarios in open quantum systems, aiming to relate the precision more directly to properties of the underlying dynamics. This feature may be employed to enhance an estimation precision, e.g., by quantum control techniques. Specifically, we derive a Cramér-Rao bound for a fairly large class of open system dynamics, which is governed by a (time-dependent) dynamical semigroup map. We illustrate the utility of this scenario through three examples.

  7. Truncated correlation hierarchy schemes for driven-dissipative multimode quantum systems

    CERN Document Server

    Casteels, Wim; Boité, Alexandre Le; Storme, Florent; Ciuti, Cristiano

    2016-01-01

    We present a method to describe driven-dissipative multi-mode systems by considering a truncated hierarchy of equations for the correlation functions. We consider two hierarchy truncation schemes with a global cutoff on the correlation order, which is the sum of the exponents of the operators involved in the correlation functions: a 'hard' cutoff corresponding to an expansion around the vacuum, which applies to a regime where the number of excitations per site is small; a 'soft' cutoff which corresponds to an expansion around coherent states, which can be applied for large excitation numbers per site. This approach is applied to describe the bunching-antibunching transition in the driven-dissipative Bose-Hubbard model for photonic systems. The results have been successfully benchmarked by comparison with calculations based on the corner-space renormalization method in 1D and 2D systems. The regime of validity and strengths of the present truncation methods are critically discussed.

  8. I. Advances in NMR Signal Processing. II. Spin Dynamics in Quantum Dissipative Systems

    Energy Technology Data Exchange (ETDEWEB)

    Lin, Yung-Ya [Univ. of California, Berkeley, CA (United States)

    1998-11-01

    Part I. Advances in IVMR Signal Processing. Improvements of sensitivity and resolution are two major objects in the development of NMR/MRI. A signal enhancement method is first presented which recovers signal from noise by a judicious combination of a priordmowledge to define the desired feasible solutions and a set theoretic estimation for restoring signal properties that have been lost due to noise contamination. The effect of noise can be significantly mitigated through the process of iteratively modifying the noisy data set to the smallest degree necessary so that it possesses a collection of prescribed properties and also lies closest to the original data set. A novel detection-estimation scheme is then introduced to analyze noisy and/or strongly damped or truncated FIDs. Based on exponential modeling, the number of signals is detected based on information estimated using the matrix pencil method. theory and the spectral parameters are Part II. Spin Dynamics in body dipole-coupled systems Quantum Dissipative Systems. Spin dynamics in manyconstitutes one of the most fundamental problems in magnetic resonance and condensed-matter physics. Its many-spin nature precludes any rigorous treatment. ‘Therefore, the spin-boson model is adopted to describe in the rotating frame the influence of the dipolar local fields on a tagged spin. Based on the polaronic transform and a perturbation treatment, an analytical solution is derived, suggesting the existence of self-trapped states in the. strong coupling limit, i.e., when transverse local field >> longitudinal local field. Such nonlinear phenomena originate from the joint action of the lattice fluctuations and the reaction field. Under semiclassical approximation, it is found that the main effect of the reaction field is the renormalization of the Hamiltonian of interest. Its direct consequence is the two-step relaxation process: the spin is initially localized in a quasiequilibrium state, which is later detrapped by

  9. Quantum dissipative dynamics of a bistable system in the sub-Ohmic to super-Ohmic regime

    Science.gov (United States)

    Magazzù, Luca; Carollo, Angelo; Spagnolo, Bernardo; Valenti, Davide

    2016-05-01

    We investigate the quantum dynamics of a multilevel bistable system coupled to a bosonic heat bath beyond the perturbative regime. We consider different spectral densities of the bath, in the transition from sub-Ohmic to super-Ohmic dissipation, and different cutoff frequencies. The study is carried out by using the real-time path integral approach of the Feynman-Vernon influence functional. We find that, in the crossover dynamical regime characterized by damped intrawell oscillations and incoherent tunneling, the short time behavior and the time scales of the relaxation starting from a nonequilibrium initial condition depend nontrivially on the spectral properties of the heat bath.

  10. Sparse polynomial space approach to dissipative quantum systems: application to the sub-ohmic spin-boson model.

    Science.gov (United States)

    Alvermann, A; Fehske, H

    2009-04-17

    We propose a general numerical approach to open quantum systems with a coupling to bath degrees of freedom. The technique combines the methodology of polynomial expansions of spectral functions with the sparse grid concept from interpolation theory. Thereby we construct a Hilbert space of moderate dimension to represent the bath degrees of freedom, which allows us to perform highly accurate and efficient calculations of static, spectral, and dynamic quantities using standard exact diagonalization algorithms. The strength of the approach is demonstrated for the phase transition, critical behavior, and dissipative spin dynamics in the spin-boson model.

  11. Quantum Markov Chain Mixing and Dissipative Engineering

    DEFF Research Database (Denmark)

    Kastoryano, Michael James

    2012-01-01

    This thesis is the fruit of investigations on the extension of ideas of Markov chain mixing to the quantum setting, and its application to problems of dissipative engineering. A Markov chain describes a statistical process where the probability of future events depends only on the state...... of the system at the present point in time, but not on the history of events. Very many important processes in nature are of this type, therefore a good understanding of their behaviour has turned out to be very fruitful for science. Markov chains always have a non-empty set of limiting distributions...... (stationary states). The aim of Markov chain mixing is to obtain (upper and/or lower) bounds on the number of steps it takes for the Markov chain to reach a stationary state. The natural quantum extensions of these notions are density matrices and quantum channels. We set out to develop a general mathematical...

  12. Engineering Dissipation to Generate Entanglement Between Remote Superconducting Quantum Bits

    Science.gov (United States)

    Schwartz, Mollie Elisheva

    Superconducting quantum circuits provide a promising avenue for scalable quantum computation and simulation. Their chief advantage is that, unlike physical atoms or electrons, these ''artificial atoms'' can be designed with nearly-arbitrarily large coupling to one another and to their electromagnetic environment. This strong coupling allows for fast quantum bit (qubit) operations, and for efficient readout. However, strong coupling comes at a price: a qubit that is strongly coupled to its environment is also strongly susceptible to losses and dissipation, as coherent information leaks from the quantum system under study into inaccessible ''bath'' modes. Extensive work in the field is dedicated to engineering away these losses to the extent possible, and to using error correction to undo the effects of losses that are unavoidable. This dissertation explores an alternate approach to dissipation: we study avenues by which dissipation itself can be used to generate, rather than destroy, quantum resources. We do so specifically in the context of quantum entanglement, one of the most important and most counter-intuitive aspects of quantum mechanics. Entanglement generation and stabilization is critical to most non-trivial implementations of quantum computing and quantum simulation, as it is the property that distinguishes a multi-qubit quantum system from a string of classical bits. The ability to harness dissipation to generate, purify, and stabilize entanglement is therefore highly desirable. We begin with an overview of quantum dissipation and measurement, followed by an introduction to entanglement and to the superconducting quantum information architecture. We then discuss three sets of experiments that highlight and explore the powerful uses of dissipation in quantum systems. First, we use an entangling measurement to probabilistically generate entanglement between two qubits separated by more than one meter of ordinary cable. This represents the first achievement

  13. Dissipative time-dependent quantum transport theory.

    Science.gov (United States)

    Zhang, Yu; Yam, Chi Yung; Chen, GuanHua

    2013-04-28

    A dissipative time-dependent quantum transport theory is developed to treat the transient current through molecular or nanoscopic devices in presence of electron-phonon interaction. The dissipation via phonon is taken into account by introducing a self-energy for the electron-phonon coupling in addition to the self-energy caused by the electrodes. Based on this, a numerical method is proposed. For practical implementation, the lowest order expansion is employed for the weak electron-phonon coupling case and the wide-band limit approximation is adopted for device and electrodes coupling. The corresponding hierarchical equation of motion is derived, which leads to an efficient and accurate time-dependent treatment of inelastic effect on transport for the weak electron-phonon interaction. The resulting method is applied to a one-level model system and a gold wire described by tight-binding model to demonstrate its validity and the importance of electron-phonon interaction for the quantum transport. As it is based on the effective single-electron model, the method can be readily extended to time-dependent density functional theory.

  14. Optical realization of the dissipative quantum oscillator

    CERN Document Server

    Longhi, Stefano

    2016-01-01

    An optical realization of the damped quantum oscillator, based on transverse light dynamics in an optical resonator with slowly-moving mirrors, is theoretically suggested. The optical resonator setting provides a simple implementation of the time-dependent Caldirola-Kanai Hamiltonian of the dissipative quantum oscillator, and enables to visualize the effects of damped oscillations in the classical (ray optics) limit and wave packet collapse in the quantum (wave optics) regime.

  15. Dissipative effects in Multilevel Systems

    Energy Technology Data Exchange (ETDEWEB)

    Solomon, A I [Department of Physics and Astronomy, Open University, Milton Keynes MK7 6AA (United Kingdom); Schirmer, S G [Department of Applied Maths and Theoretical Physics, University of Cambridge, Cambridge, CB3 0WA (United Kingdom)

    2007-11-15

    Dissipation is sometimes regarded as an inevitable and regrettable presence in the real evolution of a quantum system. However, the effects may not always be malign, although often non-intuitive and may even be beneficial. In this note we we display some of these effects for N-level systems, where N = 2,3,4. We start with an elementary introduction to dissipative effects on the Bloch Sphere, and its interior, the Bloch Ball, for a two-level system. We describe explicitly the hamiltonian evolution as well as the purely dissipative dynamics, in the latter case giving the t {yields} {infinity} limits of the motion. This discussion enables us to provide an intuitive feeling for the measures of control-reachable states. For the three-level case we discuss the impossibility of isolating a two-level (qubit) subsystem; this is a Bohm-Aharonov type consequence of dissipation. We finally exemplify the four-level case by giving constraints on the decay of two-qubit entanglement.

  16. The second law as a selection principle: The microscopic theory of dissipative processes in quantum systems.

    Science.gov (United States)

    Prigogine, I; George, C

    1983-07-01

    The second law of thermodynamics, for quantum systems, is formulated, on the microscopic level. As for classical systems, such a formulation is only possible when specific conditions are satisfied (continuous spectrum, nonvanishing of the collision operator, etc.). The unitary dynamical group can then be mapped into two contractive semigroups, reaching equilibrium either for t --> +infinity or for t --> -infinity. The second law appears as a symmetry-breaking selection principle, limiting the observables and density functions to the class that tends to thermodynamic equilibrium in the future (for t --> +infinity). The physical content of the dynamical structure is now displayed in terms of the appropriate semigroup, which is realized through a nonunitary transformation. The superposition principle of quantum mechanics has to be reconsidered as irreversible processes transform pure states into mixtures and unitary transformations are limited by the requirement that entropy remains invariant. In the semigroup representation, interacting fields lead to units that behave incoherently at equilibrium. Inversely, nonequilibrium constraints introduce correlations between these units.

  17. The Second Law as a Selection Principle: The Microscopic Theory of Dissipative Processes in Quantum Systems

    Science.gov (United States)

    Prigogine, I.; George, Cl.

    1983-07-01

    The second law of thermodynamics, for quantum systems, is formulated, on the microscopic level. As for classical systems, such a formulation is only possible when specific conditions are satisfied (continuous spectrum, nonvanishing of the collision operator, etc.). The unitary dynamical group can then be mapped into two contractive semigroups, reaching equilibrium either for t → +∞ or for t → -∞. The second law appears as a symmetry-breaking selection principle, limiting the observables and density functions to the class that tends to thermodynamic equilibrium in the future (for t → +∞). The physical content of the dynamical structure is now displayed in terms of the appropriate semigroup, which is realized through a nonunitary transformation. The superposition principle of quantum mechanics has to be reconsidered as irreversible processes transform pure states into mixtures and unitary transformations are limited by the requirement that entropy remains invariant. In the semigroup representation, interacting fields lead to units that behave incoherently at equilibrium. Inversely, nonequilibrium constraints introduce correlations between these units.

  18. Energy Dissipation in Molecular Systems

    CERN Document Server

    Tramer, André; Lahmani, Fran oise

    2005-01-01

    Energy Dissipation in Molecular Systems analyzes experimental data on the redistribution and dissipation of energy injected into molecular systems by radiation or charged particles. These processes, competing with such practically important relaxation channels as chemical reaction or stimulated emission (laser action), are the primary focus in this monograph. Among other topics, the book treats vibrational redistribution and electronic relaxation in isolated molecules and the effects of inter-molecular interactions (collisions, complex formation, solvent effects) on the relaxation paths. Primary photo-chemical processes (such as isomerization, proton or hydrogen-atom transfer, electron transfer and ionization) are also treated as particular cases of vibrational or electronic relaxation. Only a basic knowledge of quantum mechanics and spectroscopy is assumed and calculations are kept to a strict minimum, making the book more accessible to students.

  19. Quantum dissipation in a neutrino system propagating in vacuum and in matter

    Science.gov (United States)

    Guzzo, Marcelo M.; de Holanda, Pedro C.; Oliveira, Roberto L. N.

    2016-07-01

    Considering the neutrino state like an open quantum system, we analyze its propagation in vacuum or in matter. After defining what can be called decoherence and relaxation effects, we show that in general the probabilities in vacuum and in constant matter can be written in a similar way, which is not an obvious result for such system. From this result, we analyze the situation where neutrino evolution satisfies the adiabatic limit and use this formalism to study solar neutrinos. We show that the decoherence effect may not be bounded by the solar neutrino data and review some results in the literature, in particular the current results where solar neutrinos were used to put bounds on decoherence effects through a model-dependent approach. We conclude explaining how and why these models are not general and we reinterpret these constraints.

  20. 耗散系统的量子力学%Quantum Mechanics in Dissipative Systems

    Institute of Scientific and Technical Information of China (English)

    时万忠

    2000-01-01

    The phenomenologic quantum equations——the CK′s equation and the Kostin′s nonlinear Schr dinger-Lagenvin equation correspording tothe classical linear dissipasive systems are discussed by methods of SQP. The physical content of such equations is displayed more clearly in the so-called Madelung-form i. e. the hydrodynamical picture of quantum theory. The lagrangian densities corresponding to these equations are investigated as well. Especially, the nonreality of the Kostin′s Hamiltonian or nonhermitianity of the Kostin′s Hamiltonian operator is discussed.%利用SQP方案重点讨论了经典上线性阻尼系统所对应的量子力学唯象学CK方程和Kostin非线性S-L方程,用Madelung-form展示了相应量子力学方程的含义.进一步研究了与CK和Kostin量子方程相应的拉氏密度,并讨论了非线性S-L方程所对应的Hamiltonian量的非实性的原因.

  1. An example of the decoherence approach to quantum dissipative chaos

    CERN Document Server

    Brun, T A

    1995-01-01

    Quantum chaos---the study of quantized nonintegrable Hamiltonian systems---is an extremely well-developed and sophisticated field. By contrast, very little work has been done in looking at quantum versions of systems which classically exhibit {\\it dissipative} chaos. Using the decoherence formalism of Gell-Mann and Hartle, I find a quantum mechanical analog of one such system, the forced damped Duffing oscillator. I demonstrate the classical limit of the system, and discuss its decoherent histories. I show that using decoherent histories, one can define not only the quantum map of an entire density operator, but can find an analog to the Poincar\\'e map of the individual trajectory. Finally, I argue the usefulness of this model as an example of quantum dissipative chaos, as well as of a practical application of the decoherence formalism to an interesting problem.

  2. The Quantum Jump Approach to Dissipative Dynamics in Quantum Optics

    CERN Document Server

    Plenio, M B

    1998-01-01

    Dissipation, the irreversible loss of energy and coherence, from a microsystem, is the result of coupling to a much larger macrosystem (or reservoir) which is so large that one has no chance of keeping track of all of its degrees of freedom. The microsystem evolution is then described by tracing over the reservoir states, resulting in an irreversible decay as excitation leaks out of the initially excited microsystems into the outer reservoir environment. Earlier treatments of this dissipation described an ensemble of microsystems using density matrices, either in Schroedinger picture with Master equations, or in Heisenberg picture with Langevin equations. The development of experimental techniques to study single quantum systems (for example single trapped ions, or cavity radiation field modes) has stimulated the construction of theoretical methods to describe individual realizations conditioned on a particular observation record of the decay channel, in the environment. These methods, variously described as ...

  3. Dissipative Quantum Metrology with Spin Cat States

    CERN Document Server

    Huang, Jiahao; Zhong, Honghua; Ke, Yongguan; Lee, Chaohong

    2014-01-01

    We present a robust high-precision phase estimation scheme via spin cat states in the presence of particle losses. The input Greenberger-Horne-Zeilinger (GHZ) state, which may achieve the Heisenberg-limited measurement in the absence of particle losses, becomes fragile against particle losses and its achieved precision becomes even worse than the standard quantum limit (SQL). However, the input spin cat states, a kind of non-Gaussian entangled states in superposition of two spin coherent states, are of excellent robustness against particle losses and the achieved precision may still beat the SQL. For realistic measurements based upon our scheme, comparing with the population measurement, the parity measurement is more suitable for yielding higher precisions. In phase measurement with realistic dissipative systems of bosonic particles, our scheme provides a robust and realizable way to achieve high-precision measurements beyond the SQL.

  4. Entanglement distillation by dissipation and continuous quantum repeaters.

    Science.gov (United States)

    Vollbrecht, Karl Gerd H; Muschik, Christine A; Cirac, J Ignacio

    2011-09-16

    Even though entanglement is very vulnerable to interactions with the environment, it can be created by purely dissipative processes. Yet, the attainable degree of entanglement is profoundly limited in the presence of noise sources. We show that distillation can also be realized dissipatively, such that a highly entangled steady state is obtained. The schemes put forward here display counterintuitive phenomena, such as improved performance if noise is added to the system. We also show how dissipative distillation can be employed in a continuous quantum repeater architecture, in which the resources scale polynomially with the distance.

  5. Spectral properties of dissipative chaotic quantum maps.

    Science.gov (United States)

    Braun, Daniel

    1999-09-01

    I examine spectral properties of a dissipative chaotic quantum map with the help of a recently discovered semiclassical trace formula. I show that in the presence of a small amount of dissipation the traces of any finite power of the propagator of the reduced density matrix, and traces of its classical counterpart, the Frobenius-Perron operator, are identical in the limit of variant Planck's over 2pi -->0. Numerically I find that even for finite variant Planck's over 2pi the agreement can be very good. This holds in particular if the classical phase space contains a strange attractor, as long as one stays clear of bifurcations. Traces of the quantum propagator for iterations of the map agree well with the corresponding traces of the Frobenius-Perron operator if the classical dynamics is dominated by a strong point attractor. (c) 1999 American Institute of Physics.

  6. Quantum metrology with spin cat states under dissipation.

    Science.gov (United States)

    Huang, Jiahao; Qin, Xizhou; Zhong, Honghua; Ke, Yongguan; Lee, Chaohong

    2015-12-09

    Quantum metrology aims to yield higher measurement precisions via quantum techniques such as entanglement. It is of great importance for both fundamental sciences and practical technologies, from testing equivalence principle to designing high-precision atomic clocks. However, due to environment effects, highly entangled states become fragile and the achieved precisions may even be worse than the standard quantum limit (SQL). Here we present a high-precision measurement scheme via spin cat states (a kind of non-Gaussian entangled states in superposition of two quasi-orthogonal spin coherent states) under dissipation. In comparison to maximally entangled states, spin cat states with modest entanglement are more robust against losses and their achievable precisions may still beat the SQL. Even if the detector is imperfect, the achieved precisions of the parity measurement are higher than the ones of the population measurement. Our scheme provides a realizable way to achieve high-precision measurements via dissipative quantum systems of Bose atoms.

  7. Quantum Simulation of Dissipative Processes without Reservoir Engineering.

    Science.gov (United States)

    Di Candia, R; Pedernales, J S; del Campo, A; Solano, E; Casanova, J

    2015-05-29

    We present a quantum algorithm to simulate general finite dimensional Lindblad master equations without the requirement of engineering the system-environment interactions. The proposed method is able to simulate both Markovian and non-Markovian quantum dynamics. It consists in the quantum computation of the dissipative corrections to the unitary evolution of the system of interest, via the reconstruction of the response functions associated with the Lindblad operators. Our approach is equally applicable to dynamics generated by effectively non-Hermitian Hamiltonians. We confirm the quality of our method providing specific error bounds that quantify its accuracy.

  8. Quantum entanglement and quantum phase transition under dissipation in the anisoropic Heisenberg xxz model with the Dzyaloshinskii-Moriya interaction

    Directory of Open Access Journals (Sweden)

    R Afzali

    2013-03-01

    Full Text Available   Because the key issue in quantum information and quantum computing is entanglement, the investigation of the effects of environment, as a source of quantum dissipation, and interaction between environment and system on entanglement and quantum phase transition is important. In this paper, we consider two-qubit system in the anisotropic Heisenberg XXZ model with the Dzyaloshinskii-moriya interaction, and accompanied quantum dissipation. Using Lindblad dynamics, the coupling effect and also temperature effect on concurrence, as a measure of entanglement of system, is obtained. The role of DM interaction parameters in the evolution of entanglement is investigated. Furthermore, using derivative of concurrence, the effects of dissipation and DM interaction parameter on quantum phase transition are obtained. It should be noted that spin-orbit interaction or DM parameter intensively influence the process of impressments of dissipation on entanglement measure and quantum phase transition. The current research is very important in the topics of nanometric systems.

  9. Decoherence and dissipation of a spin-zero bosons system using the Weyl representation of quantum mechanics

    Energy Technology Data Exchange (ETDEWEB)

    Reis, Mauricio [Universidade Federal de Sao Joao del Rey (UFSJ), MG (Brazil); Faria, J.G. Peixoto de [CEFET-MG (Brazil); Nemes, M.C. [Universidade Federal de Minas Gerais (UFMG), Belo Horizonte, MG (Brazil); Almeida, A.M. Ozorio de [Centro Brasileiro de Pesquisas Fisicas (CBPF), Rio de Janeiro, RJ (Brazil)

    2011-07-01

    Full text. One of the first experiments showing quantum mechanical behavior was the Plank's Black Body radiation spectra. After Planck, several experiments allowed the development of important technology using the quantum properties of identical particles systems. On the other hand, one of the many types of classical limit of quantum mechanics is supposed to be achieved in the large-N limit of its dynamics. To explain classical behaviour, many scenarios are possible, one of them is to take account of the unavoidable interaction of a system with its surroundings and consider the irreversible lost of quantum information to the environment, which is sometimes called The Decoherence Program. In this case, a question naturally arises: how is that interaction and why it allows the appearance of a classical world with few quantum features, like the peculiar statistical distribution for a system composed of N-identical bosons? In this work, we address that question by setting up an Investigation upon a system composed of N-identical bosons, using the Weyl representation. In the literature, the Weyl representation is a general term which identifies the traditional Wigner function and its Fourier Transform, known as the Chord function. Due to its relation with the Classic Phase Space, the Weyl representation becomes a very suitable tool to study some dynamics properties of quantum systems as well their classical limits, and some properties of a simple system, composed of two identical bosons is studied

  10. Determinism and Dissipation in Quantum Gravity

    NARCIS (Netherlands)

    Hooft, G. 't

    2001-01-01

    Without invalidating quantum mechanics as a principle underlying the dynamics of a fundamental theory, it is possible to ask for even more basic dynamical laws that may yield quantum mechanics as the machinery needed for its statistical analysis. In conventional systems such as the Standard Model

  11. Lossless and dissipative distributed systems

    NARCIS (Netherlands)

    Pillai, HK; Willems, JC

    2002-01-01

    This paper deals with linear shift-invariant distributed systems. By this we mean systems described by constant coefficient linear partial differential equations. e de ne dissipativity with respect to a quadratic differential form, i.e., a quadratic functional in the system variables and their

  12. Non-Markovian dynamics, decoherence and entanglement in dissipative quantum systems with applications to quantum information theory of continuous variable systems; Nicht-Markovsche Dynamik, Dekohaerenz und Verschraenkung in dissipativen Quantensystemen mit Anwendung in der Quanteninformationstheorie von Systemen kontinuierlicher Variablen

    Energy Technology Data Exchange (ETDEWEB)

    Hoerhammer, C.

    2007-11-26

    In this thesis, non-Markovian dynamics, decoherence and entanglement in dissipative quantum systems are studied. In particular, applications to quantum information theory of continuous variable systems are considered. The non-Markovian dynamics are described by the Hu-Paz-Zhang master equation of quantum Brownian motion. In this context the focus is on non-Markovian effects on decoherence and separability time scales of various single- mode and two-mode continuous variable states. It is verified that moderate non-Markovian influences slow down the decay of interference fringes and quantum correlations, while strong non-Markovian effects resulting from an out-of-resonance bath can even accelerate the loss of coherence, compared to predictions of Markovian approximations. Qualitatively different scenarios including exponential, Gaussian or algebraic decay of the decoherence function are analyzed. It is shown that partial recurrence of coherence can occur in case of non-Lindblad-type dynamics. The time evolution of quantum correlations of entangled two-mode continuous variable states is examined in single-reservoir and two-reservoir models, representing noisy correlated or uncorrelated non-Markovian quantum channels. For this purpose the model of quantum Brownian motion is extended. Various separability criteria for Gaussian and non-Gaussian continuous variable systems are applied. In both types of reservoir models moderate non-Markovian effects prolong the separability time scales. However, in these models the properties of the stationary state may differ. In the two-reservoir model the initial entanglement is completely lost and both modes are finally uncorrelated. In a common reservoir both modes interact indirectly via the coupling to the same bath variables. Therefore, new quantum correlations may emerge between the two modes. Below a critical bath temperature entanglement is preserved even in the steady state. A separability criterion is derived, which depends

  13. A semiclassical theory of dissipative Henon-Heiles system

    CERN Document Server

    Bag, B C; Bag, Bidhan Chandra; Ray, Deb Shankar

    1999-01-01

    A semiclassical theory of dissipative Henon-Heiles system is proposed. Based on $\\hbar$-scaling of an equation for evolution of Wigner quasiprobability distribution function in presence of dissipation and thermal diffusion, we derive a semiclassical equation for quantum fluctuations, governed by the dissipation and the curvature of the classical potential. We show how the initial quantum noise gets amplified by classical chaotic diffusion which is expressible in terms of correlation of stochastic fluctuations of the curvature of the potential due to classical chaos and ultimately settles down to equilibrium under the influence of dissipation. We also establish that there exists a critical limit to the expansion of phase space. The limit is set by chaotic diffusion and dissipation. Our semiclassical analysis is corroborated by numerical simulation of quantum operator master equation.

  14. Fluctuation-dissipation relation in a resonantly driven quantum medium.

    Science.gov (United States)

    Erukhimova, Maria; Tokman, Mikhail

    2015-06-15

    Noise associated with the spontaneous emission in a coherently driven medium is calculated. The significant field-induced modification of relation between the noise power and damping constant in a thermal reservoir is obtained. The nonlinear noise exchange between different atomic frequencies leads to violation of standard relations dictated by the fluctuation-dissipation theorem. The developed general method is applied to the EIT system, attractive for realization of different quantum-information processing devices. It is shown that there is a significant factor defining the thermal noise at operating frequency in the EIT system. It is the averaged number of thermal photons at low frequency of ground state splitting.

  15. Controllability of Quantum Systems

    CERN Document Server

    Schirmer, S G; Solomon, A I

    2003-01-01

    An overview and synthesis of results and criteria for open-loop controllability of Hamiltonian quantum systems obtained using Lie group and Lie algebra techniques is presented. Negative results for open-loop controllability of dissipative systems are discussed, and the superiority of closed-loop (feedback) control for quantum systems is established.

  16. Minimising the heat dissipation of quantum information erasure

    Science.gov (United States)

    Hamed Mohammady, M.; Mohseni, Masoud; Omar, Yasser

    2016-01-01

    Quantum state engineering and quantum computation rely on information erasure procedures that, up to some fidelity, prepare a quantum object in a pure state. Such processes occur within Landauer's framework if they rely on an interaction between the object and a thermal reservoir. Landauer's principle dictates that this must dissipate a minimum quantity of heat, proportional to the entropy reduction that is incurred by the object, to the thermal reservoir. However, this lower bound is only reachable for some specific physical situations, and it is not necessarily achievable for any given reservoir. The main task of our work can be stated as the minimisation of heat dissipation given probabilistic information erasure, i.e., minimising the amount of energy transferred to the thermal reservoir as heat if we require that the probability of preparing the object in a specific pure state ≤ft|{\\varphi }1\\right.> be no smaller than {p}{\\varphi 1}{max}-δ . Here {p}{\\varphi 1}{max} is the maximum probability of information erasure that is permissible by the physical context, and δ ≥slant 0 the error. To determine the achievable minimal heat dissipation of quantum information erasure within a given physical context, we explicitly optimise over all possible unitary operators that act on the composite system of object and reservoir. Specifically, we characterise the equivalence class of such optimal unitary operators, using tools from majorisation theory, when we are restricted to finite-dimensional Hilbert spaces. Furthermore, we discuss how pure state preparation processes could be achieved with a smaller heat cost than Landauer's limit, by operating outside of Landauer's framework.

  17. Effects on the eigenvalues of the quantum bouncer due to dissipation

    CERN Document Server

    López, G

    2003-01-01

    Effects on the spectra of the quantum bouncer due to dissipation are given when a linear or quadratic dissipation is taken into account. Classical constant of motions and Hamiltonians are deduced for these systems and their quantized eigenvalues are estimated through perturbation theory. we found some differences when we compare the eigenvalues of these two quantities.

  18. Dissipatively driven entanglement of two nuclear spin ensembles in a double quantum dot

    Energy Technology Data Exchange (ETDEWEB)

    Schuetz, Martin J.A.; Kessler, Eric M.; Cirac, Juan Ignacio; Giedke, Geza [Max-Planck-Institut fuer Quantenoptik, Hans-Kopfermann-Str. 1, D-85748 Garching (Germany)

    2013-07-01

    Typically, quantum information schemes have been discussed in the context of isolated many-body systems subject to unitary dynamics. Here, dissipation has been identified as a mechanism that corrupts the useful quantum properties of the system under study. Recently, however, with the advent of novel ideas such as dissipative engineering, a paradigm shift could be observed in quantum physics. More and more approaches actively utilize dissipation as a driving force behind the emergence of coherent quantum phenomena. In this spirit, we propose a transport scheme for an electrically defined double quantum dot in which the two nuclear ensembles in the host environment are actively pumped into an entangled target state. Based on a self-consistent Holstein-Primakoff approximation, we derive an effective quantum master equation for the nuclear spins which features an unique entangled steady state; accordingly, long lasting entanglement is created deterministically. Prospects for the experimental realization of this proposal are briefly discussed.

  19. Thermal Reservoir coupled to External Field and Quantum Dissipation

    CERN Document Server

    Patriarca, M; Patriarca, Fabrizio Illuminati & Marco

    1992-01-01

    In the framework of the Caldeira-Leggett model of dissipative quantum mechanics, we investigate the effects of the interaction of the thermal reservoir with an external field. In particular, we discuss how the interaction modifies the conservative dynamics of the central particle, and the mechanism of dissipation. We briefly comment on possible observable consequencies.

  20. A variational approach for dissipative quantum transport in a wide parameter space

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Yu, E-mail: zhy@yangtze.hku.hk; Kwok, YanHo; Chen, GuanHua, E-mail: ghc@everest.hku.hk [Department of Chemistry, The University of Hong Kong, Pokfluam Road (Hong Kong); Yam, ChiYung [Department of Chemistry, The University of Hong Kong, Pokfluam Road (Hong Kong); Beijing Computational Science Research Center, Beijing 100094 (China)

    2015-09-14

    Recent development of theoretical method for dissipative quantum transport has achieved notable progresses in the weak or strong electron-phonon coupling regime. However, a generalized theory for dissipative quantum transport in a wide parameter space had not been established. In this work, a variational polaron theory for dissipative quantum transport in a wide range of electron-phonon coupling is developed. The optimal polaron transformation is determined by the optimization of the Feynman-Bogoliubov upper bound of free energy. The free energy minimization ends up with an optimal mean-field Hamiltonian and a minimal interaction Hamiltonian. Hence, second-order perturbation can be applied to the transformed system, resulting in an accurate and efficient method for the treatment of dissipative quantum transport with different electron-phonon coupling strength. Numerical benchmark calculation on a single site model coupled to one phonon mode is presented.

  1. A variational approach for dissipative quantum transport in a wide parameter space.

    Science.gov (United States)

    Zhang, Yu; Yam, ChiYung; Chen, GuanHua

    2015-09-14

    Recent development of theoretical method for dissipative quantum transport has achieved notable progresses in the weak or strong electron-phonon coupling regime. However, a generalized theory for dissipative quantum transport in a wide parameter space had not been established. In this work, a variational polaron theory for dissipative quantum transport in a wide range of electron-phonon coupling is developed. The optimal polaron transformation is determined by the optimization of the Feynman-Bogoliubov upper bound of free energy. The free energy minimization ends up with an optimal mean-field Hamiltonian and a minimal interaction Hamiltonian. Hence, second-order perturbation can be applied to the transformed system, resulting in an accurate and efficient method for the treatment of dissipative quantum transport with different electron-phonon coupling strength. Numerical benchmark calculation on a single site model coupled to one phonon mode is presented.

  2. Fluctuations of Quantum Radiation Pressure in Dissipative Fluid

    CERN Document Server

    Wu, C H; Wu, Chun-Hsien; Lee, Da-Shin

    2003-01-01

    Using the generalized Langevin equations involving the stress tensor approach, quantum fluctuations of electromagnetic radiation pressure in the presence of a dissipative environment have been studied. We consider a perfectly reflecting mirror which is exposed to the electromagnetic radiation pressure in a fluid at finite temperature. The dynamics of velocity fluctuations of the mirror is studied analytically in both small time and large time limits. In the small time limit, the minimum uncertainty of the mirror's position measurement from both quantum and thermal noises effects including the photon counting error in the laser interferometer is obtained based on the fluctuation-dissipation theorem as compared with the ''standard quantum limit''. In addition, the result of the large time behavior of fluctuations of the mirror's velocity in a dissipative environment can be applied to the laser interferometer of the ground-based gravitational wave detector. The role of the dissipative effects in this case is pla...

  3. On the dissipativity of uncontrollable systems

    NARCIS (Netherlands)

    Camlibel, Mehmet; Willems, Jan C.; Belur, Madhu N.

    2003-01-01

    This paper deals with dissipativity of uncontrollable linear time-invariant systems with quadratic supply rates and storage functions. A definition of dissipativity appropriate for this class of systems is given. We present a necessary and sufficient condition for dissipativeness in the single input

  4. Dissipation in a Quantum Wire: Fact and Fantasy

    Science.gov (United States)

    Das, Mukunda P.; Green, Frederick

    2008-10-01

    Where, and how, does energy dissipation of electrical energy take place in a ballistic wire? Fully two decades after the advent of the transmissive phenomenology of electrical conductance, this deceptively simple query remains unanswered. We revisit the quantum kinetic basis of dissipation and show its power to give a definitive answer to our query. Dissipation leaves a clear, quantitative trace in the non-equilibrium current noise of a quantum point contact; this signature has already been observed in the laboratory. We then highlight the current state of accepted understandings in the light of well-known yet seemingly contradictory measurements. The physics of mesoscopic transport rests not in coherent carrier transmission through a perfect and dissipationless metallic channel, but explicitly in their dissipative inelastic scattering at the wire's interfaces and adjacent macroscopic leads.

  5. Classical and quantum dissipation in non homogeneous environments

    CERN Document Server

    Illuminati, F; Sodano, P

    1994-01-01

    We generalize the oscillator model of a particle interacting with a thermal reservoir by introducing arbitrary nonlinear couplings in the particle coordinates.The equilibrium positions of the heat bath oscillators are promoted to space-time functions, which are shown to represent a modulation of the internal noise by the external forces. The model thus provides a description of classical and quantum dissipation in non homogeneous environments. In the classical case we derive a generalized Langevin equation with nonlinear multiplicative noise and a position-dependent fluctuation- dissipation theorem associated to non homogeneous dissipative forces. When time-modulation of the noise is present, a new force term is predicted besides the dissipative and random ones. The model is quantized to obtain the non homogenous influence functional and master equation for the reduced density matrix of the Brownian particle. The quantum evolution equations reproduce the correct Langevin dynamics in the semiclassical limit. T...

  6. Dissipative time-dependent quantum transport theory: Quantum interference and phonon induced decoherence dynamics

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Yu, E-mail: zhy@yangtze.hku.hk; Chen, GuanHua, E-mail: ghc@everest.hku.hk [Department of Chemistry, The University of Hong Kong, Pokfulam Road, Hong Kong (China); Yam, ChiYung [Department of Chemistry, The University of Hong Kong, Pokfulam Road, Hong Kong (China); Beijing Computational Science Research Center, Beijing 100084 (China)

    2015-04-28

    A time-dependent inelastic electron transport theory for strong electron-phonon interaction is established via the equations of motion method combined with the small polaron transformation. In this work, the dissipation via electron-phonon coupling is taken into account in the strong coupling regime, which validates the small polaron transformation. The corresponding equations of motion are developed, which are used to study the quantum interference effect and phonon-induced decoherence dynamics in molecular junctions. Numerical studies show clearly quantum interference effect of the transport electrons through two quasi-degenerate states with different couplings to the leads. We also found that the quantum interference can be suppressed by the electron-phonon interaction where the phase coherence is destroyed by phonon scattering. This indicates the importance of electron-phonon interaction in systems with prominent quantum interference effect.

  7. Dissipative time-dependent quantum transport theory: Quantum interference and phonon induced decoherence dynamics.

    Science.gov (United States)

    Zhang, Yu; Yam, ChiYung; Chen, GuanHua

    2015-04-28

    A time-dependent inelastic electron transport theory for strong electron-phonon interaction is established via the equations of motion method combined with the small polaron transformation. In this work, the dissipation via electron-phonon coupling is taken into account in the strong coupling regime, which validates the small polaron transformation. The corresponding equations of motion are developed, which are used to study the quantum interference effect and phonon-induced decoherence dynamics in molecular junctions. Numerical studies show clearly quantum interference effect of the transport electrons through two quasi-degenerate states with different couplings to the leads. We also found that the quantum interference can be suppressed by the electron-phonon interaction where the phase coherence is destroyed by phonon scattering. This indicates the importance of electron-phonon interaction in systems with prominent quantum interference effect.

  8. Internal dissipation and heat leaks in quantum thermodynamic cycles

    Science.gov (United States)

    Correa, Luis A.; Palao, José P.; Alonso, Daniel

    2015-09-01

    The direction of the steady-state heat currents across a generic quantum system connected to multiple baths may be engineered to realize virtually any thermodynamic cycle. In spite of their versatility, such continuous energy-conversion systems are generally unable to operate at maximum efficiency due to non-negligible sources of irreversible entropy production. In this paper we introduce a minimal model of irreversible absorption chiller. We identify and characterize the different mechanisms responsible for its irreversibility, namely heat leaks and internal dissipation, and gauge their relative impact in the overall cooling performance. We also propose reservoir engineering techniques to minimize these detrimental effects. Finally, by looking into a known three-qubit embodiment of the absorption cooling cycle, we illustrate how our simple model may help to pinpoint the different sources of irreversibility naturally arising in more complex practical heat devices.

  9. Dynamical Lamb effect versus dissipation in superconducting quantum circuits

    Science.gov (United States)

    Zhukov, A. A.; Shapiro, D. S.; Pogosov, W. V.; Lozovik, Yu. E.

    2016-06-01

    Superconducting circuits provide a new platform for study of nonstationary cavity QED phenomena. An example of such a phenomenon is the dynamical Lamb effect, which is the parametric excitation of an atom due to nonadiabatic modulation of its Lamb shift. This effect was initially introduced for a natural atom in a varying cavity, while we suggest its realization in a superconducting qubit-cavity system with dynamically tunable coupling. In the present paper, we study the interplay between the dynamical Lamb effect and the energy dissipation, which is unavoidable in realistic systems. We find that despite naive expectations, this interplay can lead to unexpected dynamical regimes. One of the most striking results is that photon generation from vacuum can be strongly enhanced due to qubit relaxation, which opens another channel for such a process. We also show that dissipation in the cavity can increase the qubit excited-state population. Our results can be used for experimental observation and investigation of the dynamical Lamb effect and accompanying quantum effects.

  10. The quantum Kirchhoff equation and quantum current and energy spectrum of a homogeneous mesoscopic dissipation transmission line

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    On the basis of quantization of charge, the loop equations of quantum circuits are investigated by using the Heisenberg motion equation for a mesoscopic dissipation transmission line. On the supposition that the system has a symmetry under translation in charge space, the quantum current and the quantum energy spectrum in the mesoscopic transmission line are given by solving their eigenvalue equations. Results show that the quantum current and the quantum energy spectrum are not only related to the parameters of the transmission line, but also dependent on the quantized character of the charge obviously.

  11. Quantum dissipation and decoherence of collective excitations in metallic nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Weick, G.

    2006-09-22

    The treatment of the surface plasmon as a quantum particle provides a model system for the study of decoherence and quantum dissipation in confined nanoscopic systems, where the role of the electronic correlations is preponderant. Throughout this work we treat the metallic nanoparticle in the jellium approximation where the ionic structure is replaced by a continuous and homogeneous positive charge. The external laser field puts the center of mass into a coherent superposition of its ground and first excited state and thus creates a surface plasmon. The coupling between the center of mass and the relative coordinates causes decoherence and dissipation of this collective excitation. We have developed a theoretical formalism well adapted to the study of this dissipation, which is the reduced-density-matrix formalism. There are mainly two parameters which govern the surface plasmon dynamics: the decay rate of the plasmon, and the resonance frequency. For sizes smaller than 1 nm, presents oscillations as a function of the size. By means of a semiclassical formalism using Gutzwiller's trace formula for the density of states, we have shown that those oscillations are due to the correlations of the density of states of the particles and holes in the nanoparticle. If one considers a noble-metal nanoparticle in an inert matrix, we have shown that a naive application of the Kubo formula for the surface plasmon linewidth fails to reproduce the TDLDA numerical results, which are however consistent with experimental results. We have modified the Kubo theory in order to solve this discrepancy. We have shown, by extending our semiclassical theory to the nonlinear case, that the double plasmon is indeed well defined. We have calculated the lifetime of the double plasmon associated to this second-order effect. In addition to the width, we have also addressed the value of the resonance frequency. The classical electromagnetic Mie theory gives for the resonance frequency of the

  12. The effects of dissipation on topological mechanical systems

    Science.gov (United States)

    Xiong, Ye; Wang, Tianxiang; Tong, Peiqing

    2016-09-01

    We theoretically study the effects of isotropic dissipation in a topological mechanical system which is an analogue of Chern insulator in mechanical vibrational lattice. The global gauge invariance is still conserved in this system albeit it is destroyed by the dissipation in the quantum counterpart. The chiral edge states in this system are therefore robust against strong dissipation. The dissipation also causes a dispersion of damping for the eigenstates. It will modify the equation of motion of a wave packet by an extra effective force. After taking into account the Berry curvature in the wave vector space, the trace of a free wave packet in the real space should be curved, feinting to break the Newton’s first law.

  13. Pure Gaussian state generation via dissipation: a quantum stochastic differential equation approach.

    Science.gov (United States)

    Yamamoto, Naoki

    2012-11-28

    Recently, the complete characterization of a general Gaussian dissipative system having a unique pure steady state was obtained. This result provides a clear guideline for engineering an environment such that the dissipative system has a desired pure steady state such as a cluster state. In this paper, we describe the system in terms of a quantum stochastic differential equation (QSDE) so that the environment channels can be explicitly dealt with. Then, a physical meaning of that characterization, which cannot be seen without the QSDE representation, is clarified; more specifically, the nullifier dynamics of any Gaussian system generating a unique pure steady state is passive. In addition, again based on the QSDE framework, we provide a general and practical method to implement a desired dissipative Gaussian system, which has a structure of quantum state transfer.

  14. Robust dissipativity for uncertain impulsive dynamical systems

    Directory of Open Access Journals (Sweden)

    Liu Bin

    2003-01-01

    Full Text Available We discuss the robust dissipativity with respect to the quadratic supply rate for uncertain impulsive dynamical systems. By employing the Hamilton-Jacobi inequality approach, some sufficient conditions of robust dissipativity for this kind of system are established. Finally, we specialize the obtained results to the case of uncertain linear impulsive dynamical systems.

  15. Generating higher-order quantum dissipation from lower-order parametric processes

    Science.gov (United States)

    Mundhada, S. O.; Grimm, A.; Touzard, S.; Vool, U.; Shankar, S.; Devoret, M. H.; Mirrahimi, M.

    2017-06-01

    The stabilisation of quantum manifolds is at the heart of error-protected quantum information storage and manipulation. Nonlinear driven-dissipative processes achieve such stabilisation in a hardware efficient manner. Josephson circuits with parametric pump drives implement these nonlinear interactions. In this article, we propose a scheme to engineer a four-photon drive and dissipation on a harmonic oscillator by cascading experimentally demonstrated two-photon processes. This would stabilise a four-dimensional degenerate manifold in a superconducting resonator. We analyse the performance of the scheme using numerical simulations of a realisable system with experimentally achievable parameters.

  16. Quantum and classical dissipation of charged particles

    Energy Technology Data Exchange (ETDEWEB)

    Ibarra-Sierra, V.G. [Departamento de Física, Universidad Autónoma Metropolitana at Iztapalapa, Av. San Rafael Atlixco 186, Col. Vicentina, 09340 México D.F. (Mexico); Anzaldo-Meneses, A.; Cardoso, J.L.; Hernández-Saldaña, H. [Área de Física Teórica y Materia Condensada, Universidad Autónoma Metropolitana at Azcapotzalco, Av. San Pablo 180, Col. Reynosa-Tamaulipas, Azcapotzalco, 02200 México D.F. (Mexico); Kunold, A., E-mail: akb@correo.azc.uam.mx [Área de Física Teórica y Materia Condensada, Universidad Autónoma Metropolitana at Azcapotzalco, Av. San Pablo 180, Col. Reynosa-Tamaulipas, Azcapotzalco, 02200 México D.F. (Mexico); Roa-Neri, J.A.E. [Área de Física Teórica y Materia Condensada, Universidad Autónoma Metropolitana at Azcapotzalco, Av. San Pablo 180, Col. Reynosa-Tamaulipas, Azcapotzalco, 02200 México D.F. (Mexico)

    2013-08-15

    A Hamiltonian approach is presented to study the two dimensional motion of damped electric charges in time dependent electromagnetic fields. The classical and the corresponding quantum mechanical problems are solved for particular cases using canonical transformations applied to Hamiltonians for a particle with variable mass. Green’s function is constructed and, from it, the motion of a Gaussian wave packet is studied in detail. -- Highlights: •Hamiltonian of a damped charged particle in time dependent electromagnetic fields. •Exact Green’s function of a charged particle in time dependent electromagnetic fields. •Time evolution of a Gaussian wave packet of a damped charged particle. •Classical and quantum dynamics of a damped electric charge.

  17. Non-Markovian dissipative quantum mechanics with stochastic trajectories

    Energy Technology Data Exchange (ETDEWEB)

    Koch, Werner

    2010-09-09

    All fields of physics - be it nuclear, atomic and molecular, solid state, or optical - offer examples of systems which are strongly influenced by the environment of the actual system under investigation. The scope of what is called ''the environment'' may vary, i.e., how far from the system of interest an interaction between the two does persist. Typically, however, it is much larger than the open system itself. Hence, a fully quantum mechanical treatment of the combined system without approximations and without limitations of the type of system is currently out of reach. With the single assumption of the environment to consist of an internally thermalized set of infinitely many harmonic oscillators, the seminal work of Stockburger and Grabert [Chem. Phys., 268:249-256, 2001] introduced an open system description that captures the environmental influence by means of a stochastic driving of the reduced system. The resulting stochastic Liouville-von Neumann equation describes the full non-Markovian dynamics without explicit memory but instead accounts for it implicitly through the correlations of the complex-valued noise forces. The present thesis provides a first application of the Stockburger-Grabert stochastic Liouville-von Neumann equation to the computation of the dynamics of anharmonic, continuous open systems. In particular, it is demonstrated that trajectory based propagators allow for the construction of a numerically stable propagation scheme. With this approach it becomes possible to achieve the tremendous increase of the noise sample count necessary to stochastically converge the results when investigating such systems with continuous variables. After a test against available analytic results for the dissipative harmonic oscillator, the approach is subsequently applied to the analysis of two different realistic, physical systems. As a first example, the dynamics of a dissipative molecular oscillator is investigated. Long time

  18. The dissipative quantum model of brain how do memory localize in correlated neuronal domains

    CERN Document Server

    Alfinito, E

    2000-01-01

    The mechanism of memory localization in extended domains is described in the framework of the parametric dissipative quantum model of brain. The size of the domains and the capability in memorizing depend on the number of links the system is able to establish with the external world.

  19. Deformed quantum harmonic oscillator with diffusion and dissipation

    CERN Document Server

    Isar, A

    2002-01-01

    A master equation for the deformed quantum harmonic oscillator interacting with a dissipative environment, in particular with a thermal bath, is derived in the microscopic model by using perturbation theory. The coefficients of the master equation and of equations of motion for observables depend on the deformation function. The steady state solution of the equation for the density matrix in the number representation is obtained and the equilibrium energy of the deformed harmonic oscillator is calculated in the approximation of small deformation.

  20. Deformed quantum harmonic oscillator with diffusion and dissipation

    Science.gov (United States)

    Isar, A.; Scheid, W.

    2002-07-01

    A master equation for the deformed quantum harmonic oscillator interacting with a dissipative environment, in particular with a thermal bath, is derived in the microscopic model by using perturbation theory. The coefficients of the master equation and of equations of motion for observables depend on the deformation function. The steady-state solution of the equation for the density matrix in the number representation is obtained and the equilibrium energy of the deformed harmonic oscillator is calculated in the approximation of small deformation.

  1. Dissipative systems: uncontrollability, observability and RLC realizability

    CERN Document Server

    Karikalan, Selvaraj; Abdulrazak, Rihab

    2011-01-01

    The theory of dissipativity has been primarily developed for controllable systems/behaviors. For various reasons, in the context of uncontrollable systems/behaviors, a more appropriate definition of dissipativity is in terms of the dissipation inequality, namely the {\\em existence} of a storage function. A storage function is a function such that along every system trajectory, the rate of increase of the storage function is at most the power supplied. While the power supplied is always expressed in terms of only the external variables, whether or not the storage function should be allowed to depend on unobservable/hidden variables also has various consequences on the notion of dissipativity: this paper thoroughly investigates the key aspects of both cases, and also proposes another intuitive definition of dissipativity. We first assume that the storage function can be expressed in terms of the external variables and their derivatives only and prove our first main result that, assuming the uncontrollable poles...

  2. Dissipation in small systems: Landau-Zener approach.

    Science.gov (United States)

    Barra, Felipe; Esposito, Massimiliano

    2016-06-01

    We establish a stochastic thermodynamics for a Fermionic level driven by a time-dependent force and interacting with initially thermalized levels playing the role of a reservoir. The driving induces consecutive avoided crossings between system and reservoir levels described within Landau-Zener theory. We derive the resulting system dynamics and thermodynamics and identify energy, work, heat, entropy, and dissipation. Our theory perfectly reproduces the numerically exact quantum work statistics obtained using a two point measurements approach of the total energy and provides an explicit expression for the dissipation in terms of diabatic transitions.

  3. Autoresonance in a Dissipative System

    CERN Document Server

    Glebov, Sergei; Tarkhanov, Nikolai

    2009-01-01

    We study the autoresonant solution of Duffing's equation in the presence of dissipation. This solution is proved to be an attracting set. We evaluate the maximal amplitude of the autoresonant solution and the time of transition from autoresonant growth of the amplitude to the mode of fast oscillations. Analytical results are illustrated by numerical simulations.

  4. On Dissipation in Stochastic Systems

    DEFF Research Database (Denmark)

    Thygesen, Uffe Høgsbro

    1999-01-01

    We define the property of dissipativity for controlled Ito diffusions. We investigate elementary properties, and we demonstrate that the framework is useful for control problems in which both probabilistic and worst-case representations of dynamic uncertainty are present. As an example we discuss...

  5. Dissipative Optomechanical Preparation of Macroscopic Quantum Superposition States

    Science.gov (United States)

    Abdi, M.; Degenfeld-Schonburg, P.; Sameti, M.; Navarrete-Benlloch, C.; Hartmann, M. J.

    2016-06-01

    The transition from quantum to classical physics remains an intensely debated question even though it has been investigated for more than a century. Further clarifications could be obtained by preparing macroscopic objects in spatial quantum superpositions and proposals for generating such states for nanomechanical devices either in a transient or a probabilistic fashion have been put forward. Here, we introduce a method to deterministically obtain spatial superpositions of arbitrary lifetime via dissipative state preparation. In our approach, we engineer a double-well potential for the motion of the mechanical element and drive it towards the ground state, which shows the desired spatial superposition, via optomechanical sideband cooling. We propose a specific implementation based on a superconducting circuit coupled to the mechanical motion of a lithium-decorated monolayer graphene sheet, introduce a method to verify the mechanical state by coupling it to a superconducting qubit, and discuss its prospects for testing collapse models for the quantum to classical transition.

  6. One-dimensional relativistic dissipative system with constant force and its quantization

    CERN Document Server

    López, G; Hernández, H; L\\'opez, Gustavo; L\\'opez, Xaman-Ek; Hern\\'andez, Hector

    2005-01-01

    For a relativistic particle under a constant force and a linear velocity dissipation force, a constant of motion is found. Problems are shown for getting the Hamiltoninan of this system. Thus, the quantization of this system is carried out through the constant of motion and using the quantization of the velocity variable. The dissipative relativistic quantum bouncer is outlined within this quantization approach.

  7. One-Dimensional Relativistic Dissipative System with Constant Force and its Quantization

    Science.gov (United States)

    López, G.; López, X. E.; Hernández, H.

    2006-04-01

    For a relativistic particle under a constant force and a linear velocity dissipation force, a constant of motion is found. Problems are shown for getting the Hamiltonian of this system. Thus, the quantization of this system is carried out through the constant of motion and using the quantization on the velocity variable. The dissipative relativistic quantum bouncer is outlined within this quantization approach.

  8. Designing Biomimetic, Dissipative Material Systems

    Energy Technology Data Exchange (ETDEWEB)

    Balazs, Anna C. [Univ. of Pittsburgh, PA (United States). Chemical Engineering Dept.; Whitesides, George M. [Harvard Univ., Cambridge, MA (United States). Dept. of Chemistry and Chemical Biology; Brinker, C. Jeffrey [Univ. of New Mexico, Albuquerque, NM (United States). Dept. of Chemical and Nuclear Engineering. Dept. of Chemistry. Dept. of Molecular Genetics and Microbiology. Center for Micro-Engineered Materials; Aranson, Igor S. [UChicago, LLC., Argonne, IL (United States); Chaikin, Paul [New York Univ. (NYU), NY (United States). Dept. of Physics; Dogic, Zvonimir [Brandeis Univ., Waltham, MA (United States). Dept. of Physics; Glotzer, Sharon [Univ. of Michigan, Ann Arbor, MI (United States). Dept. of Chemical Engineering. Dept. of Materials Science and Engineering. Dept. of Macromolecular Science and Engineering Physics; Hammer, Daniel [Univ. of Pennsylvania, Philadelphia, PA (United States). School of Engineering and Applied Science; Irvine, Darrell [Massachusetts Inst. of Technology (MIT), Cambridge, MA (United States). Dept. of Materials Science and Engineering and Biological Engineering; Little, Steven R. [Univ. of Pittsburgh, PA (United States). Chemical Engineering Dept.; Olvera de la Cruz, Monica [Northwestern Univ., Evanston, IL (United States). Dept. of Materials Science and Engineering; Parikh, Atul N. [Univ. of California, Davis, CA (United States). Dept. of Biomedical Engineering. Dept. of Chemical Engineering and Materials Science; Stupp, Samuel [Northwestern Univ., Evanston, IL (United States). Dept. of Materials Science and Engineering. Dept. of Chemistry. Dept. of Medicine. Dept. of Biomedical Engineering; Szostak, Jack [Harvard Univ., Cambridge, MA (United States). Dept. of Chemistry and Chemical Biology

    2016-01-21

    Throughout human history, new materials have been the foundation of transformative technologies: from bronze, paper, and ceramics to steel, silicon, and polymers, each material has enabled far-reaching advances. Today, another new class of materials is emerging—one with both the potential to provide radically new functions and to challenge our notion of what constitutes a “material”. These materials would harvest, transduce, or dissipate energy to perform autonomous, dynamic functions that mimic the behaviors of living organisms. Herein, we discuss the challenges and benefits of creating “dissipative” materials that can potentially blur the boundaries between living and non-living matter.

  9. Dynamics of fracture in dissipative systems

    Energy Technology Data Exchange (ETDEWEB)

    Rautiainen, T.T.; Kaski, K. [Helsinki Univ. of Technology, Otaniemi (Finland). Lab. of Computational Engineering; Alava, M.J. [Helsinki Univ. of Technology, Otaniemi (Finland). Lab. of Physics

    1997-12-31

    Dynamics of fracture in two-dimensional systems is studied with a dissipative network model by including the local relaxation of the force field via Maxwellian viscoelasticity. In addition to disorder the fundamentals of crack formation and propagation depend on the strength of dissipation compared to the loading rate. We investigate the dynamics of a single crack and the role of stress reduction at the crack tip when dissipation is increased. As a consequence, the crack starts to propagate slowly and it reaches terminal velocity later. If the relaxation of local forces is strong enough compared with crack velocity, crack arrest takes place. For a disordered system, the presence of strong dissipation in local dynamics is reflected as ductility and as an increase in the damage, accumulated during the fracture process. (orig.) 25 refs.

  10. Entanglement replication in driven dissipative many-body systems.

    Science.gov (United States)

    Zippilli, S; Paternostro, M; Adesso, G; Illuminati, F

    2013-01-25

    We study the dissipative dynamics of two independent arrays of many-body systems, locally driven by a common entangled field. We show that in the steady state the entanglement of the driving field is reproduced in an arbitrarily large series of inter-array entangled pairs over all distances. Local nonclassical driving thus realizes a scale-free entanglement replication and long-distance entanglement distribution mechanism that has immediate bearing on the implementation of quantum communication networks.

  11. Dynamics of quasi-stable dissipative systems

    CERN Document Server

    Chueshov, Igor

    2015-01-01

    This book is  devoted to background material and recently developed mathematical methods in the study of infinite-dimensional dissipative systems. The theory of such systems is motivated by the long-term goal to establish rigorous mathematical models for turbulent and chaotic phenomena. The aim here is to offer general methods and abstract results pertaining to fundamental dynamical systems properties related to dissipative long-time behavior. The book systematically presents, develops and uses the quasi-stability method while substantially extending it by including for consideration new classes of models and PDE systems arising in Continuum Mechanics. The book can be used as a textbook in dissipative dynamics at the graduate level.   Igor Chueshov is a Professor of Mathematics at Karazin Kharkov National University in Kharkov, Ukraine.

  12. Noether’s theorem for dissipative quantum dynamical semi-groups

    Energy Technology Data Exchange (ETDEWEB)

    Gough, John E., E-mail: jug@aber.ac.uk [Aberystwyth University, Aberystwyth SY23 3BZ, Wales (United Kingdom); Ratiu, Tudor S., E-mail: tudor.ratiu@epfl.ch [Section de Mathématiques and Bernoulli Center, École Polytechnique Fédérale de Lausanne, Lausanne CH 1015 (Switzerland); Smolyanov, Oleg G., E-mail: smolyanov@yandex.ru [Mechanics and Mathematics Faculty, Moscow State University, Moscow 119991 (Russian Federation)

    2015-02-15

    Noether’s theorem on constants of the motion of dynamical systems has recently been extended to classical dissipative systems (Markovian semi-groups) by Baez and Fong [J. Math. Phys. 54, 013301 (2013)]. We show how to extend these results to the fully quantum setting of quantum Markov dynamics. For finite-dimensional Hilbert spaces, we construct a mapping from observables to completely positive maps that leads to the natural analogue of their criterion of commutativity with the infinitesimal generator of the Markov dynamics. Using standard results on the relaxation of states to equilibrium under quantum dynamical semi-groups, we are able to characterise the constants of the motion under quantum Markov evolutions in the infinite-dimensional setting under the usual assumption of existence of a stationary strictly positive density matrix. In particular, the Noether constants are identified with the fixed point of the Heisenberg picture semi-group.

  13. Energy dissipation dataset for reversible logic gates in quantum dot-cellular automata.

    Science.gov (United States)

    Bahar, Ali Newaz; Rahman, Mohammad Maksudur; Nahid, Nur Mohammad; Hassan, Md Kamrul

    2017-02-01

    This paper presents an energy dissipation dataset of different reversible logic gates in quantum-dot cellular automata. The proposed circuits have been designed and verified using QCADesigner simulator. Besides, the energy dissipation has been calculated under three different tunneling energy level at temperature T=2 K. For estimating the energy dissipation of proposed gates; QCAPro tool has been employed.

  14. Foundations of Quantum Mechanics: Derivation of a dissipative Schrödinger equation from first principles

    Energy Technology Data Exchange (ETDEWEB)

    Gonçalves, L.A.; Olavo, L.S.F., E-mail: olavolsf@gmail.com

    2017-05-15

    Dissipation in Quantum Mechanics took some time to become a robust field of investigation after the birth of the field. The main issue hindering developments in the field is that the Quantization process was always tightly connected to the Hamiltonian formulation of Classical Mechanics. In this paper we present a quantization process that does not depend upon the Hamiltonian formulation of Classical Mechanics (although still departs from Classical Mechanics) and thus overcome the problem of finding, from first principles, a completely general Schrödinger equation encompassing dissipation. This generalized process of quantization is shown to be nothing but an extension of a more restricted version that is shown to produce the Schrödinger equation for Hamiltonian systems from first principles (even for Hamiltonian velocity dependent potential). - Highlights: • A Quantization process independent of the Hamiltonian formulation of quantum Mechanics is proposed. • This quantization method is applied to dissipative or absorptive systems. • A Dissipative Schrödinger equation is derived from first principles.

  15. Dissipative systems synthesis : A linear algebraic approach

    NARCIS (Netherlands)

    Belur, Madhu N.; Pillai, Harish K.; Trentelman, H.L.

    2007-01-01

    In this paper we consider the problem of synthesis of dissipative systems for the case that first and higher order derivatives of the concerned variables also appear in the weighting function. The problem is formulated and solved using the behavioral approach to systems and control. We relate the pr

  16. Dissipative systems synthesis : A linear algebraic approach

    NARCIS (Netherlands)

    Belur, Madhu N.; Pillai, Harish K.; Trentelman, H.L.

    2007-01-01

    In this paper we consider the problem of synthesis of dissipative systems for the case that first and higher order derivatives of the concerned variables also appear in the weighting function. The problem is formulated and solved using the behavioral approach to systems and control. We relate the pr

  17. Dissipative Systems Synthesis : a Linear Algebraic Approach

    NARCIS (Netherlands)

    Belur, Madhu N.; Pillai, Harish K.; Trentelman, H.L.

    2005-01-01

    In this paper we consider the problem of synthesis of dissipative systems for the case that first and higher order derivatives of the concerned variables also appear in the weighting function. The problem is formulated and solved using the behavioral approach to systems and control. It turns out tha

  18. About some Entropy Aspects of Dissipative Systems

    Directory of Open Access Journals (Sweden)

    Emil Dinga

    2006-10-01

    Full Text Available This paper is aspiring to get a logical explanation on the entropy velocity (i.e. on the entropy acceleration in a Universe “endowed” with a dissipative system. To this end, some concepts of dissipative structures emergence are analyzed, in a new paradigm of the logically vivid systems. In connection with the increasing global entropy, some crucial concepts as: the time arrow, the complexity degree, the specific time (that is, own time, or assigned to process time are treated and correlated. The main objective of the paper is to find out a logical explanation for accelerating of the entropy by the entropic heterogeneity accompanying the dissipative structures arising. A few answers are proposed while many other questions are stimulated in the matter.

  19. About some Entropy Aspects of Dissipative Systems

    Directory of Open Access Journals (Sweden)

    Emil Dinga

    2006-12-01

    Full Text Available This paper is aspiring to get a logical explanation on the entropy velocity (i.e. on the entropy acceleration in a Universe “endowed” with a dissipative system. To this end, some concepts of dissipative structures emergence are analyzed, in a new paradigm of the logically vivid systems. In connection with the increasing global entropy, some crucial concepts as: the time arrow, the complexity degree, the specific time (that is, own time, or assigned to process time are treated and correlated. The main objective of the paper is to find out a logical explanation for accelerating of the entropy by the entropic heterogeneity accompanying the dissipative structures arising. A few answers are proposed while many other questions are stimulated in the matter.

  20. Control of quantum thermodynamic behavior of a charged magneto-oscillator with momentum dissipation.

    Science.gov (United States)

    Rajesh, Asam; Bandyopadhyay, Malay

    2014-06-01

    In this work we expose the role of environment, confinement, and external magnetic field B in determining the low-temperature thermodynamic behavior in the context of cyclotron motion of a charged oscillator with anomalous dissipative coupling involving momentum instead of the much studied coordinate coupling. Explicit expressions for different quantum thermodynamic functions (QTFs) are obtained at low temperatures for different quantum heat baths characterized by the spectral density function μ(ω). The power-law fall of different QTFs is in conformity with the third law of thermodynamics; however, the sensitivity of decay, i.e., the power of the power-law decay, explicitly depends on μ(ω). We also discuss separately the influence of confinement and magnetic field on the low-temperature behavior of different QTFs. In this process we demonstrate how to control the low-temperature behavior of anomalous dissipative quantum systems by varying the confining length a, B, and the temperature T. Momentum dissipation reduces the effective mass of the system and we also discuss its effect on different QTFs at low temperatures.

  1. Dissipative Landau-Zener problem and thermally assisted Quantum Annealing

    Science.gov (United States)

    Arceci, Luca; Barbarino, Simone; Fazio, Rosario; Santoro, Giuseppe E.

    2017-08-01

    We revisit here the issue of thermally assisted Quantum Annealing by a detailed study of the dissipative Landau-Zener problem in the presence of a Caldeira-Leggett bath of harmonic oscillators, using both a weak-coupling quantum master equation and a quasiadiabatic path-integral approach. Building on the known zero-temperature exact results [Wubs et al., Phys. Rev. Lett. 97, 200404 (2006), 10.1103/PhysRevLett.97.200404], we show that a finite temperature bath can have a beneficial effect on the ground-state probability only if it couples also to a spin direction that is transverse with respect to the driving field, while no improvement is obtained for the more commonly studied purely longitudinal coupling. In particular, we also highlight that, for a transverse coupling, raising the bath temperature further improves the ground-state probability in the fast-driving regime. We discuss the relevance of these findings for the current quantum-annealing flux qubit chips.

  2. Complex Fluids in Energy Dissipating Systems

    Directory of Open Access Journals (Sweden)

    Francisco J. Galindo-Rosales

    2016-07-01

    Full Text Available The development of engineered systems for energy dissipation (or absorption during impacts or vibrations is an increasing need in our society, mainly for human protection applications, but also for ensuring the right performance of different sort of devices, facilities or installations. In the last decade, new energy dissipating composites based on the use of certain complex fluids have flourished, due to their non-linear relationship between stress and strain rate depending on the flow/field configuration. This manuscript intends to review the different approaches reported in the literature, analyses the fundamental physics behind them and assess their pros and cons from the perspective of their practical applications.

  3. Periodic solutions of dissipative systems revisited

    Directory of Open Access Journals (Sweden)

    Górniewicz Lech

    2006-01-01

    Full Text Available We reprove in an extremely simple way the classical theorem that time periodic dissipative systems imply the existence of harmonic periodic solutions, in the case of uniqueness. We will also show that, in the lack of uniqueness, the existence of harmonics is implied by uniform dissipativity. The localization of starting points and multiplicity of periodic solutions will be established, under suitable additional assumptions, as well. The arguments are based on the application of various asymptotic fixed point theorems of the Lefschetz and Nielsen type.

  4. Periodic solutions of dissipative systems revisited

    Directory of Open Access Journals (Sweden)

    Lech Górniewicz

    2006-05-01

    Full Text Available We reprove in an extremely simple way the classical theorem that time periodic dissipative systems imply the existence of harmonic periodic solutions, in the case of uniqueness. We will also show that, in the lack of uniqueness, the existence of harmonics is implied by uniform dissipativity. The localization of starting points and multiplicity of periodic solutions will be established, under suitable additional assumptions, as well. The arguments are based on the application of various asymptotic fixed point theorems of the Lefschetz and Nielsen type.

  5. Quantum dissipative effects in graphene-like mirrors

    CERN Document Server

    Fosco, C D; Mazzitelli, F D; Remaggi, M L

    2013-01-01

    We study quantum dissipative effects due to the accelerated motion of a single, imperfect, zero-width mirror. It is assumed that the microscopic degrees of freedom on the mirror are confined to it, like in plasma or graphene sheets. Therefore, the mirror is described by a vacuum polarization tensor $\\Pi_{\\alpha\\beta}$ concentrated on a time-dependent surface. Under certain assumptions about the microscopic model for the mirror, we obtain a rather general expression for the Euclidean effective action, a functional of the time-dependent mirror's position, in terms of two invariants that characterize the tensor $\\Pi_{\\alpha\\beta}$. The final result can be written in terms of the TE and TM reflection coefficients of the mirror, with qualitatively different contributions coming from them. We apply that general expression to derive the imaginary part of the `in-out' effective action, which measures dissipative effects induced by the mirror's motion, in different models, in particular for an accelerated graphene she...

  6. On multi-dissipative dynamic systems

    DEFF Research Database (Denmark)

    Thygesen, Uffe Høgsbro

    1999-01-01

    We consider deterministic dynamic systems with state space representations which are dissipative in the sense of Willems (1972) with respect to several supply rates. This property is of interest in robustness analysis and in multi-objective control. We give conditions under which the convex cone...

  7. Quantum fluctuations in mesoscopic systems

    Science.gov (United States)

    Benatti, F.; Carollo, F.; Floreanini, R.; Narnhofer, H.

    2017-10-01

    Recent experimental results point to the existence of coherent quantum phenomena in systems made of a large number of particles, despite the fact that for many-body systems the presence of decoherence is hardly negligible and emerging classicality is expected. This behaviour hinges on collective observables, named quantum fluctuations, that retain a quantum character even in the thermodynamic limit: they provide useful tools for studying properties of many-body systems at the mesoscopic level, in-between the quantum microscopic scale and the classical macroscopic one. We herein present the general theory of quantum fluctuations in mesoscopic systems, and study their dynamics in a quantum open system setting, taking into account the unavoidable effects of dissipation and noise induced by the external environment. As in the case of microscopic systems, decoherence is not always the only dominating effect at the mesoscopic scale: certain types of environment can provide means for entangling collective fluctuations through a purely noisy mechanism.

  8. Quantum Dynamics in Noisy Backgrounds: from Sampling to Dissipation and Fluctuations

    Science.gov (United States)

    Oliveira, O.; Paula, W. de; Frederico, T.; Hussein, M. S.

    2016-08-01

    We investigate the dynamics of a quantum system coupled linearly to Gaussian white noise using functional methods. By performing the integration over the noisy field in the evolution operator, we get an equivalent non-Hermitian Hamiltonian, which evolves the quantum state with a dissipative dynamics. We also show that if the integration over the noisy field is done for the time evolution of the density matrix, a gain contribution from the fluctuations can be accessed in addition to the loss one from the non-hermitian Hamiltonian dynamics. We illustrate our study by computing analytically the effective non-Hermitian Hamiltonian, which we found to be the complex frequency harmonic oscillator, with a known evolution operator. It leads to space and time localisation, a common feature of noisy quantum systems in general applications.

  9. Quantum Dynamics in Noisy Backgrounds: from sampling to dissipation and fluctuations

    CERN Document Server

    Oliveira, O; Frederico, T; Hussein, M S

    2015-01-01

    We investigate the dynamics of a quantum system coupled linearly to Gaussian white noise using functional methods. By performing the integration over the noisy field in the evolution operator, we get an equivalent non-Hermitian Hamiltonian, which evolves the quantum state with a dissipative dynamics. We also show that if the integration over the noisy field is done for the time evolution of the density matrix, a gain contribution from the fluctuations, can be accessed in addition to the loss one from the non-hermitian Hamiltonian dynamics. We illustrate our study by computing analytically the effective non-Hermitian Hamiltonian, which we found to be the complex frequency harmonic oscillator, with a known evolution operator. It leads to space and time localisation, a common feature of noisy quantum systems in general applications.

  10. Thermoelectric study of dissipative quantum-dot heat engines

    Science.gov (United States)

    De, Bitan; Muralidharan, Bhaskaran

    2016-10-01

    This paper examines the thermoelectric response of a dissipative quantum-dot heat engine based on the Anderson-Holstein model in two relevant operating limits, (i) when the dot phonon modes are out of equilibrium, and (ii) when the dot phonon modes are strongly coupled to a heat bath. In the first case, a detailed analysis of the physics related to the interplay between the quantum-dot level quantization, the on-site Coulomb interaction, and the electron-phonon coupling on the thermoelectric performance reveals that an n -type heat engine performs better than a p -type heat engine. In the second case, with the aid of the dot temperature estimated by incorporating a thermometer bath, it is shown that the dot temperature deviates from the bath temperature as electron-phonon interaction in the dot becomes stronger. Consequently, it is demonstrated that the dot temperature controls the direction of phonon heat currents, thereby influencing the thermoelectric performance. Finally, the conditions on the maximum efficiency with varying phonon couplings between the dot and all the other macroscopic bodies are analyzed in order to reveal the nature of the optimum junction.

  11. Quasinormal modes of black holes and dissipative open systems

    CERN Document Server

    Kim, S P

    2006-01-01

    After explaining the physical origin of quasinormal modes of perturbations in the background geometry of a black hole, I critically review the recent proposal for the quantization of black hole area based on the real part of quasinormal modes. As instantons due to the barrier of black hole potentials lie at the root of the discrete set of complex quasinormal modes frequencies, it is likely that physics of quasinormal modes can be learned from quantum theory. I propose a connection of the system of quasinormal modes of black holes with a dissipative open system, in particular, the Feshbach-Tikochinsky oscillator. This argument is supported in part by the fact that these two systems have the same group structure SU(1,1) and the same group representation of Hamiltonians, and thereby their quantum states exhibit the same behavior.

  12. Dissipative Landau-Zener quantum dynamics with transversal and longitudinal noise

    Science.gov (United States)

    Javanbakht, S.; Nalbach, P.; Thorwart, M.

    2015-05-01

    We determine the Landau-Zener transition probability in a dissipative environment including both longitudinal as well as transversal quantum-mechanical noise originating from a single noise source. For this, we use the numerically exact quasiadiabatic path integral, as well as the approximative nonequilibrium Bloch equations. We find that transversal quantum noise in general influences the Landau-Zener probability much more strongly than longitudinal quantum noise does at a given temperature and system-bath coupling strength. In other words, transversal noise contributions become important even when the coupling strength of transversal noise is smaller than that of longitudinal noise. We furthermore reveal that transversal noise renormalizes the tunnel coupling independent of temperature. Finally, we show that the effect of mixed longitudinal and transversal noise originating from a single bath cannot be obtained from an incoherent sum of purely longitudinal and purely transversal noise.

  13. Fluctuation-dissipation theorem and quantum tunneling with dissipation at finite temperature

    CERN Document Server

    Fujikawa, K; Fujikawa, Kazuo; Terashima, Hiroaki

    1998-01-01

    A reformulation of the fluctuation-dissipation theorem of Callen and Welton is presented in such a manner that the basic idea of Feynman-Vernon and Caldeira -Leggett of using an infinite number of oscillators to simulate the dissipative medium is realized manifestly without actually introducing oscillators. If one assumes the existence of a well defined dissipative coefficient $R(\\omega)$ which little depends on the temperature in the energy region we are interested in, the spontanous and induced emissions as well as induced absorption of these effective oscillators with correct Bose distribution automatically appears. Combined with a dispersion relation, we reproduce the tunneling formula in the presence of dissipation at finite temperature without referring to an explicit model Lagrangian. The fluctuation-dissipation theorem of Callen-Welton is also generalized to the fermionic dissipation (or fluctuation) which allows a transparent physical interpretation in terms of second quantized fermionic oscillators....

  14. Storage functions for dissipative linear systems are quadratic state functions

    NARCIS (Netherlands)

    Trentelman, Harry L.; Willems, Jan C.

    1997-01-01

    This paper deals with dissipative dynamical systems. Dissipative dynamical systems can be used as models for physical phenomena in which energy exchange with their environment plays a role. In a dissipative dynamical system, the book-keeping of energy is done via the supply rate and a storage functi

  15. Classification of Stably Dissipative 3D Lotka-Volterra Systems and Their Necessary and Sufficient Condition for Being Stably Dissipative

    Institute of Scientific and Technical Information of China (English)

    LIU Hai-ying

    2008-01-01

    By introducing the concepts of stably dissipative matrix and graph, some criteria conditions for stably dissipative matrix were given. On this basis, the method of graph theory was used to classify all stably dissipative 3D Lotka-Volterra systems and five classes of maximal stably dissipative graphs were obtained for these systems. Finally, the necessary and sufficient condition of being stably dissipative for every class was studied, under which the matrix associated with the graph is stably dissipative.

  16. Permanent dissipative structures in water: the matrix of life? Experimental evidences and their quantum origin.

    Science.gov (United States)

    Elia, V; Germano, R; Napoli, E

    2015-01-01

    This paper presents a short review of the evidence - both experimental and theoretical - of the formation of dissipative structures in liquid water induced by three kinds of physical perturbations having a low energy content: extremely diluted solution (EDS), iteratively filtered water (IFW), and iteratively nafionated water (INW). Particular attention is devoted to the very recent discovery that such structures are tremendously persistent even in the solid phase: large ponderal quantities of supramolecular aggregates of water (with each nucleus hundreds of nanometers in size) have been observed - at ambient pressure and temperature - using easily-reproducible experimental methods. The nature of these dissipative structures is analyzed and explained in terms of the thermodynamics of far-from-equilibrium systems and irreversible processes, showing their spontaneous quantum origin. Are these kinds of structures the matrix itself of life?.

  17. Energy dissipation dataset for reversible logic gates in quantum dot-cellular automata

    Directory of Open Access Journals (Sweden)

    Ali Newaz Bahar

    2017-02-01

    Full Text Available This paper presents an energy dissipation dataset of different reversible logic gates in quantum-dot cellular automata. The proposed circuits have been designed and verified using QCADesigner simulator. Besides, the energy dissipation has been calculated under three different tunneling energy level at temperature T=2 K. For estimating the energy dissipation of proposed gates; QCAPro tool has been employed.

  18. Dynamical entanglement formation and dissipation effects in two double quantum dots

    Energy Technology Data Exchange (ETDEWEB)

    Contreras-Pulido, L D [Centro de Investigacion CientIfica y de Educacion Superior de Ensenada, Apartado Postal 2732, Ensenada, BC 22860 (Mexico); Rojas, F [Departamento de Fisica Teorica, Centro de Ciencias de la Materia Condensada, Universidad Nacional Autonoma de Mexico, Ensenada, Baja California 22800 (Mexico)

    2006-11-01

    We study the static and dynamic formation of entanglement in charge states of a two double quantum dot array with two mobile electrons under the effect of an external driving field. We include dissipation via contact with a phonon bath. By using the density matrix formalism and an open quantum system approach, we describe the dynamical behaviour of the charge distribution (polarization), concurrence (measure of the degree of entanglement) and Bell state probabilities (two qubit states with maximum entanglement) of such a system, including the role of dot asymmetry and temperature effects. Our results show that it is possible to obtain entangled states as well as a most probable Bell state, which can be controlled by the driving field. We also evaluate how the entanglement formation based on charge states deteriorates as the temperature or asymmetry increases.

  19. Evolution of Quantum State for Mesoscopic Circuits with Dissipation

    Institute of Scientific and Technical Information of China (English)

    WAN Hua-Ming; LUO Hai-Mei; WANG Yi-Fan

    2005-01-01

    Based on the maximum entropy principle, we present a density matrix of mesoscopic RLC circuit to make it possible to analyze the connection of the initial condition with temperature. Our results show that the quantum state evolution is closely related to the initial condition, and that the system evolves to generalized coherent state if it is in ground state initially, and evolves to squeezed state if it is in excited state initially.

  20. Dissipatively Stabilized Quantum Sensor Based on Indirect Nuclear-Nuclear Interactions

    Science.gov (United States)

    Chen, Q.; Schwarz, I.; Plenio, M. B.

    2017-07-01

    We propose to use a dissipatively stabilized nitrogen vacancy (NV) center as a mediator of interaction between two nuclear spins that are protected from decoherence and relaxation of the NV due to the periodical resets of the NV center. Under ambient conditions this scheme achieves highly selective high-fidelity quantum gates between nuclear spins in a quantum register even at large NV-nuclear distances. Importantly, this method allows for the use of nuclear spins as a sensor rather than a memory, while the NV spin acts as an ancillary system for the initialization and readout of the sensor. The immunity to the decoherence and relaxation of the NV center leads to a tunable sharp frequency filter while allowing at the same time the continuous collection of the signal to achieve simultaneously high spectral selectivity and high signal-to-noise ratio.

  1. Dissipation through localized loss in bosonic systems with long-range interactions

    Science.gov (United States)

    Vidanović, Ivana; Cocks, Daniel; Hofstetter, Walter

    2014-05-01

    In recent years, controlled dissipation has proven to be a useful tool for the probing of a quantum system in an ultracold setup. In this paper we consider the dynamics of bosons induced by a dissipative local defect. We address superfluid and supersolid phases close to half filling that are ground states of an extended Bose-Hubbard Hamiltonian. To this end, we solve the master equation using the Gutzwiller approximation and find that in the superfluid phase repulsive nearest-neighbor interactions can lead to enhanced dissipation processes. On the other hand, our mean-field approach indicates that the effective loss rates are significantly suppressed deep in the supersolid phase where repulsive nearest-neighbor interactions play a dominant role. Our numerical results are explained by analytical arguments and, in particular, in the limit of strong dissipation we recover the quantum Zeno effect.

  2. Uncanny Schr\\"odinger cats in driven-dissipative systems

    CERN Document Server

    Minganti, F; Lolli, J; Casteels, W; Ciuti, C

    2016-01-01

    Since their conception, Schr\\"odinger's cats have captured the collective imagination. Photonic cat states are superpositions of two coherent states with opposite phases and with a significant number of photons. Recently, these states have been observed in the transient dynamics of a driven-dissipative resonator subject to engineered two-photon processes. Here we present an exact analytical solution of the steady-state density matrix for this class of systems by including one-photon losses, that are considered detrimental for the achievement of cat states. We demonstrate that the unique steady state is a statistical mixture of two cat-like states with opposite parity, in spite of significant one-photon losses. The transient dynamics to the steady-state depends dramatically on the initial state and can pass through a metastable regime lasting orders of magnitudes longer than the photon lifetime. By considering individual quantum trajectories in photon counting configuration, we find that the system intermitten...

  3. Phase diagram and correlation functions of the two-dimensional dissipative quantum XY model

    Science.gov (United States)

    Hou, Changtao; Varma, Chandra M.

    2016-11-01

    The two-dimensional quantum XY model, with a Caldeira-Leggett form of dissipation, is applicable to the quantum-critical properties of diverse experimental systems, ranging from superconductor to insulator transitions, ferromagnetic and antiferromagnetic transitions in metals, to the loop-current order transition in cuprates. We solve the reexpression of this model in terms of orthogonal topological excitations, vortices, and a variety of instantons, by renormalization group methods. The calculations explain the extraordinary properties of the model discovered in Monte Carlo calculations: the product form of the quantum-critical fluctuations in space and time, a spatial correlation length proportional to the logarithm of the temporal correlation length near the transition from a disordered to a fully ordered state, and the occurrence of a phase with spatial order without temporal order. They are intimately related to the flow of the metric of time in relation to the metric of space, i.e., of the dynamical critical exponent z . These properties appear to be essential in understanding the strange metallic phase found in a variety of quantum-critical transitions as well as the accompanying high-temperature superconductivity.

  4. Electrostatic Nonlinear Structures in Dissipative Electron-Positron-Ion Quantum Plasmas

    Institute of Scientific and Technical Information of China (English)

    S. A. Khan; Q. Haque

    2008-01-01

    @@ Low frequency (in comparison to ion plasma frequency) ion-acoustic shocks and solitons in superdense electron-positron-ion quantum plasmas are studied.The quantum hydrodynamic model is used incorporating quantum Bohm forces and Fermi-Dirac statistical corrections to derive the deformed Korteweg de Vries-Burgers (dKdVB) equation in weakly nonlinear limit.The travelling wave solution of dKdVB equation is presented and results are discussed in different limits.It is found that shock height increases with increase of quantum pressure, positron concentration and dissipation.Further, it is seen that the width of soliton decreases with increase of quantum pressure.

  5. Material Systems for Blast-Energy Dissipation

    Energy Technology Data Exchange (ETDEWEB)

    James Schondel; Henry S. Chu

    2010-10-01

    Lightweight panels have been designed to protect buildings and vehicles from blast pressures by activating energy dissipation mechanisms under the influence of blast loading. Panels were fabricated which featured a variety of granular materials and hydraulic dissipative deformation mechanisms and the test articles were subjected to full-scale blast loading. The force time-histories transmitted by each technology were measured by a novel method that utilized inexpensive custom-designed force sensors. The array of tests revealed that granular materials can effectively dissipate blast energy if they are employed in a way that they easily crush and rearrange. Similarly, hydraulic dissipation can effectively dissipate energy if the panel features a high fraction of porosity and the panel encasement features low compressive stiffness.

  6. Exact stabilization of entangled states in finite time by dissipative quantum circuits

    Science.gov (United States)

    Johnson, Peter D.; Ticozzi, Francesco; Viola, Lorenza

    2017-07-01

    Open quantum systems evolving according to discrete-time dynamics are capable, unlike continuous-time counterparts, to converge to a stable equilibrium in finite time with zero error. We consider dissipative quantum circuits consisting of sequences of quantum channels subject to specified quasi-locality constraints, and determine conditions under which stabilization of a pure multipartite entangled state of interest may be exactly achieved in finite time. Special emphasis is devoted to characterizing scenarios where finite-time stabilization may be achieved robustly with respect to the order of the applied quantum maps, as suitable for unsupervised control architectures. We show that if a decomposition of the physical Hilbert space into virtual subsystems is found, which is compatible with the locality constraint and relative to which the target state factorizes, then robust stabilization may be achieved by independently cooling each component. We further show that if the same condition holds for a scalable class of pure states, a continuous-time quasi-local Markov semigroup ensuring rapid mixing can be obtained. Somewhat surprisingly, we find that the commutativity of the canonical parent Hamiltonian one may associate to the target state does not directly relate to its finite-time stabilizability properties, although in all cases where we can guarantee robust stabilization, a (possibly noncanonical) commuting parent Hamiltonian may be found. Aside from graph states, quantum states amenable to finite-time robust stabilization include a class of universal resource states displaying two-dimensional symmetry-protected topological order, along with tensor network states obtained by generalizing a construction due to Bravyi and Vyalyi [Quantum Inf. Comput. 5, 187 (2005)]. Extensions to representative classes of mixed graph-product and thermal states are also discussed.

  7. Dissipative dynamics of superconducting hybrid qubit systems

    Energy Technology Data Exchange (ETDEWEB)

    Montes, Enrique; Calero, Jesus M; Reina, John H, E-mail: enriquem@univalle.edu.c, E-mail: j.reina-estupinan@physics.ox.ac.u [Departamento de Fisica, Universidad del Valle, A.A. 25360, Cali (Colombia)

    2009-05-01

    We perform a theoretical study of composed superconducting qubit systems for the case of a coupled qubit configuration based on a hybrid qubit circuit made of both charge and phase qubits, which are coupled via a sigma{sub x} x sigma{sub z} interaction. We compute the system's eigen-energies in terms of the qubit transition frequencies and the strength of the inter-qubit coupling, and describe the sensitivity of the energy crossing/anti-crossing features to such coupling. We compute the hybrid system's dissipative dynamics for the cases of i) collective and ii) independent decoherence, whereby the system interacts with one common and two different baths of harmonic oscillators, respectively. The calculations have been performed within the Bloch-Redfield formalism and we report the solutions for the populations and the coherences of the system's reduced density matrix. The dephasing and relaxation rates are explicitly calculated as a function of the heat bath temperature.

  8. Lagrangian approach and dissipative magnetic systems

    Energy Technology Data Exchange (ETDEWEB)

    Bose, Thomas, E-mail: thomas.bose@physik.uni-halle.de [Martin-Luther-University, Physics Department, Von-Seckendorff-Platz 1, 06114 Halle (Germany); Trimper, Steffen, E-mail: steffen.trimper@physik.uni-halle.de [Martin-Luther-University, Physics Department, Von-Seckendorff-Platz 1, 06114 Halle (Germany)

    2011-06-13

    A Lagrangian is introduced which includes the coupling between magnetic moments m and the degrees of freedom σ of a reservoir. In case the system-reservoir coupling breaks the time reversal symmetry the magnetic moments perform a damped precession around an effective field which is self-organized by the mutual interaction of the moments. The resulting evolution equation has the form of the Landau-Lifshitz-Gilbert equation. In case the bath variables are constant vector fields the moments m fulfill the reversible Landau-Lifshitz equation. Applying Noether's theorem we find conserved quantities under rotation in space and within the configuration space of the moments. -- Highlights: → We propose a new approach for describing magnetic systems with dissipation on a mesoscopic scale. → The Lagrangian consists of an active magnetic system and a bath. → The coupling between both subsystems breaks the time reversal symmetry. → The suggested Lagrangian leads to the Landau-Lifshitz equation with damping. → We consider symmetry operations by means of Noether's theorem.

  9. Quantum dynamics in open quantum-classical systems.

    Science.gov (United States)

    Kapral, Raymond

    2015-02-25

    Often quantum systems are not isolated and interactions with their environments must be taken into account. In such open quantum systems these environmental interactions can lead to decoherence and dissipation, which have a marked influence on the properties of the quantum system. In many instances the environment is well-approximated by classical mechanics, so that one is led to consider the dynamics of open quantum-classical systems. Since a full quantum dynamical description of large many-body systems is not currently feasible, mixed quantum-classical methods can provide accurate and computationally tractable ways to follow the dynamics of both the system and its environment. This review focuses on quantum-classical Liouville dynamics, one of several quantum-classical descriptions, and discusses the problems that arise when one attempts to combine quantum and classical mechanics, coherence and decoherence in quantum-classical systems, nonadiabatic dynamics, surface-hopping and mean-field theories and their relation to quantum-classical Liouville dynamics, as well as methods for simulating the dynamics.

  10. Robust Stabilization of Uncertain Systems Based on Energy Dissipation Concepts

    Science.gov (United States)

    Gupta, Sandeep

    1996-01-01

    Robust stability conditions obtained through generalization of the notion of energy dissipation in physical systems are discussed in this report. Linear time-invariant (LTI) systems which dissipate energy corresponding to quadratic power functions are characterized in the time-domain and the frequency-domain, in terms of linear matrix inequalities (LMls) and algebraic Riccati equations (ARE's). A novel characterization of strictly dissipative LTI systems is introduced in this report. Sufficient conditions in terms of dissipativity and strict dissipativity are presented for (1) stability of the feedback interconnection of dissipative LTI systems, (2) stability of dissipative LTI systems with memoryless feedback nonlinearities, and (3) quadratic stability of uncertain linear systems. It is demonstrated that the framework of dissipative LTI systems investigated in this report unifies and extends small gain, passivity, and sector conditions for stability. Techniques for selecting power functions for characterization of uncertain plants and robust controller synthesis based on these stability results are introduced. A spring-mass-damper example is used to illustrate the application of these methods for robust controller synthesis.

  11. A dissipative model of solar system

    Science.gov (United States)

    Vladimir, V. G.

    2009-04-01

    rotation of planets, and the small tidal deformations arising under influence of gradients of gravitational forces. The method of division of movements receives the equations describing movements of the centers of weights of planets and their own rotations. In the offered model takes place a dissipation of the energy which source are internally viscous forces of each planet. The system supposes the first integral - the law of preservation of the kinetic moment concerning the centre of weights of system. As a result of deformations of planets in the law of the universal gravitation which has been written down for material points, there are small conservative amendments. The equations of movement describe movement of the centers of weights of planets and their rotation around of the centers of weights in view of the tidal phenomena and the dissipative forces. The connected system of the equations consists of 3N the vector equations of the second order representing the theorems of movement of the centers of weights of planets, and N the vector equations of the first order determining changes of the own kinetic moments of each planet. Stationary values of full mechanical energy on the variety set in integral of the kinetic moment, correspond to stationary movements - to rotations of system as firm body with constant angular speed around of the centre of weights of all system. Angular speed of stationary rotation is directed along a constant vector of the kinetic moment, and the axis of rotation is the main central axis of inertia of system. We shall notice, that deformations of planets in stationary movement are constant, as in system of coordinates rotating with constant angular speed centrifugal forces and forces of gravitational interaction of planets are constant. Stationary configurations of system are determined according to Routh`s technique as stationary points of the changed potential energy submitted by the sum potential energies of centrifugal and gravitational

  12. Three-Dimensional Dissipative Optical Solitons in a Dielectric Medium with Quantum Dots

    Directory of Open Access Journals (Sweden)

    Gubin M.Yu.

    2015-01-01

    Full Text Available We consider the problem of formation of three-dimensional spatio-temporal dissipative solitons (laser bullets in a dense ensemble of two-level quantum dots. The principal possibility of effective laser bullets generation in an all-dielectric metamaterials with quantum dots is shown. The phenomenon arises due to the simultaneous appearance of strong local field effects and significant corrections to diffraction effects during the propagation of short optical pulses in such medium.

  13. Balance laws and centro velocity in dissipative systems

    NARCIS (Netherlands)

    Groesen, van E.; Mainardi, F.

    1990-01-01

    Starting with a density that is conserved for a dynamical system when dissipation is ignored, a local conservation law is derived for which the total flux (integrated over the spatial domain) is unique. When dissipation is incorporated, the conservation law becomes a balance law. The contribution du

  14. Balance laws and centro velocity in dissipative systems

    NARCIS (Netherlands)

    van Groesen, Embrecht W.C.; Mainardi, F.

    1990-01-01

    Starting with a density that is conserved for a dynamical system when dissipation is ignored, a local conservation law is derived for which the total flux (integrated over the spatial domain) is unique. When dissipation is incorporated, the conservation law becomes a balance law. The contribution

  15. Quantum vacuum fluctuations in presence of dissipative bodies: Dynamical approach for nonequilibrium and squeezed states

    Science.gov (United States)

    Rubio López, Adrián E.

    2017-01-01

    The present work contributes to the study of nonequilibrium aspects of the Casimir forces with the introduction of squeezed states in the calculations. Throughout this article two main results can be found, being both strongly correlated. Primarily, the more formal result involves the development of a first-principles canonical quantization formalism to study the quantum vacuum in the presence of different dissipative material bodies in completely general scenarios. For this purpose, we consider a one-dimensional quantum scalar field interacting with the volume elements' degrees of freedom of the material bodies, which are modeled as a set of composite systems consisting of quantum harmonic oscillators interacting with an environment (provided as an infinite set of quantum harmonic oscillators acting as a thermal bath). Solving the full dynamics of the composite system through its Heisenberg equations, we study each contribution to the field operator by employing general properties of the Green function. We deduce the long-time limit of the contributions to the field operator. In agreement with previous works, we show that the expectation values of the components of the energy-momentum tensor present two contributions, one associated to the thermal baths and the other one associated to the field's initial conditions. This allows the direct study of steady situations involving different initial states for the field (keeping arbitrary thermal states for the baths). This leads to the other main result, consisting of computing the Casimir force when the field is initially in thermal or continuum-single-mode squeezed states (the latter being characterized by a given bandwidth and frequency). Time averaging is required for the squeezed case, showing that both results can be given in a unified way, while for the thermal state, all the well-known equilibrium results can be successfully reproduced. Finally, we compared the initial conditions' contribution and the total

  16. Anatomy of quantum critical wave functions in dissipative impurity problems

    Science.gov (United States)

    Blunden-Codd, Zach; Bera, Soumya; Bruognolo, Benedikt; Linden, Nils-Oliver; Chin, Alex W.; von Delft, Jan; Nazir, Ahsan; Florens, Serge

    2017-02-01

    Quantum phase transitions reflect singular changes taking place in a many-body ground state; however, computing and analyzing large-scale critical wave functions constitutes a formidable challenge. Physical insights into the sub-Ohmic spin-boson model are provided by the coherent-state expansion (CSE), which represents the wave function by a linear combination of classically displaced configurations. We find that the distribution of low-energy displacements displays an emergent symmetry in the absence of spontaneous symmetry breaking while experiencing strong fluctuations of the order parameter near the quantum critical point. Quantum criticality provides two strong fingerprints in critical low-energy modes: an algebraic decay of the average displacement and a constant universal average squeezing amplitude. These observations, confirmed by extensive variational matrix-product-state (VMPS) simulations and field theory arguments, offer precious clues into the microscopics of critical many-body states in quantum impurity models.

  17. Dissipativity Analysis of Descriptor Systems Using Image Space Characterization

    Directory of Open Access Journals (Sweden)

    Liang Qiao

    2014-01-01

    Full Text Available In this paper, we analyze the dissipativity for descriptor systems with impulsive behavior based on image space analysis. First, a new image space is used to characterize state responses for descriptor systems. Based on such characterization and an integral property of delta function, a new necessary and sufficient condition for the dissipativity of descriptor systems is derived using the linear matrix inequality (LMI approach. Also, some of the earlier related results on dissipativity for linear systems are investigated in the framework proposed in this paper. Finally, two examples are given to show the validity of the derived results.

  18. Scattering theory for open quantum systems

    Energy Technology Data Exchange (ETDEWEB)

    Behrndt, Jussi [Technische Univ. Berlin (Germany). Inst. fuer Mathematik; Malamud, Mark M. [Donetsk National University (Ukraine). Dept. of Mathematics; Neidhardt, Hagen [Weierstrass-Institut fuer Angewandte Analysis und Stochastik (WIAS) im Forschungsverbund Berlin e.V. (Germany)

    2006-07-01

    Quantum systems which interact with their environment are often modeled by maximal dissipative operators or so-called Pseudo-Hamiltonians. In this paper the scattering theory for such open systems is considered. First it is assumed that a single maximal dissipative operator A{sub D} in a Hilbert space H is used to describe an open quantum system. In this case the minimal self-adjoint dilation K of A{sub D} can be regarded as the Hamiltonian of a closed system which contains the open system {l_brace}A{sub D},h{r_brace}, but since K is necessarily not semibounded from below, this model is difficult to interpret from a physical point of view. In the second part of the paper an open quantum system is modeled with a family {l_brace}A({mu}){r_brace} of maximal dissipative operators depending on energy {mu}, and it is shown that the open system can be embedded into a closed system where the Hamiltonian is semibounded. Surprisingly it turns out that the corresponding scattering matrix can be completely recovered from scattering matrices of single Pseudo-Hamiltonians as in the first part of the paper. The general results are applied to a class of Sturm-Liouville operators arising in dissipative and quantum transmitting Schroedinger-Poisson systems. (orig.)

  19. Energy-dissipation-model for metallurgical multi-phase-systems

    Energy Technology Data Exchange (ETDEWEB)

    Mavrommatis, K.T. [Rheinisch-Westfaelische Technische Hochschule Aachen, Aachen (Germany)

    1996-12-31

    Entropy production in real processes is directly associated with the dissipation of energy. Both are potential measures for the proceed of irreversible processes taking place in metallurgical systems. Many of these processes in multi-phase-systems could then be modelled on the basis of the energy-dissipation associated with. As this entity can often be estimated using very simple assumptions from first principles, the evolution of an overall measure of systems behaviour can be studied constructing an energy-dissipation -based model of the system. In this work a formulation of this concept, the Energy-Dissipation-Model (EDM), for metallurgical multi-phase-systems is given. Special examples are studied to illustrate the concept, and benefits as well as the range of validity are shown. This concept might be understood as complement to usual CFD-modelling of complex systems on a more abstract level but reproducing essential attributes of complex metallurgical systems. (author)

  20. Efficient calculation of dissipative quantum transport properties in semiconductor nanostructures

    Energy Technology Data Exchange (ETDEWEB)

    Greck, Peter

    2012-11-26

    We present a novel quantum transport method that follows the non-equilibrium Green's function (NEGF) framework but side steps any self-consistent calculation of lesser self-energies by replacing them by a quasi-equilibrium expression. We termed this method the multi-scattering Buettiker-Probe (MSB) method. It generalizes the so-called Buettiker-Probe model but takes into account all relevant individual scattering mechanisms. It is orders of magnitude more efficient than a fully selfconsistent non-equilibrium Green's function calculation for realistic devices, yet accurately reproduces the results of the latter method as well as experimental data. This method is fairly easy to implement and opens the path towards realistic three-dimensional quantum transport calculations. In this work, we review the fundamentals of the non-equilibrium Green's function formalism for quantum transport calculations. Then, we introduce our novel MSB method after briefly reviewing the original Buettiker-Probe model. Finally, we compare the results of the MSB method to NEGF calculations as well as to experimental data. In particular, we calculate quantum transport properties of quantum cascade lasers in the terahertz (THz) and the mid-infrared (MIR) spectral domain. With a device optimization algorithm based upon the MSB method, we propose a novel THz quantum cascade laser design. It uses a two-well period with alternating barrier heights and complete carrier thermalization for the majority of the carriers within each period. We predict THz laser operation for temperatures up to 250 K implying a new temperature record.

  1. Deformation quantization of noncommutative quantum mechanics and dissipation

    Energy Technology Data Exchange (ETDEWEB)

    Bastos, C [Departamento de Fisica, Instituto Superior Tecnico, Avenida Rovisco Pais 1, 1049-001 Lisbon (Portugal); Bertolami, O [Departamento de Fisica, Instituto Superior Tecnico, Avenida Rovisco Pais 1, 1049-001 Lisbon (Portugal); Dias, N C [Departamento de Matematica, Universidade Lusofona de Humanidades e Tecnologias, Avenida Campo Grande 376, 1749-024 Lisbon (Portugal); Prata, J N [Departamento de Matematica, Universidade Lusofona de Humanidades e Tecnologias, Avenida Campo Grande 376, 1749-024 Lisbon (Portugal)

    2007-05-15

    We review the main features of the Weyl-Wigner formulation of noncommutative quantum mechanics. In particular, we present a *-product and a Moyal bracket suitable for this theory as well as the concept of noncommutative Wigner function. The properties of these quasi-distributions are discussed as well as their relation to the sets of ordinary Wigner functions and positive Liouville probability densities. Based on these notions we propose criteria for assessing whether a commutative regime has emerged in the realm of noncommutative quantum mechanics. To induce this noncommutative-commutative transition, we couple a particle to an external bath of oscillators. The master equation for the Brownian particle is deduced.

  2. Fluctuations of the dissipated energy in a granular system

    Science.gov (United States)

    Lasanta, Antonio; Hurtado, Pablo I.; Garrido, Pedro L.; Brey, J. Javier

    2011-03-01

    Large fluctuations, play an important role in many fields of science as they crucially determine the fate of a system. The statistics of these fluctuations encodes essential information on the physics of the system at hand. This is particularly important in systems far from equilibrium, where no general theory exists up to date capable of predicting macroscopic and fluctuating behavior in terms of microscopic physics.The study of fluctuations far from equilibrium may open the door to such general theory. In this work we follow this path by studying the fluctuations of the dissipated energy in an oversimplified model of a granular system. The model, first proposed and solved by Levanony and Levine [1], is a simple one dimensional diffusive lattice system which includes energy dissipation as a main ingredient. When subject to boundary heat baths, the system reaches an steady state characterized by a highly nonlinear temperature profile and a nonzero average energy dissipation. For long but finite times, the time-averaged dissipated energy fluctuates, obeying a large deviation principle. We study the large deviation function (LDF) of the dissipated energy by means of advanced Monte Carlo techniques [2], arriving to the following results: (i) the LDF of the dissipated energy has only a positive branch, meaning that for long times only positive dissipation is expected, (ii) as a result of microscopic time-irreversibility, the LDF does not obeys the Gallavotti-Cohen fluctuation theorem, (iii) the LDF is Gaussian around the average dissipation, but non-Gaussian, asymmetric tails quickly develop away from the average, and (iv) the granular system adopts a precise optimal profile in order to facilitate a given dissipation fluctuation, different from the steady profile. We compare our numerical results with predictions based on hydrodynamic fluctuation theory [3], finding good agreement.

  3. Quantum transport of vortices in a weakly dissipative ring threaded by an Aharonov-Casher flux: A tight-binding model

    Energy Technology Data Exchange (ETDEWEB)

    Zhu, J. [Texas Center for Superconductivity, University of Houston, Houston, Texas 77204-5932 (United States)]|[Department of Physics, University of Hong Kong, Pokfulam Road (Hong Kong); Wang, Z.D. [Department of Physics, University of Hong Kong, Pokfulam Road (Hong Kong)

    1997-11-01

    Based on the tight-binding model and taking into account the effect of dissipation as well as the disorder, we study quantum interference via the Aharonov-Casher effect for fluxons in a ring-shaped superconductor. The electrical resistance in terms of the transmission probability for a quantum vortex to traverse the ring is calculated. It is shown that a quantum interference effect is exhibited in the resistance in the presence of weak dissipation. Our analysis may also be applied to a Josephson-junction array system. In particular, by including the disorder effect, we are able to explain the experimental measurements in the dissipative regime done by Elion {ital et al.} [Phys. Rev. Lett. {bold 71}, 2311 (1993)]. {copyright} {ital 1997} {ital The American Physical Society}

  4. Non-dissipative effects in nonequilibrium systems

    CERN Document Server

    Maes, Christian

    2018-01-01

    This book introduces and discusses both the fundamental aspects and the measurability of applications of time-symmetric kinetic quantities, outlining the features that constitute the non-dissipative branch of non-equilibrium physics. These specific features of non-equilibrium dynamics have largely been ignored in standard statistical mechanics texts. This introductory-level book offers novel material that does not take the traditional line of extending standard thermodynamics to the irreversible domain. It shows that although stationary dissipation is essentially equivalent with steady non-equilibrium and ubiquitous in complex phenomena, non-equilibrium is not determined solely by the time-antisymmetric sector of energy-entropy considerations. While this should not be very surprising, this book provides timely, simple reminders of the role of time-symmetric and kinetic aspects in the construction of non-equilibrium statistical mechanics.

  5. Introduction: Dissipative localized structures in extended systems

    Science.gov (United States)

    Tlidi, Mustapha; Taki, Majid; Kolokolnikov, Theodore

    2007-09-01

    Localized structures belong to the class of dissipative structures found far from equilibrium. Contributions from the most representative groups working on a various fields of natural science such as biology, chemistry, plant ecology, mathematics, optics, and laser physics are presented. The aim of this issue is to gather specialists from these fields towards a cross-fertilization among these active areas of research and thereby to present an overview of the state of art in the formation and the characterization of dissipative localized structures. Nonlinear optics and laser physics have an important part in this issue because of potential applications in information technology. In particular, localized structures could be used as "bits" for parallel information storage and processing.

  6. Conformal invariance and Hamilton Jacobi theory for dissipative systems

    Science.gov (United States)

    Kiehn, R. M.

    1975-01-01

    For certain dissipative systems, a comparison can be made between the Hamilton-Jacobi theory and the conformal invariance of action theory. The two concepts are not identical, but the conformal action theory covers the Hamilton-Jacobi theory.

  7. Rayleigh-Lagrange formalism for classical dissipative systems.

    Science.gov (United States)

    Virga, Epifanio G

    2015-01-01

    It is often believed that the Rayleigh-Lagrange formalism for classical dissipative systems is unable to encompass forces described by nonlinear functions of the velocities. Here we show that this is indeed a misconception.

  8. Transmission Dynamics of a Driven Two-Level System Dissipated by Leads

    Institute of Scientific and Technical Information of China (English)

    ZHANG Ping; FAN Wen-Bin; ZHAO Xian-Geng

    2001-01-01

    We study the transmission dynamics of a driven two-level system dissipated by the two leads. Using the nonequilibrium Green function, we derive an analytical transmission formula for an electron incident from the left lead,through the double quantum dots, to the right lead. The Landauer-type conductance and current are also given.A discussion of the internal tunnelling dynamics reveals crucial effects of the localization and delocalization on the transport of the system.

  9. Stochastic pump effect and geometric phases in dissipative and stochastic systems

    Energy Technology Data Exchange (ETDEWEB)

    Sinitsyn, Nikolai [Los Alamos National Laboratory

    2008-01-01

    The success of Berry phases in quantum mechanics stimulated the study of similar phenomena in other areas of physics, including the theory of living cell locomotion and motion of patterns in nonlinear media. More recently, geometric phases have been applied to systems operating in a strongly stochastic environment, such as molecular motors. We discuss such geometric effects in purely classical dissipative stochastic systems and their role in the theory of the stochastic pump effect (SPE).

  10. Scale-free entanglement replication in driven-dissipative many body systems

    CERN Document Server

    Zippilli, S; Adesso, G; Illuminati, F

    2012-01-01

    We study the dynamics of independent arrays of many-body dissipative systems, subject to a common driving by an entangled light field. We show that in the steady state the global system orders in a series of inter-array strongly entangled pairs over all distances. Such scale-free entanglement replication and long-distance distribution mechanism has potential applications for the implementation of robust quantum networked communication.

  11. Correspondence behavior of classical and quantum dissipative directed transport via thermal noise

    Science.gov (United States)

    Carlo, Gabriel G.; Ermann, Leonardo; Rivas, Alejandro M. F.; Spina, María E.

    2016-04-01

    We systematically study several classical-quantum correspondence properties of the dissipative modified kicked rotator, a paradigmatic ratchet model. We explore the behavior of the asymptotic currents for finite ℏeff values in a wide range of the parameter space. We find that the correspondence between the classical currents with thermal noise providing fluctuations of size ℏeff and the quantum ones without it is very good in general with the exception of specific regions. We systematically consider the spectra of the corresponding classical Perron-Frobenius operators and quantum superoperators. By means of an average distance between the classical and quantum sets of eigenvalues we find that the correspondence is unexpectedly quite uniform. This apparent contradiction is solved with the help of the Weyl-Wigner distributions of the equilibrium eigenvectors, which reveal the key role of quantum effects by showing surviving coherences in the asymptotic states.

  12. Quantum System Identification

    OpenAIRE

    Burgarth, Daniel; Yuasa, Kazuya

    2011-01-01

    The aim of quantum system identification is to estimate the ingredients inside a black box, in which some quantum-mechanical unitary process takes place, by just looking at its input-output behavior. Here we establish a basic and general framework for quantum system identification, that allows us to classify how much knowledge about the quantum system is attainable, in principle, from a given experimental setup. Prior knowledge on some elements of the black box helps the system identification...

  13. Corner-Space Renormalization Method for Driven-Dissipative Two-Dimensional Correlated Systems.

    Science.gov (United States)

    Finazzi, S; Le Boité, A; Storme, F; Baksic, A; Ciuti, C

    2015-08-21

    We present a theoretical method to study driven-dissipative correlated quantum systems on lattices with two spatial dimensions (2D). The steady-state density matrix of the lattice is obtained by solving the master equation in a corner of the Hilbert space. The states spanning the corner space are determined through an iterative procedure, using eigenvectors of the density matrix of smaller lattice systems, merging in real space two lattices at each iteration and selecting M pairs of states by maximizing their joint probability. The accuracy of the results is then improved by increasing the dimension M of the corner space until convergence is reached. We demonstrate the efficiency of such an approach by applying it to the driven-dissipative 2D Bose-Hubbard model, describing lattices of coupled cavities with quantum optical nonlinearities.

  14. The dissipative quantum Duffing oscillator: A comparison of Floquet-based approaches

    Energy Technology Data Exchange (ETDEWEB)

    Vierheilig, Carmen, E-mail: Carmen.Vierheilig@physik.uni-regensburg.de [Institut fuer Theoretische Physik, Universitaet Regensburg, Universitaetsstrasse 31, 93040 Regensburg (Germany); Grifoni, Milena [Institut fuer Theoretische Physik, Universitaet Regensburg, Universitaetsstrasse 31, 93040 Regensburg (Germany)

    2010-10-05

    We study the dissipative quantum Duffing oscillator in the deep quantum regime with two different approaches: The first is based on the exact Floquet states of the linear oscillator and the nonlinearity is treated perturbatively. It well describes the nonlinear oscillator dynamics away from resonance. The second, in contrast, is applicable at and in the vicinity of an N-photon resonance and it exploits quasi-degenerate perturbation theory for the nonlinear oscillator in Floquet space. It is perturbative both in driving and nonlinearity. A combination of both approaches yields the possibility to cover a wide range of driving frequencies. As an example we discuss the dissipative dynamics of the Duffing oscillator near and at the one-photon resonance.

  15. Steady States of Infinite-Size Dissipative Quantum Chains via Imaginary Time Evolution

    Science.gov (United States)

    Gangat, Adil A.; I, Te; Kao, Ying-Jer

    2017-07-01

    Directly in the thermodynamic limit, we show how to combine local imaginary and real-time evolution of tensor networks to efficiently and accurately find the nonequilibrium steady states (NESSs) of one-dimensional dissipative quantum lattices governed by a local Lindblad master equation. The imaginary time evolution first bypasses any highly correlated portions of the real-time evolution trajectory by directly converging to the weakly correlated subspace of the NESS, after which, real-time evolution completes the convergence to the NESS with high accuracy. We demonstrate the power of the method with the dissipative transverse field quantum Ising chain. We show that a crossover of an order parameter shown to be smooth in previous finite-size studies remains smooth in the thermodynamic limit.

  16. Understanding of the dissipation mechanism in ternary fission for the system 197Au+197Au

    Science.gov (United States)

    Tian, Jun-Long; Li, Xian; Wu, Xi-Zhen; Li, Zhu-Xia; Yan, Shi-Wei

    2009-03-01

    The mass number distributions of three fragments from the ternary fission of the system 197Au+197Au are reproduced rather well by using the improved quantum molecular dynamics (ImQMD) model without any adjusting parameter. It is found that the probability of ternary fission evidently depends on the incident energy and the impact parameter, and the two-body dissipation is the main mechanism responsible for the formation of the third fragment with comparable mass.

  17. Synthesis of dissipative output feedback controllers. Application to mechanical systems

    Energy Technology Data Exchange (ETDEWEB)

    Johannessen, Erling Aarsand

    1997-12-31

    This thesis presents new results on the synthesis of linear controllers with passivity, or more general, dissipativity properties. These methods may be applied to obtain more accurate control over mechanical systems and in the control of chemical processes that involve dissipative subsystems. The thesis presents two different approaches for synthesis of dissipative controllers: (1) A method that exploits the Riccati equation solution to the state space formulation of the H{sub {infinity}} control problem is investigated, illustrated by synthesising a controller for damping of flexible modes in a beam. (2) A more general method for dissipative control synthesis is developed that retains the well-known techniques of loop-shaping and frequency weighting in H{sub {infinity}}. A method is also presented for controller synthesis directly from frequency response data. 82 refs., 34 figs., 3 tabs.

  18. Advanced quantum communication systems

    Science.gov (United States)

    Jeffrey, Evan Robert

    Quantum communication provides several examples of communication protocols which cannot be implemented securely using only classical communication. Currently, the most widely known of these is quantum cryptography, which allows secure key exchange between parties sharing a quantum channel subject to an eavesdropper. This thesis explores and extends the realm of quantum communication. Two new quantum communication protocols are described. The first is a new form of quantum cryptography---relativistic quantum cryptography---which increases communication efficiency by exploiting a relativistic bound on the power of an eavesdropper, in addition to the usual quantum mechanical restrictions intrinsic to quantum cryptography. By doing so, we have observed over 170% improvement in communication efficiency over a similar protocol not utilizing relativity. A second protocol, Quantum Orienteering, allows two cooperating parties to communicate a specific direction in space. This application shows the possibility of using joint measurements, or projections onto an entangled state, in order to extract the maximum useful information from quantum bits. For two-qubit communication, the maximal fidelity of communication using only separable operations is 73.6%, while joint measurements can improve the efficiency to 78.9%. In addition to implementing these protocols, we have improved several resources for quantum communication and quantum computing. Specifically, we have developed improved sources of polarization-entangled photons, a low-loss quantum memory for polarization qubits, and a quantum random number generator. These tools may be applied to a wide variety of future quantum and classical information systems.

  19. Real-time path-integral approach for dissipative quantum dot-cavity quantum electrodynamics: impure dephasing-induced effects

    Science.gov (United States)

    Nahri, Davoud G.; Mathkoor, Faisal H. A.; Ooi, C. H. Raymond

    2017-02-01

    A dissipative quantum dot (QD)-cavity system, where the QD is initially prepared in the excited state with no photon in the cavity, coupled to a longitudinal acoustic (LA) phonon reservoir is studied using a numerically exact real-time path-integral approach. Three distinct dynamical regimes of weak (WC), strong (SC), and coherent coupling (CC) are discussed and more accurate conditions identifying them are presented. Our results show that to have the CC regime, which is characterized by clear vacuum Rabi oscillation (VRO), vacuum Rabi splitting (VRS) should be larger than the sum of the widths of the corresponding peaks. In order to distinguish between contributions of population decay and impure dephasing, induced by LA phonon bath and the dissipations, we propose a two-part phenomenological expression, corresponding to the population decay and impure dephasing, which fits the QD-cavity decay curves perfectly and is used to calculate the corresponding spectra. We demonstrate that the effective population decay rate (the emission rate) increases from the carrier recombination rate to a maximum value, which is the mean of the QD and cavity dissipation rates, with QD-cavity coupling strength. To study the role of the effective impure dephasing rate on the width of the central peak of the spectra we introduce a quantity that can also be applied in determining the distinct coupling regimes. This quantity enables us to identify the onset of the SC regime as the point where the impure dephasing term begins to contribute to the central band of the spectrum significantly, as a result of the existence of VRO with a very small frequency (unclear VRO) at the corresponding decay curve. Its contribution to the width of the central peak increases with the coupling strength up to the onset of the CC regime, then reduces as a result of the appearance of sidebands in the spectra, which originates from clear VRO. The effective population decay and impure dephasing rate contribute

  20. Quantizing polaritons in inhomogeneous dissipative systems

    Science.gov (United States)

    Drezet, Aurélien

    2017-02-01

    In this article we provide a general analysis of canonical quantization for polaritons in dispersive and dissipative electromagnetic inhomogeneous media. We compare several approaches based either on the Huttner-Barnett model [B. Huttner and S. M. Barnett, Phys. Rev. A 46, 4306 (1992), 10.1103/PhysRevA.46.4306] or the Green function, Langevin-noise method [T. Gruner and D.-G. Welsch, Phys. Rev. A 53, 1818 (1996), 10.1103/PhysRevA.53.1818] which includes only material oscillators as fundamental variables. We show that in order to preserve unitarity, causality, and time symmetry, one must necessarily include with an equal footing both electromagnetic modes and material fluctuations in the evolution equations. This becomes particularly relevant for all nanophotonics and plasmonics problems involving spatially localized antennas or devices.

  1. A study of Quantum Correlations in Open Quantum Systems

    CERN Document Server

    Chakrabarty, Indranil; Siddharth, Nana

    2010-01-01

    In this work, we study quantum correlations in mixed states. The states studied are modelled by a two-qubit system interacting with its environment via a quantum nondemolition (purely dephasing) as well as dissipative type of interaction. The entanglement dynamics of this two qubit system is analyzed and the existence of entangled states which do not violate Bell's inequality, but can still be useful as a potential resource for teleportation are reported. In addition, a comparative study of various measures of quantum correlations, like Concurrence, Bell's inequality, Discord and Teleportation fidelity, is made on these states, generated by the above evolutions. Interestingly, examples are found, of states, where entanglement is vanishing, but discord is non-vanishing, bringing out the fact that entanglement is a subset of quantum correlations.

  2. Entanglement generated by dissipation

    CERN Document Server

    Krauter, Hanna; Jensen, Kasper; Wasilewski, Wojciech; Petersen, Jonas M; Cirac, J Ignacio; Polzik, Eugene S

    2010-01-01

    Entanglement is not only one of the most striking features of Quantum Mechanics but also an essential ingredient in most applications in the field of Quantum Information. Unfortunately, this property is very fragile. In experiments conducted so far, coupling of the system to a quantum mechanical environment, commonly referred to as dissipation, either inhibits entanglement or prevents its generation. In this Letter, we report on an experiment in which dissipation induces entanglement between two atomic objects rather than impairing it. This counter-intuitive effect is achieved by engineering the dissipation by means of laser- and magnetic fields, and leads to entanglement which is very robust and therefore long-lived. Our system consists of two distant macroscopic ensembles containing about 10^{12} atoms coupled to the environment composed of the vacuum modes of the electromagnetic field. The two atomic objects are kept entangled by dissipation at room temperature for about 0.015s. The prospects of using this...

  3. Dissipative Quantum Tunneling of a Single Defect in a Submicron Bismuth Wire Below 1 K

    Science.gov (United States)

    Chun, Kookjin

    The quantum mechanical problem of a particle tunneling in a double-well potential is of great theoretical and experimental interest. Interaction of the tunneling system with a dissipative environment can have a striking effect on the tunneling dynamics. A very interesting case is that of ohmic dissipation, which occurs when an atom tunnels in a metal in the presence of conduction electrons. We have studied the electrical resistance of submicron Bi wires at low temperature. Due to quantum interference of the conduction electrons, the resistance is highly sensitive to the motion of even a single scattering center. We observe discrete switching of the resistance due to the motion of bistable defects in the sample. We have measured the tunneling rates of a particular defect over the temperature range 0.1-2 K and magnetic field range 0-7 T. The energy asymmetry, varepsilon, of this defect varied over the range 40-420 mK depending on the value of the magnetic field. The temperature dependence of the tunneling rates is qualitatively different for the cases k_{B}T effect of Joule heating on the dynamics of the defect in the same sample. The ratio of the fast and slow transition rates of a defect depends on temperature through the detailed balance relation, gamma_{f}/ gamma_{s} e^ {varepsilon / k_{B}T}. We interpret this ratio as a local thermometer. When varepsilon / k_{B}T > 1, this ratio is sensitive to small changes in the temperature T seen by the defect. Since the defect is strongly coupled to the conduction electrons in the sample below 1 K, we interpret its sensitivity to drive current as an indication of electron heating. As the drive current increases, the defect temperature approaches a power law dependence with the drive current, independent of the nominal lattice temperature. The data are consistent with a simple model of heating, and strong thermal coupling between the defect and the electron bath. We also tried to measure the electron temperature directly

  4. Quantum state engineering in hybrid open quantum systems

    Science.gov (United States)

    Joshi, Chaitanya; Larson, Jonas; Spiller, Timothy P.

    2016-04-01

    We investigate a possibility to generate nonclassical states in light-matter coupled noisy quantum systems, namely, the anisotropic Rabi and Dicke models. In these hybrid quantum systems, a competing influence of coherent internal dynamics and environment-induced dissipation drives the system into nonequilibrium steady states (NESSs). Explicitly, for the anisotropic Rabi model, the steady state is given by an incoherent mixture of two states of opposite parities, but as each parity state displays light-matter entanglement, we also find that the full state is entangled. Furthermore, as a natural extension of the anisotropic Rabi model to an infinite spin subsystem, we next explored the NESS of the anisotropic Dicke model. The NESS of this linearized Dicke model is also an inseparable state of light and matter. With an aim to enrich the dynamics beyond the sustainable entanglement found for the NESS of these hybrid quantum systems, we also propose to combine an all-optical feedback strategy for quantum state protection and for establishing quantum control in these systems. Our present work further elucidates the relevance of such hybrid open quantum systems for potential applications in quantum architectures.

  5. Robust Performance And Dissipation of Stochastic Control Systems

    DEFF Research Database (Denmark)

    Thygesen, Uffe Høgsbro

    The topic of the present dissertation is robustness and performance issues in nonlinear control systems. The control systems in our study are described by nominal models consisting of nonlinear deterministic or stochastic differential equations in a Euclidean state space. The nominal models...... and topology on the space of supply rates. For instance, we give conditions under which the available storage is a continuous convex function of the supply rate. Dissipation theory in the existing literature applies only to deterministic systems. This is unfortunate since robust control applications typically...... are subject to perturbations which are completely unknown dynamic systems, except that they are known to possess certain properties of dissipation. A dissipation property restricts the dynamic behaviour of the perturbation to conform with a bounded resource; for instance energy. The main contribution...

  6. The Rabi Oscillation in Subdynamic System for Quantum Computing

    Directory of Open Access Journals (Sweden)

    Bi Qiao

    2015-01-01

    Full Text Available A quantum computation for the Rabi oscillation based on quantum dots in the subdynamic system is presented. The working states of the original Rabi oscillation are transformed to the eigenvectors of subdynamic system. Then the dissipation and decoherence of the system are only shown in the change of the eigenvalues as phase errors since the eigenvectors are fixed. This allows both dissipation and decoherence controlling to be easier by only correcting relevant phase errors. This method can be extended to general quantum computation systems.

  7. Electrical Dissipative Structures in Membrane-Coupled Compartment Systems

    Science.gov (United States)

    Feudel, U.; Feistel, R.; Ebeling, W.

    Reaction-diffusion systems with charged particles are studied. Conditions for the arising of electrical dissipative structures in a compartment system consisting of two boxes separated by a membrane are derived. The appearance of a polar dissipative structure is proved for a simple capacitor model in combination with a simple second order chemical kinetics which leads to an analytically solvable problem. Electrical dissipative structures can in principle be considered as non equilibrium electrical batteries. The theoretical efficiency of such batteries is estimated.Translated AbstractElektrische Dissipative Strukturen in Membrangekoppelten SystemenEs werden Reaktions-Diffusionssysteme mit geladenen Teilchen studiert. Bedingungen für die Entstehung elektrischer dissipativer Strukturen in einem Kompartment-System, bestehend aus zwei durch eine Membran getrennten Zellen werden abgeleitet. Die Entstehung einer polaren dissipativen Struktur wird für ein einfaches Kondensatorenmodell in Kombination mit einer einfachen chemischen Kinetik, das analytische Lösbarkeit gestattet, nachgewiesen. Elektrische dissipative Strukturen können im Prinzip als elektrische Batterien fern von Gleichgewicht betrachtet werden. Der theoretische Wirkungsgrad einer solchen Batterie wird berechnet.

  8. Vector dissipativity theory for large-scale impulsive dynamical systems

    Directory of Open Access Journals (Sweden)

    Haddad Wassim M.

    2004-01-01

    Full Text Available Modern complex large-scale impulsive systems involve multiple modes of operation placing stringent demands on controller analysis of increasing complexity. In analyzing these large-scale systems, it is often desirable to treat the overall impulsive system as a collection of interconnected impulsive subsystems. Solution properties of the large-scale impulsive system are then deduced from the solution properties of the individual impulsive subsystems and the nature of the impulsive system interconnections. In this paper, we develop vector dissipativity theory for large-scale impulsive dynamical systems. Specifically, using vector storage functions and vector hybrid supply rates, dissipativity properties of the composite large-scale impulsive systems are shown to be determined from the dissipativity properties of the impulsive subsystems and their interconnections. Furthermore, extended Kalman-Yakubovich-Popov conditions, in terms of the impulsive subsystem dynamics and interconnection constraints, characterizing vector dissipativeness via vector system storage functions, are derived. Finally, these results are used to develop feedback interconnection stability results for large-scale impulsive dynamical systems using vector Lyapunov functions.

  9. Open quantum system identification

    CERN Document Server

    Schirmer, Sophie G; Zhou, Weiwei; Gong, Erling; Zhang, Ming

    2012-01-01

    Engineering quantum systems offers great opportunities both technologically and scientifically for communication, computation, and simulation. The construction and operation of large scale quantum information devices presents a grand challenge and a major issue is the effective control of coherent dynamics. This is often in the presence of decoherence which further complicates the task of determining the behaviour of the system. Here, we show how to determine open system Markovian dynamics of a quantum system with restricted initialisation and partial output state information.

  10. DECAY OF ENERGY FOR A DISSIPATIVE ANISOTROPIC ELASTIC SYSTEM

    Institute of Scientific and Technical Information of China (English)

    Qin Yuming; Liu Xin; Deng Shuxian

    2011-01-01

    In this article, we study the large-time behavior of energy for a N-dimensional dissipative anisotropic elastic system. By means of multiplicative techniques, energy method, and Zuazua's estimate technique, we prove the decay property of energy for anisotropic elastic system.

  11. Algorithmic issues in the synthesis of dissipative systems

    NARCIS (Netherlands)

    Belur, MN; Trentelman, HL

    2002-01-01

    In this paper we discuss algorithmic issues that arise in the problem of synthesis of dissipative systems. We deal with linear differential systems that can be controlled only through a restricted set of variables called the control variables. The main feature of this paper is that we assume the sys

  12. Detailed study of dissipative quantum dynamics of K-2 attached to helium nanodroplets

    CERN Document Server

    Schlesinger, Martin

    2011-01-01

    We thoroughly investigate vibrational quantum dynamics of dimers attached to He droplets motivated by recent measurements with K-2 [1]. For those femtosecond pump-probe experiments, crucial observed features are not reproduced by gas phase calculations but agreement is found using a description based on dissipative quantum dynamics, as briefly shown in [2]. Here we present a detailed study of the influence of possible effects induced by the droplet. The helium droplet causes electronic decoherence, shifts of potential surfaces, and relaxation of wave packets in attached dimers. Moreover, a realistic description of (stochastic) desorption of dimers off the droplet needs to be taken into account. Step by step we include and study the importance of these effects in our full quantum calculation. This allows us to reproduce and explain all major experimental findings. We find that desorption is fast and occurs already within 2-10 ps after electronic excitation. A further finding is that slow vibrational motion in ...

  13. Quantum noise and mixedness of a pumped dissipative non-linear oscillator

    CERN Document Server

    Bajer, J; Andrzejewski, M; Bajer, Jiri; Miranowicz, Adam; Andrzejewski, Mateusz

    2004-01-01

    Evolutions of quantum noise, characterized by quadrature squeezing parameter and Fano factor, and of mixedness, quantified by quantum von Neumann and linear entropies, of a pumped dissipative non-linear oscillator are studied. The model can describe a signal mode interacting with a thermal reservoir in a parametrically pumped cavity with a Kerr non-linearity. It is discussed that the initial pure states, including coherent states, Fock states, and finite superpositions of coherent states evolve into the same steady mixed state as verified by the quantum relative entropy and the Bures metric. It is shown analytically and verified numerically that the steady state can be well approximated by a nonclassical Gaussian state exhibiting quadrature squeezing and sub-Poissonian statistics for the cold thermal reservoir. It is found a rapid increase in the mixedness, especially for the initial Fock states and superpositions of coherent states, during a very short time interval, and then for longer evolution times a dec...

  14. Study on the stability of switched dissipative Hamiltonian systems

    Institute of Scientific and Technical Information of China (English)

    ZHU Liying; WANG Yuzhen

    2006-01-01

    The hybrid Hamiltonian system is a kind of important nonlinear hybrid systems. Such a system not only plays an important role in the development of hybrid control theory, but also finds many applications in practical control designs for obtaining better control performances. This paper investigates the stability of switched dissipative Hamiltonian systems under arbitrary switching paths. Under a realistic assumption, it is shown that the Hamiltonian functions of all the subsystems can be used as the multiple-Lyapunov functions for the switched dissipative Hamiltonian system. Based on this and using the dissipative Hamiltonian structural properties, this paper then proves that the P-norm of the state of switched dissipative Hamiltonian system converges to zero with the time increasing, and presents two sufficient conditions for the asymptotical stability under arbitrary switching paths. Utilizing these new results, this paper also obtains two useful corollaries for the asymptotical stability of switched nonlinear time-invariant systems. Finally, two examples are studied by using the new results proposed in this paper, and some numerical simulations are carried out to support our new results.

  15. Sorting quantum systems efficiently

    Science.gov (United States)

    Ionicioiu, Radu

    2016-05-01

    Measuring the state of a quantum system is a fundamental process in quantum mechanics and plays an essential role in quantum information and quantum technologies. One method to measure a quantum observable is to sort the system in different spatial modes according to the measured value, followed by single-particle detectors on each mode. Examples of quantum sorters are polarizing beam-splitters (PBS) – which direct photons according to their polarization – and Stern-Gerlach devices. Here we propose a general scheme to sort a quantum system according to the value of any d-dimensional degree of freedom, such as spin, orbital angular momentum (OAM), wavelength etc. Our scheme is universal, works at the single-particle level and has a theoretical efficiency of 100%. As an application we design an efficient OAM sorter consisting of a single multi-path interferometer which is suitable for a photonic chip implementation.

  16. Self-organization in a driven dissipative plasma system

    Science.gov (United States)

    Shaikh, Dastgeer; Dasgupta, B.; Hu, Q.; Zank, G. P.

    2010-02-01

    We perform a fully self-consistent three-dimensional numerical simulation for a compressible, dissipative magnetoplasma driven by large-scale perturbations, that contain a fairly broad spectrum of characteristic modes, ranging from largest scales to intermediate scales and down to the smallest scales, where the energy of the system is dissipated by collisional (ohmic) and viscous dissipations. Additionally, our simulation includes nonlinear interactions amongst a wide range of fluctuations that are initialized with random spectral amplitudes, leading to the cascade of spectral energy in the inertial range spectrum, and takes into account large-scale as well as small-scale perturbations that may have been induced by the background plasma fluctuations, as well as the non-adiabatic exchange of energy leading to the migration of energy from the energy-containing modes or randomly injected energy driven by perturbations and further dissipated by the smaller scales. Besides demonstrating the comparative decays of the total energy and the dissipation rate of the energy, our results show the existence of a perpendicular component of the current, thus clearly confirming that the self-organized state is non-force free.

  17. Statistical entropy of open quantum systems

    Science.gov (United States)

    Durão, L. M. M.; Caldeira, A. O.

    2016-12-01

    Dissipative quantum systems are frequently described within the framework of the so-called "system-plus-reservoir" approach. In this work we assign their description to the Maximum Entropy Formalism and compare the resulting thermodynamic properties with those of the well-established approaches. Due to the non-negligible coupling to the heat reservoir, these systems are nonextensive by nature, and the former task may require the use of nonextensive parameter dependent informational entropies. In doing so, we address the problem of choosing appropriate forms of those entropies in order to describe a consistent thermodynamics for dissipative quantum systems. Nevertheless, even having chosen the most successful and popular forms of those entropies, we have proven our model to be a counterexample where this sort of approach leads us to wrong results.

  18. Open quantum spin systems in semiconductor quantum dots and atoms in optical lattices

    Energy Technology Data Exchange (ETDEWEB)

    Schwager, Heike

    2012-07-04

    In this Thesis, we study open quantum spin systems from different perspectives. The first part is motivated by technological challenges of quantum computation. An important building block for quantum computation and quantum communication networks is an interface between material qubits for storage and data processing and travelling photonic qubits for communication. We propose the realisation of a quantum interface between a travelling-wave light field and the nuclear spins in a quantum dot strongly coupled to a cavity. Our scheme is robust against cavity decay as it uses the decay of the cavity to achieve the coupling between nuclear spins and the travelling-wave light fields. A prerequiste for such a quantum interface is a highly polarized ensemble of nuclear spins. High polarization of the nuclear spin ensemble is moreover highly desirable as it protects the potential electron spin qubit from decoherence. Here we present the theoretical description of an experiment in which highly asymmetric dynamic nuclear spin pumping is observed in a single self-assembled InGaAs quantum dot. The second part of this Thesis is devoted to fundamental studies of dissipative spin systems. We study general one-dimensional spin chains under dissipation and propose a scheme to realize a quantum spin system using ultracold atoms in an optical lattice in which both coherent interaction and dissipation can be engineered and controlled. This system enables the study of non-equilibrium and steady state physics of open and driven spin systems. We find, that the steady state expectation values of different spin models exhibit discontinuous behaviour at degeneracy points of the Hamiltonian in the limit of weak dissipation. This effect can be used to dissipatively probe the spectrum of the Hamiltonian. We moreover study spin models under the aspect of state preparation and show that dissipation drives certain spin models into highly entangled state. Finally, we study a spin chain with

  19. Quantum coherence and correlations in quantum system

    Science.gov (United States)

    Xi, Zhengjun; Li, Yongming; Fan, Heng

    2015-01-01

    Criteria of measure quantifying quantum coherence, a unique property of quantum system, are proposed recently. In this paper, we first give an uncertainty-like expression relating the coherence and the entropy of quantum system. This finding allows us to discuss the relations between the entanglement and the coherence. Further, we discuss in detail the relations among the coherence, the discord and the deficit in the bipartite quantum system. We show that, the one-way quantum deficit is equal to the sum between quantum discord and the relative entropy of coherence of measured subsystem. PMID:26094795

  20. Tidal Dissipation and Obliquity Evolution in Hot Jupiter Systems

    CERN Document Server

    Valsecchi, Francesca

    2014-01-01

    Two formation scenarios have been proposed to explain the tight orbits of hot Jupiters. These giant planets could be formed in low-obliquity orbits via disk migration or in high-obliquity orbits via high-eccentricity migration, where gravitational interactions with a companion are at play, together with tidal dissipation. Here we target the observed misaligned hot Jupiter systems to investigate whether their current properties are consistent with high-eccentricity migration. Specifically, we study whether tidal dissipation in the star can be responsible for the observed distribution of misalignments and orbital separations. Improving on previous studies, we use detailed models for the stellar component, thus accounting for how convection (and thus tidal dissipation) depends on the host star properties. We find that the currently observed degree of misalignment increases as the amount of surface convection in the host star decreases. This trend supports the hypothesis that tides are the mechanism shaping the o...

  1. Construction of Lyapunov Function for Dissipative Gyroscopic System

    Institute of Scientific and Technical Information of China (English)

    XU Wei; YUAN Bo; AO Ping

    2011-01-01

    @@ We introduce a force decomposition to construct a potential function in deterministic dynamics described by ordinary differential equations in the context of dissipative gyroscopic systems.Such a potential function serves as the corresponding Lyapunov function for the dynamics,hence it gives both quantitative and qualitative descriptions for stability of motion.As an example we apply our force decomposition to a four-dimensional dissipative gyroscopic system.We explicitly obtain the potential function for all parameter regimes in the linear limit,including those regimes where the Lyapunov function was previously believed not to exist.%We introduce a force decomposition to construct a potential function in deterministic dynamics described by ordinary differential equations in the context of dissipative gyroscopic systems. Such a potential function serves as the corresponding Lyapunov function for the dynamics, hence it gives both quantitative and qualitative descriptions for stability of motion. As an example we apply our force decomposition to a four-dimensional dissipative gyroscopic system. We explicitly obtain the potential function for all parameter regimes in the linear limit, including those regimes where the Lyapunov function was previously believed not to exist.

  2. Entropy as a Metric Generator of Dissipation in Complete Metriplectic Systems

    Directory of Open Access Journals (Sweden)

    Massimo Materassi

    2016-08-01

    Full Text Available This lecture is a short review on the role entropy plays in those classical dissipative systems whose equations of motion may be expressed via a Leibniz Bracket Algebra (LBA. This means that the time derivative of any physical observable f of the system is calculated by putting this f in a “bracket” together with a “special observable” F, referred to as a Leibniz generator of the dynamics. While conservative dynamics is given an LBA formulation in the Hamiltonian framework, so that F is the Hamiltonian H of the system that generates the motion via classical Poisson brackets or quantum commutation brackets, an LBA formulation can be given to classical dissipative dynamics through the Metriplectic Bracket Algebra (MBA: the conservative component of the dynamics is still generated via Poisson algebra by the total energy H, while S, the entropy of the degrees of freedom statistically encoded in friction, generates dissipation via a metric bracket. The motivation of expressing through a bracket algebra and a motion-generating function F is to endow the theory of the system at hand with all the powerful machinery of Hamiltonian systems in terms of symmetries that become evident and readable. Here a (necessarily partial overview of the types of systems subject to MBA formulation is presented, and the physical meaning of the quantity S involved in each is discussed. Here the aim is to review the different MBAs for isolated systems in a synoptic way. At the end of this collection of examples, the fact that dissipative dynamics may be constructed also in the absence of friction with microscopic degrees of freedom is stressed. This reasoning is a hint to introduce dissipation at a more fundamental level.

  3. Quantum system identification.

    Science.gov (United States)

    Burgarth, Daniel; Yuasa, Kazuya

    2012-02-24

    The aim of quantum system identification is to estimate the ingredients inside a black box, in which some quantum-mechanical unitary process takes place, by just looking at its input-output behavior. Here we establish a basic and general framework for quantum system identification, that allows us to classify how much knowledge about the quantum system is attainable, in principle, from a given experimental setup. We show that controllable closed quantum systems can be estimated up to unitary conjugation. Prior knowledge on some elements of the black box helps the system identification. We present an example in which a Bell measurement is more efficient to identify the system. When the topology of the system is known, the framework enables us to establish a general criterion for the estimability of the coupling constants in its Hamiltonian.

  4. Entangling Atoms and Ions in Dissipative Environments

    CERN Document Server

    Beige, A; Braun, D; Huelga, S F; Knight, P L; Plenio, M B; Vedral, V

    2000-01-01

    Quantum information processing rests on our ability to manipulate quantum superpositions through coherent unitary transformations, and to establish entanglement between constituent quantum components of the processor. The quantum information processor (a linear ion trap, or a cavity confining the radiation field for example) exists in a dissipative environment. We discuss ways in which entanglement can be established within such dissipative environments. We can even make use of a strong interaction of the system with its environment to produce entanglement in a controlled way.

  5. Entransy dissipation analysis and optimization of separated heat pipe system

    Institute of Scientific and Technical Information of China (English)

    QIAN XiaoDong; LI Zhen; MENG JiAn; LI ZhiXin

    2012-01-01

    Seperated heat pipe systems are widely used in the fields of waste heat recovery and air conditioning due to their high heat transfer capability,and optimization of heat transfer process plays an important role in high-efficiency energy utilization and energy conservation.In this paper,the entransy dissipation analysis is conducted for the separated heat pipe system,and the result indicates that minimum thermal resistance principle is applicable to the optimization of the separated heat pipe system.Whether in the applications of waste heat recovery or air conditioning,the smaller the entransy-dissipation-based thermal resistance of the separated heat pipe system is,the better the heat transfer performance will be.Based on the minimum thermal resistance principle,the optimal area allocation relationship between evaporator and condenser is deduced,which is numerically verified in the optimation design of separated heat pipe system.

  6. Quantum identification system

    OpenAIRE

    Dusek, Miloslav; Haderka, Ondrej; Hendrych, Martin; Myska, Robert

    1998-01-01

    A secure quantum identification system combining a classical identification procedure and quantum key distribution is proposed. Each identification sequence is always used just once and new sequences are ``refuelled'' from a shared provably secret key transferred through the quantum channel. Two identification protocols are devised. The first protocol can be applied when legitimate users have an unjammable public channel at their disposal. The deception probability is derived for the case of ...

  7. Phase-slip-induced dissipation in an atomic Bose-Hubbard system.

    Science.gov (United States)

    McKay, D; White, M; Pasienski, M; DeMarco, B

    2008-05-01

    Phase-slips control dissipation in many bosonic systems, determining the critical velocity of superfluid helium and the generation of resistance in thin superconducting wires. Technological interest has been largely motivated by applications involving nanoscale superconducting circuit elements, such as standards based on quantum phase-slip junctions. Although phase slips caused by thermal fluctuations at high temperatures are well understood, controversy remains over the role of phase slips in small-scale superconductors--in solids, problems such as uncontrolled noise sources and disorder complicate their study and application. Here we show that phase slips can lead to dissipation in a clean and well-characterized Bose-Hubbard system, by experimentally studying the transport of ultracold atoms trapped in an optical lattice. In contrast to previous work, we explore a low-velocity regime described by the three-dimensional Bose-Hubbard model that is unaffected by instabilities, and we measure the effect of temperature on the dissipation strength. The damping rate of atomic motion (the analogue of electrical resistance in a solid) in the confining parabolic potential is well fitted by a model that includes finite damping at zero temperature. The low-temperature behaviour is consistent with the theory of quantum tunnelling of phase slips, whereas at higher temperatures a crossover consistent with a transition to thermal activation of phase slips is evident. Motion-induced features reminiscent of vortices and vortex rings associated with phase slips are also observed in time-of-flight imaging. These results clarify the role of phase slips in superfluid systems. They may also be of relevance in understanding the source of metallic phases observed in thin films, or serve as a test bed for theories of bosonic dissipation based upon variants of the Bose-Hubbard model.

  8. Bifurcations and Patterns in Nonlinear Dissipative Systems

    Energy Technology Data Exchange (ETDEWEB)

    Guenter Ahlers

    2005-05-27

    This project consists of experimental investigations of heat transport, pattern formation, and bifurcation phenomena in non-linear non-equilibrium fluid-mechanical systems. These issues are studies in Rayleigh-B\\'enard convection, using both pure and multicomponent fluids. They are of fundamental scientific interest, but also play an important role in engineering, materials science, ecology, meteorology, geophysics, and astrophysics. For instance, various forms of convection are important in such diverse phenomena as crystal growth from a melt with or without impurities, energy production in solar ponds, flow in the earth's mantle and outer core, geo-thermal stratifications, and various oceanographic and atmospheric phenomena. Our work utilizes computer-enhanced shadowgraph imaging of flow patterns, sophisticated digital image analysis, and high-resolution heat transport measurements.

  9. Randomized control of open quantum systems

    CERN Document Server

    Viola, L

    2006-01-01

    The problem of open-loop dynamical control of generic open quantum systems is addressed. In particular, I focus on the task of effectively switching off environmental couplings responsible for unwanted decoherence and dissipation effects. After revisiting the standard framework for dynamical decoupling via deterministic controls, I describe a different approach whereby the controller intentionally acquires a random component. An explicit error bound on worst-case performance of stochastic decoupling is presented.

  10. Quantum Cost Efficient Reversible BCD Adder for Nanotechnology Based Systems

    CERN Document Server

    Islam, Md Saiful; Begum, Zerina

    2011-01-01

    Reversible logic allows low power dissipating circuit design and founds its application in cryptography, digital signal processing, quantum and optical information processing. This paper presents a novel quantum cost efficient reversible BCD adder for nanotechnology based systems using PFAG gate. It has been demonstrated that the proposed design offers less hardware complexity and requires minimum number of garbage outputs than the existing counterparts. The remarkable property of the proposed designs is that its quantum realization is given in NMR technology.

  11. Statistics of the dissipated energy in driven diffusive systems.

    Science.gov (United States)

    Lasanta, A; Hurtado, Pablo I; Prados, A

    2016-03-01

    Understanding the physics of non-equilibrium systems remains one of the major open questions in statistical physics. This problem can be partially handled by investigating macroscopic fluctuations of key magnitudes that characterise the non-equilibrium behaviour of the system of interest; their statistics, associated structures and microscopic origin. During the last years, some new general and powerful methods have appeared to delve into fluctuating behaviour that have drastically changed the way to address this problem in the realm of diffusive systems: macroscopic fluctuation theory (MFT) and a set of advanced computational techniques that make it possible to measure the probability of rare events. Notwithstanding, a satisfactory theory is still lacking in a particular case of intrinsically non-equilibrium systems, namely those in which energy is not conserved but dissipated continuously in the bulk of the system (e.g. granular media). In this work, we put forward the dissipated energy as a relevant quantity in this case and analyse in a pedagogical way its fluctuations, by making use of a suitable generalisation of macroscopic fluctuation theory to driven dissipative media.

  12. Quantum system identification

    CERN Document Server

    Raginsky, M

    2003-01-01

    We formulate and study, in general terms, the problem of quantum system identification, i.e., the determination (or estimation) of unknown quantum channels through their action on suitably chosen input density operators. We also present a quantitative analysis of the worst-case performance of these schemes.

  13. Quantum Vacuum Fluctuations in Presence of Dissipative Bodies: Dynamical Approach for Non-Equilibrium and Squeezed States

    CERN Document Server

    Lopez, Adrian E Rubio

    2016-01-01

    This work contributes to the study of non-equilibrium aspects of the Casimir forces with the introduction of squeezed states in the calculations. Throughout this article two main results can be found, being both strongly correlated. Primarily, the more formal result involves the development of a first-principles canonical quantization formalism to study the vacuum in presence different dissipative bodies in completely general scenarios. We considered a one-dimensional quantum scalar field interacting with the volume elements' degrees of freedom of the material bodies, which are modeled as composite systems consisting in a harmonic oscillators interacting with an environment. Solving the full dynamics of the composite system through its Heisenberg equations, we studied each contribution to the field operator by employing general properties of the Green function. We deduced the long-time limit of the field operator. In agreement with previous works, we showed that the expectation values of the components of the...

  14. Quantum System Identification

    CERN Document Server

    Burgarth, Daniel

    2011-01-01

    The aim of quantum system identification is to estimate the ingredients inside a black box, in which some quantum-mechanical unitary process takes place, by just looking at its input-output behavior. Here we establish a basic and general framework for quantum system identification, that allows us to classify how much knowledge about the quantum system is attainable, in principle, from a given experimental setup. Prior knowledge on some elements of the black box helps the system identification. We present an example in which a Bell measurement is more efficient to identify the system. When the topology of the system is known, the framework enables us to establish a general criterion for the estimability of the coupling constants in its Hamiltonian.

  15. CONCEPTUAL ANALYSIS AND RANDOM ATTRACTOR FOR DISSIPATIVE RANDOM DYNAMICAL SYSTEMS

    Institute of Scientific and Technical Information of China (English)

    Li Yuhong; Zdzistaw Brze(z)niak; Zhou Jianzhong

    2008-01-01

    The aim of this work is to understand better the long time behaviour of asymptotically compact random dynamical systems (RDS), which can be generated by solutions of some stochastic partial differential equations on unbounded domains. The conceptual analysis for the long time behavior of RDS will be done through some examples. An application of those analysis will be demonstrated through the proof of the existence of random attractors for asymptotically compact dissipative RDS.

  16. Quantum Simulation for Open-System Dynamics

    Science.gov (United States)

    Wang, Dong-Sheng; de Oliveira, Marcos Cesar; Berry, Dominic; Sanders, Barry

    2013-03-01

    Simulations are essential for predicting and explaining properties of physical and mathematical systems yet so far have been restricted to classical and closed quantum systems. Although forays have been made into open-system quantum simulation, the strict algorithmic aspect has not been explored yet is necessary to account fully for resource consumption to deliver bounded-error answers to computational questions. An open-system quantum simulator would encompass classical and closed-system simulation and also solve outstanding problems concerning, e.g. dynamical phase transitions in non-equilibrium systems, establishing long-range order via dissipation, verifying the simulatability of open-system dynamics on a quantum Turing machine. We construct an efficient autonomous algorithm for designing an efficient quantum circuit to simulate many-body open-system dynamics described by a local Hamiltonian plus decoherence due to separate baths for each particle. The execution time and number of gates for the quantum simulator both scale polynomially with the system size. DSW funded by USARO. MCO funded by AITF and Brazilian agencies CNPq and FAPESP through Instituto Nacional de Ciencia e Tecnologia-Informacao Quantica (INCT-IQ). DWB funded by ARC Future Fellowship (FT100100761). BCS funded by AITF, CIFAR, NSERC and USARO.

  17. Beyond mean-field bistability in driven-dissipative lattices: Bunching-antibunching transition and quantum simulation

    Science.gov (United States)

    Mendoza-Arenas, J. J.; Clark, S. R.; Felicetti, S.; Romero, G.; Solano, E.; Angelakis, D. G.; Jaksch, D.

    2016-02-01

    In the present work we investigate the existence of multiple nonequilibrium steady states in a coherently driven X Y lattice of dissipative two-level systems. A commonly used mean-field ansatz, in which spatial correlations are neglected, predicts a bistable behavior with a sharp shift between low- and high-density states. In contrast one-dimensional matrix product methods reveal these effects to be artifacts of the mean-field approach, with both disappearing once correlations are taken fully into account. Instead, a bunching-antibunching transition emerges. This indicates that alternative approaches should be considered for higher spatial dimensions, where classical simulations are currently infeasible. Thus we propose a circuit QED quantum simulator implementable with current technology to enable an experimental investigation of the model considered.

  18. Observation of parity-time symmetry breaking transitions in a dissipative Floquet system of ultracold atoms

    CERN Document Server

    Li, Jiaming; Liu, Ji; de Melo, Leonardo; Joglekar, Yogesh N; Luo, Le

    2016-01-01

    Open physical systems with balanced loss and gain exhibit a transition, absent in their solitary counterparts, which engenders modes that exponentially decay or grow with time and thus spontaneously breaks the parity-time PT symmetry. This PT-symmetry breaking is induced by modulating the strength or the temporal profile of the loss and gain, but also occurs in a pure dissipative system without gain. It has been observed that, in classical systems with mechanical, electrical, and electromagnetic setups with static loss and gain, the PT-symmetry breaking transition leads to extraordinary behavior and functionalities. However, its observation in a quantum system is yet to be realized. Here we report on the first quantum simulation of PT-symmetry breaking transitions using ultracold Li-6 atoms. We simulate static and Floquet dissipative Hamiltonians by generating state-dependent atom loss in a noninteracting Fermi gas, and observe the PT-symmetry breaking transitions by tracking the atom number for each state. W...

  19. Finite and profinite quantum systems

    CERN Document Server

    Vourdas, Apostolos

    2017-01-01

    This monograph provides an introduction to finite quantum systems, a field at the interface between quantum information and number theory, with applications in quantum computation and condensed matter physics. The first major part of this monograph studies the so-called `qubits' and `qudits', systems with periodic finite lattice as position space. It also discusses the so-called mutually unbiased bases, which have applications in quantum information and quantum cryptography. Quantum logic and its applications to quantum gates is also studied. The second part studies finite quantum systems, where the position takes values in a Galois field. This combines quantum mechanics with Galois theory. The third part extends the discussion to quantum systems with variables in profinite groups, considering the limit where the dimension of the system becomes very large. It uses the concepts of inverse and direct limit and studies quantum mechanics on p-adic numbers. Applications of the formalism include quantum optics and ...

  20. Efficient method for the calculation of dissipative quantum transport in quantum cascade lasers.

    Science.gov (United States)

    Greck, Peter; Birner, Stefan; Huber, Bernhard; Vogl, Peter

    2015-03-09

    We present a novel and very efficient method for calculating quantum transport in quantum cascade lasers (QCLs). It follows the nonequilibrium Green's function (NEGF) framework but sidesteps the calculation of lesser self-energies by replacing them by a quasi-equilibrium expression. This method generalizes the phenomenological Büttiker probe model by taking into account individual scattering mechanisms. It is orders of magnitude more efficient than a fully self-consistent NEGF calculation for realistic devices. We apply this method to a new THz QCL design which works up to 250 K - according to our calculations.

  1. Quantum many body systems

    Energy Technology Data Exchange (ETDEWEB)

    Rivasseau, Vincent [Paris-Sud Univ. Orsay (France). Laboratoire de Physique Theorique; Seiringer, Robert [McGill Univ., Montreal, QC (Canada). Dept. of Mathematics and Statistics; Solovej, Jan Philip [Copenhagen Univ. (Denmark). Dept. of Mathematics; Spencer, Thomas [Institute for Advanced Study, Princeton, NJ (United States). School of Mathematics

    2012-11-01

    The book is based on the lectures given at the CIME school ''Quantum many body systems'' held in the summer of 2010. It provides a tutorial introduction to recent advances in the mathematics of interacting systems, written by four leading experts in the field: V. Rivasseau illustrates the applications of constructive Quantum Field Theory to 2D interacting electrons and their relation to quantum gravity; R. Seiringer describes a proof of Bose-Einstein condensation in the Gross-Pitaevski limit and explains the effects of rotating traps and the emergence of lattices of quantized vortices; J.-P. Solovej gives an introduction to the theory of quantum Coulomb systems and to the functional analytic methods used to prove their thermodynamic stability; finally, T. Spencer explains the supersymmetric approach to Anderson localization and its relation to the theory of random matrices. All the lectures are characterized by their mathematical rigor combined with physical insights.

  2. Analysis of base isolation and energy dissipation systems for NPP structures using fragility models

    Energy Technology Data Exchange (ETDEWEB)

    Vulpe, A. [Technical Univ. of Iasi (Romania). Dept. of Structural Mechanics; Carausu, A. [Technical Univ. of Iasi (Romania). Dept. od Mathematics

    1995-12-31

    Some extensions of analytical models for base isolation and energy dissipation systems, involving fragility models, are presented. The equation of motion is extended with a term corresponding to Energy Dissipation effect, and the fragility of IEDS (Isolation and Energy Dissipations Systems) is evaluated using a bilinear regression line. (author). 11 refs., 2 figs.

  3. Evolutionary Conditions in the Dissipative MHD System Revisited

    CERN Document Server

    Inoue, Tsuyoshi

    2007-01-01

    The evolutionary conditions for the dissipative continuous magnetohydrodynamic (MHD) shocks are studied. We modify Hada's approach in the stability analysis of the MHD shock waves. The matching conditions between perturbed shock structure and asymptotic wave modes shows that all types of the MHD shocks, including the intermediate shocks, are evolutionary and perturbed solutions are uniquely defined. We also adopt our formalism to the MHD shocks in the system with resistivity without viscosity, which is often used in numerical simulation, and show that all types of shocks that are found in the system satisfy the evolutionary condition and perturbed solutions are uniquely defined. These results suggest that the intermediate shocks may appear in reality.

  4. Controlling the quantum-memory-assisted entropic uncertainty relation by quantum-jump-based feedback control in dissipative environments

    Science.gov (United States)

    Yu, Min; Fang, Mao-Fa

    2017-09-01

    The dynamic properties of the quantum-memory-assisted entropic uncertainty relation for a system comprised of a qubit to be measured and a memory qubit are investigated. We explore the behaviors of the entropic uncertainty and its lower bound in three different cases: Only one of the two qubits interacts with an external environment and subjects to quantum-jump-based feedback control, or both of the two qubits independently experience their own environments and local quantum-jump-based feedback control. Our results reveal that the quantum-jump-based feedback control with an appropriate feedback parameter can reduce the entropic uncertainty and its lower bound, and for the three different scenarios, the reduction in the uncertainty relates to different physical quantities. Besides, we find out that the quantum-jump-based feedback control not only can remarkably decrease the entropic uncertainty, but also can make the uncertainty reach its lower bound where the dynamical map becomes unital.

  5. Dynamics of a Landau-Zener transitions in a two-level system driven by a dissipative environment

    Science.gov (United States)

    Ateuafack, M. E.; Diffo, J. T.; Fai, L. C.

    2016-02-01

    The paper investigates the effects of a two-level quantum system coupled to transversal and longitudinal dissipative environment. The time-dependent phase accumulation, LZ transition probability and entropy in the presence of fast-ohmic, sub-ohmic and super-ohmic quantum noise are derived. Analytical results are obtained in terms of temperature, dissipation strength, LZ parameter and bath cutoff frequency. The bath is observed to modify the standard occupation difference by a decaying random phase factor and also produces dephasing during the transfer of population. The dephasing characteristics or the initial non-zero decoherence rate are observed to increase in time with the bath temperature and depend on the system-bath coupling strength and cutoff frequency. These parameters are found to strongly affect the memory and thus tailor the coherence process of the system.

  6. Dynamics of a Landau–Zener transitions in a two-level system driven by a dissipative environment

    Energy Technology Data Exchange (ETDEWEB)

    Ateuafack, M.E., E-mail: esouamath@yahoo.fr [Mesoscopic and Multilayer Structures Laboratory, Department of Physics, Faculty of Science, University of Dschang (Cameroon); Diffo, J.T., E-mail: diffojaures@yahoo.com [Mesoscopic and Multilayer Structures Laboratory, Department of Physics, Faculty of Science, University of Dschang (Cameroon); Department of Physics, Higher Teachers' Training College, The University of Maroua, PO Box 55 Maroua (Cameroon); Fai, L.C., E-mail: corneliusfai@yahoo.fr [Mesoscopic and Multilayer Structures Laboratory, Department of Physics, Faculty of Science, University of Dschang (Cameroon)

    2016-02-15

    The paper investigates the effects of a two-level quantum system coupled to transversal and longitudinal dissipative environment. The time-dependent phase accumulation, LZ transition probability and entropy in the presence of fast-ohmic, sub-ohmic and super-ohmic quantum noise are derived. Analytical results are obtained in terms of temperature, dissipation strength, LZ parameter and bath cutoff frequency. The bath is observed to modify the standard occupation difference by a decaying random phase factor and also produces dephasing during the transfer of population. The dephasing characteristics or the initial non-zero decoherence rate are observed to increase in time with the bath temperature and depend on the system-bath coupling strength and cutoff frequency. These parameters are found to strongly affect the memory and thus tailor the coherence process of the system.

  7. Cluster Mean-Field Approach to the Steady-State Phase Diagram of Dissipative Spin Systems

    Directory of Open Access Journals (Sweden)

    Jiasen Jin

    2016-07-01

    Full Text Available We show that short-range correlations have a dramatic impact on the steady-state phase diagram of quantum driven-dissipative systems. This effect, never observed in equilibrium, follows from the fact that ordering in the steady state is of dynamical origin, and is established only at very long times, whereas in thermodynamic equilibrium it arises from the properties of the (free energy. To this end, by combining the cluster methods extensively used in equilibrium phase transitions to quantum trajectories and tensor-network techniques, we extend them to nonequilibrium phase transitions in dissipative many-body systems. We analyze in detail a model of spin-1/2 on a lattice interacting through an XYZ Hamiltonian, each of them coupled to an independent environment that induces incoherent spin flips. In the steady-state phase diagram derived from our cluster approach, the location of the phase boundaries and even its topology radically change, introducing reentrance of the paramagnetic phase as compared to the single-site mean field where correlations are neglected. Furthermore, a stability analysis of the cluster mean field indicates a susceptibility towards a possible incommensurate ordering, not present if short-range correlations are ignored.

  8. Cluster Mean-Field Approach to the Steady-State Phase Diagram of Dissipative Spin Systems

    Science.gov (United States)

    Jin, Jiasen; Biella, Alberto; Viyuela, Oscar; Mazza, Leonardo; Keeling, Jonathan; Fazio, Rosario; Rossini, Davide

    2016-07-01

    We show that short-range correlations have a dramatic impact on the steady-state phase diagram of quantum driven-dissipative systems. This effect, never observed in equilibrium, follows from the fact that ordering in the steady state is of dynamical origin, and is established only at very long times, whereas in thermodynamic equilibrium it arises from the properties of the (free) energy. To this end, by combining the cluster methods extensively used in equilibrium phase transitions to quantum trajectories and tensor-network techniques, we extend them to nonequilibrium phase transitions in dissipative many-body systems. We analyze in detail a model of spin-1 /2 on a lattice interacting through an X Y Z Hamiltonian, each of them coupled to an independent environment that induces incoherent spin flips. In the steady-state phase diagram derived from our cluster approach, the location of the phase boundaries and even its topology radically change, introducing reentrance of the paramagnetic phase as compared to the single-site mean field where correlations are neglected. Furthermore, a stability analysis of the cluster mean field indicates a susceptibility towards a possible incommensurate ordering, not present if short-range correlations are ignored.

  9. On hyperbolic-dissipative systems of composite type

    Science.gov (United States)

    Tan, Zhong; Wang, Yanjin

    2016-01-01

    The Shizuta-Kawashima condition plays the fundamental role in guaranteeing global stability for systems of hyperbolic-parabolic/hyperbolic with relaxation. However, there are many important physical systems not satisfying this coupling condition, which are of composite type with regard to dissipation. The compressible Navier-Stokes equations with zero heat conductivity and Euler equations of adiabatic flow through porous media are two typical examples. In this paper, we construct the global unique solution near constant equilibria to these two systems in three dimensions for the small Hℓ (ℓ > 3) initial data. Our proof is based on a reformation of the systems in terms of the pressure, velocity and entropy, a scaled energy estimates with minimal fractional derivative counts in conjunction with the linear L2-L2 decay estimates to extract a fast enough decay of velocity gradient, which is used to close the energy estimates for the non-dissipative entropy. We also include an application to certain two-phase models.

  10. A Forbidden Web in a Quasi-Dissipative System

    Institute of Scientific and Technical Information of China (English)

    DAI Jun; WANG Wen-Xiu; JIANG Yu-Mei; HE Yue; CHEN Wen; HE Da-Ren

    2005-01-01

    @@ A simultaneous transition of the system nature from everywhere smooth and conservative to piecewise smooth and quasi-dissipative is observed in a kicked billiard when adjusting single controlling parameter.The transition induces the appearance of a special kind of fat fractal forbidden web, which grows up and cuts off more parts from the original conservative stochastic web so that the remnant transient web becomes increasingly thinner.We numerically show a power law σ∝βν, where σ is the fractal exponent of the forbidden web,β is the control parameter, and the scaling exponent ν = 0.288 ± 0.007, which describes this process.

  11. Quantum degenerate systems

    Energy Technology Data Exchange (ETDEWEB)

    Micheli, Fiorenza de [Centro de Estudios Cientificos, Arturo Prat 514, Valdivia (Chile); Instituto de Fisica, Pontificia Universidad Catolica de Valparaiso, Casilla 4059, Valparaiso (Chile); Zanelli, Jorge [Centro de Estudios Cientificos, Arturo Prat 514, Valdivia (Chile); Universidad Andres Bello, Av. Republica 440, Santiago (Chile)

    2012-10-15

    A degenerate dynamical system is characterized by a symplectic structure whose rank is not constant throughout phase space. Its phase space is divided into causally disconnected, nonoverlapping regions in each of which the rank of the symplectic matrix is constant, and there are no classical orbits connecting two different regions. Here the question of whether this classical disconnectedness survives quantization is addressed. Our conclusion is that in irreducible degenerate systems-in which the degeneracy cannot be eliminated by redefining variables in the action-the disconnectedness is maintained in the quantum theory: there is no quantum tunnelling across degeneracy surfaces. This shows that the degeneracy surfaces are boundaries separating distinct physical systems, not only classically, but in the quantum realm as well. The relevance of this feature for gravitation and Chern-Simons theories in higher dimensions cannot be overstated.

  12. End-Directedness and Context in Nonliving Dissipative Systems

    Science.gov (United States)

    Dixon, James A.; Kay, Bruce A.; Davis, Tehran J.; Kondepudi, Dilip

    Biological organisms are distinguished from non-living systems, in part, by their ability to choose and strive towards particular ends. This end-directed behavior is seen across all five biological kingdoms, from single-celled organisms to the most advanced primates. The ubiquitous nature of end-directedness, across such a wide variety of biological entities, suggests that a deeper principle may be at work. We propose that end-directedness, rather than being a special ability of living systems, is actually a fundamental property of a larger class of physical systems, called dissipative structures, which are formed and maintained by the flow of energy and matter. Our work shows that dissipative structures "behave so as to persist", seeking states that increase their rate of entropy production, and thus facilitate their own persistence. In addition, we suggest that biological entities create their exquisite sensitivity to context by interweaving this fundamental end-directedness with the contextual and physical constraints of their environments. The result is a repertoire of complex behavior. We provide an example of such complex behavior emerging from contextual and physical constraints coupled with end-directedness.

  13. Energy diffusion controlled reaction rate in dissipative Hamiltonian systems

    Institute of Scientific and Technical Information of China (English)

    Deng Mao-Lin; Zhu Wei-Qiu

    2007-01-01

    In this paper the energy diffusion controlled reaction rate in dissipative Hamiltonian systems is investigated by using the stochastic averaging method for quasi Hamiltonian systems. The boundary value problem of mean first-passage time (MFPT) of averaged system is formulated and the energy diffusion controlled reaction rate is obtained as the inverse of MFPT. The energy diffusion controlled reaction rate in the classical Kramers bistable potential and in a two-dimensional bistable potential with a heat bath are obtained by using the proposed approach respectively. The obtained results are then compared with those from Monte Carlo simulation of original systems and from the classical Kramers theory. It is shown that the reaction rate obtained by using the proposed approach agrees well with that from Monte Carlo simulation and is more accurate than the classical Kramers rate.

  14. Quantum Cybernetics and Complex Quantum Systems Science - A Quantum Connectionist Exploration

    OpenAIRE

    Gonçalves, Carlos Pedro

    2014-01-01

    Quantum cybernetics and its connections to complex quantum systems science is addressed from the perspective of complex quantum computing systems. In this way, the notion of an autonomous quantum computing system is introduced in regards to quantum artificial intelligence, and applied to quantum artificial neural networks, considered as autonomous quantum computing systems, which leads to a quantum connectionist framework within quantum cybernetics for complex quantum computing systems. Sever...

  15. Quantum Cybernetics and Complex Quantum Systems Science - A Quantum Connectionist Exploration

    OpenAIRE

    Gonçalves, Carlos Pedro

    2014-01-01

    Quantum cybernetics and its connections to complex quantum systems science is addressed from the perspective of complex quantum computing systems. In this way, the notion of an autonomous quantum computing system is introduced in regards to quantum artificial intelligence, and applied to quantum artificial neural networks, considered as autonomous quantum computing systems, which leads to a quantum connectionist framework within quantum cybernetics for complex quantum computing systems. Sever...

  16. Scheme of thinking quantum systems

    CERN Document Server

    Yukalov, V I

    2009-01-01

    A general approach describing quantum decision procedures is developed. The approach can be applied to quantum information processing, quantum computing, creation of artificial quantum intelligence, as well as to analyzing decision processes of human decision makers. Our basic point is to consider an active quantum system possessing its own strategic state. Processing information by such a system is analogous to the cognitive processes associated to decision making by humans. The algebra of probability operators, associated with the possible options available to the decision maker, plays the role of the algebra of observables in quantum theory of measurements. A scheme is advanced for a practical realization of decision procedures by thinking quantum systems. Such thinking quantum systems can be realized by using spin lattices, systems of magnetic molecules, cold atoms trapped in optical lattices, ensembles of quantum dots, or multilevel atomic systems interacting with electromagnetic field.

  17. Scheme of thinking quantum systems

    Science.gov (United States)

    Yukalov, V. I.; Sornette, D.

    2009-11-01

    A general approach describing quantum decision procedures is developed. The approach can be applied to quantum information processing, quantum computing, creation of artificial quantum intelligence, as well as to analyzing decision processes of human decision makers. Our basic point is to consider an active quantum system possessing its own strategic state. Processing information by such a system is analogous to the cognitive processes associated to decision making by humans. The algebra of probability operators, associated with the possible options available to the decision maker, plays the role of the algebra of observables in quantum theory of measurements. A scheme is advanced for a practical realization of decision procedures by thinking quantum systems. Such thinking quantum systems can be realized by using spin lattices, systems of magnetic molecules, cold atoms trapped in optical lattices, ensembles of quantum dots, or multilevel atomic systems interacting with electromagnetic field.

  18. Dissipative Boussinesq System of Equations in the Bénard-Marangoni Phenomenon

    CERN Document Server

    Kraenkel, R A; Pereira, J G; Manna, M A

    1993-01-01

    Abstract: By using the long-wave approximation, a system of coupled evolution equations for the bulk velocity and the surface perturbations of a dissipation, and it can be interpreted as a dissipative generalization of the usual Boussinesq system of equations. As a particular case, a strictly dissipative version of the Boussinesq system is obtained. Finnaly, some speculations are made on the nature of the physical phenomena described by this system of equations.

  19. Quantum iterated function systems.

    Science.gov (United States)

    Łoziński, Artur; Zyczkowski, Karol; Słomczyński, Wojciech

    2003-10-01

    An iterated function system (IFS) is defined by specifying a set of functions in a classical phase space, which act randomly on an initial point. In an analogous way, we define a quantum IFS (QIFS), where functions act randomly with prescribed probabilities in the Hilbert space. In a more general setting, a QIFS consists of completely positive maps acting in the space of density operators. This formalism is designed to describe certain problems of nonunitary quantum dynamics. We present exemplary classical IFSs, the invariant measure of which exhibits fractal structure, and study properties of the corresponding QIFSs and their invariant states.

  20. Nonconventional fluctuation dissipation process in non-Hamiltonian dynamical systems

    Science.gov (United States)

    Bianucci, Marco

    2016-08-01

    Here, we introduce a statistical approach derived from dynamics, for the study of the geophysical fluid dynamics phenomena characterized by a weak interaction among the variables of interest and the rest of the system. The approach is reminiscent of the one developed some years ago [M. Bianucci, R. Mannella, P. Grigolini and B. J. West, Phys. Rev. E 51, 3002 (1995)] to derive statistical mechanics of macroscopic variables on interest starting from Hamiltonian microscopic dynamics. However, in the present work, we are interested to generalize this approach beyond the context of the foundation of thermodynamics, in fact, we take into account the cases where the system of interest could be non-Hamiltonian (dissipative) and also the interaction with the irrelevant part can be of a more general type than Hamiltonian. As such example, we will refer to a typical case from geophysical fluid dynamics: the complex ocean-atmosphere interaction that gives rise to the El Niño Southern Oscillation (ENSO). Here, changing all the scales, the role of the “microscopic” system is played by the atmosphere, while the ocean (or some ocean variables) plays the role of the intrinsically dissipative macroscopic system of interest. Thus, the chaotic and divergent features of the fast atmosphere dynamics remains in the decaying properties of the correlation functions and of the response function of the atmosphere variables, while the exponential separation of the perturbed (or close) single trajectories does not play a direct role. In the present paper, we face this problem in the frame of a not formal Langevin approach, limiting our discussion to physically based rather than mathematics arguments. Elsewhere, we obtain these results via a much more formal procedure, using the Zwanzing projection method and some elements from the Lie Algebra field.

  1. Quantum-statistical approach to electromagnetic wave propagation and dissipation inside dielectric media, nanophotonic and plasmonic waveguides

    CERN Document Server

    Zloshchastiev, Konstantin G

    2016-01-01

    Quantum-statistical effects occur during the propagation of electromagnetic (EM) waves inside the dielectric media or metamaterials, which include a large class of nanophotonic and plasmonic waveguides with dissipation and noise. Exploiting the formal analogy between the Schroedinger equation and the Maxwell equations for dielectric linear media, we rigorously derive the effective Hamiltonian operator which describes such propagation. This operator turns out to be essentially non-Hermitian in general, and pseudo-Hermitian in some special cases. Using the density operator approach for general non-Hermitian Hamiltonians, we derive a master equation that describes the statistical ensembles of EM wave modes. The method also describes the quantum dissipative and decoherence processes which happen during the wave's propagation, and, among other things, it reveals the conditions that are necessary to control the energy and information loss inside the above-mentioned materials.

  2. Nonstationary Superconductivity: Quantum Dissipation and Time-Dependent Ginzburg-Landau Equation

    Directory of Open Access Journals (Sweden)

    Anatoly A. Barybin

    2011-01-01

    Full Text Available Transport equations of the macroscopic superfluid dynamics are revised on the basis of a combination of the conventional (stationary Ginzburg-Landau equation and Schrödinger's equation for the macroscopic wave function (often called the order parameter by using the well-known Madelung-Feynman approach to representation of the quantum-mechanical equations in hydrodynamic form. Such an approach has given (a three different contributions to the resulting chemical potential for the superfluid component, (b a general hydrodynamic equation of superfluid motion, (c the continuity equation for superfluid flow with a relaxation term involving the phenomenological parameters GL and GL, (d a new version of the time-dependent Ginzburg-Landau equation for the modulus of the order parameter which takes into account dissipation effects and reflects the charge conservation property for the superfluid component. The conventional Ginzburg-Landau equation also follows from our continuity equation as a particular case of stationarity. All the results obtained are mutually consistent within the scope of the chosen phenomenological description and, being model-neutral, applicable to both the low-c and high-c superconductors.

  3. Quantum chemical insights in energy dissipation and carotenoid radical cation formation in light harvesting complexes.

    Science.gov (United States)

    Wormit, Michael; Dreuw, Andreas

    2007-06-21

    Light harvesting complexes (LHCs) have been identified in all photosynthetic organisms. To understand their function in light harvesting and energy dissipation, detailed knowledge about possible excitation energy transfer (EET) and electron transfer (ET) processes in these pigment proteins is of prime importance. This again requires the study of electronically excited states of the involved pigment molecules, in LHCs of chlorophylls and carotenoids. This paper represents a critical review of recent quantum chemical calculations on EET and ET processes between pigment pairs relevant for the major LHCs of green plants (LHC-II) and of purple bacteria (LH2). The theoretical methodology for a meaningful investigation of such processes is described in detail, and benefits and limitations of standard methods are discussed. The current status of excited state calculations on chlorophylls and carotenoids is outlined. It is focused on the possibility of EET and ET in the context of chlorophyll fluorescence quenching in LHC-II and carotenoid radical cation formation in LH2. In the context of non-photochemical quenching of green plants, it is shown that replacement of the carotenoid violaxanthin by zeaxanthin in its binding pocket of LHC-II can not result in efficient quenching. In LH2, our computational results give strong evidence that the S(1) states of the carotenoids are involved in carotenoid cation formation. By comparison of theoretical findings with recent experimental data, a general mechanism for carotenoid radical cation formation is suggested.

  4. Entanglement dynamics of a pure bipartite system in dissipative environments

    Energy Technology Data Exchange (ETDEWEB)

    Tahira, Rabia; Ikram, Manzoor; Azim, Tasnim; Suhail Zubairy, M [Centre for Quantum Physics, COMSATS Institute of Information Technology, Islamabad (Pakistan)

    2008-10-28

    We investigate the phenomenon of sudden death of entanglement in a bipartite system subjected to dissipative environments with arbitrary initial pure entangled state between two atoms. We find that in a vacuum reservoir the presence of the state where both atoms are in excited states is a necessary condition for the sudden death of entanglement. Otherwise entanglement remains for an infinite time and decays asymptotically with the decay of individual qubits. For pure 2-qubit entangled states in a thermal environment, we observe that the sudden death of entanglement always happens. The sudden death time of the entangled states is related to the temperature of the reservoir and the initial preparation of the entangled states.

  5. Quantum critical points in quantum impurity systems

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Hyun Jung [Theoretische Physik III, Elektronische Korrelationen und Magnetismus, Universitaet Augsburg (Germany); Bulla, Ralf [Theoretische Physik III, Elektronische Korrelationen und Magnetismus, Universitaet Augsburg (Germany)]. E-mail: bulla@cpfs.mpg.de

    2005-04-30

    The numerical renormalization group method is used to investigate zero-temperature phase transitions in quantum impurity systems, in particular in the soft-gap Anderson model, where an impurity couples to a non-trivial fermionic bath. In this case, zero-temperature phase transitions occur between two different phases whose fixed points can be built up of non-interacting single-particle states. However, the quantum critical point cannot be described by non-interacting fermionic or bosonic excitations.

  6. Quantum critical points in quantum impurity systems

    Science.gov (United States)

    Lee, Hyun Jung; Bulla, Ralf

    2005-04-01

    The numerical renormalization group method is used to investigate zero-temperature phase transitions in quantum impurity systems, in particular in the soft-gap Anderson model, where an impurity couples to a non-trivial fermionic bath. In this case, zero-temperature phase transitions occur between two different phases whose fixed points can be built up of non-interacting single-particle states. However, the quantum critical point cannot be described by non-interacting fermionic or bosonic excitations.

  7. Dynamics of a qubit coupled to a dissipative nonlinear quantum oscillator: an effective bath approach

    CERN Document Server

    Vierheilig, Carmen; Grifoni, Milena

    2010-01-01

    We consider a qubit coupled to a nonlinear quantum oscillator, the latter coupled to an Ohmic bath, and investigate the qubit dynamics. This composed system can be mapped onto that of a qubit coupled to an effective bath. An approximate mapping procedure to determine the spectral density of the effective bath is given. Specifically, within a linear response approximation the effective spectral density is given by the knowledge of the linear susceptibility of the nonlinear quantum oscillator. To determine the actual form of the susceptibility, we consider its periodically driven counterpart, the problem of the quantum Duffing oscillator within linear response theory in the driving amplitude. Knowing the effective spectral density, the qubit dynamics is investigated. In particular, an analytic formula for the qubit's population difference is derived. Within the regime of validity of our theory, a very good agreement is found with predictions obtained from a Bloch-Redfield master equation approach applied to the...

  8. Fröhlich Condensate: Emergence of Synergetic Dissipative Structures in Information Processing Biological and Condensed Matter Systems

    Directory of Open Access Journals (Sweden)

    Roberto Luzzi

    2012-10-01

    Full Text Available We consider the case of a peculiar complex behavior in open boson systems sufficiently away from equilibrium, having relevance in the functioning of information-processing biological and condensed matter systems. This is the so-called Fröhlich–Bose–Einstein condensation, a self-organizing-synergetic dissipative structure, a phenomenon apparently working in biological processes and present in several cases of systems of boson-like quasi-particles in condensed inorganic matter. Emphasis is centered on the quantum-mechanical-statistical irreversible thermodynamics of these open systems, and the informational characteristics of the phenomena.

  9. Dissipative Effect and Tunneling Time

    Directory of Open Access Journals (Sweden)

    Samyadeb Bhattacharya

    2011-01-01

    Full Text Available The quantum Langevin equation has been studied for dissipative system using the approach of Ford et al. Here, we have considered the inverted harmonic oscillator potential and calculated the effect of dissipation on tunneling time, group delay, and the self-interference term. A critical value of the friction coefficient has been determined for which the self-interference term vanishes. This approach sheds new light on understanding the ion transport at nanoscale.

  10. Passivity and Dissipativity as Design and Analysis Tools for Networked Control Systems

    Science.gov (United States)

    Yu, Han

    2012-01-01

    In this dissertation, several control problems are studied that arise when passive or dissipative systems are interconnected and controlled over a communication network. Since communication networks can impact the systems' stability and performance, there is a need to extend the results on control of passive or dissipative systems to networked…

  11. Passivity and Dissipativity as Design and Analysis Tools for Networked Control Systems

    Science.gov (United States)

    Yu, Han

    2012-01-01

    In this dissertation, several control problems are studied that arise when passive or dissipative systems are interconnected and controlled over a communication network. Since communication networks can impact the systems' stability and performance, there is a need to extend the results on control of passive or dissipative systems to networked…

  12. Quantum dynamics of a BEC interacting with a single-mode quantized field under the influence of a dissipation process: thermal and squeezed vacuum reservoirs

    Science.gov (United States)

    Ghasemian, E.; Tavassoly, M. K.

    2017-09-01

    In this paper we consider a system consisting of a number of two-level atoms in a Bose-Einstein condensate (BEC) and a single-mode quantized field, which interact with each other in the presence of two different damping sources, i.e. cavity and atomic reservoirs. The reservoirs which we consider here are thermal and squeezed vacuum ones corresponding to field and atom modes. Strictly speaking, by considering both types of reservoirs for each of the atom and field modes, we investigate the quantum dynamics of the interacting bosons in the system. Then, via solving the quantum Langevin equations for such a dissipative BEC system, we obtain analytical expressions for the time dependence of atomic population inversion, mean atom as well as photon number and quadrature squeezing in the field and atom modes. Our investigations demonstrate that for modeling the real physical systems, considering the dissipation effects is essential. Also, numerical calculations which are presented show that the atomic population inversion, the mean number of atoms in the BEC and the photons in the cavity possess damped oscillatory behavior due to the presence of reservoirs. In addition, non-classical squeezing effects in the field quadrature can be observed especially when squeezed vacuum reservoirs are taken into account. As an outstanding property of this model, we may refer to the fact that one can extract the atom-field coupling constant from the frequency of oscillations in the mentioned quantities such as atomic population inversion.

  13. Correlated electrons in a dissipative environment

    Science.gov (United States)

    Bulla, R.

    2009-12-01

    When a system of correlated electrons is embedded in a dissipative environment, new emergent phenomena might occur due to the interplay of correlation and dissipation. Here we focus on quantum impurity systems with coupling to a bosonic bath. For the theoretical investigation we introduce the bosonic numerical renormalization group method which has been initially set up for the spin-boson model. The role of both correlations and dissipation is described in the context of two-electron transfer systems. We also discuss prospects for the investigation of lattice models of correlated electrons with coupling to a dissipative bath.

  14. Quantum Darwinism and non-Markovian dissipative dynamics from quantum phases of the spin-1/2 X X model

    Science.gov (United States)

    Giorgi, Gian Luca; Galve, Fernando; Zambrini, Roberta

    2015-08-01

    Quantum Darwinism explains the emergence of a classical description of objects in terms of the creation of many redundant registers in an environment containing their classical information. This amplification phenomenon, where only classical information reaches the macroscopic observer and through which different observers can agree on the objective existence of such object, has been revived lately for several types of situations, successfully explaining classicality. We explore quantum Darwinism in the setting of an environment made of two level systems which are initially prepared in the ground state of the XX model, which exhibits different phases; we find that the different phases have different abilities to redundantly acquire classical information about the system, the "ferromagnetic phase" being the only one able to complete quantum Darwinism. At the same time we relate this ability to how non-Markovian the system dynamics is, based on the interpretation that non-Markovian dynamics is associated with backflow of information from environment to system, thus spoiling the information transfer needed for Darwinism. Finally, we explore mixing of bath registers by allowing a small interaction among them, finding that this spoils the stored information as previously found in the literature.

  15. Nonequilibrium fluctuation-dissipation relations for one- and two-particle correlation functions in steady-state quantum transport

    Energy Technology Data Exchange (ETDEWEB)

    Ness, H., E-mail: herve.ness@kcl.ac.uk [Department of Physics, School of Natural and Mathematical Sciences, King' s College London, Strand, London WC2R 2LS (United Kingdom); Department of Physics, University of York, Heslington, York YO10 5DD (United Kingdom); European Theoretical Spectroscopy Facility (ETSF), Liege (Belgium); Dash, L. K. [European Theoretical Spectroscopy Facility (ETSF), Liege (Belgium); Department of Physics and Astronomy, University College London, Gower Street, London WC1E 6BT (United Kingdom)

    2014-04-14

    We study the non-equilibrium (NE) fluctuation-dissipation (FD) relations in the context of quantum thermoelectric transport through a two-terminal nanodevice in the steady-state. The FD relations for the one- and two-particle correlation functions are derived for a model of the central region consisting of a single electron level. Explicit expressions for the FD relations of the Green's functions (one-particle correlations) are provided. The FD relations for the current-current and charge-charge (two-particle) correlations are calculated numerically. We use self-consistent NE Green's functions calculations to treat the system in the absence and in the presence of interaction (electron-phonon) in the central region. We show that, for this model, there is no single universal FD theorem for the NE steady state. There are different FD relations for each different class of problems. We find that the FD relations for the one-particle correlation function are strongly dependent on both the NE conditions and the interactions, while the FD relations of the current-current correlation function are much less dependent on the interaction. The latter property suggests interesting applications for single-molecule and other nanoscale transport experiments.

  16. Nonequilibrium fluctuation-dissipation relations for one- and two-particle correlation functions in steady-state quantum transport.

    Science.gov (United States)

    Ness, H; Dash, L K

    2014-04-14

    We study the non-equilibrium (NE) fluctuation-dissipation (FD) relations in the context of quantum thermoelectric transport through a two-terminal nanodevice in the steady-state. The FD relations for the one- and two-particle correlation functions are derived for a model of the central region consisting of a single electron level. Explicit expressions for the FD relations of the Green's functions (one-particle correlations) are provided. The FD relations for the current-current and charge-charge (two-particle) correlations are calculated numerically. We use self-consistent NE Green's functions calculations to treat the system in the absence and in the presence of interaction (electron-phonon) in the central region. We show that, for this model, there is no single universal FD theorem for the NE steady state. There are different FD relations for each different class of problems. We find that the FD relations for the one-particle correlation function are strongly dependent on both the NE conditions and the interactions, while the FD relations of the current-current correlation function are much less dependent on the interaction. The latter property suggests interesting applications for single-molecule and other nanoscale transport experiments.

  17. Quantum Iterated Function Systems

    CERN Document Server

    Lozinski, A; Slomczynski, W; Lozinski, Artur; Zyczkowski, Karol; Slomczynski, Wojciech

    2003-01-01

    Iterated functions system (IFS) is defined by specifying a set of functions in a classical phase space, which act randomly on the initial point. In an analogous way, we define quantum iterated functions system (QIFS), where functions act randomly with prescribed probabilities in the Hilbert space. In a more general setting a QIFS consists of completely positive maps acting in the space of density operators. We present exemplary classical IFSs, the invariant measure of which exhibits fractal structure, and study properties of the corresponding QIFSs and their invariant state.

  18. The dynamical feature of transition of a Hamiltonian system to a dissipative system

    Institute of Scientific and Technical Information of China (English)

    Zhang Guang-Cai; Zhang Hong-Jun

    2004-01-01

    The mechanism of generation and annihilation of attractors during transition from a Hamiltonian system to a dissipative system is studied numerically using the dissipative standard map. The transient process related to the formationof attracting basins of periodic attractors is studied by discussing the evolution of the KAM tori of the standard map. The result shows that as damping increases, attractors are mainly generated from elliptic orbits of the Hamiltonian system and annihilated by colliding with unstable periodic orbits originating from the corresponding hyperbolic orbits of the Hamiltonian system. The transient process also exhibits the general feature of bifurcation.

  19. Bohm-Aharonov type effects in dissipative atomic systems

    CERN Document Server

    Solomon, A I; Solomon, Allan I.; Schirmer, Sonia G.

    2005-01-01

    A state in quantum mechanics is defined as a positive operator of norm 1. For finite systems, this may be thought of as a positive matrix of trace 1. This constraint of positivity imposes severe restrictions on the allowed evolution of such a state. From the mathematical viewpoint, we describe the two forms of standard dynamical equations - global (Kraus) and local (Lindblad) - and show how each of these gives rise to a semi-group description of the evolution. We then look at specific examples from atomic systems, involving 3-level systems for simplicity, and show how these mathematical constraints give rise to non-intuitive physical phenomena, reminiscent of Bohm-Aharonov effects. In particular, we show that for a multi-level atomic system it is generally impossible to isolate the levels, and this leads to observable effects on the population relaxation and decoherence.

  20. Quantum Monte Carlo simulation of a dissipative chain of Josephson junctions

    Energy Technology Data Exchange (ETDEWEB)

    Bobbert, P.A. (Delft Univ. of Tech. (Netherlands))

    1991-02-01

    The phase diagram of a chain of Josephson junctions with self-capacitance and Ohmic dissipation is studied in a Monte Carlo simulation. The problem is mapped onto a generalized 2d Coulomb gas model. Apart from the expected dipole transition a theoretically predicted quadrupole transition at a critical strength of the dissipation is clearly observed. (orig.).

  1. Darwinism in Quantum Systems?

    CERN Document Server

    Iqbal, A

    2002-01-01

    We find quantum mechanics playing a role in evolutionary dynamics described by the notion of an Evolutionary Stable Strategy (ESS). An ESS being a refinement of Nash equilibrium concept is a stable strategy in an evolutionary game with replicator dynamic as the underlying process. We investigate ESSs in two and three player symmetric quantum games played by the proposed scheme of applying $^{\\prime}$identity$^{\\prime}$ and $^{\\prime}$Pauli spin-flip$^{\\prime}$ operators on an initial state with classical probabilities. The mixed Nash equilibrium (NE) we search for is not affected by a switchover between two forms of the game, one quantized and other classical, however it is an ESS when the game is played classically.We show no such mixed NE exists for two player games but there is a class of three player games where they do exist.Our results imply that an evolutionary approach originating with Darwin's idea of natural selection can be used even for quantum systems. It also indicates the possibility of genetic...

  2. Duality quantum algorithm efficiently simulates open quantum systems

    OpenAIRE

    Shi-Jie Wei; Dong Ruan; Gui-Lu Long

    2016-01-01

    Because of inevitable coupling with the environment, nearly all practical quantum systems are open system, where the evolution is not necessarily unitary. In this paper, we propose a duality quantum algorithm for simulating Hamiltonian evolution of an open quantum system. In contrast to unitary evolution in a usual quantum computer, the evolution operator in a duality quantum computer is a linear combination of unitary operators. In this duality quantum algorithm, the time evolution of the op...

  3. The distribution of absorptive power dissipation in irradiated nanoparticulate system

    Science.gov (United States)

    Li, Jiayu; Yang, Jian; Gu, Xiaobing

    2016-10-01

    The knowledge of local radiant absorption is important to the nanostructure optimization, it is beneficial to the applications in energy harvesting, optical heating, photocatalysis, etc. In this paper, FDTD model is constructed for the distribution of absorptive power dissipation in irradiated nanoparticulate system. The theoretical model extended from Mie theory is used to examine the FDTD model, the parameters and conditions set for FDTD simulation are confirmed based on the comparison. Then, the influence of Ag nanoparticle on the absorptive properties of nearby TiO2 nanoparticle is investigated by FDTD simulation at the wavelength of 0.25 μm. It is indicated that suitable distance between TiO2 and Ag particles is beneficial to the spectral radiant absorption of TiO2 particle. Considering the agglomeration of nanoparticles and the oxidation at the TiO2-Ag interface, the Ag core coated with Al2O3 shell is suggested, and the simulated results indicated that the shell thickness and the Ag core size need to be optimized for enhancing the radiant absorption of TiO2 particle.

  4. Global Classical Solutions to Partially Dissipative Quasilinear Hyperbolic Systems with One Weakly Linearly Degenerate Characteristic

    Institute of Scientific and Technical Information of China (English)

    Peng QU; Cunming LIU

    2012-01-01

    For a kind of partially dissipative quasilinear hyperbolic systems without Shizuta-Kawashima condition,in which all the characteristics,except a weakly linearly degenerate one,are involved in the dissipation,the global existence of H2 classical solution to the Cauchy problem with small initial data is obtained.

  5. On nonlinear controllability and series expansions for Lagrangian systems with dissipative forces

    NARCIS (Netherlands)

    Cortes, J.; Martinez, S.; Bullo, F.

    2002-01-01

    This paper presents series expansions and nonlinear controllability results for Lagrangian systems subject to dissipative forces. The treatment relies on the assumption of dissipative forces of linear isotropic nature. The approach is based on the affine connection formalism for Lagrangian control s

  6. Power-dissipation comparison of two dependability approaches for multi-processor systems

    NARCIS (Netherlands)

    Zhao, Yong; Zhang, Xiao; Kerkhoff, Hans G.; Zhao, Yong

    2013-01-01

    The additional power dissipation involved in introducing a high dependability in multi-processor systems is nowadays becoming a major concern (power-aware dependability). In this paper, the power dissipation components of a recently implemented scan-test based dependability testing approach for a mu

  7. Cauchy Problem for Quasilinear Hyperbolic Systems with Higher Order Dissipative Terms

    Institute of Scientific and Technical Information of China (English)

    Wei-guo Zhang

    2003-01-01

    In this paper, the author studies the global existence, singularities and life span of smooth solutions of the Cauchy problem for a class of quasilinear hyperbolic systems with higher order dissipative terms and gives their applications to nonlinear wave equations with higher order dissipative terms.

  8. Quantum Effects in Biological Systems

    CERN Document Server

    2016-01-01

    Since the last decade the study of quantum mechanical phenomena in biological systems has become a vibrant field of research. Initially sparked by evidence of quantum effects in energy transport that is instrumental for photosynthesis, quantum biology asks the question of how methods and models from quantum theory can help us to understand fundamental mechanisms in living organisms. This approach entails a paradigm change challenging the related disciplines: The successful framework of quantum theory is taken out of its low-temperature, microscopic regimes and applied to hot and dense macroscopic environments, thereby extending the toolbox of biology and biochemistry at the same time. The Quantum Effects in Biological Systems conference is a platform for researchers from biology, chemistry and physics to present and discuss the latest developments in the field of quantum biology. After meetings in Lisbon (2009), Harvard (2010), Ulm (2011), Berkeley (2012), Vienna (2013), Singapore (2014) and Florence (2015),...

  9. Quantum walks public key cryptographic system

    OpenAIRE

    Vlachou, C; Rodrigues, J.; Mateus, P.; Paunković, N.; Souto, A.

    2016-01-01

    Quantum Cryptography is a rapidly developing field of research that benefits from the properties of Quantum Mechanics in performing cryptographic tasks. Quantum walks are a powerful model for quantum computation and very promising for quantum information processing. In this paper, we present a quantum public-key cryptographic system based on quantum walks. In particular, in the proposed protocol the public key is given by a quantum state generated by performing a quantum walk. We show that th...

  10. Robust dissipative filtering for continuous-time polytopic uncertain neutral systems

    Institute of Scientific and Technical Information of China (English)

    Duan Guangren; L(u) Lingling; Wu Aiguo

    2009-01-01

    This article is concerned with the problem of robust dissipative filtering for continuous-time polytopic uncertain neutral systems. The main purpose is to obtain a stable and proper linear filter such that the filtering error system is strictly dissipative. A new criterion for the dissipativity of neutral systems is first provided in terms of linear matrix inequalities (LMI). Then, an LMI sufficient condition for the existence of a robust filter is established and a design procedure is proposed for this type of systems. Two numerical examples are given. One illustrates the less conservativeness of the proposed criterion; the other demonstrates the validity of the filtering design procedure.

  11. Darwinism in quantum systems?

    Science.gov (United States)

    Iqbal, A.; Toor, A. H.

    2002-03-01

    We investigate the role of quantum mechanical effects in the central stability concept of evolutionary game theory, i.e., an evolutionarily stable strategy (ESS). Using two and three-player symmetric quantum games we show how the presence of quantum phenomenon of entanglement can be crucial to decide the course of evolutionary dynamics in a population of interacting individuals.

  12. Scaling laws to quantify tidal dissipation in star-planet systems

    CERN Document Server

    Auclair-Desrotour, Pierre; Poncin-Lafitte, Christophe Le

    2015-01-01

    Planetary systems evolve over secular time scales. One of the key mechanisms that drive this evolution is tidal dissipation. Submitted to tides, stellar and planetary fluid layers do not behave like rocky ones. Indeed, they are the place of resonant gravito-inertial waves. Therefore, tidal dissipation in fluid bodies strongly depends on the excitation frequency while this dependence is smooth in solid ones. Thus, the impact of the internal structure of celestial bodies must be taken into account when studying tidal dynamics. The purpose of this work is to present a local model of tidal gravito-inertial waves allowing us to quantify analytically the internal dissipation due to viscous friction and thermal diffusion, and to study the properties of the resonant frequency spectrum of the dissipated energy. We derive from this model scaling laws characterizing tidal dissipation as a function of fluid parameters (rotation, stratification, diffusivities) and discuss them in the context of star-planet systems.

  13. Feedback control of quantum system

    Institute of Scientific and Technical Information of China (English)

    DONG Dao-yi; CHEN Zong-hai; ZHANG Chen-bin; CHEN Chun-lin

    2006-01-01

    Feedback is a significant strategy for the control of quantum system.Information acquisition is the greatest difficulty in quantum feedback applications.After discussing several basic methods for information acquisition,we review three kinds of quantum feedback control strategies:quantum feedback control with measurement,coherent quantum feedback,and quantum feedback control based on cloning and recognition.The first feedback strategy can effectively acquire information,but it destroys the coherence in feedback loop.On the contrary,coherent quantum feedback does not destroy the coherence,but the capability of information acquisition is limited.However,the third feedback scheme gives a compromise between information acquisition and measurement disturbance.

  14. Quantum point contacts in quantum wire systems

    Energy Technology Data Exchange (ETDEWEB)

    Sternemann, E.; Buchholz, S.S.; Fischer, S.F.; Kunze, U. [Werkstoffe und Nanoelektronik, Ruhr-Universitaet Bochum (Germany); Reuter, D.; Wieck, A.D. [Angewandte Festkoerperphysik, Ruhr-Universitaet Bochum (Germany)

    2010-07-01

    Quantum point contacts (QPCs) attract high interest for applications as magnetic focussing, beam splitting (quantum Hall edge states), spin filtering and electron thermometry. Here, we investigate QPCs in complex quantum wire (QWR) systems such as quantum rings. The QPCs were realized by lithographical definition of a short (150 nm) constriction (170 nm width) in (a) a 540 nm wide QWR and (b) 520 nm wide QWR leads of a QWR ring as in. Nanogates on top of the constrictions allow for the control of occupied modes in the QPCs. The devices are based on a GaAs/AlGaAs heterostructure with a 2DEG 55 nm below the surface, patterned by electron beam lithography and wet-chemical etching. Two- and four-terminal conductance measurements at temperatures between 23 mK and 4.2 K were performed using lock-in technique. Our measurements reveal that QPCs in 1D nanostructures can be prepared to show subband separations of 6 meV, clear conductance quantization as well as the 0.7 anomaly. We further show that electron injection across a QPC into a QWR ring allows for electron interference (Aharonov-Bohm effect).

  15. Typical and rare fluctuations in nonlinear driven diffusive systems with dissipation

    Science.gov (United States)

    Hurtado, Pablo I.; Lasanta, A.; Prados, A.

    2013-08-01

    We consider fluctuations of the dissipated energy in nonlinear driven diffusive systems subject to bulk dissipation and boundary driving. With this aim, we extend the recently introduced macroscopic fluctuation theory to nonlinear driven dissipative media, starting from the fluctuating hydrodynamic equations describing the system mesoscopic evolution. Interestingly, the action associated with a path in mesoscopic phase space, from which large-deviation functions for macroscopic observables can be derived, has the same simple form as in nondissipative systems. This is a consequence of the quasielasticity of microscopic dynamics, required in order to have a nontrivial competition between diffusion and dissipation at the mesoscale. Euler-Lagrange equations for the optimal density and current fields that sustain an arbitrary dissipation fluctuation are also derived. A perturbative solution thereof shows that the probability distribution of small fluctuations is always Gaussian, as expected from the central limit theorem. On the other hand, strong separation from the Gaussian behavior is observed for large fluctuations, with a distribution which shows no negative branch, thus violating the Gallavotti-Cohen fluctuation theorem, as expected from the irreversibility of the dynamics. The dissipation large-deviation function exhibits simple and general scaling forms for weakly and strongly dissipative systems, with large fluctuations favored in the former case but heavily suppressed in the latter. We apply our results to a general class of diffusive lattice models for which dissipation, nonlinear diffusion, and driving are the key ingredients. The theoretical predictions are compared to extensive numerical simulations of the microscopic models, and excellent agreement is found. Interestingly, the large-deviation function is in some cases nonconvex beyond some dissipation. These results show that a suitable generalization of macroscopic fluctuation theory is capable of

  16. Robustness of Linear Systems towards Multi-Dissipative Pertubations

    DEFF Research Database (Denmark)

    Thygesen, Uffe Høgsbro; Poulsen, Niels Kjølstad

    1997-01-01

    We consider the question of robust stability of a linear time invariant plant subject to dynamic perturbations, which are dissipative in the sense of Willems with respect to several quadratic supply rates. For instance, parasitic dynamics are often both small gain and passive. We reduce several r...

  17. Dissipative open systems theory as a foundation for the thermodynamics of linear systems

    Science.gov (United States)

    Delvenne, Jean-Charles; Sandberg, Henrik

    2017-03-01

    In this paper, we advocate the use of open dynamical systems, i.e. systems sharing input and output variables with their environment, and the dissipativity theory initiated by Jan Willems as models of thermodynamical systems, at the microscopic and macroscopic level alike. We take linear systems as a study case, where we show how to derive a global Lyapunov function to analyse networks of interconnected systems. We define a suitable notion of dynamic non-equilibrium temperature that allows us to derive a discrete Fourier law ruling the exchange of heat between lumped, discrete-space systems, enriched with the Maxwell-Cattaneo correction. We complete these results by a brief recall of the steps that allow complete derivation of the dissipation and fluctuation in macroscopic systems (i.e. at the level of probability distributions) from lossless and deterministic systems. This article is part of the themed issue 'Horizons of cybernetical physics'.

  18. Dissipative open systems theory as a foundation for the thermodynamics of linear systems.

    Science.gov (United States)

    Delvenne, Jean-Charles; Sandberg, Henrik

    2017-03-06

    In this paper, we advocate the use of open dynamical systems, i.e. systems sharing input and output variables with their environment, and the dissipativity theory initiated by Jan Willems as models of thermodynamical systems, at the microscopic and macroscopic level alike. We take linear systems as a study case, where we show how to derive a global Lyapunov function to analyse networks of interconnected systems. We define a suitable notion of dynamic non-equilibrium temperature that allows us to derive a discrete Fourier law ruling the exchange of heat between lumped, discrete-space systems, enriched with the Maxwell-Cattaneo correction. We complete these results by a brief recall of the steps that allow complete derivation of the dissipation and fluctuation in macroscopic systems (i.e. at the level of probability distributions) from lossless and deterministic systems.This article is part of the themed issue 'Horizons of cybernetical physics'. © 2017 The Author(s).

  19. Quantum optimal control of wave packet dynamics under the influence of dissipation

    Energy Technology Data Exchange (ETDEWEB)

    Ohtsuki, Yukiyoshi; Nakagami, Kazuyuki; Zhu, Wusheng; Rabitz, Herschel

    2003-02-01

    Optimal control within the density matrix formalism is applied to the production of desired non-equilibrium distributions in condensed phases. The time evolution of a molecular system modeled by a displaced harmonic oscillator is assumed to be described by the Markoffian master equation with phenomenological relaxation parameters. The physical objectives of concern are the creation of a specified vibronic state, population inversion and wave packet shaping. The effects of an initial thermal distribution and dissipation on these targets are examined. In order to transfer a large amount of population (i.e., the strong-field regime) to a target wave packet in an electronic excited state, it is shown that creating a shaped packet in the ground state is often required to achieve high yield. This control pathway cannot be taken into account within the weak-field approximation, and is especially important when the target state includes vibrational states that are weakly accessible from the initial state or that have preferential indirect excitation paths from the initial state. Although relaxation effects usually reduce the control efficiency, under certain conditions, the bath-induced dynamics can help to create an objective state.

  20. Quantum Effects in Biological Systems

    Science.gov (United States)

    Roy, Sisir

    2014-07-01

    The debates about the trivial and non-trivial effects in biological systems have drawn much attention during the last decade or so. What might these non-trivial sorts of quantum effects be? There is no consensus so far among the physicists and biologists regarding the meaning of "non-trivial quantum effects". However, there is no doubt about the implications of the challenging research into quantum effects relevant to biology such as coherent excitations of biomolecules and photosynthesis, quantum tunneling of protons, van der Waals forces, ultrafast dynamics through conical intersections, and phonon-assisted electron tunneling as the basis for our sense of smell, environment assisted transport of ions and entanglement in ion channels, role of quantum vacuum in consciousness. Several authors have discussed the non-trivial quantum effects and classified them into four broad categories: (a) Quantum life principle; (b) Quantum computing in the brain; (c) Quantum computing in genetics; and (d) Quantum consciousness. First, I will review the above developments. I will then discuss in detail the ion transport in the ion channel and the relevance of quantum theory in brain function. The ion transport in the ion channel plays a key role in information processing by the brain.

  1. Decoherence in quantum spin systems

    NARCIS (Netherlands)

    De Raedt, H; Dobrovitski, VV; Landau, DP; Lewis, SP; Schuttler, HB

    2003-01-01

    Computer simulations of decoherence in quantum spin systems require the solution of the time-dependent Schrodinger equation for interacting quantum spin systems over extended periods of time. We use exact diagonalization, the Chebyshev polynomial technique, four Suzuki-formula algorithms, and the sh

  2. Quantum Positioning System

    CERN Document Server

    Bahder, T B

    2004-01-01

    A quantum positioning system (QPS) is proposed that can provide a user with all four of his space-time coordinates. The user must carry a corner cube reflector, a good clock, and have a two-way classical channel of communication with the origin of the reference frame. Four pairs of entangled photons (biphotons) are sent through four interferometers: three interferometers are used to determine the user's spatial position, and an additional interferometer is used to synchronize the user's clock to coordinate time in the reference frame. The spatial positioning part of the QPS is similar to a classical time-of-arrival (TOA) system, however, a classical TOA system (such as GPS) must have synchronized clocks that keep coordinate time and therefore the clocks must have long-term stability, whereas in the QPS only a photon coincidence counter is needed and the clocks need only have short-term stability. Several scenarios are considered for a QPS: one is a terrestrial system and another is a space-based-system compos...

  3. Quantum technologies with hybrid systems.

    Science.gov (United States)

    Kurizki, Gershon; Bertet, Patrice; Kubo, Yuimaru; Mølmer, Klaus; Petrosyan, David; Rabl, Peter; Schmiedmayer, Jörg

    2015-03-31

    An extensively pursued current direction of research in physics aims at the development of practical technologies that exploit the effects of quantum mechanics. As part of this ongoing effort, devices for quantum information processing, secure communication, and high-precision sensing are being implemented with diverse systems, ranging from photons, atoms, and spins to mesoscopic superconducting and nanomechanical structures. Their physical properties make some of these systems better suited than others for specific tasks; thus, photons are well suited for transmitting quantum information, weakly interacting spins can serve as long-lived quantum memories, and superconducting elements can rapidly process information encoded in their quantum states. A central goal of the envisaged quantum technologies is to develop devices that can simultaneously perform several of these tasks, namely, reliably store, process, and transmit quantum information. Hybrid quantum systems composed of different physical components with complementary functionalities may provide precisely such multitasking capabilities. This article reviews some of the driving theoretical ideas and first experimental realizations of hybrid quantum systems and the opportunities and challenges they present and offers a glance at the near- and long-term perspectives of this fascinating and rapidly expanding field.

  4. Quantum technologies with hybrid systems

    Science.gov (United States)

    Kurizki, Gershon; Bertet, Patrice; Kubo, Yuimaru; Mølmer, Klaus; Petrosyan, David; Rabl, Peter; Schmiedmayer, Jörg

    2015-01-01

    An extensively pursued current direction of research in physics aims at the development of practical technologies that exploit the effects of quantum mechanics. As part of this ongoing effort, devices for quantum information processing, secure communication, and high-precision sensing are being implemented with diverse systems, ranging from photons, atoms, and spins to mesoscopic superconducting and nanomechanical structures. Their physical properties make some of these systems better suited than others for specific tasks; thus, photons are well suited for transmitting quantum information, weakly interacting spins can serve as long-lived quantum memories, and superconducting elements can rapidly process information encoded in their quantum states. A central goal of the envisaged quantum technologies is to develop devices that can simultaneously perform several of these tasks, namely, reliably store, process, and transmit quantum information. Hybrid quantum systems composed of different physical components with complementary functionalities may provide precisely such multitasking capabilities. This article reviews some of the driving theoretical ideas and first experimental realizations of hybrid quantum systems and the opportunities and challenges they present and offers a glance at the near- and long-term perspectives of this fascinating and rapidly expanding field. PMID:25737558

  5. Stability and Control of Large-Scale Dynamical Systems A Vector Dissipative Systems Approach

    CERN Document Server

    Haddad, Wassim M

    2011-01-01

    Modern complex large-scale dynamical systems exist in virtually every aspect of science and engineering, and are associated with a wide variety of physical, technological, environmental, and social phenomena, including aerospace, power, communications, and network systems, to name just a few. This book develops a general stability analysis and control design framework for nonlinear large-scale interconnected dynamical systems, and presents the most complete treatment on vector Lyapunov function methods, vector dissipativity theory, and decentralized control architectures. Large-scale dynami

  6. Noncommutative mathematics for quantum systems

    CERN Document Server

    Franz, Uwe

    2016-01-01

    Noncommutative mathematics is a significant new trend of mathematics. Initially motivated by the development of quantum physics, the idea of 'making theory noncommutative' has been extended to many areas of pure and applied mathematics. This book is divided into two parts. The first part provides an introduction to quantum probability, focusing on the notion of independence in quantum probability and on the theory of quantum stochastic processes with independent and stationary increments. The second part provides an introduction to quantum dynamical systems, discussing analogies with fundamental problems studied in classical dynamics. The desire to build an extension of the classical theory provides new, original ways to understand well-known 'commutative' results. On the other hand the richness of the quantum mathematical world presents completely novel phenomena, never encountered in the classical setting. This book will be useful to students and researchers in noncommutative probability, mathematical physi...

  7. EDITORIAL: CAMOP: Quantum Non-Stationary Systems CAMOP: Quantum Non-Stationary Systems

    Science.gov (United States)

    Dodonov, Victor V.; Man'ko, Margarita A.

    2010-09-01

    -stationary systems, they nonetheless show some general trends. However, readers should remember that these comments represent the personal points of view of their authors. About a third of the comments are devoted to the evolution of quantum systems in the presence of dissipation or other sources of decoherence. This area, started by Landau in 1927, still contains many extremely interesting and unsolved problems. Here they are discussed in view of such different applications as the dynamics of quantum entanglement, cavity QED, optomechanics and the dynamical Casimir effect. Another group of comments deals with different (e.g. geometrical, tomographic, PT-symmetric) approaches to the dynamics of quantum systems, which have been developed in the past two decades. In particular, the problem of transition from quantum to classical description is considered and the inequalities generalizing the standard uncertainty relations are discussed in this connection. Three comments are devoted to the applications of nonclassical states, analytic representations and the algebraic techniques for resolving problems in quantum information and quantum statistical physics. The other contributions are related to different aspects of the dynamics of concrete physical systems, such as the wave-packet approach to the description of transport phenomena in mesoscopic systems, tunneling phenomena in low-dimensional semiconductor structures and resonance states of two-electron quantum dots. We thank all the authors and referees for their efforts in preparing this special issue. We hope that the comments in this collection will be useful for interested readers.

  8. Heat dissipation and information flow for delayed bistable Langevin systems near coherence resonance

    Science.gov (United States)

    Xiao, Tiejun

    2016-11-01

    In this paper, stochastic thermodynamics of delayed bistable Langevin systems near coherence resonance is discussed. We calculate the heat dissipation rate and the information flow of a delayed bistable Langevin system under various noise intensities. Both the heat dissipation rate and the information flow are found to be bell-shaped functions of the noise intensity, which implies that coherence resonance manifests itself in the thermodynamic properties.

  9. Dissipativity analysis for discrete singular systems with time-varying delay.

    Science.gov (United States)

    Feng, Zhiguang; Li, Wenxing; Lam, James

    2016-09-01

    In this paper, the issue of dissipativity analysis for discrete singular systems with time-varying delay is investigated. By using a recently developed inequality, which is less conservative than the Jensen inequality, and the improved reciprocally convex combination approach, sufficient criteria are established to guarantee the admissibility and dissipativity of the considered system. Moreover, H∞ performance characterization and passivity analysis are carried out. Numerical examples are presented to illustrate the effectiveness of the proposed method.

  10. Decoherence in infinite quantum systems

    Energy Technology Data Exchange (ETDEWEB)

    Blanchard, Philippe; Hellmich, Mario [Faculty of Physics, University of Bielefeld, Universitaetsstr. 25, 33615 Bielefeld (Germany); Bundesamt fuer Strahlenschutz (Federal Office for Radiation Protection), Willy-Brandt-Strasse 5, 38226 Salzgitter (Germany)

    2012-09-01

    We review and discuss a notion of decoherence formulated in the algebraic framework of quantum physics. Besides presenting some sufficient conditions for the appearance of decoherence in the case of Markovian time evolutions we provide an overview over possible decoherence scenarios. The framework for decoherence we establish is sufficiently general to accommodate quantum systems with infinitely many degrees of freedom.

  11. Reliable filtering with strict dissipativity for T-S fuzzy time-delay systems.

    Science.gov (United States)

    Su, Xiaojie; Shi, Peng; Wu, Ligang; Basin, Michael V

    2014-12-01

    In this paper, the problem of reliable filter design with strict dissipativity has been investigated for a class of discrete-time T-S fuzzy time-delay systems. Our attention is focused on the design of a reliable filter to ensure a strictly dissipative performance for the filtering error system. Based on the reciprocally convex approach, firstly, a sufficient condition of reliable dissipativity analysis is proposed for T-S fuzzy systems with time-varying delays and sensor failures. Then, a reliable filter with strict dissipativity is designed by solving a convex optimization problem, which can be efficiently solved by standard numerical algorithms. Finally, numerical examples are provided to illustrate the effectiveness of the developed techniques.

  12. Nuclear dissipation effects on fission and evaporation in systems of intermediate fissility

    Directory of Open Access Journals (Sweden)

    Gelli N.

    2010-03-01

    Full Text Available The systems of intermediate fissility 132Ce and 158Er have been studied experimentally and theoretically in order to investigate the dissipation properties of nuclear matter. Cross sections of fusion-fission and evaporation residues channels together with charged particles multiplicities in both channels, their spectra, angular correlations and mass-energy distribution of fission fragments have been measured. Theoretical analysis has been performed using multi-dimensional stochastic approach with realistic treatment of particle evaporation. The results of analysis show that full one-body or unusually strong two-body dissipation allows to reproduce experimental data. No temperature dependent dissipation was needed.

  13. Role of interactions in a dissipative many-body localized system

    Science.gov (United States)

    Everest, Benjamin; Lesanovsky, Igor; Garrahan, Juan P.; Levi, Emanuele

    2017-01-01

    Recent experimental and theoretical efforts have focused on the effect of dissipation on quantum many-body systems in their many-body localized (MBL) phase. While in the presence of dephasing noise such systems reach a unique ergodic state, their dynamics is characterized by slow relaxation manifested in nonexponential decay of self-correlations. Here we shed light on a currently much debated issue, namely, the role of interactions for this relaxation dynamics. We focus on the experimentally relevant situation of the evolution from an initial charge density wave in the presence of strong dephasing noise. We find a crossover from a regime dominated by disorder to a regime dominated by interactions, with an accompanying change of time correlators from stretched exponential to compressed exponential form. The strongly interacting regime can be explained in terms of nucleation and growth dynamics of relaxing regions—reminiscent of the kinetics of crystallization in soft matter systems—and should be observable experimentally. This interaction-driven crossover suggests that the competition between interactions and noise gives rise to a much richer structure of the MBL phase than anticipated so far.

  14. Mesoscopic systems: classical irreversibility and quantum coherence.

    Science.gov (United States)

    Barbara, Bernard

    2012-09-28

    relaxation of S(z) with dissipation to the bath of two-level systems with which they interact most. Finally, let us mention that these experiments on quantum oscillations are, most of the time, performed in the classical regime of Rabi oscillations, suggesting that decoherence mechanisms might also be treated classically.

  15. Positive Tensor Network Approach for Simulating Open Quantum Many-Body Systems

    Science.gov (United States)

    Werner, A. H.; Jaschke, D.; Silvi, P.; Kliesch, M.; Calarco, T.; Eisert, J.; Montangero, S.

    2016-06-01

    Open quantum many-body systems play an important role in quantum optics and condensed matter physics, and capture phenomena like transport, the interplay between Hamiltonian and incoherent dynamics, and topological order generated by dissipation. We introduce a versatile and practical method to numerically simulate one-dimensional open quantum many-body dynamics using tensor networks. It is based on representing mixed quantum states in a locally purified form, which guarantees that positivity is preserved at all times. Moreover, the approximation error is controlled with respect to the trace norm. Hence, this scheme overcomes various obstacles of the known numerical open-system evolution schemes. To exemplify the functioning of the approach, we study both stationary states and transient dissipative behavior, for various open quantum systems ranging from few to many bodies.

  16. ROBUST DISSIPATIVE CONTROL FOR STATE-DELAYED SYSTEMS WITH DISSIPATIVE UNCERTAINTY

    Institute of Scientific and Technical Information of China (English)

    LI; Zhi-hu(

    2001-01-01

    [1]Milner R, Parrow J, Walker D. A calculus of mobile processes[J]. Information and computation, 1992,100:1~77.[2]Milner R. Communication and Concurrency[M]. [s.l.]: Prentice Hall, 1989.[3]Pierce B, Sangiorgi D. Typing and subtyping for mobile processes[J]. Journal of Mathematical Structures in Computer Science, 1996,6(5):409~453.[4]Dam M. On the decidability of process equivalence for the π-calculus[J]. Theoretical Computer Science,1997,163:214~228.[5]Montanari U, Pistore M. Checking bismilarity for finitary π-calculus[A]. CONCUR'95[C]. Lecture Notes in Computer Science 962, Springer, 1995.42~56.[6]Victor B, Moller F. The mobility workbench--A tool for the π-calculus[A]. CAV'94[C]. Lecture Notes in Comuter Science 8188, Springer,1994.428~440.[7]李舟军.传值CCS和π-演算中互模拟等价的验证理论与算法[D].长沙:国防科技大学,1999.[8]Lin H. Symbolic transition graph with assignment[A]. CONCUR'96 [C], Lecture Notes in Computer Science 1119,Springer, 1996.50~65.[9]Boreale M, De Nicola R. A symbolic semantis for the π-calculus[J]. Information and Computation, 1996,126:34~52.[10]Pugh W, Bultan T, Gerber R. Symbolic model checking of infinite state systems using Presberger arithmetic [A].CAV'97[C]. Lecture Notes in Computer Science 1254, Springer, 1997.[11]Wolper P, Boigelot B. An automata-theoretic approach to Presburger arithmetic constraints[A]. Proceedings of Static Analysis Symposium[C]. Lecture in Computer Science 983, Springer, 1995.21~32.

  17. Description of a dissipative quantum spin dynamics with a Landau-Lifshitz/Gilbert like damping and complete derivation of the classical Landau-Lifshitz equation

    Science.gov (United States)

    Wieser, Robert

    2015-03-01

    The classical Landau-Lifshitz equation has been derived from quantum mechanics. Starting point is the assumption of a non-Hermitian Hamilton operator to take the energy dissipation into account. The corresponding quantum mechanical spin dynamics along with the time dependent Schrödinger, Liouville and Heisenberg equation has been described and the similarities and differences between classical and quantum mechanical spin dynamics have been discussed. Furthermore, a time dependent Schrödinger equation corresponding to the classical Landau-Lifshitz-Gilbert equation and two ways to include temperature into the quantum mechanical spin dynamics have been proposed.

  18. Preconditioned quantum linear system algorithm.

    Science.gov (United States)

    Clader, B D; Jacobs, B C; Sprouse, C R

    2013-06-21

    We describe a quantum algorithm that generalizes the quantum linear system algorithm [Harrow et al., Phys. Rev. Lett. 103, 150502 (2009)] to arbitrary problem specifications. We develop a state preparation routine that can initialize generic states, show how simple ancilla measurements can be used to calculate many quantities of interest, and integrate a quantum-compatible preconditioner that greatly expands the number of problems that can achieve exponential speedup over classical linear systems solvers. To demonstrate the algorithm's applicability, we show how it can be used to compute the electromagnetic scattering cross section of an arbitrary target exponentially faster than the best classical algorithm.

  19. Dissipative many-electron dynamics of ionizing systems.

    Science.gov (United States)

    Tremblay, Jean Christophe; Klinkusch, Stefan; Klamroth, Tillmann; Saalfrank, Peter

    2011-01-28

    In this paper, we perform many-electron dynamics using the time-dependent configuration-interaction method in its reduced density matrix formulation (ρ-TDCI). Dissipation is treated implicitly using the Lindblad formalism. To include the effect of ionization on the state-resolved dynamics, we extend a recently introduced heuristic model for ionizing states to the ρ-TDCI method, which leads to a reduced density matrix evolution that is not norm-preserving. We apply the new method to the laser-driven excitation of H(2) in a strongly dissipative environment, for which the state-resolve lifetimes are tuned to a few femtoseconds, typical for dynamics of adsorbate at metallic surfaces. Further testing is made on the laser-induced intramolecular charge transfer in a quinone derivative as a model for a molecular switch. A modified scheme to treat ionizing states is proposed to reduce the computational burden associated with the density matrix propagation, and it is thoroughly tested and compared to the results obtained with the former model. The new approach scales favorably (∼N(2)) with the number of configurations N used to represent the reduced density matrix in the ρ-TDCI method, as compared to a N(3) scaling for the model in its original form.

  20. Chaos and Energy Spreading for Time-Dependent Hamiltonians, and the Various Regimes in the Theory of Quantum Dissipation

    Science.gov (United States)

    Cohen, Doron

    2000-08-01

    We make the first steps toward a generic theory for energy spreading and quantum dissipation. The Wall formula for the calculation of friction in nuclear physics and the Drude formula for the calculation of conductivity in mesoscopic physics can be regarded as two special results of the general formulation. We assume a time-dependent Hamiltonian H(Q, P; x(t)) with x(t)=Vt, where V is slow in a classical sense. The rate-of-change V is not necessarily slow in the quantum-mechanical sense. The dynamical variables (Q, P) may represent some "bath" which is being parametrically driven by x. This bath may consist of just a few degrees of freedom, but it is assumed to be classically chaotic. In the case of either the Wall or Drude formula, the dynamical variables (Q, P) may represent a single particle. In any case, dissipation means an irreversible systematic growth of the (average) energy. It is associated with the stochastic spreading of energy across levels. The latter can be characterized by a transition probability kernel Pt(n ∣ m), where n and m are level indices. This kernel is the main object of the present study. In the classical limit, due to the (assumed) chaotic nature of the dynamics, the second moment of Pt(n ∣ m) exhibits a crossover from ballistic to diffusive behavior. In order to capture this crossover within quantum mechanics, a proper theory for the quantal Pt(n ∣ m) should be constructed. We define the V regimes where either perturbation theory or semiclassical considerations are applicable in order to establish this crossover. In the limit ℏ→0 perturbation theory does not apply but semiclassical considerations can be used in order to argue that there is detailed correspondence, during the crossover time, between the quantal and the classical Pt(n ∣ m). In the perturbative regime there is a lack of such correspondence. Namely, Pt(n ∣ m) is characterized by a perturbative core-tail structure that persists during the crossover time. In

  1. Stabilizing entanglement against local dissipation

    Energy Technology Data Exchange (ETDEWEB)

    Sauer, Simeon; Gneiting, Clemens; Buchleitner, Andreas [Albert-Ludwigs-Universitaet, Freiburg (Germany)

    2013-07-01

    Natural dissipative processes in multipartite quantum systems are mostly of local nature and therefore affect entanglement adversely. In their presence, initially highly entangled states generically evolve into at most weakly entangled states. We investigate by what means this detrimental process can be counteracted. It is shown that a suitable, dissipator-adapted static system Hamiltonian can preserve entanglement in the stationary state to a significant but limited extend. We then extend our analysis to the general class of periodically driven Hamiltonians and show that they are subject to similar limitations. Finally, we develop incoherent but local control strategies which overcome these limits.

  2. Screening in quantum charged systems

    Science.gov (United States)

    Martin, Ph. A.; Gruber, Ch.

    1984-07-01

    For stationary states of quantum charged systems in ν dimensions, ν>=2, it is proven that the reduced-density matrices satisfy a set of sum rules whenever the clustering is faster than |x|-(ν+l). These sum rules, describing the screening properties, are analogous to those previously derived for classical systems. For neutral quantum fluids, it is shown that the clustering cannot be faster than the decay of the force.

  3. Quantum contextuality in complex systems

    CERN Document Server

    Cabello, Adan

    2010-01-01

    We show that, for a system of several qubits, there is an inequality for the correlations between three compatible dichotomic measurements which must be satisfied by any noncontextual theory, but is violated by any quantum state. Remarkably, the violation grows exponentially with the number of qubits, and the tolerated error per correlation also increases with the number of qubits, showing that state-independent quantum contextuality is experimentally observable in complex systems.

  4. Universal blind quantum computation for hybrid system

    Science.gov (United States)

    Huang, He-Liang; Bao, Wan-Su; Li, Tan; Li, Feng-Guang; Fu, Xiang-Qun; Zhang, Shuo; Zhang, Hai-Long; Wang, Xiang

    2017-08-01

    As progress on the development of building quantum computer continues to advance, first-generation practical quantum computers will be available for ordinary users in the cloud style similar to IBM's Quantum Experience nowadays. Clients can remotely access the quantum servers using some simple devices. In such a situation, it is of prime importance to keep the security of the client's information. Blind quantum computation protocols enable a client with limited quantum technology to delegate her quantum computation to a quantum server without leaking any privacy. To date, blind quantum computation has been considered only for an individual quantum system. However, practical universal quantum computer is likely to be a hybrid system. Here, we take the first step to construct a framework of blind quantum computation for the hybrid system, which provides a more feasible way for scalable blind quantum computation.

  5. Quantum Dot Systems: a versatile platform for quantum simulations

    NARCIS (Netherlands)

    Barthelemy, P.J.C.; Vandersypen, L.M.K.

    2013-01-01

    Quantum mechanics often results in extremely complex phenomena, especially when the quantum system under consideration is composed of many interacting particles. The states of these many-body systems live in a space so large that classical numerical calculations cannot compute them. Quantum simulati

  6. Quantum Dot Systems: a versatile platform for quantum simulations

    NARCIS (Netherlands)

    Barthelemy, P.J.C.; Vandersypen, L.M.K.

    2013-01-01

    Quantum mechanics often results in extremely complex phenomena, especially when the quantum system under consideration is composed of many interacting particles. The states of these many-body systems live in a space so large that classical numerical calculations cannot compute them. Quantum

  7. Active control of probability amplitudes in a mesoscale system via feedback-induced suppression of dissipation and noise

    Science.gov (United States)

    Gupta, Chaitanya; Peña Perez, Aldo; Fischer, Sean R.; Weinreich, Stephen B.; Murmann, Boris; Howe, Roger T.

    2016-12-01

    We demonstrate that a three-terminal potentiostat circuit reduces the coupling between an electronic excitation transfer (EET) system and its environment, by applying a low-noise voltage to its electrical terminals. Inter-state interference is preserved in the EET system by attenuating the dissipation in the quantum system arising from coupling to the surrounding thermodynamic bath. A classical equivalent circuit is introduced to model the environment-coupled excitation transfer for a simplified, two-state system. This model provides a qualitative insight into how the electronic feedback affects the transition probabilities and selectively reduces dissipative coupling for one of the participant energy levels EET system. Furthermore, we show that the negative feedback also constrains r.m.s. fluctuations of the energy of environmental vibrational states, resulting in persistent spectral coherence between the decoupled state and vibronic levels of the complementary state. The decoupled vibronic channel therefore can serve as a probe for characterizing the vibronic structure of the complementary channel of the EET system.

  8. Introduction to quantum spin systems

    Directory of Open Access Journals (Sweden)

    A. Langari

    2008-06-01

    Full Text Available This manuscript is the collection of lectures given in the summer school on strongly correlated electron systems held at Isfahan university of technology, June 2007. A short overview on quantum magnetism and spin systems is presented. The numerical exact diagonalization (Lanczos alghorithm is explained in a pedagogical ground. This is a method to get some ground state properties on finite cluster of lattice models. Two extensions of Lanczos method to get the excited states and also finite temperature properties of quantum models are also explained. The basic notions of quantum phase transition is discussed in term of Ising model in transverse field. Its phase diagram and critical properties are explained using the quantum renormalization group approach. Most of the topics are in tutorial level with hints to recent research activities.

  9. Effect of a Dissipative Term in the Drift Waves Hamiltonian System

    CERN Document Server

    Oyarzabal, Ricardo S; Batista, Antonio M; Caldas, Iberê L; Viana, Ricardo L; Iarosz, Kelly C

    2015-01-01

    This paper analyses the Hamiltonian model of drift waves which describes the chaotic transport of particles in the plasma confinement. With one drift wave the system is integrable and it presents stable orbits. When one wave is added the system may or may not be integrable depending on the phase of each wave velocity. If the two waves have the same phase velocity, the system is integrable. When the phase velocities between the two waves are different, the system shows chaotic behaviour. In this model we add a small dissipation. In the presence of a weak dissipation, for different initial conditions, we observe transient orbits which converge to periodic attractors.

  10. The effects of oppositely sloping boundaries with Ekman dissipation in a nonlinear baroclinic system

    Science.gov (United States)

    Weng, H.-Y.

    1990-01-01

    The present analytical and numerical examination of the effect of the slope Delta with dissipation delta on baroclinic flows in linear and nonlinear systems uses a modified Eady channel model with oppositely sloping top and bottom Ekman layers, and truncates the spectral wave solution up to six components. Comparisons are made wherever possible with results from beta-plane dissipative systems. In the linear system, the combined effect of Delta and delta strongly stabilizes long waves. In a nonlinear system without wave-wave interaction, Delta stabilizes the flow even for small delta and reduces the domain of vacillation while enlarging the domain of single-wave steady state.

  11. Defect-related internal dissipation in mechanical resonators and the study of coupled mechanical systems.

    Energy Technology Data Exchange (ETDEWEB)

    Friedmann, Thomas Aquinas; Czaplewski, David A.; Sullivan, John Patrick; Modine, Normand Arthur; Wendt, Joel Robert; Aslam, Dean (Michigan State University, Lansing, MI); Sepulveda-Alancastro, Nelson (University of Puerto Rico, Mayaguez, PR)

    2007-01-01

    Understanding internal dissipation in resonant mechanical systems at the micro- and nanoscale is of great technological and fundamental interest. Resonant mechanical systems are central to many sensor technologies, and microscale resonators form the basis of a variety of scanning probe microscopies. Furthermore, coupled resonant mechanical systems are of great utility for the study of complex dynamics in systems ranging from biology to electronics to photonics. In this work, we report the detailed experimental study of internal dissipation in micro- and nanomechanical oscillators fabricated from amorphous and crystalline diamond materials, atomistic modeling of dissipation in amorphous, defect-free, and defect-containing crystalline silicon, and experimental work on the properties of one-dimensional and two-dimensional coupled mechanical oscillator arrays. We have identified that internal dissipation in most micro- and nanoscale oscillators is limited by defect relaxation processes, with large differences in the nature of the defects as the local order of the material ranges from amorphous to crystalline. Atomistic simulations also showed a dominant role of defect relaxation processes in controlling internal dissipation. Our studies of one-dimensional and two-dimensional coupled oscillator arrays revealed that it is possible to create mechanical systems that should be ideal for the study of non-linear dynamics and localization.

  12. Low-Dissipation Advection Schemes Designed for Large Eddy Simulations of Hypersonic Propulsion Systems

    Science.gov (United States)

    White, Jeffrey A.; Baurle, Robert A.; Fisher, Travis C.; Quinlan, Jesse R.; Black, William S.

    2012-01-01

    The 2nd-order upwind inviscid flux scheme implemented in the multi-block, structured grid, cell centered, finite volume, high-speed reacting flow code VULCAN has been modified to reduce numerical dissipation. This modification was motivated by the desire to improve the codes ability to perform large eddy simulations. The reduction in dissipation was accomplished through a hybridization of non-dissipative and dissipative discontinuity-capturing advection schemes that reduces numerical dissipation while maintaining the ability to capture shocks. A methodology for constructing hybrid-advection schemes that blends nondissipative fluxes consisting of linear combinations of divergence and product rule forms discretized using 4th-order symmetric operators, with dissipative, 3rd or 4th-order reconstruction based upwind flux schemes was developed and implemented. A series of benchmark problems with increasing spatial and fluid dynamical complexity were utilized to examine the ability of the candidate schemes to resolve and propagate structures typical of turbulent flow, their discontinuity capturing capability and their robustness. A realistic geometry typical of a high-speed propulsion system flowpath was computed using the most promising of the examined schemes and was compared with available experimental data to demonstrate simulation fidelity.

  13. Quantum walk public-key cryptographic system

    Science.gov (United States)

    Vlachou, C.; Rodrigues, J.; Mateus, P.; Paunković, N.; Souto, A.

    2015-12-01

    Quantum Cryptography is a rapidly developing field of research that benefits from the properties of Quantum Mechanics in performing cryptographic tasks. Quantum walks are a powerful model for quantum computation and very promising for quantum information processing. In this paper, we present a quantum public-key cryptographic system based on quantum walks. In particular, in the proposed protocol the public-key is given by a quantum state generated by performing a quantum walk. We show that the protocol is secure and analyze the complexity of public key generation and encryption/decryption procedures.

  14. Duality quantum algorithm efficiently simulates open quantum systems.

    Science.gov (United States)

    Wei, Shi-Jie; Ruan, Dong; Long, Gui-Lu

    2016-07-28

    Because of inevitable coupling with the environment, nearly all practical quantum systems are open system, where the evolution is not necessarily unitary. In this paper, we propose a duality quantum algorithm for simulating Hamiltonian evolution of an open quantum system. In contrast to unitary evolution in a usual quantum computer, the evolution operator in a duality quantum computer is a linear combination of unitary operators. In this duality quantum algorithm, the time evolution of the open quantum system is realized by using Kraus operators which is naturally implemented in duality quantum computer. This duality quantum algorithm has two distinct advantages compared to existing quantum simulation algorithms with unitary evolution operations. Firstly, the query complexity of the algorithm is O(d(3)) in contrast to O(d(4)) in existing unitary simulation algorithm, where d is the dimension of the open quantum system. Secondly, By using a truncated Taylor series of the evolution operators, this duality quantum algorithm provides an exponential improvement in precision compared with previous unitary simulation algorithm.

  15. Duality quantum algorithm efficiently simulates open quantum systems

    Science.gov (United States)

    Wei, Shi-Jie; Ruan, Dong; Long, Gui-Lu

    2016-07-01

    Because of inevitable coupling with the environment, nearly all practical quantum systems are open system, where the evolution is not necessarily unitary. In this paper, we propose a duality quantum algorithm for simulating Hamiltonian evolution of an open quantum system. In contrast to unitary evolution in a usual quantum computer, the evolution operator in a duality quantum computer is a linear combination of unitary operators. In this duality quantum algorithm, the time evolution of the open quantum system is realized by using Kraus operators which is naturally implemented in duality quantum computer. This duality quantum algorithm has two distinct advantages compared to existing quantum simulation algorithms with unitary evolution operations. Firstly, the query complexity of the algorithm is O(d3) in contrast to O(d4) in existing unitary simulation algorithm, where d is the dimension of the open quantum system. Secondly, By using a truncated Taylor series of the evolution operators, this duality quantum algorithm provides an exponential improvement in precision compared with previous unitary simulation algorithm.

  16. Dissipation, correlation and lags in heat engines

    Science.gov (United States)

    Campisi, Michele; Fazio, Rosario

    2016-08-01

    By modelling heat engines as driven multi-partite system we show that their dissipation can be expressed in terms of the lag (relative entropy) between the perturbed state of each partition and their equilibrium state, and the correlations that build up among the partitions. We show that the non-negativity of the overall dissipation implies Carnot formulation of the second law. We illustrate the rich interplay between correlations and lags with a two-qubit device driven by a quantum gate.

  17. Robust dissipative filtering for continuous-time polytopic uncertain time-delay systems

    Institute of Scientific and Technical Information of China (English)

    LV Ling-ling; DUAN Guang-ren; WU Ai-guo

    2010-01-01

    This paper focuses on the problem of dissipative filtering for linear continuous-time polytopic uncertain time-delay systems.To obtain a stable and proper linear filter such that the filtering error system is strictly dissipative for all admissible uncertainties,a new dissipativity criterion which realizes separation between the Lyapunov matrices and the system dynamic matrices is firstly provided in terms of linear matrix inequalities (LMI).Then an LMI sufficient condition for the existence of a robust filter is established and a design procedure is proposed for this type of systems.One numerical example demonstrates less conservativeness of the proposed criterion,the other numerical example illustrates the validity of the proposed filter design.

  18. Evolution and Stability of Dark Holographic Solitons in Photorefractive Dissipative Systems

    Institute of Scientific and Technical Information of China (English)

    ZHANG Hui-Lan; LIU Jin-Song

    2006-01-01

    @@ The dynamics evolution of dark holographic solutions in a dissipative system is investigated namerically provided that the double balance, i.e. diffraction is balanced by nonlinearity and loss is balanced by gain, is satisfied. The influence of the system parameters, such as the linear loss of the crystal, the external biased field and the angel between input beams, on the stable propagation of soliton beams is discussed numerically. Results show that such solitons can be easily amplified or absorbed by adjusting these system parameters. Furthermore, numerical simulations indicate that dissipative dark holographic solitons are stable for small perturbation on amplitude.

  19. Quantum energy teleportation in a quantum Hall system

    Energy Technology Data Exchange (ETDEWEB)

    Yusa, Go; Izumida, Wataru; Hotta, Masahiro [Department of Physics, Tohoku University, Sendai 980-8578 (Japan)

    2011-09-15

    We propose an experimental method for a quantum protocol termed quantum energy teleportation (QET), which allows energy transportation to a remote location without physical carriers. Using a quantum Hall system as a realistic model, we discuss the physical significance of QET and estimate the order of energy gain using reasonable experimental parameters.

  20. Mapping between finite temperature classical and zero temperature quantum systems: Quantum critical jamming and quantum dynamical heterogeneities

    Science.gov (United States)

    Nussinov, Zohar; Johnson, Patrick; Graf, Matthias J.; Balatsky, Alexander V.

    2013-05-01

    Many electronic systems (e.g., the cuprate superconductors and heavy fermions) exhibit striking features in their dynamical response over a prominent range of experimental parameters. While there are some empirical suggestions of particular increasing length scales that accompany such transitions in some cases, this identification is not universal and in numerous instances no large correlation length is evident. To better understand, as a matter of principle, such behavior in quantum systems, we extend a known mapping (earlier studied in stochastic or supersymmetric quantum mechanics) between finite temperature classical Fokker-Planck systems and related quantum systems at zero temperature to include general nonequilibrium dynamics. Unlike Feynman mappings or stochastic quantization methods in field theories (as well as more recent holographic type dualities), the classical systems that we consider and their quantum duals reside in the same number of space-time dimensions. The upshot of our very broad and rigorous result is that a Wick rotation exactly relates (i) the dynamics in general finite temperature classical dissipative systems to (ii) zero temperature dynamics in the corresponding dual many-body quantum systems. Using this correspondence, we illustrate that, even in the absence of imposed disorder, many continuum quantum fluid systems (and possible lattice counterparts) may exhibit a zero-point “quantum dynamical heterogeneity” wherein the dynamics, at a given instant, is spatially nonuniform. While the static length scales accompanying this phenomenon do not seem to exhibit a clear divergence in standard correlation functions, the length scale of the dynamical heterogeneities can increase dramatically. We further study “quantum jamming” and illustrate how a hard-core bosonic system can undergo a zero temperature quantum critical metal-to-insulator-type transition with an extremely large effective dynamical exponent z>4 that is consistent with

  1. Quantum Linear Systems Theory

    Science.gov (United States)

    2013-02-15

    Matthew James, Andre Carvalho and Michael Hush completed some work analyzing cross-phase modulation using single photon quantum filtering techniques...ANU Michael Hush January – June, 2012, Postdoc, ANU Matthew R. James Professor, Australian National University Ian R. Petersen Professor...appear, IEEE Trans. Aut. Control., 2013. A. R. R. Carvalho, M. R. Hush , and M. R. James, “Cavity driven by a single photon: Conditional dynamics and

  2. Quantum Communication Systems

    Science.gov (United States)

    2008-03-15

    Standard Form 298 (Rev. 8/98) Prescribed by ANSI Std. Z39-18 Publications: 1) W. Wasilewski and...K. Banaszek, Protecting an optical qubit against photon loss, Phys. Rev. A 75, 042316 (2007) 2) K. Banaszek and W. Wasilewski , Linear-optics...manipulations of photon-loss codes, Proceedings of NATO Advanced Research Workshop "Quantum Communication and Security" 3) W. Wasilewski , P. Kolenderski

  3. The extrema of an action principle for dissipative mechanical systems

    CERN Document Server

    Lin, Tongling

    2013-01-01

    A least action principle for damping motion has been previously proposed with a Hamiltonian and a Lagrangian containing the energy dissipated by friction. Due to the space-time nonlocality of the Lagrangian, mathematical uncertainties persist about the appropriate variational calculus and the nature (maxima, minima and inflection) of the stationary action. The aim of this work is to make numerical simulation of damped motion and to compare the actions of different paths in order to get evidence of the existence and the nature of stationary action. The model is a small particle subject to conservative and friction forces. Two conservative forces and three friction forces are considered. The comparison of the actions of the perturbed paths with that of the Newtonian path reveals the existence of extrema of action which are minima for zero or very weak friction and shift to maxima when the motion is overdamped. In the intermediate case, the action of the Newtonian path is neither least nor most, meaning that the...

  4. Effective Constraints for Quantum Systems

    CERN Document Server

    Bojowald, Martin; Skirzewski, Aureliano; Tsobanjan, Artur

    2008-01-01

    An effective formalism for quantum constrained systems is presented which allows manageable derivations of solutions and observables, including a treatment of physical reality conditions without requiring full knowledge of the physical inner product. Instead of a state equation from a constraint operator, an infinite system of constraint functions on the quantum phase space of expectation values and moments of states is used. The examples of linear constraints as well as the free non-relativistic particle in parameterized form illustrate how standard problems of constrained systems can be dealt with in this framework.

  5. Hypothesis testing with open quantum systems.

    Science.gov (United States)

    Mølmer, Klaus

    2015-01-30

    Using a quantum circuit model we derive the maximal ability to distinguish which of several candidate Hamiltonians describe an open quantum system. This theory, in particular, provides the maximum information retrievable from continuous quantum measurement records, available when a quantum system is perturbatively coupled to a broadband quantized environment.

  6. Electro-Optomechanical Transduction & Quantum Hard-Sphere Model for Dissipative Rydberg-EIT Media

    DEFF Research Database (Denmark)

    Zeuthen, Emil

    established the requirements for efficient performance, we turn to the question of optimization. We address this by developing a unifying equivalent-circuit formalism for electro-optomechanical transducers. This approach accommodates arbitrary linear circuits and integrates the novel optomechanical...... transduction functionality into the well-established framework of electrical engineering, thereby facilitating its implementation in potential applications such as nuclear magnetic resonance imaging and radio astronomy. We consider such optomechanical sensing of weak electrical signals and discuss how......, thus capturing the dualistic particle-wave nature of light as it manifests itself in dissipative Rydberg-EIT media. Using this approach, we analyze the saturation behavior of the transmission through one-dimensional Rydberg-EIT media in the regime of non-perturbative single-polariton EIT-decay relevant...

  7. Open Quantum Systems An Introduction

    CERN Document Server

    Rivas, ´Angel

    2012-01-01

    In this volume the fundamental theory of open quantum systems is revised in the light of modern developments in the field. A unified approach to the quantum evolution of open systems is presented by merging concepts and methods traditionally employed by different communities, such as quantum optics, condensed matter, chemical physics and mathematical physics. The mathematical structure and the general properties of the dynamical maps underlying open system dynamics are explained in detail. The microscopic derivation of dynamical equations, including both Markovian and non-Markovian evolutions, is also discussed. Because of the step-by-step explanations, this work is a useful reference to novices in this field. However, experienced researches can also benefit from the presentation of recent results.

  8. Quantum cloning attacks against PUF-based quantum authentication systems

    Science.gov (United States)

    Yao, Yao; Gao, Ming; Li, Mo; Zhang, Jian

    2016-08-01

    With the advent of physical unclonable functions (PUFs), PUF-based quantum authentication systems have been proposed for security purposes, and recently, proof-of-principle experiment has been demonstrated. As a further step toward completing the security analysis, we investigate quantum cloning attacks against PUF-based quantum authentication systems and prove that quantum cloning attacks outperform the so-called challenge-estimation attacks. We present the analytical expression of the false-accept probability by use of the corresponding optimal quantum cloning machines and extend the previous results in the literature. In light of these findings, an explicit comparison is made between PUF-based quantum authentication systems and quantum key distribution protocols in the context of cloning attacks. Moreover, from an experimental perspective, a trade-off between the average photon number and the detection efficiency is discussed in detail.

  9. Global dissipative solutions for the two-component Camassa-Holm shallow water system

    Directory of Open Access Journals (Sweden)

    Yujuan Wang

    2015-01-01

    Full Text Available This article presents a continuous semigroup of globally defined weak dissipative solutions for the two-component Camassa-Holm system. Such solutions are established by using a new approach based on characteristics a set of new variables overcoming the difficulties inherent in multi-component systems.

  10. Thermal sine-Gordon system in the presence of different types of dissipation

    DEFF Research Database (Denmark)

    Salerno, M.; Samuelsen, Mogens Rugholm; Svensmark, Henrik

    1988-01-01

    The effects of thermal fluctuations on solitons and phonons of the sine-Gordon system are investigated in the presence of a αφt-βφxxt dissipation. The analysis requires the assumption of a more general autocorrelation function for the noise than the one used in previous works. We verify that this......The effects of thermal fluctuations on solitons and phonons of the sine-Gordon system are investigated in the presence of a αφt-βφxxt dissipation. The analysis requires the assumption of a more general autocorrelation function for the noise than the one used in previous works. We verify...

  11. Radiative Corrections and Quantum Gates in Molecular Systems

    Science.gov (United States)

    Reina, John H.; Beausoleil, Ray G.; Spiller, Tim P.; Munro, William J.

    2004-12-01

    We propose a method for quantum information processing using molecules coupled to an external laser field. This utilizes molecular interactions, control of the external field, and an effective energy shift of the doubly excited state of two coupled molecules. Such a level shift has been seen in the two-photon resonance experiments recently reported by Hettich etal. Here we show that this can be explained in terms of the QED Lamb shift. We quantify the performance of the proposed quantum logic gates in the presence of dissipative mechanisms. The unitary transformations required for performing one- and two-qubit operations can be implemented with present day molecular technology. The proposed techniques can also be applied to coupled quantum dot and biomolecular systems.

  12. Ocean tidal dissipation and its role in solar system satellite evolution

    Science.gov (United States)

    Chen, Erinna M.

    The history of satellites in the Solar System is quite diverse. For example, satellites like Io and Enceladus exhibit active volcanism currently, while satellites like Ganymede and Tethys show signs of geologic activity in the deep past, but not at present. The energy dissipated by tides has been identified as a major heat source for satellites, but calculations for satellite tidal dissipation primarily focus on dissipation in a solid layer, such as the ice shell. An exciting discovery of the NASA spacecraft missions Galileo and Cassini is that global-scale, deep, liquid water oceans are present on many of the outer Solar System satellites. Tyler (2008) suggested that tidal dissipation due to flow in these oceans could potentially be a significant and previously neglected source of heat. However, a critical free parameter in Tyler's model is the effective turbulent viscosity in the ocean. The value of the effective viscosity is unconstrained and because the amount of tidal dissipation scales with this parameter, the amount of ocean tidal dissipation is also unconstrained. In order to address this uncertainty, we developed a numerical model that solves the shallow-water equations on a spherical shell and includes a nonlinear bottom friction parameterization for viscous dissipation. The bottom friction coefficient has a well-established value in the terrestrial literature; however, the nonlinearity of this term in the equations of motion make the model far more computationally expensive than a model that includes turbulent viscosity. Thus, we provide numerically-derived scalings that map the bottom friction coefficient and satellite parameters to an equivalent effective turbulent viscosity. Because tides depend on both the thermal structure of a satellite as well as characteristics of the satellite's orbit, models that couple thermal and orbital evolution are required to understand the history of a satellite. We use our numerically-derived scalings to adapt a coupled

  13. Dynamics of complex quantum systems

    CERN Document Server

    Akulin, Vladimir M

    2014-01-01

    This book gathers together a range of similar problems that can be encountered in different fields of modern quantum physics and that have common features with regard to multilevel quantum systems. The main motivation was to examine from a uniform standpoint various models and approaches that have been developed in atomic, molecular, condensed matter, chemical, laser and nuclear physics in various contexts. The book should help senior-level undergraduate, graduate students and researchers putting particular problems in these fields into a broader scientific context and thereby taking advantage of well-established techniques used in adjacent fields. This second edition has been expanded to include substantial new material (e.g. new sections on Dynamic Localization and on Euclidean Random Matrices and new chapters on Entanglement, Open Quantum Systems, and Coherence Protection). It is based on the author’s lectures at the Moscow Institute of Physics and Technology, at the CNRS Aimé Cotton Laboratory, and on ...

  14. Estimation of the kinetic energy dissipation in fall-arrest system and manikin during fall impact.

    Science.gov (United States)

    Wu, John Z; Powers, John R; Harris, James R; Pan, Christopher S

    2011-04-01

    Fall-arrest systems (FASs) have been widely applied to provide a safe stop during fall incidents for occupational activities. The mechanical interaction and kinetic energy exchange between the human body and the fall-arrest system during fall impact is one of the most important factors in FAS ergonomic design. In the current study, we developed a systematic approach to evaluate the energy dissipated in the energy absorbing lanyard (EAL) and in the harness/manikin during fall impact. The kinematics of the manikin and EAL during the impact were derived using the arrest-force time histories that were measured experimentally. We applied the proposed method to analyse the experimental data of drop tests at heights of 1.83 and 3.35 m. Our preliminary results indicate that approximately 84-92% of the kinetic energy is dissipated in the EAL system and the remainder is dissipated in the harness/manikin during fall impact. The proposed approach would be useful for the ergonomic design and performance evaluation of an FAS. STATEMENT OF RELEVANCE: Mechanical interaction, especially kinetic energy exchange, between the human body and the fall-arrest system during fall impact is one of the most important factors in the ergonomic design of a fall-arrest system. In the current study, we propose an approach to quantify the kinetic energy dissipated in the energy absorbing lanyard and in the harness/body system during fall impact.

  15. Three dimensional Simulations of Self-Organization in a Driven Dissipative Plasma System

    Science.gov (United States)

    Shaikh, Dastgeer; Dasgupta, B.; Hu, Q.; Zank, G. P.

    2009-11-01

    We perform a fully self-consistent 3-D numerical simulation for a compressible, driven dissipative magneto-plasma driven by large-scale perturbations, that contain a fairly broader spectrum of characteristic modes, ranging from largest scales to intermediate scales and down to the smallest scales, where the energy of the system are dissipated by collisional (Ohmic) and viscous dissipations. Additionally, our simulation includes nonlinear interactions amongst a wide range of ?uctuations that are initialized with random spectral amplitudes, leading to the cascade of spectral energy in the inertial range spectrum, and takes into account large scale as well as small scale perturbation that may have been induced by the background plasma ?uctuations, also the non adiabatic exchange of energy leading to the migration of energy from the energy containing modes or randomly injected energy driven by perturbations and further dissipated by the smaller scales. Besides demonstrating the comparative decays of total energy and dissipation rate of energy, our results show the existence of a perpendicular component of current, thus clearly con?rming that the self-organized state is non-force free.

  16. On the Isomorphism between Dissipative Systems, Fractal Self-Similarity and Electrodynamics. Toward an Integrated Vision of Nature

    Directory of Open Access Journals (Sweden)

    Giuseppe Vitiello

    2014-05-01

    Full Text Available In electrodynamics there is a mutual exchange of energy and momentum between the matter field and the electromagnetic field and the total energy and momentum are conserved. For a constant magnetic field and harmonic scalar potential, electrodynamics is shown to be isomorph to a system of damped/amplified harmonic oscillators. These can be described by squeezed coherent states which in turn are isomorph to self-similar fractal structures. Under the said conditions of constant magnetic field and harmonic scalar potential, electrodynamics is thus isomorph to fractal self-similar structures and squeezed coherent states. At a quantum level, dissipation induces noncommutative geometry with the squeezing parameter playing a relevant role. Ubiquity of fractals in Nature and relevance of coherent states and electromagnetic interaction point to a unified, integrated vision of Nature.

  17. Energy dissipation from a correlated system driven out of equilibrium

    Science.gov (United States)

    Rameau, J. D.; Freutel, S.; Kemper, A. F.; Sentef, M. A.; Freericks, J. K.; Avigo, I.; Ligges, M.; Rettig, L.; Yoshida, Y.; Eisaki, H.; Schneeloch, J.; Zhong, R. D.; Xu, Z. J.; Gu, G. D.; Johnson, P. D.; Bovensiepen, U.

    2016-12-01

    In complex materials various interactions have important roles in determining electronic properties. Angle-resolved photoelectron spectroscopy (ARPES) is used to study these processes by resolving the complex single-particle self-energy and quantifying how quantum interactions modify bare electronic states. However, ambiguities in the measurement of the real part of the self-energy and an intrinsic inability to disentangle various contributions to the imaginary part of the self-energy can leave the implications of such measurements open to debate. Here we employ a combined theoretical and experimental treatment of femtosecond time-resolved ARPES (tr-ARPES) show how population dynamics measured using tr-ARPES can be used to separate electron-boson interactions from electron-electron interactions. We demonstrate a quantitative analysis of a well-defined electron-boson interaction in the unoccupied spectrum of the cuprate Bi2Sr2CaCu2O8+x characterized by an excited population decay time that maps directly to a discrete component of the equilibrium self-energy not readily isolated by static ARPES experiments.

  18. Maximal dissipation and well-posedness for the compressible Euler system

    OpenAIRE

    Feireisl, Eduard

    2014-01-01

    We discuss the problem of well-posedness of the compressible (barotropic) Euler system in the framework of weak solutions. The principle of maximal dissipation introduced by C.M. Dafermos is adapted and combined with the concept of admissible weak solutions. We use the method of convex integration in the spirit of the recent work of C.DeLellis and L.Sz´ekelyhidi to show various counterexamples to well-posedness. On the other hand, we conjecture that the principle of maximal dissipation should...

  19. Maximal Dissipation and Well-posedness for the Compressible Euler System

    Science.gov (United States)

    Feireisl, Eduard

    2014-09-01

    We discuss the problem of well-posedness of the compressible (barotropic) Euler system in the framework of weak solutions. The principle of maximal dissipation introduced by C.M. Dafermos is adapted and combined with the concept of admissible weak solutions. We use the method of convex integration in the spirit of the recent work of C.DeLellis and L.Székelyhidi to show various counterexamples to well-posedness. On the other hand, we conjecture that the principle of maximal dissipation should be retained as a possible criterion of uniqueness as it is violated by the oscillatory solutions obtained in the process of convex integration.

  20. Photon antibunching and bunching in a ring-resonator waveguide quantum electrodynamics system.

    Science.gov (United States)

    Chen, Zihao; Zhou, Yao; Shen, Jung-Tsung

    2016-07-15

    We numerically investigate the photonic state generation and its nonclassical correlations in a ring-resonator waveguide quantum electrodynamics system. Specifically, we discuss photon antibunching and bunching in various scenarios, including the imperfect resonator with backscattering and dissipations. Our numerical results indicate that an imperfect ring resonator with backscattering can enhance the quality of antibunching. In addition, we also identify the quantum photonic halo phenomenon in the photon scattering dynamics and the shoulder effect in the second-order correlation function.

  1. Quantum Indeterminacy of Cosmic Systems

    Energy Technology Data Exchange (ETDEWEB)

    Hogan, Craig J. [Fermi National Accelerator Laboratory (FNAL), Batavia, IL (United States)

    2013-12-30

    It is shown that quantum uncertainty of motion in systems controlled mainly by gravity generally grows with orbital timescale $H^{-1}$, and dominates classical motion for trajectories separated by distances less than $\\approx H^{-3/5}$ in Planck units. For example, the cosmological metric today becomes indeterminate at macroscopic separations, $H_0^{-3/5}\\approx 60$ meters. Estimates suggest that entangled non-localized quantum states of geometry and matter may significantly affect fluctuations during inflation, and connect the scale of dark energy to that of strong interactions.

  2. Quantum Indeterminacy of Cosmic Systems

    Energy Technology Data Exchange (ETDEWEB)

    Hogan, Craig J. [Fermi National Accelerator Laboratory (FNAL), Batavia, IL (United States)

    2013-12-30

    It is shown that quantum uncertainty of motion in systems controlled mainly by gravity generally grows with orbital timescale $H^{-1}$, and dominates classical motion for trajectories separated by distances less than $\\approx H^{-3/5}$ in Planck units. For example, the cosmological metric today becomes indeterminate at macroscopic separations, $H_0^{-3/5}\\approx 60$ meters. Estimates suggest that entangled non-localized quantum states of geometry and matter may significantly affect fluctuations during inflation, and connect the scale of dark energy to that of strong interactions.

  3. Design of Constant Gain Dissipative Controllers for Eigensystem Assignment in Passive Systems

    Science.gov (United States)

    Maghami, Peiman G.; Gupta, Sandeep

    1998-01-01

    Partial eigensystem assignment with output feedback can lead to an unstable closed-loop system. However, output feedback with passive linear time-invariant systems, such as flexible space structures, is guaranteed to be stable if the controller is dissipative. This paper presents a novel approach for synthesis of dissipative output feedback gain matrices for assigning a selected number of closed-loop poles. Dissipativity of a gain matrix is known to be equivalent to positive semidefiniteness of the symmetric part of the matrix. A sequential procedure is presented to assign one self-conjugate pair of closed-loop eigenvalues at each step using dissipative output feedback gain matrices, while ensuring that the eigenvalues assigned in the previous steps are not disturbed. The problem of assigning one closed-loop pair is reduced to a constrained solution of a system of quadratic equations, and necessary and sufficient conditions for the existence of a solution are presented. A minimax approach is presented for determining parameters which satisfy these conditions. This method can assign as many closed-loop system poles as the number of control inputs. A numerical example of damping enhancement for a flexible structure is presented to demonstrate the approach.

  4. On the generalized Helmholtz conditions for Lagrangian systems with dissipative forces

    CERN Document Server

    Crampin, M; Sarlet, W

    2010-01-01

    In two recent papers necessary and sufficient conditions for a given system of second-order ordinary differential equations to be of Lagrangian form with additional dissipative forces were derived. We point out that these conditions are not independent and prove a stronger result accordingly.

  5. Energy-Based Lyapunov Functions for Forced Hamiltonian Systems with Dissipation

    NARCIS (Netherlands)

    Maschke, Bernhard; Ortega, Romeo; Schaft, Arjan J. van der

    2000-01-01

    In this paper, we propose a constructive procedure to modify the Hamiltonian function of forced Hamiltonian systems with dissipation in order to generate Lyapunov functions for nonzero equilibria. A key step in the procedure, which is motivated from energy-balance considerations standard in network

  6. Mode competition in a system of two parametrically driven pendulums; the dissipative case

    NARCIS (Netherlands)

    Banning, E.J.; Weele, van der J.P.; Ross, J.C.; Kettenis, M.M.; Kleine, de E.

    1997-01-01

    In this paper we study the dynamics of a system of two linearly coupled, parametrically driven pendulums, subject to viscous dissipation. It is a continuation of the previous paper (E.J. Banning and J.P. van der Weele (1995)), in which we treated the Hamiltonian case. The damping has several importa

  7. Quasi-periodic Bifurcations of Invariant Circles in Low-dimensional Dissipative Dynamical Systems

    NARCIS (Netherlands)

    Vitolo, Renato; Broer, Henk; Simo, Carles

    2011-01-01

    This paper first summarizes the theory of quasi-periodic bifurcations for dissipative dynamical systems. Then it presents algorithms for the computation and continuation of invariant circles and of their bifurcations. Finally several applications are given for quasiperiodic bifurcations of Hopf, sad

  8. Energy-Based Lyapunov Functions for Forced Hamiltonian Systems with Dissipation

    NARCIS (Netherlands)

    Maschke, Bernhard; Ortega, Romeo; Schaft, Arjan J. van der

    2000-01-01

    In this paper, we propose a constructive procedure to modify the Hamiltonian function of forced Hamiltonian systems with dissipation in order to generate Lyapunov functions for nonzero equilibria. A key step in the procedure, which is motivated from energy-balance considerations standard in network

  9. ON THE SOLVABILITY OF GENERAL LINEAR METHODS FOR DISSIPATIVE DYNAMICAL SYSTEMS

    Institute of Scientific and Technical Information of China (English)

    Ai-guo Xiao

    2000-01-01

    The main purpose of the present paper is to examine the existence and local uniqueness of solutions of the implicit equations arising in the application of a weakly algebraically stable general linear methods to dissipative dynamical systems, and to extend the existing relevant results of Runge-Kutta methods by Humphries and Stuart(1994).

  10. LIE GROUP INTEGRATION FOR CONSTRAINED GENERALIZED HAMILTONIAN SYSTEM WITH DISSIPATION BY PROJECTION METHOD

    Institute of Scientific and Technical Information of China (English)

    张素英; 邓子辰

    2004-01-01

    For the constrained generalized Hamiltonian system with dissipation, by introducing Lagrange multiplier and using projection technique, the Lie group integration method was presented, which can preserve the inherent structure of dynamic system and the constraint-invariant. Firstly, the constrained generalized Hamiltonian system with dissipative was converted to the non-constraint generalized Hamiltonian system, then Lie group integration algorithm for the non-constraint generalized Hamiltonian system was discussed, finally the projection method for generalized Hamiltonian system with constraint was given. It is found that the constraint invariant is ensured by projection technique, and after introducing Lagrange multiplier the Lie group character of the dynamic system can't be destroyed while projecting to the constraint manifold. The discussion is restricted to the case of holonomic constraint. A presented numerical example shows the effectiveness of the method.

  11. Direct and Indirect Couplings in Coherent Feedback Control of Linear Quantum Systems

    CERN Document Server

    Zhang, Guofeng

    2010-01-01

    The purpose of this paper is to study and design direct and indirect couplings for use in coherent feedback control of a class of linear quantum stochastic systems. A general physical model for a nominal linear quantum system coupled directly and indirectly to external systems is presented. Fundamental properties of stability, dissipation, passivity, and gain for this class of linear quantum models are presented and characterized using complex Lyapunov equations and linear matrix inequalities (LMIs). Coherent $H^\\infty$ and LQG synthesis methods are extended to accommodate direct couplings using multistep optimization. Examples are given to illustrate the results.

  12. Topology of a dissipative spin: Dynamical Chern number, bath-induced nonadiabaticity, and a quantum dynamo effect

    Science.gov (United States)

    Henriet, Loïc; Sclocchi, Antonio; Orth, Peter P.; Le Hur, Karyn

    2017-02-01

    We analyze the topological deformations of the ground state manifold of a quantum spin-1/2 in a magnetic field H =H (sinθ cosϕ ,sinθ sinϕ ,cosθ ) induced by a coupling to an ohmic quantum dissipative environment at zero temperature. From Bethe ansatz results and a variational approach, we confirm that the Chern number associated with the geometry of the reduced spin ground state manifold is preserved in the delocalized phase for α <1 . We report a divergence of the Berry curvature at αc=1 for magnetic fields aligned along the equator θ =π /2 . This divergence is caused by the complete quenching of the transverse magnetic field by the bath associated with a gap closing that occurs at the localization Kosterlitz-Thouless quantum phase transition in this model. Recent experiments in quantum circuits have engineered nonequilibrium protocols to access topological properties from a measurement of a dynamical Chern number defined via the out-of-equilibrium spin expectation values. Applying a numerically exact stochastic Schrödinger approach we find that, for a fixed field sweep velocity θ (t )=v t , the bath induces a crossover from (quasi)adiabatic to nonadiabatic dynamical behavior when the spin bath coupling α increases. We also investigate the particular regime H /ωc≪v /H ≪1 with large bath cutoff frequency ωc, where the dynamical Chern number vanishes already at α =1 /2 . In this regime, the mapping to an interacting resonance level model enables us to analytically describe the behavior of the dynamical Chern number in the vicinity of α =1 /2 . We further provide an intuitive physical explanation of the bath-induced breakdown of adiabaticity in analogy to the Faraday effect in electromagnetism. We demonstrate that the driving of the spin leads to the production of a large number of bosonic excitations in the bath, which strongly affect the spin dynamics. Finally, we quantify the spin-bath entanglement and formulate an analogy with an effective

  13. Controllability for single-input mechanical control systems with dissipation

    Institute of Scientific and Technical Information of China (English)

    Jianling KANG; Hong WANG; Huawen YE

    2005-01-01

    Within the affine connection framework of Lagrangian control systems,based on the results of Sussmann on small-time locally controllability of single-input affine nonlinear control systems,the controllability results for mechanical control systems with single-input are extended to the case of the systems with isotropic damping,where the Lagrangian is the kinetic energy associated with a Riemannian metric.A sufficient condition of negative small-time locally controllability for the system is obtained.Then,it is demonstrated that such systems are small-time locally configuration controllable if and only if the dimension of the configuration manifold is one.Finally,two examples are given to illustrate the results.Lie bracketting of vector fields and the symmetric product show the advantages in the discussion.

  14. Variational principle for nonlinear wave propagation in dissipative systems.

    Science.gov (United States)

    Dierckx, Hans; Verschelde, Henri

    2016-02-01

    The dynamics of many natural systems is dominated by nonlinear waves propagating through the medium. We show that in any extended system that supports nonlinear wave fronts with positive surface tension, the asymptotic wave-front dynamics can be formulated as a gradient system, even when the underlying evolution equations for the field variables cannot be written as a gradient system. The variational potential is simply given by a linear combination of the occupied volume and surface area of the wave front and changes monotonically over time.

  15. Impulsive and hybrid dynamical systems stability, dissipativity, and control

    CERN Document Server

    Haddad, Wassim M; Nersesov, Sergey G

    2014-01-01

    This book develops a general analysis and synthesis framework for impulsive and hybrid dynamical systems. Such a framework is imperative for modern complex engineering systems that involve interacting continuous-time and discrete-time dynamics with multiple modes of operation that place stringent demands on controller design and require implementation of increasing complexity--whether advanced high-performance tactical fighter aircraft and space vehicles, variable-cycle gas turbine engines, or air and ground transportation systems. Impulsive and Hybrid Dynamical Systems goes beyond similar

  16. Dissipative parametric modulation instability and pattern formation in nonlinear optical systems

    Science.gov (United States)

    Perego, A. M.; Tarasov, N.; Churkin, D. V.; Turitsyn, S. K.; Staliunas, K.

    2016-04-01

    We present the essential features of the dissipative parametric instability, in the universal complex Ginzburg- Landau equation. Dissipative parametric instability is excited through a parametric modulation of frequency dependent losses in a zig-zag fashion in the spectral domain. Such damping is introduced respectively for spectral components in the +ΔF and in the -ΔF region in alternating fashion, where F can represent wavenumber or temporal frequency depending on the applications. Such a spectral modulation can destabilize the homogeneous stationary solution of the system leading to growth of spectral sidebands and to the consequent pattern formation: both stable and unstable patterns in one- and in two-dimensional systems can be excited. The dissipative parametric instability provides an useful and interesting tool for the control of pattern formation in nonlinear optical systems with potentially interesting applications in technological applications, like the design of mode- locked lasers emitting pulse trains with tunable repetition rate; but it could also find realizations in nanophotonics circuits or in dissipative polaritonic Bose-Einstein condensates.

  17. Keldysh field theory for driven open quantum systems.

    Science.gov (United States)

    Sieberer, L M; Buchhold, M; Diehl, S

    2016-09-01

    Recent experimental developments in diverse areas-ranging from cold atomic gases to light-driven semiconductors to microcavity arrays-move systems into the focus which are located on the interface of quantum optics, many-body physics and statistical mechanics. They share in common that coherent and driven-dissipative quantum dynamics occur on an equal footing, creating genuine non-equilibrium scenarios without immediate counterpart in equilibrium condensed matter physics. This concerns both their non-thermal stationary states and their many-body time evolution. It is a challenge to theory to identify novel instances of universal emergent macroscopic phenomena, which are tied unambiguously and in an observable way to the microscopic drive conditions. In this review, we discuss some recent results in this direction. Moreover, we provide a systematic introduction to the open system Keldysh functional integral approach, which is the proper technical tool to accomplish a merger of quantum optics and many-body physics, and leverages the power of modern quantum field theory to driven open quantum systems.

  18. Keldysh field theory for driven open quantum systems

    Science.gov (United States)

    Sieberer, L. M.; Buchhold, M.; Diehl, S.

    2016-09-01

    Recent experimental developments in diverse areas—ranging from cold atomic gases to light-driven semiconductors to microcavity arrays—move systems into the focus which are located on the interface of quantum optics, many-body physics and statistical mechanics. They share in common that coherent and driven-dissipative quantum dynamics occur on an equal footing, creating genuine non-equilibrium scenarios without immediate counterpart in equilibrium condensed matter physics. This concerns both their non-thermal stationary states and their many-body time evolution. It is a challenge to theory to identify novel instances of universal emergent macroscopic phenomena, which are tied unambiguously and in an observable way to the microscopic drive conditions. In this review, we discuss some recent results in this direction. Moreover, we provide a systematic introduction to the open system Keldysh functional integral approach, which is the proper technical tool to accomplish a merger of quantum optics and many-body physics, and leverages the power of modern quantum field theory to driven open quantum systems.

  19. Polygamy of entanglement in multipartite quantum systems

    Science.gov (United States)

    Kim, Jeong San

    2009-08-01

    We show that bipartite entanglement distribution (or entanglement of assistance) in multipartite quantum systems is by nature polygamous. We first provide an analytical upper bound for the concurrence of assistance in bipartite quantum systems and derive a polygamy inequality of multipartite entanglement in arbitrary-dimensional quantum systems.

  20. Quantum phase transitions in constrained Bose systems

    OpenAIRE

    Bonnes, Lars

    2011-01-01

    This doctoral thesis studies low dimensional quantum systems that can be realized in recent cold atom experiments. From the viewpoint of quantum statistical mechanics, the main emphasis is on the detailed study of the different quantum and thermal phases and their transitions using numerical methods, such as quantum Monte Carlo and the Tensor Network Renormalization Group. The first part of this work deals with a lattice Boson model subject to strong three-body losses. In a quantum-Zeno li...

  1. Electro-Optomechanical Transduction & Quantum Hard-Sphere Model for Dissipative Rydberg-EIT Media

    DEFF Research Database (Denmark)

    Zeuthen, Emil

    transduction functionality into the well-established framework of electrical engineering, thereby facilitating its implementation in potential applications such as nuclear magnetic resonance imaging and radio astronomy. We consider such optomechanical sensing of weak electrical signals and discuss how...... the equivalent circuit formalism can be used to optimize the electrical circuit design. We also discuss the parameter requirements for transducing microwave photons in the quantum regime. Part II: Effective photon-photon interactions can be engineered by combining long-range Rydberg interactions between atoms....... We introduce a new approach to analyzing this challenging many-body problem in the limit of large optical depth per blockade radius. The idea is to separate the single-polariton EIT physics from the Rydberg-Rydberg interactions in a serialized manner while using a hard-sphere model for the latter...

  2. Overview of progress in quantum systems control

    Institute of Scientific and Technical Information of China (English)

    CONG Shuang; ZHENG Yisong; JI Beichen; DAI Yi

    2007-01-01

    The development of the theory on quantum systems control in the last 20 years is reviewed in detail.The research on the controllability of quantum systems is first introduced,then the study on the quantum open-loop control methods often used for controlling simple quantum systems is analyzed briefly.The learning control method and the feedback control method are mainly discussed for they are two important methods in quantum systems control and their advantages and disadvantages are presented.According to the trends in quantum systems control development,the paper predicts the future trends of its development and applications.A complete design procedure necessary for the quantum control system is presented.Finally,several vital problems hindering the advancement of quantum control are pointed out.

  3. Understanding quantum work in a quantum many-body system.

    Science.gov (United States)

    Wang, Qian; Quan, H T

    2017-03-01

    Based on previous studies in a single-particle system in both the integrable [Jarzynski, Quan, and Rahav, Phys. Rev. X 5, 031038 (2015)2160-330810.1103/PhysRevX.5.031038] and the chaotic systems [Zhu, Gong, Wu, and Quan, Phys. Rev. E 93, 062108 (2016)1539-375510.1103/PhysRevE.93.062108], we study the the correspondence principle between quantum and classical work distributions in a quantum many-body system. Even though the interaction and the indistinguishability of identical particles increase the complexity of the system, we find that for a quantum many-body system the quantum work distribution still converges to its classical counterpart in the semiclassical limit. Our results imply that there exists a correspondence principle between quantum and classical work distributions in an interacting quantum many-body system, especially in the large particle number limit, and further justify the definition of quantum work via two-point energy measurements in quantum many-body systems.

  4. A unified Lie systems theory for closed and open Markovian dynamical quantum systems

    Energy Technology Data Exchange (ETDEWEB)

    Schulte-Herbrueggen, Thomas [Technical University of Munich (TUM) (Germany); Dirr, Gunther [University of Wuerzburg (Germany)

    2016-07-01

    Lie groups and Lie semigroups with their symmetries provide a unified framework to pinpoint the dynamic behaviour of closed and open quantum systems under all kinds of controls. Recently, we showed that all Markovian quantum maps can be represented by Lie semigroups. These semigroups come with the geometry of affine maps, whose translational parts determine the respective fixed points. We exploit this geometry for dissipative fixed-point engineering of unique target states be they pure or mixed. We extend capabilities by combining coherent control with simplest noise controls. Particular light is shed on reachability and open-loop versus closed-loop control design.

  5. Global Classical Solutions for Partially Dissipative Hyperbolic System of Balance Laws

    Science.gov (United States)

    Xu, Jiang; Kawashima, Shuichi

    2014-02-01

    The basic existence theory of Kato and Majda enables us to obtain local-in-time classical solutions to generally quasilinear hyperbolic systems in the framework of Sobolev spaces (in x) with higher regularity. However, it remains a challenging open problem whether classical solutions still preserve well-posedness in the case of critical regularity. This paper is concerned with partially dissipative hyperbolic system of balance laws. Under the entropy dissipative assumption, we establish the local well-posedness and blow-up criterion of classical solutions in the framework of Besov spaces with critical regularity with the aid of the standard iteration argument and Friedrichs' regularization method. Then we explore the theory of function spaces and develop an elementary fact that indicates the relation between homogeneous and inhomogeneous Chemin-Lerner spaces (mixed space-time Besov spaces). This fact allows us to capture the dissipation rates generated from the partial dissipative source term and further obtain the global well-posedness and stability by assuming at all times the Shizuta-Kawashima algebraic condition. As a direct application, the corresponding well-posedness and stability of classical solutions to the compressible Euler equations with damping are also obtained.

  6. Quantum Information Processing in Disordered and Complex Quantum Systems

    CERN Document Server

    De, A S; Ahufinger, V; Briegel, H J; Sanpera, A; Lewenstein, M; De, Aditi Sen; Sen, Ujjwal; Ahufinger, Veronica; Briegel, Hans J.; Sanpera, Anna; Lewenstein, Maciej

    2005-01-01

    We investigate quantum information processing and manipulations in disordered systems of ultracold atoms and trapped ions. First, we demonstrate generation of entanglement and local realization of quantum gates in a quantum spin glass system. Entanglement in such systems attains significantly high values, after quenched averaging, and has a stable positive value for arbitrary times. Complex systems with long range interactions, such as ion chains or dipolar atomic gases, can be modeled by neural network Hamiltonians. In such systems, we find the characteristic time of persistence of quenched averaged entanglement, and also find the time of its revival.

  7. Quantum Computing in Solid State Systems

    CERN Document Server

    Ruggiero, B; Granata, C

    2006-01-01

    The aim of Quantum Computation in Solid State Systems is to report on recent theoretical and experimental results on the macroscopic quantum coherence of mesoscopic systems, as well as on solid state realization of qubits and quantum gates. Particular attention has been given to coherence effects in Josephson devices. Other solid state systems, including quantum dots, optical, ion, and spin devices which exhibit macroscopic quantum coherence are also discussed. Quantum Computation in Solid State Systems discusses experimental implementation of quantum computing and information processing devices, and in particular observations of quantum behavior in several solid state systems. On the theoretical side, the complementary expertise of the contributors provides models of the various structures in connection with the problem of minimizing decoherence.

  8. Numerical renormalization group method for quantum impurity systems

    Science.gov (United States)

    Bulla, Ralf; Costi, Theo A.; Pruschke, Thomas

    2008-04-01

    In the early 1970s, Wilson developed the concept of a fully nonperturbative renormalization group transformation. When applied to the Kondo problem, this numerical renormalization group (NRG) method gave for the first time the full crossover from the high-temperature phase of a free spin to the low-temperature phase of a completely screened spin. The NRG method was later generalized to a variety of quantum impurity problems. The purpose of this review is to give a brief introduction to the NRG method, including some guidelines for calculating physical quantities, and to survey the development of the NRG method and its various applications over the last 30 years. These applications include variants of the original Kondo problem such as the non-Fermi-liquid behavior in the two-channel Kondo model, dissipative quantum systems such as the spin-boson model, and lattice systems in the framework of the dynamical mean-field theory.

  9. Transition State Theory for dissipative systems without a dividing surface

    CERN Document Server

    Revuelta, F; Benito, R M; Borondo, F

    2015-01-01

    Transition State Theory is a central cornerstone in reaction dynamics. Its key step is the identification of a dividing surface that is crossed only once by all reactive trajectories. This assumption is often badly violated, especially when the reactive system is coupled to an environment. The calculations made in this way then overestimate the reaction rate and the results depend critically on the choice of the dividing surface. In this Letter, we study the phase space of a stochastically driven system close to an energetic barrier in order to identify the geometric structure unambiguously determining the reactive trajectories, which is then incorporated in a simple rate formula for reactions in condensed phase that is both independent of the dividing surface and exact.

  10. Eigenfunctions in chaotic quantum systems

    Energy Technology Data Exchange (ETDEWEB)

    Baecker, Arnd

    2007-07-01

    The structure of wavefunctions of quantum systems strongly depends on the underlying classical dynamics. In this text a selection of articles on eigenfunctions in systems with fully chaotic dynamics and systems with a mixed phase space is summarized. Of particular interest are statistical properties like amplitude distribution and spatial autocorrelation function and the implication of eigenfunction structures on transport properties. For systems with a mixed phase space the separation into regular and chaotic states does not always hold away from the semiclassical limit, such that chaotic states may completely penetrate into the region of the regular island. The consequences of this flooding are discussed and universal aspects highlighted. (orig.)

  11. Comparison of cumulative dissipated energy between the Infiniti and Centurion phacoemulsification systems

    Directory of Open Access Journals (Sweden)

    Chen M

    2015-07-01

    Full Text Available Ming Chen,1 Erik Anderson,2 Geoffrey Hill,3 John J Chen,4 Thomas Patrianakos2 1Department of Surgery, University of Hawaii, Honolulu, HI, 2Department of Ophthalmology, John H Stroger, Jr Hospital of Cook County, Chicago, IL, 3Department of Ophthalmology, UT Southwestern Medical Center, Dallas, TX, 4Biostatistics Core, John A Burns School of Medicine, University of Hawaii, Honolulu, HI, USA Purpose: To compare cumulative dissipated energy between two phacoemulsification machines. Setting: An ambulatory surgical center, Honolulu, Hawaii, USA. Design: Retrospective chart review. Methods: A total of 2,077 consecutive cases of cataract extraction by phacoemulsification performed by five surgeons from November 2012 to November 2014 were included in the study; 1,021 consecutive cases were performed using the Infiniti Vision System, followed by 1,056 consecutive cases performed using the Centurion Vision System. Results: The Centurion phacoemulsification system required less energy to remove a cataractous lens with an adjusted average energy reduction of 38% (5.09 percent-seconds (P<0.001 across all surgeons in comparison to the Infiniti phacoemulsification system. The reduction in cumulative dissipated energy was statistically significant for each surgeon, with a range of 29%–45% (2.25–12.54 percent-seconds (P=0.005–<0.001. Cumulative dissipated energy for both the Infiniti and Centurion systems varied directly with patient age, increasing an average of 2.38 percent-seconds/10 years. Conclusion: The Centurion phacoemulsification system required less energy to remove a cataractous lens in comparison to the Infiniti phacoemulsification system. Keywords: phacoemulsification, cumulative dissipated energy, Centurion Vision System, Infiniti Vision System

  12. Scaling relations for forced oscillators in the transition from a dissipative to a Hamiltonian system

    DEFF Research Database (Denmark)

    Flensberg, Karsten; Svensmark, Henrik

    1993-01-01

    The dynamics and the stability of a forced damped nonlinear oscillator driven at twice its resonance frequency is studied. At the transition from a dissipative system to a Hamiltonian system, simple scalings relations are found by the use of the Floquet theory of the linearized problem. The Floqu...... exponents and the period-doubling bifurcation point are determined analytically in the limit of small damping. The theory is compared to numerical calculations on a Duffing oscillator and excellent agreement is found.......The dynamics and the stability of a forced damped nonlinear oscillator driven at twice its resonance frequency is studied. At the transition from a dissipative system to a Hamiltonian system, simple scalings relations are found by the use of the Floquet theory of the linearized problem. The Floquet...

  13. Büttiker probes for dissipative phonon quantum transport in semiconductor nanostructures

    Science.gov (United States)

    Miao, K.; Sadasivam, S.; Charles, J.; Klimeck, G.; Fisher, T. S.; Kubis, T.

    2016-03-01

    Theoretical prediction of phonon transport in modern semiconductor nanodevices requires atomic resolution of device features and quantum transport models covering coherent and incoherent effects. The nonequilibrium Green's function method is known to serve this purpose well but is numerically expensive in simulating incoherent scattering processes. This work extends the efficient Büttiker probe approach widely used in electron transport to phonons and considers salient implications of the method. Different scattering mechanisms such as impurity, boundary, and Umklapp scattering are included, and the method is shown to reproduce the experimental thermal conductivity of bulk Si and Ge over a wide temperature range. Temperature jumps at the lead/device interface are captured in the quasi-ballistic transport regime consistent with results from the Boltzmann transport equation. Results of this method in Si/Ge heterojunctions illustrate the impact of atomic relaxation on the thermal interface conductance and the importance of inelastic scattering to activate high-energy channels for phonon transport. The resultant phonon transport model is capable of predicting the thermal performance in the heterostructure efficiently.

  14. Perturbative approach to Markovian open quantum systems.

    Science.gov (United States)

    Li, Andy C Y; Petruccione, F; Koch, Jens

    2014-05-08

    The exact treatment of Markovian open quantum systems, when based on numerical diagonalization of the Liouville super-operator or averaging over quantum trajectories, is severely limited by Hilbert space size. Perturbation theory, standard in the investigation of closed quantum systems, has remained much less developed for open quantum systems where a direct application to the Lindblad master equation is desirable. We present such a perturbative treatment which will be useful for an analytical understanding of open quantum systems and for numerical calculation of system observables which would otherwise be impractical.

  15. Variational Study on a Dissipative Two-Level System

    Institute of Scientific and Technical Information of China (English)

    ZHU Wei-Wing; REN Qing-Bao; CHEN Qing-Hu

    2008-01-01

    A new variational approach is proposed to study the ground-state of a two-level system coupled to a dispersionless phonon bath. By the extended coherent state, where the more phonon correlations are easily incorporated, we can obtain very accurate ground state energy and the tunnelling reduction factor in all regime of tunnelling matrix element δo and coupling parameter s. The relative difference between the present ones and those by exact numerical diagonalization is less then 0.001%. In addition, some simple analytical results are given in the limits of δo/s → 0 and ∞.

  16. A Diffusion Equation for Quantum Adiabatic Systems

    CERN Document Server

    Jain, S R

    1998-01-01

    For ergodic adiabatic quantum systems, we study the evolution of energy distribution as the system evolves in time. Starting from the von Neumann equation for the density operator, we obtain the quantum analogue of the Smoluchowski equation on coarse-graining over the energy spectrum. This result brings out the precise notion of quantum diffusion.

  17. Logical entropy of quantum dynamical systems

    Directory of Open Access Journals (Sweden)

    Ebrahimzadeh Abolfazl

    2016-01-01

    Full Text Available This paper introduces the concepts of logical entropy and conditional logical entropy of hnite partitions on a quantum logic. Some of their ergodic properties are presented. Also logical entropy of a quantum dynamical system is dehned and ergodic properties of dynamical systems on a quantum logic are investigated. Finally, the version of Kolmogorov-Sinai theorem is proved.

  18. Resonances in open quantum systems

    Science.gov (United States)

    Eleuch, Hichem; Rotter, Ingrid

    2017-02-01

    The Hamilton operator of an open quantum system is non-Hermitian. Its eigenvalues are generally complex and provide not only the energies but also the lifetimes of the states of the system. The states may couple via the common environment of scattering wave functions into which the system is embedded. This causes an external mixing (EM) of the states. Mathematically, EM is related to the existence of singular (the so-called exceptional) points. The eigenfunctions of a non-Hermitian operator are biorthogonal, in contrast to the orthogonal eigenfunctions of a Hermitian operator. A quantitative measure for the ratio between biorthogonality and orthogonality is the phase rigidity of the wave functions. At and near an exceptional point (EP), the phase rigidity takes its minimum value. The lifetimes of two nearby eigenstates of a quantum system bifurcate under the influence of an EP. At the parameter value of maximum width bifurcation, the phase rigidity approaches the value one, meaning that the two eigenfunctions become orthogonal. However, the eigenfunctions are externally mixed at this parameter value. The S matrix and therewith the cross section do contain, in the one-channel case, almost no information on the EM of the states. The situation is completely different in the case with two (or more) channels where the resonance structure is strongly influenced by the EM of the states and interesting features of non-Hermitian quantum physics are revealed. We provide numerical results for two and three nearby eigenstates of a non-Hermitian Hamilton operator that are embedded in one common continuum and are influenced by two adjoining EPs. The results are discussed. They are of interest for an experimental test of the non-Hermitian quantum physics as well as for applications.

  19. Robust Control of Uncertain Systems via Dissipative LQG-Type Controllers

    Science.gov (United States)

    Joshi, Suresh M.

    2000-01-01

    Optimal controller design is addressed for a class of linear, time-invariant systems which are dissipative with respect to a quadratic power function. The system matrices are assumed to be affine functions of uncertain parameters confined to a convex polytopic region in the parameter space. For such systems, a method is developed for designing a controller which is dissipative with respect to a given power function, and is simultaneously optimal in the linear-quadratic-Gaussian (LQG) sense. The resulting controller provides robust stability as well as optimal performance. Three important special cases, namely, passive, norm-bounded, and sector-bounded controllers, which are also LQG-optimal, are presented. The results give new methods for robust controller design in the presence of parametric uncertainties.

  20. The Impact of Decoherence and Dissipation on Cosmological Systems and on the Generation of Entanglement

    OpenAIRE

    2010-01-01

    The physics of open quantum systems, and therefore the phenomenon of decoherence, has become important in many branches of research. Within this thesis, we investigate the system--environment interaction in the context of different problems. The influence of decoherence is ubiquitous and, due to the scale independence of quantum theory, not limited to microscopic systems. One of the great open problems in theoretical physics is the appearance of a cosmological constant which differs by many o...

  1. Mode competition in a system of two parametrically driven pendulums; the dissipative case

    Science.gov (United States)

    Banning, E. J.; van der Weele, J. P.; Ross, J. C.; Kettenis, M. M.; de Kleine, E.

    1997-02-01

    In this paper we study the dynamics of a system of two linearly coupled, parametrically driven pendulums, subject to viscous dissipation. It is a continuation of the previous paper (E.J. Banning and J.P. van der Weele (1995)), in which we treated the Hamiltonian case. The damping has several important consequences. For instance, the driving amplitude now has to exceed a threshold value in order to excite non-trivial motion in the system. Furthermore, dissipative systems (can) exhibit attraction in phase space, making limit cycles, Arnol'd tongues and chaotic attractors a distinct possibility. We discuss these features in detail. Another consequence of the dissipation is that it breaks the time-reversal symmetry of the system. This means that several, formerly distinct motions now fall within the same symmetry class and may for instance annihilate each other in a saddle-node bifurcation. Implications of this are encountered throughout the paper, and we shall pay special attention to its effect on the interaction between two of the normal modes of the system.

  2. Dissipation of bentazone, pyrimethanil and boscalid in biochar and digestate based soil mixtures for biopurification systems

    Energy Technology Data Exchange (ETDEWEB)

    Mukherjee, Santanu, E-mail: s.mukherjee@fz-juelich.de [Institute of Bio- and Geosciences (IBG-3), Agrosphere Institute, Forschungszentrum Jülich GmbH, 52425 Jülich (Germany); Tappe, Wolfgang; Weihermueller, Lutz; Hofmann, Diana; Köppchen, Stephan [Institute of Bio- and Geosciences (IBG-3), Agrosphere Institute, Forschungszentrum Jülich GmbH, 52425 Jülich (Germany); Laabs, Volker; Schroeder, Tom [BASF SE, Crop Protection, 67117, Limburgerhof (Germany); Vereecken, Harry [Institute of Bio- and Geosciences (IBG-3), Agrosphere Institute, Forschungszentrum Jülich GmbH, 52425 Jülich (Germany); Burauel, Peter [Sustainable Campus, Forschungszentrum Jülich GmbH, 52425 Jülich (Germany)

    2016-02-15

    Biopurification systems, such as biofilters, are biotechnological tools to prevent point sources of pesticide pollution stemming from on-farm operations. For the purification processes pesticide sorption and mineralization and/or dissipation are essential and both largely depend on the type of filling materials and the pesticide in use. In this paper the mineralization and dissipation of three contrasting {sup 14}C-labeled pesticides (bentazone, boscalid, and pyrimethanil) were investigated in laboratory incubation experiments using sandy soil, biochar produced from Pine woodchips, and/or digestate obtained from anaerobic digestion process using maize silage, chicken manure, beef and pig urine as feedstock. The results indicate that the addition of digestate increased pesticide mineralization, whereby the mineralization was not proportional to the digestate loads in the mixture, indicating a saturation effect in the turnover rate of pesticides. This effect was in correlation with the amount of water extractable DOC, obtained from the digestate based mixtures. Mixing biochar into the soil generally reduced total mineralization and led to larger sorption/sequestration of the pesticides, resulting in faster decrease of the extractable fraction. Also the addition of biochar to the soil/digestate mixtures reduced mineralization compared to the digestate alone mixture but mineralization rates were still higher as for the biochar/soil alone. In consequence, the addition of biochar to the soil generally decreased pesticide dissipation times and larger amounts of biochar led to high amounts of non-extractable residues of pesticide in the substrates. Among the mixtures tested, a mixture of digestate (5%) and biochar (5%) gave optimal results with respect to mineralization and simultaneous sorption for all three pesticides. - Highlights: • Biochar and digestate significantly affects the dissipation pattern of pesticides. • Addition of digestate enhanced mineralization of

  3. Simulation of n-qubit quantum systems. III. Quantum operations

    Science.gov (United States)

    Radtke, T.; Fritzsche, S.

    2007-05-01

    During the last decade, several quantum information protocols, such as quantum key distribution, teleportation or quantum computation, have attracted a lot of interest. Despite the recent success and research efforts in quantum information processing, however, we are just at the beginning of understanding the role of entanglement and the behavior of quantum systems in noisy environments, i.e. for nonideal implementations. Therefore, in order to facilitate the investigation of entanglement and decoherence in n-qubit quantum registers, here we present a revised version of the FEYNMAN program for working with quantum operations and their associated (Jamiołkowski) dual states. Based on the implementation of several popular decoherence models, we provide tools especially for the quantitative analysis of quantum operations. Apart from the implementation of different noise models, the current program extension may help investigate the fragility of many quantum states, one of the main obstacles in realizing quantum information protocols today. Program summaryTitle of program: Feynman Catalogue identifier: ADWE_v3_0 Program summary URL:http://cpc.cs.qub.ac.uk/summaries/ADWE_v3_0 Program obtainable from: CPC Program Library, Queen's University of Belfast, N. Ireland Licensing provisions: None Operating systems: Any system that supports MAPLE; tested under Microsoft Windows XP, SuSe Linux 10 Program language used:MAPLE 10 Typical time and memory requirements: Most commands that act upon quantum registers with five or less qubits take ⩽10 seconds of processor time (on a Pentium 4 processor with ⩾2 GHz or equivalent) and 5-20 MB of memory. Especially when working with symbolic expressions, however, the memory and time requirements critically depend on the number of qubits in the quantum registers, owing to the exponential dimension growth of the associated Hilbert space. For example, complex (symbolic) noise models (with several Kraus operators) for multi-qubit systems

  4. Could nanostructure be unspeakable quantum system?

    CERN Document Server

    Aristov, V V

    2010-01-01

    Heisenberg, Bohr and others were forced to renounce on the description of the objective reality as the aim of physics because of the paradoxical quantum phenomena observed on the atomic level. The contemporary quantum mechanics created on the base of their positivism point of view must divide the world into speakable apparatus which amplifies microscopic events to macroscopic consequences and unspeakable quantum system. Examination of the quantum phenomena corroborates the confidence expressed by creators of quantum theory that the renunciation of realism should not apply on our everyday macroscopic world. Nanostructures may be considered for the present as a boundary of realistic description for all phenomena including the quantum one.

  5. Dissipative exciton transfer in donor bridge acceptor systems: numerical renormalization group calculation of equilibrium properties

    Science.gov (United States)

    Tornow, Sabine; Tong, Ning-Hua; Bulla, Ralf

    2006-07-01

    We present a detailed model study of exciton transfer processes in donor-bridge-acceptor (DBA) systems. Using a model which includes the intermolecular Coulomb interaction and the coupling to a dissipative environment we calculate the phase diagram, the absorption spectrum as well as dynamic equilibrium properties with the numerical renormalization group. This method is non-perturbative and therefore allows one to cover the full parameter space, especially the case when the intermolecular Coulomb interaction is of the same order as the coupling to the environment and perturbation theory cannot be applied. For DBA systems with up to six sites we found a transition to the localized phase (self-trapping) depending on the coupling to the dissipative environment. We discuss various criteria which favour delocalized exciton transfer.

  6. Dissipative exciton transfer in donor-bridge-acceptor systems: numerical renormalization group calculation of equilibrium properties

    Energy Technology Data Exchange (ETDEWEB)

    Tornow, Sabine [Theoretische Physik III, Elektronische Korrelationen und Magnetismus, Universitaet Augsburg, 86135 Augsburg (Germany); Tong, Ning-Hua [Institut fuer Theorie der Kondensierten Materie, Universitaet Karlsruhe, 76128 Karlsruhe (Germany); Bulla, Ralf [Theoretische Physik III, Elektronische Korrelationen und Magnetismus, Universitaet Augsburg, 86135 Augsburg (Germany)

    2006-07-05

    We present a detailed model study of exciton transfer processes in donor-bridge-acceptor (DBA) systems. Using a model which includes the intermolecular Coulomb interaction and the coupling to a dissipative environment we calculate the phase diagram, the absorption spectrum as well as dynamic equilibrium properties with the numerical renormalization group. This method is non-perturbative and therefore allows one to cover the full parameter space, especially the case when the intermolecular Coulomb interaction is of the same order as the coupling to the environment and perturbation theory cannot be applied. For DBA systems with up to six sites we found a transition to the localized phase (self-trapping) depending on the coupling to the dissipative environment. We discuss various criteria which favour delocalized exciton transfer.

  7. Experimental Investigation of the Evolution of Gaussian Quantum Discord in an Open System

    DEFF Research Database (Denmark)

    Madsen, Lars S.; Berni, Adriano; Lassen, Mikael;

    2012-01-01

    Gaussian quantum discord is a measure of quantum correlations in Gaussian systems. Using Gaussian discord, we quantify the quantum correlations of a bipartite entangled state and a separable two-mode mixture of coherent states. We experimentally analyze the effect of noise addition and dissipatio...... on Gaussian discord and show that the former noise degrades the discord, while the latter noise for some states leads to an increase of the discord. In particular, we experimentally demonstrate the near death of discord by noisy evolution and its revival through dissipation....

  8. Plate Tectonics as a Far-From-Equilibrium Self-Organized Dissipative System

    Science.gov (United States)

    Anderson, D. L.

    2001-12-01

    A fluid above the critical Rayleigh number is far from equilibrium and spontaneously organizes itself into patterns involving the collective motion of large numbers of molecules which are resisted by the viscosity of the fluid. No external template is involved in forming the pattern. In 1928 Pearson showed that Bénard's experiments were driven by variations in surface tension at the top of the fluid and the surface motions drove convection in the fluid. In this case, the surface organized itself AND the underlying fluid. Both internal buoyancy driven flow and flow driven by surface forces can be far-from-equilibrium self-organized open systems that receive energy and matter from the environment. In the Earth, the cold thermal boundary layer at the surface drives plate tectonics and introduces temperature, shear and pressure gradients into the mantle that drive mantle convection. The mantle provides energy and material but may not provide the template. Plate tectonics is therefore a candidate for a far-from-equilibrium dissipative self-organizing system. Alternatively, one could view mantle convection as the self-organized system and the plates as simply the surface manifestation. Lithospheric architecture also imposes lateral temperature gradients onto the mantle which can drive and organize flow. Far-from-equilibrium self-organization requires; an open system, interacting parts, nonlinearities or feedbacks, an outside steady source of energy or matter, multiple possible states and a source of dissipation. In uniform fluids viscosity is the source of dissipation. Sources of dissipation in the plate system include bending, breaking, folding, shearing, tearing, collision and basal drag. These can change rapidly, in contrast to plate driving forces, and introduce the sort of fluctuations that can reorganize far-from-equilibrium systems. Global plate reorganizations can alternatively be thought of as convective overturns of the mantle, or thermal weakening of plates

  9. Cosymplectic and contact structures for time-dependent and dissipative Hamiltonian systems

    Science.gov (United States)

    de León, M.; Sardón, C.

    2017-06-01

    In this paper, we apply the geometric Hamilton-Jacobi theory to obtain solutions of classical hamiltonian systems that are either compatible with a cosymplectic or a contact structure. As it is well known, the first structure plays a central role in the theory of time-dependent hamiltonians, whilst the second is here used to treat classical hamiltonians including dissipation terms. The interest of a geometric Hamilton-Jacobi equation is the primordial observation that if a hamiltonian vector field X H can be projected into a configuration manifold by means of a 1-form dW , then the integral curves of the projected vector field X_HdW can be transformed into integral curves of X H provided that W is a solution of the Hamilton-Jacobi equation. In this way, we use the geometric Hamilton-Jacobi theory to derive solutions of physical systems with a time-dependent hamiltonian formulation or including dissipative terms. Explicit, new expressions for a geometric Hamilton-Jacobi equation are obtained on a cosymplectic and a contact manifold. These equations are later used to solve physical examples containing explicit time dependence, as it is the case of a unidimensional trigonometric system, and two dimensional nonlinear oscillators as Winternitz-Smorodinsky oscillators and for explicit dissipative behavior, we solve the example of a unidimensional damped oscillator.

  10. Optimal Control of Finite Dimensional Quantum Systems

    CERN Document Server

    Mendonca, Paulo E M F

    2009-01-01

    This thesis addresses the problem of developing a quantum counter-part of the well established classical theory of control. We dwell on the fundamental fact that quantum states are generally not perfectly distinguishable, and quantum measurements typically introduce noise in the system being measured. Because of these, it is generally not clear whether the central concept of the classical control theory -- that of observing the system and then applying feedback -- is always useful in the quantum setting. We center our investigations around the problem of transforming the state of a quantum system into a given target state, when the system can be prepared in different ways, and the target state depends on the choice of preparation. We call this the "quantum tracking problem" and show how it can be formulated as an optimization problem that can be approached both numerically and analytically. This problem provides a simple route to the characterization of the quantum trade-off between information gain and distu...

  11. Past Quantum States of a Monitored System

    DEFF Research Database (Denmark)

    Gammelmark, Søren; Julsgaard, Brian; Mølmer, Klaus

    2013-01-01

    A density matrix ρ(t) yields probabilistic information about the outcome of measurements on a quantum system. We introduce here the past quantum state, which, at time T, accounts for the state of a quantum system at earlier times tstate Ξ(t) is composed of two objects, ρ......(t) and E(t), conditioned on the dynamics and the probing of the system until t and in the time interval [t, T], respectively. The past quantum state is characterized by its ability to make better predictions for the unknown outcome of any measurement at t than the conventional quantum state at that time....... On the one hand, our formalism shows how smoothing procedures for estimation of past classical signals by a quantum probe [M. Tsang, Phys. Rev. Lett. 102 250403 (2009)] apply also to describe the past state of the quantum system itself. On the other hand, it generalizes theories of pre- and postselected...

  12. Classical equations for quantum systems

    Energy Technology Data Exchange (ETDEWEB)

    Gell-Mann, M. (Theoretical Astrophysics Group (T-6), Los Alamos National Laboratory, Los Alamos, New Mexico 87545) (United States) (Santa Fe Institute, 1660 Old Pecos Trail, Santa Fe, New Mexico 87501); Hartle, J.B. (Department of Physics, University of California enSanta Barbara, Santa Barbara, (California) 93106)

    1993-04-15

    The origin of the phenomenological deterministic laws that approximately govern the quasiclassical domain of familiar experience is considered in the context of the quantum mechanics of closed systems such as the universe as a whole. A formulation of quantum mechanics is used that predicts probabilities for the individual members of a set of alternative coarse-grained histories that [ital decohere], which means that there is negligible quantum interference between the individual histories in the set. We investigate the requirements for coarse grainings to yield decoherent sets of histories that are quasiclassical, i.e., such that the individual histories obey, with high probability, effective classical equations of motion interrupted continually by small fluctuations and occasionally by large ones. We discuss these requirements generally but study them specifically for coarse grainings of the type that follows a distinguished subset of a complete set of variables while ignoring the rest. More coarse graining is needed to achieve decoherence than would be suggested by naive arguments based on the uncertainty principle. Even coarser graining is required in the distinguished variables for them to have the necessary inertia to approach classical predictability in the presence of the noise consisting of the fluctuations that typical mechanisms of decoherence produce. We describe the derivation of phenomenological equations of motion explicitly for a particular class of models.

  13. Quantum memristors

    Science.gov (United States)

    Pfeiffer, P.; Egusquiza, I. L.; di Ventra, M.; Sanz, M.; Solano, E.

    2016-07-01

    Technology based on memristors, resistors with memory whose resistance depends on the history of the crossing charges, has lately enhanced the classical paradigm of computation with neuromorphic architectures. However, in contrast to the known quantized models of passive circuit elements, such as inductors, capacitors or resistors, the design and realization of a quantum memristor is still missing. Here, we introduce the concept of a quantum memristor as a quantum dissipative device, whose decoherence mechanism is controlled by a continuous-measurement feedback scheme, which accounts for the memory. Indeed, we provide numerical simulations showing that memory effects actually persist in the quantum regime. Our quantization method, specifically designed for superconducting circuits, may be extended to other quantum platforms, allowing for memristor-type constructions in different quantum technologies. The proposed quantum memristor is then a building block for neuromorphic quantum computation and quantum simulations of non-Markovian systems.

  14. The Bullwhip Effect: Concretization of Entropic Information Dissipation in Supply Chain Systems

    Directory of Open Access Journals (Sweden)

    Tarik Saikouk

    2012-08-01

    Full Text Available Supply chains represent complex and dynamic systems that incorporate autonomous firms interacting with one another to fulfill a common goal, while insuring their own ones. These firms’ behaviors are considered to be non-linear and sometimes unpredictable. This makes information transfer in the supply chain complex and causes instability when information transferred is incomplete or incorrect. This instability is characterized by the Bullwhip Effect that represents concretization of entropy, namely the degree of disorder within a system. In this paper we develop a new analytical approach assuming that the bullwhip effect is a consequence of the entropy of the supply chain system that is represented by information dissipation.

  15. The effects of two-dimensional bifurcations and quantum beats in a system of combined atomic force and scanning tunneling microscopes with quantum dots

    Science.gov (United States)

    Zhukovsky, V. Ch.; Krevchik, V. D.; Semenov, M. B.; Krevchik, P. V.; Zaytsev, R. V.; Egorov, I. A.

    2016-11-01

    The field and temperature dependence of the probability of two-dimensional dissipative tunneling is studied in the framework of one-instanton approximation for a model double-well oscillator potential in an external electric field at finite temperature with account for the influence of two local phonon modes for quantum dots in a system of a combined atomic force and a scanning tunneling microscope. It is demonstrated that in the mode of synchronous parallel transfer of tunneling particles from the cantilever tip to the quantum dot the two local phonon modes result in the occurrence of two stable peaks in the curve of the 2D dissipative tunneling probability as a function of the field. Qualitative comparison of the theoretical curve in the limit of weak dissociation and the experimental current-voltage characteristic for quantum dots that grow from colloidal gold under a cantilever tip at the initial stage of quantum-dot formation when the quantum dot size does not exceed 10 nm is performed. It is established that one of the two stable peaks that correspond to interaction of tunneling particles with two local phonon modes in the temperature dependence of the 2D dissipative tunneling probability can be split in two, which corresponds to the tunneling channel interference mechanism. It is found that the theoretically predicted and experimentally observed mode of quantum beats occurs near the bifurcation point.

  16. Quantum mechanics in complex systems

    Science.gov (United States)

    Hoehn, Ross Douglas

    This document should be considered in its separation; there are three distinct topics contained within and three distinct chapters within the body of works. In a similar fashion, this abstract should be considered in three parts. Firstly, we explored the existence of multiply-charged atomic ions by having developed a new set of dimensional scaling equations as well as a series of relativistic augmentations to the standard dimensional scaling procedure and to the self-consistent field calculations. Secondly, we propose a novel method of predicting drug efficacy in hopes to facilitate the discovery of new small molecule therapeutics by modeling the agonist-protein system as being similar to the process of Inelastic Electron Tunneling Spectroscopy. Finally, we facilitate the instruction in basic quantum mechanical topics through the use of quantum games; this method of approach allows for the generation of exercises with the intent of conveying the fundamental concepts within a first year quantum mechanics classroom. Furthermore, no to be mentioned within the body of the text, yet presented in appendix form, certain works modeling the proliferation of cells types within the confines of man-made lattices for the purpose of facilitating artificial vascular transplants. In Chapter 2, we present a theoretical framework which describes multiply-charged atomic ions, their stability within super-intense laser fields, also lay corrections to the systems due to relativistic effects. Dimensional scaling calculations with relativistic corrections for systems: H, H-, H 2-, He, He-, He2-, He3- within super-intense laser fields were completed. Also completed were three-dimensional self consistent field calculations to verify the dimensionally scaled quantities. With the aforementioned methods the system's ability to stably bind 'additional' electrons through the development of multiple isolated regions of high potential energy leading to nodes of high electron density is shown

  17. Joint system quantum descriptions arising from local quantumness

    CERN Document Server

    Cooney, Tom; Navascues, Miguel; Perez-Garcia, David; Villanueva, Ignacio

    2012-01-01

    Bipartite correlations generated by non-signalling physical systems that admit a finite-dimensional local quantum description cannot exceed the quantum limits, i.e., they can always be interpreted as distant measurements of a bipartite quantum state. Here we consider the effect of dropping the assumption of finite dimensionality. Remarkably, we find that the same result holds provided that we relax the tensor structure of space-like separated measurements to mere commutativity. We argue why an extension of this result to tensor representations seems unlikely.

  18. boundary dissipation

    Directory of Open Access Journals (Sweden)

    Mehmet Camurdan

    1998-01-01

    are coupled by appropriate trace operators. This overall model differs from those previously studied in the literature in that the elastic chamber floor is here more realistically modeled by a hyperbolic Kirchoff equation, rather than by a parabolic Euler-Bernoulli equation with Kelvin-Voight structural damping, as in past literature. Thus, the hyperbolic/parabolic coupled system of past literature is replaced here by a hyperbolic/hyperbolic coupled model. The main result of this paper is a uniform stabilization of the coupled PDE system by a (physically appealing boundary dissipation.

  19. Quantum speed limits in open system dynamics.

    Science.gov (United States)

    del Campo, A; Egusquiza, I L; Plenio, M B; Huelga, S F

    2013-02-01

    Bounds to the speed of evolution of a quantum system are of fundamental interest in quantum metrology, quantum chemical dynamics, and quantum computation. We derive a time-energy uncertainty relation for open quantum systems undergoing a general, completely positive, and trace preserving evolution which provides a bound to the quantum speed limit. When the evolution is of the Lindblad form, the bound is analogous to the Mandelstam-Tamm relation which applies in the unitary case, with the role of the Hamiltonian being played by the adjoint of the generator of the dynamical semigroup. The utility of the new bound is exemplified in different scenarios, ranging from the estimation of the passage time to the determination of precision limits for quantum metrology in the presence of dephasing noise.

  20. Non-Markovian dynamics of open quantum systems

    Science.gov (United States)

    Fleming, Chris H.

    An open quantum system is a quantum system that interacts with some environment whose degrees of freedom have been coarse grained away. This model describes non-equilibrium processes more general than scattering-matrix formulations. Furthermore, the microscopically-derived environment provides a model of noise, dissipation and decoherence far more general than Markovian (white noise) models. The latter are fully characterized by Lindblad equations and can be motivated phenomenologically. Non-Markovian processes consistently account for backreaction with the environment and can incorporate effects such as finite temperature and spatial correlations. We consider linear systems with bilinear coupling to the environment, or quantum Brownian motion, and nonlinear systems with weak coupling to the environment. For linear systems we provide exact solutions with analytical results for a variety of spectral densities. Furthermore, we point out an important mathematical subtlety which led to incorrect master-equation coefficients in earlier derivations, given nonlocal dissipation. For nonlinear systems we provide perturbative solutions by translating the formalism of canonical perturbation theory into the context of master equations. It is shown that unavoidable degeneracy causes an unfortunate reduction in accuracy between perturbative master equations and their solutions. We also extend the famous theorem of Lindblad, Gorini, Kossakowski and Sudarshan on completely positivity to non-Markovian master equations. Our application is primarily to model atoms interacting via a common electromagnetic field. The electromagnetic field contains correlations in both space and time, which are related to its relativistic (photon-mediated) nature. As such, atoms residing in the same field experience different environmental effects depending upon their relative position and orientation. Our more accurate solutions were necessary to assess sudden death of entanglement at zero temperature

  1. Zero Dissipation Limit to Rarefaction Waves for the p-System

    Institute of Scientific and Technical Information of China (English)

    Hui Ying WANG

    2005-01-01

    We study the zero-dissipation problem for a one-dimensional model system for the isentropic flow of a compressible viscous gas, the so-called p-system with viscosity. When the solution of the inviscid problem is a rarefaction wave with finite strength, there exists unique solution to the viscous problem with the same initial data which converges to the given inviscid solution as e goes to zero.The proof consists of a scaling argument and elementary energy analysis, based on the underlying wave structure.

  2. Synthesis of dexterity measure of mechanisms by evolution of dissipative system

    Directory of Open Access Journals (Sweden)

    Grešl M.

    2007-11-01

    Full Text Available The paper deals with the new approach of solving traditional kinematical synthesis of mechanisms. The kinematical synthesis is reformulated as nonlinear dynamical problem. All searched parameters of the mechanism are in this dynamical dissipative system introduced as time-varying during motion of mechanism’s dimension iteration. The synthesis process is realized as the time evolution of such system. One of the most important objectives of the machine synthesis is the dexterity measure. The new approach is applied to optimization of this property.

  3. Use of discrete Wigner functions in the study of a hybrid dissipative system

    Science.gov (United States)

    Reboiro, M.; Civitarese, O.; Ramirez, R.; Tielas, D.

    2017-09-01

    The persistence of coherence in a hybrid dissipative system, which is composed of superconducting flux-qubits (SFQs) and an electron ensemble, is analyzed. Both the interactions between the electrons and the SFQs are taken into account. The time evolution of the hybrid system is discussed in terms of the discrete Wigner function of each subsystem and in terms of the entropic uncertainty relations. The inclusion of a linewidth, both for the electrons and the SFQs, influences the coherence of each subsystem and the pattern of spin squeezing of the corresponding steady state.

  4. Toda Lattice Solutions of Differential-Difference Equations for Dissipative Systems

    CERN Document Server

    Igarashi, Y; Nakanishi, K; Igarashi, Yuji; Itoh, Katsumi; Nakanishi, Ken

    1998-01-01

    In a certain class of differential-difference equations for dissipative systems, we show that hyperbolic tangent model is the only the nonlinear system of equations which can admit some particular solutions of the Toda lattice. We give one parameter family of exact solutions, which include as special cases the Toda lattice solutions as well as the Whitham's solutions in the Newell's model. Our solutions can be used to describe temporal-spatial density patterns observed in the optimal velocity model for traffic flow.

  5. Hybrid quantum systems of atoms and ions

    CERN Document Server

    Zipkes, Christoph; Palzer, Stefan; Sias, Carlo; Köhl, Michael

    2010-01-01

    In recent years, ultracold atoms have emerged as an exceptionally controllable experimental system to investigate fundamental physics, ranging from quantum information science to simulations of condensed matter models. Here we go one step further and explore how cold atoms can be combined with other quantum systems to create new quantum hybrids with tailored properties. Coupling atomic quantum many-body states to an independently controllable single-particle gives access to a wealth of novel physics and to completely new detection and manipulation techniques. We report on recent experiments in which we have for the first time deterministically placed a single ion into an atomic Bose Einstein condensate. A trapped ion, which currently constitutes the most pristine single particle quantum system, can be observed and manipulated at the single particle level. In this single-particle/many-body composite quantum system we show sympathetic cooling of the ion and observe chemical reactions of single particles in situ...

  6. Hybrid quantum systems of atoms and ions

    Energy Technology Data Exchange (ETDEWEB)

    Zipkes, Christoph; Ratschbacher, Lothar; Palzer, Stefan; Sias, Carlo; Koehl, Michael [Cavendish Laboratory, University of Cambridge, JJ Thomson Avenue, Cambridge CB3 0HE (United Kingdom)

    2011-01-10

    In recent years, ultracold atoms have emerged as an exceptionally controllable experimental system to investigate fundamental physics, ranging from quantum information science to simulations of condensed matter models. Here we go one step further and explore how cold atoms can be combined with other quantum systems to create new quantum hybrids with tailored properties. Coupling atomic quantum many-body states to an independently controllable single-particle gives access to a wealth of novel physics and to completely new detection and manipulation techniques. We report on recent experiments in which we have for the first time deterministically placed a single ion into an atomic Bose Einstein condensate. A trapped ion, which currently constitutes the most pristine single particle quantum system, can be observed and manipulated at the single particle level. In this single-particle/many-body composite quantum system we show sympathetic cooling of the ion and observe chemical reactions of single particles in situ.

  7. Quantum Q systems: from cluster algebras to quantum current algebras

    Science.gov (United States)

    Di Francesco, Philippe; Kedem, Rinat

    2017-02-01

    This paper gives a new algebraic interpretation for the algebra generated by the quantum cluster variables of the A_r quantum Q-system (Di Francesco and Kedem in Int Math Res Not IMRN 10:2593-2642, 2014). We show that the algebra can be described as a quotient of the localization of the quantum algebra U_{√{q}}({n}[u,u^{-1}])subset U_{√{q}}(widehat{{sl}}_2), in the Drinfeld presentation. The generating current is made up of a subset of the cluster variables which satisfy the Q-system, which we call fundamental. The other cluster variables are given by a quantum determinant-type formula, and are polynomials in the fundamental generators. The conserved quantities of the discrete evolution (Di Francesco and Kedem in Adv Math 228(1):97-152, 2011) described by quantum Q-system generate the Cartan currents at level 0, in a non-standard polarization. The rest of the quantum affine algebra is also described in terms of cluster variables.

  8. Quantum Q systems: from cluster algebras to quantum current algebras

    Science.gov (United States)

    Di Francesco, Philippe; Kedem, Rinat

    2016-11-01

    This paper gives a new algebraic interpretation for the algebra generated by the quantum cluster variables of the A_r quantum Q-system (Di Francesco and Kedem in Int Math Res Not IMRN 10:2593-2642, 2014). We show that the algebra can be described as a quotient of the localization of the quantum algebra U_{√{q}}({{n}}[u,u^{-1}])subset U_{√{q}}(widehat{{{sl}}}_2) , in the Drinfeld presentation. The generating current is made up of a subset of the cluster variables which satisfy the Q-system, which we call fundamental. The other cluster variables are given by a quantum determinant-type formula, and are polynomials in the fundamental generators. The conserved quantities of the discrete evolution (Di Francesco and Kedem in Adv Math 228(1):97-152, 2011) described by quantum Q-system generate the Cartan currents at level 0, in a non-standard polarization. The rest of the quantum affine algebra is also described in terms of cluster variables.

  9. Quantum chaos in open systems a quantum state diffusion analysis

    CERN Document Server

    Brun, T A; Schack, R; Brun, Todd A; Percival, Ian C; Schack, Rudiger

    1995-01-01

    Except for the universe, all quantum systems are open, and according to quantum state diffusion theory, many systems localize to wave packets in the neighborhood of phase space points. This is due to decoherence from the interaction with the environment, and makes the quasiclassical limit of such systems both more realistic and simpler in many respects than the more familiar quasiclassical limit for closed systems. A linearized version of this theory leads to the correct classical dynamics in the macroscopic limit, even for nonlinear and chaotic systems. We apply the theory to the forced, damped Duffing oscillator, comparing the numerical results of the full and linearized equations, and argue that this can be used to make explicit calculations in the decoherent histories formalism of quantum mechanics.

  10. Dissipative production of a maximally entangled steady state

    CERN Document Server

    Lin, Y; Reiter, F; Tan, T R; Bowler, R; S\\orensen, A S; Leibfried, D; Wineland, D J

    2013-01-01

    Entangled states are a key resource in fundamental quantum physics, quantum cryp-tography, and quantum computation [1].To date, controlled unitary interactions applied to a quantum system, so-called "quantum gates", have been the most widely used method to deterministically create entanglement [2]. These processes require high-fidelity state preparation as well as minimizing the decoherence that inevitably arises from coupling between the system and the environment and imperfect control of the system parameters. Here, on the contrary, we combine unitary processes with engineered dissipation to deterministically produce and stabilize an approximate Bell state of two trapped-ion qubits independent of their initial state. While previous works along this line involved the application of sequences of multiple time-dependent gates [3] or generated entanglement of atomic ensembles dissipatively but relied on a measurement record for steady-state entanglement [4], we implement the process in a continuous time-indepen...

  11. Quasi-Periodically Driven Quantum Systems

    Science.gov (United States)

    Verdeny, Albert; Puig, Joaquim; Mintert, Florian

    2016-10-01

    Floquet theory provides rigorous foundations for the theory of periodically driven quantum systems. In the case of non-periodic driving, however, the situation is not so well understood. Here, we provide a critical review of the theoretical framework developed for quasi-periodically driven quantum systems. Although the theoretical footing is still under development, we argue that quasi-periodically driven quantum systems can be treated with generalisations of Floquet theory in suitable parameter regimes. Moreover, we provide a generalisation of the Floquet-Magnus expansion and argue that quasi-periodic driving offers a promising route for quantum simulations.

  12. Simulating open quantum systems: from many-body interactions to stabilizer pumping

    CERN Document Server

    Mueller, M; Zhou, Y L; Roos, C F; Zoller, P

    2011-01-01

    In a recent experiment, Barreiro et al. demonstrated the fundamental building blocks of an open-system quantum simulator with trapped ions [Nature 470, 486 (2011)]. Using up to five ions, single- and multi-qubit entangling gate operations were combined with optical pumping in stroboscopic sequences. This enabled the implementation of both coherent many-body dynamics as well as dissipative processes by controlling the coupling of the system to an artificial, suitably tailored environment. This engineering was illustrated by the dissipative preparation of entangled two- and four-qubit states, the simulation of coherent four-body spin interactions and the quantum non-demolition measurement of a multi-qubit stabilizer operator. In the present paper, we present the theoretical framework of this gate-based ("digital") simulation approach for open-system dynamics with trapped ions. In addition, we discuss how within this simulation approach minimal instances of spin models of interest in the context of topological q...

  13. Anisotropic Landau-Lifshitz-Gilbert models of dissipation in qubits

    Science.gov (United States)

    Crowley, Philip J. D.; Green, A. G.

    2016-12-01

    We derive a microscopic model for dissipative dynamics in a system of mutually interacting qubits coupled to a thermal bath that generalizes the dissipative model of Landau-Lifshitz-Gilbert to the case of anisotropic bath couplings. We show that the dissipation acts to bias the quantum trajectories towards a reduced phase space. This model applies to a system of superconducting flux qubits whose coupling to the environment is necessarily anisotropic. We study the model in the context of the D-Wave computing device and show that the form of environmental coupling in this case produces dynamics that are closely related to several models proposed on phenomenological grounds.

  14. Open system dynamics with non-Markovian quantum trajectories

    CERN Document Server

    Strunz, W T; Gisin, Nicolas; Strunz, Walter T; Diosi, Lajos; Gisin, Nicolas

    1999-01-01

    A non-Markovian stochastic Schroedinger equation for a quantum system coupled to an environment of harmonic oscillators is presented. Its solutions, when averaged over the noise, reproduce the standard reduced density operator without any approximation. We illustrate the power of this approach with several examples, including exponentially decaying bath correlations and extreme non-Markovian cases, where the `environment' consists of only a single oscillator. The latter case shows the decay and revival of a `Schroedinger cat' state. For strong coupling to a dissipative environment with memory, the asymptotic state can be reached in a finite time. Our description of open systems is compatible with different positions of the `Heisenberg cut' between system and environment.

  15. Steady and optimal entropy squeezing of a two-level atom with quantum-jump-based feedback and classical driving in a dissipative cavity

    Science.gov (United States)

    Yu, Min; Fang, Mao-Fa

    2016-10-01

    We investigate the entropy squeezing of a two-level atom coupled to a dissipative cavity under two different controls: In the first case, quantum-jump-based feedback is alone applied, whereas in the second case we consider the combined effect of quantum-jump-based feedback and classical driving, in which we provide a scheme to generate and protect steady and optimal entropy squeezing of the two-level atom. The results show that the entropy squeezing of atomic polarization components greatly depends on the control of quantum-jump-based feedback and classical driving. Under the condition of designing proper quantum-jump-based feedback parameters, the entropy squeezing can be generated and protected. Furthermore, when both quantum-jump-based feedback and classical driving are simultaneously applied, steady and optimal entropy squeezing of the two-level atom can be obtained even though there is initially no entropy squeezing, which is explained by making use of the steady-state solution of the atom.

  16. Adiabatic Quantum Search in Open Systems.

    Science.gov (United States)

    Wild, Dominik S; Gopalakrishnan, Sarang; Knap, Michael; Yao, Norman Y; Lukin, Mikhail D

    2016-10-07

    Adiabatic quantum algorithms represent a promising approach to universal quantum computation. In isolated systems, a key limitation to such algorithms is the presence of avoided level crossings, where gaps become extremely small. In open quantum systems, the fundamental robustness of adiabatic algorithms remains unresolved. Here, we study the dynamics near an avoided level crossing associated with the adiabatic quantum search algorithm, when the system is coupled to a generic environment. At zero temperature, we find that the algorithm remains scalable provided the noise spectral density of the environment decays sufficiently fast at low frequencies. By contrast, higher order scattering processes render the algorithm inefficient at any finite temperature regardless of the spectral density, implying that no quantum speedup can be achieved. Extensions and implications for other adiabatic quantum algorithms will be discussed.

  17. Tailoring superradiance to design artificial quantum systems

    Science.gov (United States)

    Longo, Paolo; Keitel, Christoph H.; Evers, Jörg

    2016-03-01

    Cooperative phenomena arising due to the coupling of individual atoms via the radiation field are a cornerstone of modern quantum and optical physics. Recent experiments on x-ray quantum optics added a new twist to this line of research by exploiting superradiance in order to construct artificial quantum systems. However, so far, systematic approaches to deliberately design superradiance properties are lacking, impeding the desired implementation of more advanced quantum optical schemes. Here, we develop an analytical framework for the engineering of single-photon superradiance in extended media applicable across the entire electromagnetic spectrum, and show how it can be used to tailor the properties of an artificial quantum system. This “reverse engineering” of superradiance not only provides an avenue towards non-linear and quantum mechanical phenomena at x-ray energies, but also leads to a unified view on and a better understanding of superradiance across different physical systems.

  18. Tailoring superradiance to design artificial quantum systems.

    Science.gov (United States)

    Longo, Paolo; Keitel, Christoph H; Evers, Jörg

    2016-03-24

    Cooperative phenomena arising due to the coupling of individual atoms via the radiation field are a cornerstone of modern quantum and optical physics. Recent experiments on x-ray quantum optics added a new twist to this line of research by exploiting superradiance in order to construct artificial quantum systems. However, so far, systematic approaches to deliberately design superradiance properties are lacking, impeding the desired implementation of more advanced quantum optical schemes. Here, we develop an analytical framework for the engineering of single-photon superradiance in extended media applicable across the entire electromagnetic spectrum, and show how it can be used to tailor the properties of an artificial quantum system. This "reverse engineering" of superradiance not only provides an avenue towards non-linear and quantum mechanical phenomena at x-ray energies, but also leads to a unified view on and a better understanding of superradiance across different physical systems.

  19. Adiabatic Quantum Search in Open Systems

    Science.gov (United States)

    Wild, Dominik S.; Gopalakrishnan, Sarang; Knap, Michael; Yao, Norman Y.; Lukin, Mikhail D.

    2016-10-01

    Adiabatic quantum algorithms represent a promising approach to universal quantum computation. In isolated systems, a key limitation to such algorithms is the presence of avoided level crossings, where gaps become extremely small. In open quantum systems, the fundamental robustness of adiabatic algorithms remains unresolved. Here, we study the dynamics near an avoided level crossing associated with the adiabatic quantum search algorithm, when the system is coupled to a generic environment. At zero temperature, we find that the algorithm remains scalable provided the noise spectral density of the environment decays sufficiently fast at low frequencies. By contrast, higher order scattering processes render the algorithm inefficient at any finite temperature regardless of the spectral density, implying that no quantum speedup can be achieved. Extensions and implications for other adiabatic quantum algorithms will be discussed.

  20. CONFIGURATION CONTROLLABILITY FOR NON-ZERO POTENTIAL MECHANICAL CONTROL SYSTEMS WITH DISSIPATION

    Institute of Scientific and Technical Information of China (English)

    KANG Jian-ling; WANG Hong; YE Hua-wen

    2005-01-01

    Within the affine connection framework of Lagrangian control systems, based on the results of Sussmann on controllability of general affine control systems defined on a finite-dimensional manifold, a computable sufficient condition of configuration controllability for the simple mechanical control systems was extended to the case of systems with strictly dissipative energy terms of linear isotropic nature, and a sufficient condition of equilibrium controllability for the systems was also given, where Lagrangian is kinetic energy minus potential energy. Lie bracketting of vector fields in controllable Lie algebra, and the symmetric product associated with Levi-Civita connection show virtues in the discussion. Liouville vector field simplified the computation of controllable Lie algebra for the systems, although the terms of potential energy complicated the study of configuration controllability.

  1. Dissipative Optomechanics in a Michelson--Sagnac Interferometer

    OpenAIRE

    Xuereb, A.; Schnabel, R.; Hammerer, K.

    2011-01-01

    Dissipative optomechanics studies the coupling of the motion of an optical element to the decay rate of a cavity. We propose and theoretically explore a realization of this system in the optical domain, using a combined Michelson--Sagnac interferometer, which enables a strong and tunable dissipative coupling. Quantum interference in such a setup results in the suppression of the lower motional sideband, leading to strongly enhanced cooling in the non-sideband-resolved regime. With state-of-th...

  2. Geometric quenches in quantum integrable systems

    NARCIS (Netherlands)

    Mossel, J.; Palacios, G.; Caux, J.S.

    2010-01-01

    We consider the generic problem of suddenly changing the geometry of an integrable, one-dimensional many-body quantum system. We show how the physics of an initial quantum state released into a bigger system can be completely described within the framework of the algebraic Bethe ansatz, by providing

  3. Linear response theory for quantum open systems

    OpenAIRE

    Wei, J. H.; Yan, YiJing

    2011-01-01

    Basing on the theory of Feynman's influence functional and its hierarchical equations of motion, we develop a linear response theory for quantum open systems. Our theory provides an effective way to calculate dynamical observables of a quantum open system at its steady-state, which can be applied to various fields of non-equilibrium condensed matter physics.

  4. BANDWIDTH OF QUANTUM OPTICAL COMMUNICATION SYSTEM

    Directory of Open Access Journals (Sweden)

    I. R. Gulakov

    2012-01-01

    Full Text Available Impact of registered optical radiation intensity, overvoltage, dimensions of photosensitive surface, structure of p-n junction and avalanche photodetectors dead time operating in the photon counting mode on quantum optical system capacity has been carried out in this investigation. As a result, the quantum optical system maximum capacity of 81 kbit/s has been obtained.

  5. Statistical investigation and thermal properties for a 1-D impact system with dissipation

    Energy Technology Data Exchange (ETDEWEB)

    Díaz I, Gabriel, E-mail: gabriel.diaz.iturry@gmail.com; Livorati, André L.P., E-mail: livorati@rc.unesp.br; Leonel, Edson D., E-mail: edleonel@rc.unesp.br

    2016-05-06

    Highlights: • The dynamics of a 1-D dissipative impact system is studied. • Statistical properties for the average velocity, root mean square velocity and its deviation are characterized. • A thermodynamics formalism is developed as function of the statistical variable. • The formalism shows itself to be robust, and we can predict numerical values without doing numerical simulations. - Abstract: The behavior of the average velocity, its deviation and average squared velocity are characterized using three techniques for a 1-D dissipative impact system. The system – a particle, or an ensemble of non-interacting particles, moving in a constant gravitation field and colliding with a varying platform – is described by a nonlinear mapping. The average squared velocity allows to describe the temperature for an ensemble of particles as a function of the parameters using: (i) straightforward numerical simulations; (ii) analytically from the dynamical equations; (iii) using the probability distribution function. Comparing analytical and numerical results for the three techniques, one can check the robustness of the developed formalism, where we are able to estimate numerical values for the statistical variables, without doing extensive numerical simulations. Also, extension to other dynamical systems is immediate, including time dependent billiards.

  6. General scaling laws of chaotic escape in dissipative multistable systems subjected to autoresonant excitations

    Energy Technology Data Exchange (ETDEWEB)

    Chacon, Ricardo, E-mail: rchacon@unex.e [Departamento de Fisica Aplicada, Escuela de IngenierIas Industriales, Universidad de Extremadura, Apartado Postal 382, E-06071 Badajoz (Spain)

    2010-06-04

    Theory concerning the emergence and control of chaotic escape from a potential well by means of autoresonant excitations is presented in the context of generic, dissipative and multistable systems. General scaling laws relating both the onset and lifetime of transient chaos to the parameters of autoresonant excitations are derived theoretically using vibrational mechanics, Melnikov analysis and energy-based autoresonance theory. Numerical experiments show that these scaling laws are robust against both the presence of noise and driving re-shaping. (fast track communication)

  7. Solution of the inverse Langevin problem for open dissipative systems with anisotropic interparticle interaction

    Energy Technology Data Exchange (ETDEWEB)

    Lisin, E. A.; Lisina, I. I.; Vaulina, O. S.; Petrov, O. F. [Joint Institute for High Temperatures of the Russian Academy of Sciences, 13 bd.2 Izhorskaya St., Moscow 125412, Russia and Moscow Institute of Physics and Technology, 9 Institutskiy Per., Dolgoprudny, Moscow Region 141700 (Russian Federation)

    2015-03-15

    Solution of the inverse Langevin problem is presented for open dissipative systems with anisotropic interparticle interaction. Possibility of applying this solution for experimental determining the anisotropic interaction forces between dust particles in complex plasmas with ion flow is considered. For this purpose, we have tested the method on the results of numerical simulation of chain structures of particles with quasidipole-dipole interaction, similar to the one occurring due to effects of ion focusing in gas discharges. Influence of charge spatial inhomogeneity and fluctuations on the results of recovery is also discussed.

  8. Quantum information theory with Gaussian systems

    Energy Technology Data Exchange (ETDEWEB)

    Krueger, O.

    2006-04-06

    This thesis applies ideas and concepts from quantum information theory to systems of continuous-variables such as the quantum harmonic oscillator. The focus is on three topics: the cloning of coherent states, Gaussian quantum cellular automata and Gaussian private channels. Cloning was investigated both for finite-dimensional and for continuous-variable systems. We construct a private quantum channel for the sequential encryption of coherent states with a classical key, where the key elements have finite precision. For the case of independent one-mode input states, we explicitly estimate this precision, i.e. the number of key bits needed per input state, in terms of these parameters. (orig.)

  9. Open quantum system approach to the Gibbons-Hawking effect of de Sitter space-time.

    Science.gov (United States)

    Yu, Hongwei

    2011-02-11

    We analyze, in the paradigm of open quantum systems, the reduced dynamics of a freely falling two-level detector in de Sitter space-time in weak interaction with a reservoir of fluctuating quantized conformal scalar fields in the de Sitter-invariant vacuum. We find that the detector is asymptotically driven to a thermal state at the Gibbons-Hawking temperature, regardless of its initial state. Our discussion, therefore, shows that the Gibbons-Hawking effect of de Sitter space-time can be understood as a manifestation of thermalization phenomena that involves decoherence and dissipation in open quantum systems.

  10. Classical Equations for Quantum Systems

    CERN Document Server

    Gell-Mann, Murray; Gell-Mann, Murray; Hartle, James B.

    1993-01-01

    The origin of the phenomenological deterministic laws that approximately govern the quasiclassical domain of familiar experience is considered in the context of the quantum mechanics of closed systems such as the universe as a whole. We investigate the requirements for coarse grainings to yield decoherent sets of histories that are quasiclassical, i.e. such that the individual histories obey, with high probability, effective classical equations of motion interrupted continually by small fluctuations and occasionally by large ones. We discuss these requirements generally but study them specifically for coarse grainings of the type that follows a distinguished subset of a complete set of variables while ignoring the rest. More coarse graining is needed to achieve decoherence than would be suggested by naive arguments based on the uncertainty principle. Even coarser graining is required in the distinguished variables for them to have the necessary inertia to approach classical predictability in the presence of t...

  11. Evolving Systems: Adaptive Key Component Control and Inheritance of Passivity and Dissipativity

    Science.gov (United States)

    Frost, S. A.; Balas, M. J.

    2010-01-01

    We propose a new framework called Evolving Systems to describe the self-assembly, or autonomous assembly, of actively controlled dynamical subsystems into an Evolved System with a higher purpose. Autonomous assembly of large, complex flexible structures in space is a target application for Evolving Systems. A critical requirement for autonomous assembling structures is that they remain stable during and after assembly. The fundamental topic of inheritance of stability, dissipativity, and passivity in Evolving Systems is the primary focus of this research. In this paper, we develop an adaptive key component controller to restore stability in Nonlinear Evolving Systems that would otherwise fail to inherit the stability traits of their components. We provide sufficient conditions for the use of this novel control method and demonstrate its use on an illustrative example.

  12. Coherent Dynamics of Complex Quantum Systems

    CERN Document Server

    Akulin, Vladimir M

    2006-01-01

    A large number of modern problems in physics, chemistry, and quantum electronics require a consideration of population dynamics in complex multilevel quantum systems. The purpose of this book is to provide a systematic treatment of these questions and to present a number of exactly solvable problems. It considers the different dynamical problems frequently encountered in different areas of physics from the same perspective, based mainly on the fundamental ideas of group theory and on the idea of ensemble average. Also treated are concepts of complete quantum control and correction of decoherence induced errors that are complementary to the idea of ensemble average. "Coherent Dynamics of Complex Quantum Systems" is aimed at senior-level undergraduate students in the areas of Atomic, Molecular, and Laser Physics, Physical Chemistry, Quantum Optics and Quantum Informatics. It should help them put particular problems in these fields into a broader scientific context and thereby take advantage of the well-elabora...

  13. Non-Markovian dynamics of quantum coherence of two-level system driven by classical field

    Science.gov (United States)

    Huang, Zhiming; Situ, Haozhen

    2017-09-01

    In this paper, we study the quantum coherence dynamics of two-level atom system embedded in non-Markovian reservoir in the presence of classical driving field. We analyze the influence of memory effects, classical driving, and detuning on the quantum coherence. It is found that the quantum coherence has different behaviors in resonant case and non-resonant case. In the resonant case, in stark contrast with previous results, the strength of classical driving plays a negative effect on quantum coherence, while detuning parameter has the opposite effect. However, in non-resonant case through a long time, classical driving and detuning parameter have a different influence on quantum coherence compared with resonant case. Due to the memory effect of environment, in comparison with Markovian regime, quantum coherence presents vibrational variations in non-Markovian regime. In the resonant case, all quantum coherence converges to a fixed maximum value; in the non-resonant case, quantum coherence evolves to different stable values. For zero-coherence initial states, quantum coherence can be generated with evolution time. Our discussions and results should be helpful in manipulating and preserving the quantum coherence in dissipative environment with classical driving field.

  14. Quantum-to-classical crossover near quantum critical point.

    Science.gov (United States)

    Vasin, M; Ryzhov, V; Vinokur, V M

    2015-12-21

    A quantum phase transition (QPT) is an inherently dynamic phenomenon. However, while non-dissipative quantum dynamics is described in detail, the question, that is not thoroughly understood is how the omnipresent dissipative processes enter the critical dynamics near a quantum critical point (QCP). Here we report a general approach enabling inclusion of both adiabatic and dissipative processes into the critical dynamics on the same footing. We reveal three distinct critical modes, the adiabatic quantum mode (AQM), the dissipative classical mode [classical critical dynamics mode (CCDM)], and the dissipative quantum critical mode (DQCM). We find that as a result of the transition from the regime dominated by thermal fluctuations to that governed by the quantum ones, the system acquires effective dimension d + zΛ(T), where z is the dynamical exponent, and temperature-depending parameter Λ(T) ∈ [0, 1] decreases with the temperature such that Λ(T = 0) = 1 and Λ(T → ∞) = 0. Our findings lead to a unified picture of quantum critical phenomena including both dissipation- and dissipationless quantum dynamic effects and offer a quantitative description of the quantum-to-classical crossover.

  15. Dynamics of a Landau–Zener non-dissipative system with fluctuating energy levels

    Energy Technology Data Exchange (ETDEWEB)

    Fai, L.C. [Mesoscopic and Multilayer Structures Laboratory, Department of Physics, Faculty of Science, University of Dschang, Dschang (Cameroon); Diffo, J.T., E-mail: diffojaures@yahoo.com [Mesoscopic and Multilayer Structures Laboratory, Department of Physics, Faculty of Science, University of Dschang, Dschang (Cameroon); Department of Physics, Higher Teachers’ Training College, The University of Maroua, Maroua (Cameroon); Ateuafack, M.E.; Tchoffo, M.; Fouokeng, G.C. [Mesoscopic and Multilayer Structures Laboratory, Department of Physics, Faculty of Science, University of Dschang, Dschang (Cameroon)

    2014-12-01

    This paper considers a Landau–Zener (two-level) system influenced by a three-dimensional Gaussian and non-Gaussian coloured noise and finds a general form of the time dependent diabatic quantum bit (qubit) flip transition probabilities in the fast, intermediate and slow noise limits. The qubit flip probability is observed to mimic (for low-frequencies noise) that of the standard LZ problem. The qubit flip probability is also observed to be the measure of quantum coherence of states. The transition probability is observed to be tailored by non-Gaussian low-frequency noise and otherwise by Gaussian low-frequency coloured noise. Intermediate and fast noise limits are observed to alter the memory of the system in time and found to improve and control quantum information processing.

  16. Energy Input and Dissipation in the Ionosphere-Thermosphere (IT) System

    Science.gov (United States)

    Huang, C. Y.; Huang, Y.; Su, Y. J.; Sutton, E. K.; Hairston, M. R.

    2015-12-01

    AFRL The long-held view of energy input and dissipation into the IT system says that the primary region in which dynamic and electrodynamic processes occur is the auroral zone. Recent observations have indicated that this may not be completely true. The dominant form of energy input to the IT system is electromagnetic, and not particle precipitation. Poynting flux measured on DMSP spacecraft during storms indicates that energy can be deposited at all local times (LTs) in both hemispheres at polar latitudes as well as in the auroral zones. One major effect of this energy input is Joule heating of the ionosphere and thermosphere. We have analyzed the ion temperature measured by DMSP for a number of storms. During storm main phases, the increase in ion temperature maximizes at polar latitudes. We have processed neutral densities from CHAMP, GRACE and GOCE which show localized Joule heating at extremely high latitudes in both hemispheres. We conclude that energy input and dissipation occurs in the polar cap as well as in the auroral zones. Our results require a re-examination of the processes by which energy can enter the IT system, as well as where and how energy is transferred to ions and neutrals

  17. Mixed convolved action for classical and fractional-derivative dissipative dynamical systems.

    Science.gov (United States)

    Dargush, G F

    2012-12-01

    The principle of mixed convolved action provides a new rigorous weak variational formalism for a broad range of initial value problems in mathematical physics and mechanics. Here, the focus is initially on classical single-degree-of-freedom oscillators incorporating either Kelvin-Voigt or Maxwell dissipative elements and then, subsequently, on systems that utilize fractional-derivative constitutive models. In each case, an appropriate mixed convolved action is formulated, and a corresponding weak form is discretized in time using temporal shape functions to produce an algorithm suitable for numerical solution. Several examples are considered to validate the mixed convolved action principles and to investigate the performance of the numerical algorithms. For undamped systems, the algorithm is found to be symplectic and unconditionally stable with respect to the time step. In the case of dissipative systems, the approach is shown to be robust and to be accurate with good convergence characteristics for both classical and fractional-derivative based models. As part of the derivations, some interesting results in the calculus of Caputo fractional derivatives also are presented.

  18. Quantum Dynamics of Nonlinear Cavity Systems

    OpenAIRE

    Nation, Paul D.

    2010-01-01

    We investigate the quantum dynamics of three different configurations of nonlinear cavity systems. To begin, we carry out a quantum analysis of a dc superconducting quantum interference device (SQUID) mechanical displacement detector comprised of a SQUID with a mechanically compliant loop segment. The SQUID is approximated by a nonlinear current-dependent inductor, inducing a flux tunable nonlinear Duffing term in the cavity equation of motion. Expressions are derived for the detector signal ...

  19. Quantum equilibria for macroscopic systems

    Energy Technology Data Exchange (ETDEWEB)

    Grib, A [Department of Theoretical Physics and Astronomy, Russian State Pedagogical University, St. Petersburg (Russian Federation); Khrennikov, A [Centre for Mathematical Modelling in Physics and Cognitive Sciences Vaexjoe University (Sweden); Parfionov, G [Department of Mathematics, St. Petersburg State University of Economics and Finances (Russian Federation); Starkov, K [Department of Mathematics, St. Petersburg State University of Economics and Finances (Russian Federation)

    2006-06-30

    Nash equilibria are found for some quantum games with particles with spin-1/2 for which two spin projections on different directions in space are measured. Examples of macroscopic games with the same equilibria are given. Mixed strategies for participants of these games are calculated using probability amplitudes according to the rules of quantum mechanics in spite of the macroscopic nature of the game and absence of Planck's constant. A possible role of quantum logical lattices for the existence of macroscopic quantum equilibria is discussed. Some examples for spin-1 cases are also considered.

  20. Non-perturbative description of quantum systems

    CERN Document Server

    Feranchuk, Ilya; Le, Van-Hoang; Ulyanenkov, Alexander

    2015-01-01

    This book introduces systematically the operator method for the solution of the Schrödinger equation. This method permits to describe the states of quantum systems in the entire range of parameters of Hamiltonian with a predefined accuracy. The operator method is unique compared with other non-perturbative methods due to its ability to deliver in zeroth approximation the uniformly suitable estimate for both ground and excited states of quantum system. The method has been generalized for the application to quantum statistics and quantum field theory.  In this book, the numerous applications of operator method for various physical systems are demonstrated. Simple models are used to illustrate the basic principles of the method which are further used for the solution of complex problems of quantum theory for many-particle systems. The results obtained are supplemented by numerical calculations, presented as tables and figures.

  1. Characteristics of the Kind of Intense Convective Systems With Forcing and Dissipation and Its Forecasting

    Institute of Scientific and Technical Information of China (English)

    李志锦; 丑纪范

    1994-01-01

    According to the theory of the nonlinear dynamical systems with forcing and dissipation,theconceptual ideas are proposed that the intense convective system is an attractor of the meso-scale dynamicalsystem,in which the large-scale fields serve as the bifurcation parameters that evolve slowly.The intenseconvective systems occur explosively when the intensity of the large-scale system passes a bifurcation point.Thus,its prediction is just to predict the evolution of the attractor,independent of the mesoscale initial con-ditions.A primitive spectral limited-area model has been developed and two realistic cases,which were cap-tured by the Eastern China area mesoscale experiment,have been simulated by using this model.The resultshave proved the theoretical points.

  2. Energy propagation in dissipative systems Part I: Centrovelocity for linear systems

    NARCIS (Netherlands)

    Groesen, van Embrecht; Mainardi, Francesco

    1989-01-01

    Based on a balance equation for the energy density, an expression for the centrovelocity is derived which differs from the usual energy-flux velocity by a loss-flux term as a consequence of the presence of dissipation. In this part the expression is investigated for linear wave equations, in particu

  3. Characterization of dynamical regimes and entanglement sudden death in a microcavity quantum dot system

    Energy Technology Data Exchange (ETDEWEB)

    Vera, Carlos A; Quesada M, Nicolas; Vinck-Posada, Herbert; Rodriguez, Boris A, E-mail: nquesada@pegasus.udea.edu.c [Instituto de Fisica, Universidad de Antioquia, Medellin, AA 1226 Medellin (Colombia)

    2009-09-30

    The relation between the dynamical regimes (weak and strong coupling) and entanglement for a dissipative quantum dot microcavity system is studied. In the framework of a phenomenological temperature model an analysis in both temporal (population dynamics) and frequency domain (photoluminescence) is carried out in order to identify the associated dynamical behavior. The Wigner function and concurrence are employed to quantify the entanglement in each regime. We find that sudden death of entanglement is a typical characteristic of the strong coupling regime.

  4. Performance-Based Seismic Retrofit of Soft-Story Woodframe Buildings Using Energy-Dissipation Systems

    Science.gov (United States)

    Tian, Jingjing

    Low-rise woodframe buildings with disproportionately flexible ground stories represent a significant percentage of the building stock in seismically vulnerable communities in the Western United States. These structures have a readily identifiable structural weakness at the ground level due to an asymmetric distribution of large openings in the perimeter wall lines and to a lack of interior partition walls, resulting in a soft story condition that makes the structure highly susceptible to severe damage or collapse under design-level earthquakes. The conventional approach to retrofitting such structures is to increase the ground story stiffness. An alternate approach is to increase the energy dissipation capacity of the structure via the incorporation of supplemental energy dissipation devices (dampers), thereby relieving the energy dissipation demands on the framing system. Such a retrofit approach is consistent with a Performance-Based Seismic Retrofit (PBSR) philosophy through which multiple performance levels may be targeted. The effectiveness of such a retrofit is presented via examination of the seismic response of a full-scale four-story building that was tested on the outdoor shake table at NEES-UCSD and a full-scale three-story building that was tested using slow pseudo-dynamic hybrid testing at NEES-UB. In addition, a Direct Displacement Design (DDD) methodology was developed as an improvement over current DDD methods by considering torsion, with or without the implementation of damping devices, in an attempt to avoid the computational expense of nonlinear time-history analysis (NLTHA) and thus facilitating widespread application of PBSR in engineering practice.

  5. Simulation of n-qubit quantum systems. V. Quantum measurements

    Science.gov (United States)

    Radtke, T.; Fritzsche, S.

    2010-02-01

    The FEYNMAN program has been developed during the last years to support case studies on the dynamics and entanglement of n-qubit quantum registers. Apart from basic transformations and (gate) operations, it currently supports a good number of separability criteria and entanglement measures, quantum channels as well as the parametrizations of various frequently applied objects in quantum information theory, such as (pure and mixed) quantum states, hermitian and unitary matrices or classical probability distributions. With the present update of the FEYNMAN program, we provide a simple access to (the simulation of) quantum measurements. This includes not only the widely-applied projective measurements upon the eigenspaces of some given operator but also single-qubit measurements in various pre- and user-defined bases as well as the support for two-qubit Bell measurements. In addition, we help perform generalized and POVM measurements. Knowing the importance of measurements for many quantum information protocols, e.g., one-way computing, we hope that this update makes the FEYNMAN code an attractive and versatile tool for both, research and education. New version program summaryProgram title: FEYNMAN Catalogue identifier: ADWE_v5_0 Program summary URL:http://cpc.cs.qub.ac.uk/summaries/ADWE_v5_0.html Program obtainable from: CPC Program Library, Queen's University, Belfast, N. Ireland Licensing provisions: Standard CPC licence, http://cpc.cs.qub.ac.uk/licence/licence.html No. of lines in distributed program, including test data, etc.: 27 210 No. of bytes in distributed program, including test data, etc.: 1 960 471 Distribution format: tar.gz Programming language: Maple 12 Computer: Any computer with Maple software installed Operating system: Any system that supports Maple; the program has been tested under Microsoft Windows XP and Linux Classification: 4.15 Catalogue identifier of previous version: ADWE_v4_0 Journal reference of previous version: Comput. Phys. Commun

  6. Green's functions technique for calculating the emission spectrum in a quantum dot-cavity system

    Directory of Open Access Journals (Sweden)

    Edgar Arturo Gómez

    2016-12-01

    Full Text Available We introduce the Green's functions technique as an alternative theory to the quantum regression theorem formalism for calculating the two-time correlation functions in open quantum systems at the steady state. In order to investigate the potential of this theoretical approach, we consider a dissipative system composed of a single quantum dot inside a semiconductor cavity and the emission spectrum is computed due to the quantum dot as well as the cavity. We propose an algorithm based on the Green's functions technique for computing the emission spectrum that can easily be adapted to more complex open quantum systems. We found that the numerical results based on the Green's functions technique are in perfect agreement with the quantum regression theorem formalism. Moreover, it allows overcoming the inherent theoretical difficulties associated with the direct application of the quantum regression theorem in open quantum systems. Received: 6 September 2016, Accepted: 5 November 2016; Edited by: J. P. Paz; DOI: http://dx.doi.org/10.4279/PIP.080008 Cite as: E A Gómez, J D Hernández-Rivero, H Vinck-Posada, Papers in Physics 8, 080008 (2016

  7. The concentration gradient flow battery as electricity storage system: Technology potential and energy dissipation

    Science.gov (United States)

    van Egmond, W. J.; Saakes, M.; Porada, S.; Meuwissen, T.; Buisman, C. J. N.; Hamelers, H. V. M.

    2016-09-01

    Unlike traditional fossil fuel plants, the wind and the sun provide power only when the renewable resource is available. To accommodate large scale use of renewable energy sources for efficient power production and utilization, energy storage systems are necessary. Here, we introduce a scalable energy storage system which operates by performing cycles during which energy generated from renewable resource is first used to produce highly concentrated brine and diluate, followed up mixing these two solutions in order to generate power. In this work, we present theoretical results of the attainable energy density as function of salt type and concentration. A linearized Nernst-Planck model is used to describe water, salt and charge transport. We validate our model with experiments over wide range of sodium chloride concentrations (0.025-3 m) and current densities (-49 to +33 A m-2). We find that depending on current density, charge and discharge steps have significantly different thermodynamic efficiency. In addition, we show that at optimal current densities, mechanisms of energy dissipation change with salt concentration. We find the highest thermodynamic efficiency at low concentrate concentrations. When using salt concentrations above 1 m, water and co-ion transport contribute to high energy dissipation due to irreversible mixing.

  8. Optimal state transfer of a single dissipative two-level system

    Science.gov (United States)

    Jirari, Hamza; Wu, Ning

    2016-04-01

    Optimal state transfer of a single two-level system (TLS) coupled to an Ohmic boson bath via off-diagonal TLS-bath coupling is studied by using optimal control theory. In the weak system-bath coupling regime where the time-dependent Bloch-Redfield formalism is applicable, we obtain the Bloch equation to probe the evolution of the dissipative TLS in the presence of a time-dependent external control field. By using the automatic differentiation technique to compute the gradient for the cost functional, we calculate the optimal transfer integral profile that can achieve an ideal transfer within a dimer system in the Fenna-Matthews-Olson (FMO) model. The robustness of the control profile against temperature variation is also analyzed.

  9. Exceptional points for parameter estimation in open quantum systems: Analysis of the Bloch equations

    CERN Document Server

    Am-Shallem, Morag; Moiseyev, Nimrod

    2014-01-01

    The dynamics of open quantum systems is typically described by a quantum dynamical semigroup generator ${\\cal L}$. The eigenvalues of ${\\cal L}$ are complex, reflecting unitary as well as dissipative dynamics. For certain values of parameters defining ${\\cal L}$, non-hermitian degeneracies emerge, i.e. exceptional points ($EP$). We study the implications of such points in the open system dynamics of a two-level-system described by the Bloch equation. This open system has become the paradigm of diverse fields in physics, from NMR to quantum information and elementary particles. We find as a function of detuning and driving amplitude a continuous line of exceptional points merging into two cusps of triple degeneracy. The dynamical signature of these $EP$ points is a unique time evolution. This unique feature can be employed experimentally to locate the $EP$ points and thereby to determine the intrinsic system parameters for any desired accuracy.

  10. Energy-dissipating and self-repairing SMA-ECC composite material system

    Science.gov (United States)

    Li, Xiaopeng; Li, Mo; Song, Gangbing

    2015-02-01

    Structural component ductility and energy dissipation capacity are crucial factors for achieving reinforced concrete structures more resistant to dynamic loading such as earthquakes. Furthermore, limiting post-event residual damage and deformation allows for immediate re-operation or minimal repairs. These desirable characteristics for structural ‘resilience’, however, present significant challenges due to the brittle nature of concrete, its deformation incompatibility with ductile steel, and the plastic yielding of steel reinforcement. Here, we developed a new composite material system that integrates the unique ductile feature of engineered cementitious composites (ECC) with superelastic shape memory alloy (SMA). In contrast to steel reinforced concrete (RC) and SMA reinforced concrete (SMA-RC), the SMA-ECC beams studied in this research exhibited extraordinary energy dissipation capacity, minimal residual deformation, and full self-recovery of damage under cyclic flexural loading. We found that the tensile strain capacity of ECC, tailored up to 5.5% in this study, allows it to work compatibly with superelastic SMA. Furthermore, the distributed microcracking damage mechanism in ECC is critical for sufficient and reliable recovery of damage upon unloading. This research demonstrates the potential of SMA-ECC for improving resilience of concrete structures under extreme hazard events.

  11. A New Eddy Dissipation Rate Formulation for the Terminal Area PBL Prediction System(TAPPS)

    Science.gov (United States)

    Charney, Joseph J.; Kaplan, Michael L.; Lin, Yuh-Lang; Pfeiffer, Karl D.

    2000-01-01

    The TAPPS employs the MASS model to produce mesoscale atmospheric simulations in support of the Wake Vortex project at Dallas Fort-Worth International Airport (DFW). A post-processing scheme uses the simulated three-dimensional atmospheric characteristics in the planetary boundary layer (PBL) to calculate the turbulence quantities most important to the dissipation of vortices: turbulent kinetic energy and eddy dissipation rate. TAPPS will ultimately be employed to enhance terminal area productivity by providing weather forecasts for the Aircraft Vortex Spacing System (AVOSS). The post-processing scheme utilizes experimental data and similarity theory to determine the turbulence quantities from the simulated horizontal wind field and stability characteristics of the atmosphere. Characteristic PBL quantities important to these calculations are determined based on formulations from the Blackadar PBL parameterization, which is regularly employed in the MASS model to account for PBL processes in mesoscale simulations. The TAPPS forecasts are verified against high-resolution observations of the horizontal winds at DFW. Statistical assessments of the error in the wind forecasts suggest that TAPPS captures the essential features of the horizontal winds with considerable skill. Additionally, the turbulence quantities produced by the post-processor are shown to compare favorably with corresponding tower observations.

  12. Limit cycles in quantum systems

    Energy Technology Data Exchange (ETDEWEB)

    Niemann, Patrick

    2015-04-27

    In this thesis we investigate Limit Cycles in Quantum Systems. Limit cycles are a renormalization group (RG) topology. When degrees of freedom are integrated out, the coupling constants flow periodically in a closed curve. The presence of limit cycles is restricted by the necessary condition of discrete scale invariance. A signature of discrete scale invariance and limit cycles is log-periodic behavior. The first part of this thesis is concerned with the study of limit cycles with the similarity renormalization group (SRG). Limit cycles are mainly investigated within conventional renormalization group frameworks, where degrees of freedom, which are larger than a given cutoff, are integrated out. In contrast, in the SRG potentials are unitarily transformed and thereby obtain a band-diagonal structure. The width of the band structure can be regarded as an effective cutoff. We investigate the appearance of limit cycles in the SRG evolution. Our aim is to extract signatures as well as the scaling factor of the limit cycle. We consider the 1/R{sup 2}-potential in a two-body system and a three-body system with large scattering lengths. Both systems display a limit cycle. Besides the frequently used kinetic energy generator we apply the exponential and the inverse generator. In the second part of this thesis, Limit Cycles at Finite Density, we examine the pole structure of the scattering amplitude for distinguishable fermions at zero temperature in the medium. Unequal masses and a filled Fermi sphere for each fermion species are considered. We focus on negative scattering lengths and the unitary limit. The properties of the three-body spectrum in the medium and implications for the phase structure of ultracold Fermi gases are discussed.

  13. Quantum discord protection of a two-qutrit V-type atomic system from decoherence by partially collapsing measurements

    Science.gov (United States)

    Behzadi, N.; Faizi, E.; Heibati, O.

    2017-10-01

    In this paper, by exploiting the weak measurement and quantum measurement reversal procedure, we propose a scheme to show how one can protect the geometric quantum discord (GQD) of a two-qutrit V-type atomic system each of which interacts with a dissipative reservoir independently. We examine the scheme for the GQD of the initial two-qutrit Werner and Horodecki states for different classes of weak measurement strengths. It is found out that the presented protocol enables us to suppress decoherence due to the amplitude damping channel and preserve the quantum discord of the two-qutrit system successfully.

  14. EXACT SOLITRAY WAVE SOLUTIONS AND SINGULAR SOLUTIONS TO THE TWO-DIMENSIONAL NONLINEAR DISSIPATIVE-DISPERSIVE SYSTEM

    Institute of Scientific and Technical Information of China (English)

    李志斌; 陈天华

    2002-01-01

    An algorithm for constructing exact solitary wave solutions and singular solutions for a class of nonlinear dissipative-dispersive system is presented. With the aid of symbolic manipulation system Maple, some explicit solutions are obtained for the system in physically interesting but non-integrable cases.

  15. Temperature and voltage measurement in quantum systems far from equilibrium

    Science.gov (United States)

    Shastry, Abhay; Stafford, Charles A.

    2016-10-01

    We show that a local measurement of temperature and voltage for a quantum system in steady state, arbitrarily far from equilibrium, with arbitrary interactions within the system, is unique when it exists. This is interpreted as a consequence of the second law of thermodynamics. We further derive a necessary and sufficient condition for the existence of a solution. In this regard, we find that a positive temperature solution exists whenever there is no net population inversion. However, when there is a net population inversion, we may characterize the system with a unique negative temperature. Voltage and temperature measurements are treated on an equal footing: They are simultaneously measured in a noninvasive manner, via a weakly coupled thermoelectric probe, defined by requiring vanishing charge and heat dissipation into the probe. Our results strongly suggest that a local temperature measurement without a simultaneous local voltage measurement, or vice versa, is a misleading characterization of the state of a nonequilibrium quantum electron system. These results provide a firm mathematical foundation for voltage and temperature measurements far from equilibrium.

  16. The convergence problem for dissipative autonomous systems classical methods and recent advances

    CERN Document Server

    Haraux, Alain

    2015-01-01

    The book investigates classical and more recent methods of study for the asymptotic behavior of dissipative continuous dynamical systems with applications to ordinary and partial differential equations, the main question being convergence (or not) of the solutions to an equilibrium. After reviewing the basic concepts of topological dynamics and the definition of gradient-like systems on a metric space, the authors present a comprehensive exposition of stability theory relying on the so-called linearization method. For the convergence problem itself, when the set of equilibria is infinite, the only general results that do not require very special features of the non-linearities are presently consequences of a gradient inequality discovered by S. Lojasiewicz. The application of this inequality jointly with the so-called Liapunov-Schmidt reduction requires a rigorous exposition of Semi-Fredholm operator theory and the theory of real analytic maps on infinite dimensional Banach spaces, which cannot be found anywh...

  17. Dissipative Optomechanics in a Michelson--Sagnac Interferometer

    CERN Document Server

    Xuereb, André; Hammerer, Klemens

    2011-01-01

    Dissipative optomechanics studies the coupling of the motion of an optical element to the decay rate of a quasi-resonant cavity. We propose and theoretically explore a realization of this system in the optical domain, using a combined Michelson--Sagnac interferometer, which enables a strong and tunable dissipative coupling in an optical setup. Quantum interference in such a setup results in the suppression of the lower motional sideband, leading to strongly enhanced cooling in the non-sideband-resolved regime. With state-of-the-art parameters, ground-state cooling and low-power quantum-limited position transduction are both possible.

  18. Workshop on quantum stochastic differential equations for the quantum simulation of physical systems

    Science.gov (United States)

    2016-09-22

    SECURITY CLASSIFICATION OF: This is a report on the “Workshop on quantum stochastic differential equations for the quantum simulation of physical ...mathematical tools to the quantum simulation of physical systems of interest to the Army. There were participants from US Government agencies, industry, and... quantum stochastic differential equations for the quantum simulation of physical systems Report Title This is a report on the “Workshop on quantum

  19. Variational principles for dissipative (sub)systems, with applications to the theory of dispersion and geometrical optics

    CERN Document Server

    Dodin, I Y; Ruiz, D E

    2016-01-01

    Applications of variational methods are typically restricted to conservative systems. Some extensions to dissipative systems have been reported too but require ad hoc techniques such as artificial doubling of variables. Here, a different approach is proposed. We show that, for a broad class of dissipative systems of practical interest, variational principles can be formulated using constant Lagrange multipliers and Lagrangians nonlocal in time, which allow treating reversible and irreversible dynamics on the same footing. A general variational theory of linear dispersion is formulated as an example. In particular, we present a variational formulation for linear geometrical optics in a general dissipative medium, which is allowed to be nonstationary, inhomogeneous, nonisotropic, and exhibit both temporal and spatial dispersion simultaneously.

  20. Variational principles for dissipative (sub)systems, with applications to the theory of linear dispersion and geometrical optics

    Science.gov (United States)

    Dodin, I. Y.; Zhmoginov, A. I.; Ruiz, D. E.

    2017-04-01

    Applications of variational methods are typically restricted to conservative systems. Some extensions to dissipative systems have been reported too but require ad hoc techniques such as the artificial doubling of the dynamical variables. Here, a different approach is proposed. We show that, for a broad class of dissipative systems of practical interest, variational principles can be formulated using constant Lagrange multipliers and Lagrangians nonlocal in time, which allow treating reversible and irreversible dynamics on the same footing. A general variational theory of linear dispersion is formulated as an example. In particular, we present a variational formulation for linear geometrical optics in a general dissipative medium, which is allowed to be nonstationary, inhomogeneous, anisotropic, and exhibit both temporal and spatial dispersion simultaneously.

  1. Controlled merging and annihilation of localised dissipative structures in an AC-driven damped nonlinear Schrödinger system

    Science.gov (United States)

    Jang, Jae K.; Erkintalo, Miro; Luo, Kathy; Oppo, Gian-Luca; Coen, Stéphane; Murdoch, Stuart G.

    2016-03-01

    We report studies of controlled interactions of localised dissipative structures in a system described by the AC-driven damped nonlinear Schrödinger equation (equivalent to the Lugiato-Lefever model). Extensive numerical simulations reveal a variety of interaction scenarios that are governed by the properties of the system driver, notably its gradients. In our experiments, performed with a nonlinear optical fibre (Kerr) resonator, the phase profile of the driver is used to induce interactions of the dissipative structures on demand. We observe both merging and annihilation of localised structures, i.e. interactions governed by the dissipative, out-of-equilibrium nature of the system. These interactions fundamentally differ from those typically found for conventional conservative solitons.

  2. Quantum entanglement in condensed matter systems

    Energy Technology Data Exchange (ETDEWEB)

    Laflorencie, Nicolas, E-mail: laflo@irsamc.ups-tlse.fr

    2016-08-03

    This review focuses on the field of quantum entanglement applied to condensed matter physics systems with strong correlations, a domain which has rapidly grown over the last decade. By tracing out part of the degrees of freedom of correlated quantum systems, useful and non-trivial information can be obtained through the study of the reduced density matrix, whose eigenvalue spectrum (the entanglement spectrum) and the associated Rényi entropies are now well recognized to contain key features. In particular, the celebrated area law for the entanglement entropy of ground-states will be discussed from the perspective of its subleading corrections which encode universal details of various quantum states of matter, e.g. symmetry breaking states or topological order. Going beyond entropies, the study of the low-lying part of the entanglement spectrum also allows to diagnose topological properties or give a direct access to the excitation spectrum of the edges, and may also raise significant questions about the underlying entanglement Hamiltonian. All these powerful tools can be further applied to shed some light on disordered quantum systems where impurity/disorder can conspire with quantum fluctuations to induce non-trivial effects. Disordered quantum spin systems, the Kondo effect, or the many-body localization problem, which have all been successfully (re)visited through the prism of quantum entanglement, will be discussed in detail. Finally, the issue of experimental access to entanglement measurement will be addressed, together with its most recent developments.

  3. Quantum entanglement in condensed matter systems

    Science.gov (United States)

    Laflorencie, Nicolas

    2016-08-01

    This review focuses on the field of quantum entanglement applied to condensed matter physics systems with strong correlations, a domain which has rapidly grown over the last decade. By tracing out part of the degrees of freedom of correlated quantum systems, useful and non-trivial information can be obtained through the study of the reduced density matrix, whose eigenvalue spectrum (the entanglement spectrum) and the associated Rényi entropies are now well recognized to contain key features. In particular, the celebrated area law for the entanglement entropy of ground-states will be discussed from the perspective of its subleading corrections which encode universal details of various quantum states of matter, e.g. symmetry breaking states or topological order. Going beyond entropies, the study of the low-lying part of the entanglement spectrum also allows to diagnose topological properties or give a direct access to the excitation spectrum of the edges, and may also raise significant questions about the underlying entanglement Hamiltonian. All these powerful tools can be further applied to shed some light on disordered quantum systems where impurity/disorder can conspire with quantum fluctuations to induce non-trivial effects. Disordered quantum spin systems, the Kondo effect, or the many-body localization problem, which have all been successfully (re)visited through the prism of quantum entanglement, will be discussed in detail. Finally, the issue of experimental access to entanglement measurement will be addressed, together with its most recent developments.

  4. An Application of Quantum Finite Automata to Interactive Proof Systems

    CERN Document Server

    Nishimura, H; Nishimura, Harumichi; Yamakami, Tomoyuki

    2004-01-01

    Quantum finite automata have been studied intensively since their introduction in late 1990s as a natural model of a quantum computer with finite-dimensional quantum memory space. This paper seeks their direct application to interactive proof systems in which a mighty quantum prover communicates with a quantum-automaton verifier through a common communication cell. Our quantum interactive proof systems are juxtaposed to Dwork-Stockmeyer's classical interactive proof systems whose verifiers are two-way probabilistic automata. We demonstrate strengths and weaknesses of our systems and further study how various restrictions on the behaviors of quantum-automaton verifiers affect the power of quantum interactive proof systems.

  5. Emergent "Quantum" Theory in Complex Adaptive Systems.

    Science.gov (United States)

    Minic, Djordje; Pajevic, Sinisa

    2016-04-30

    Motivated by the question of stability, in this letter we argue that an effective quantum-like theory can emerge in complex adaptive systems. In the concrete example of stochastic Lotka-Volterra dynamics, the relevant effective "Planck constant" associated with such emergent "quantum" theory has the dimensions of the square of the unit of time. Such an emergent quantum-like theory has inherently non-classical stability as well as coherent properties that are not, in principle, endangered by thermal fluctuations and therefore might be of crucial importance in complex adaptive systems.

  6. Open quantum systems and error correction

    Science.gov (United States)

    Shabani Barzegar, Alireza

    Quantum effects can be harnessed to manipulate information in a desired way. Quantum systems which are designed for this purpose are suffering from harming interaction with their surrounding environment or inaccuracy in control forces. Engineering different methods to combat errors in quantum devices are highly demanding. In this thesis, I focus on realistic formulations of quantum error correction methods. A realistic formulation is the one that incorporates experimental challenges. This thesis is presented in two sections of open quantum system and quantum error correction. Chapters 2 and 3 cover the material on open quantum system theory. It is essential to first study a noise process then to contemplate methods to cancel its effect. In the second chapter, I present the non-completely positive formulation of quantum maps. Most of these results are published in [Shabani and Lidar, 2009b,a], except a subsection on geometric characterization of positivity domain of a quantum map. The real-time formulation of the dynamics is the topic of the third chapter. After introducing the concept of Markovian regime, A new post-Markovian quantum master equation is derived, published in [Shabani and Lidar, 2005a]. The section of quantum error correction is presented in three chapters of 4, 5, 6 and 7. In chapter 4, we introduce a generalized theory of decoherence-free subspaces and subsystems (DFSs), which do not require accurate initialization (published in [Shabani and Lidar, 2005b]). In Chapter 5, we present a semidefinite program optimization approach to quantum error correction that yields codes and recovery procedures that are robust against significant variations in the noise channel. Our approach allows us to optimize the encoding, recovery, or both, and is amenable to approximations that significantly improve computational cost while retaining fidelity (see [Kosut et al., 2008] for a published version). Chapter 6 is devoted to a theory of quantum error correction (QEC

  7. ZERO DISSIPATION LIMIT TO CONTACT DISCONTINUITY FOR THE COMPRESSIBLE NAVIER-STOKES SYSTEM OF GENERAL GAS

    Institute of Scientific and Technical Information of China (English)

    Hakho HONG

    2016-01-01

    The zero dissipation limit to the contact discontinuities for one-dimensional com-pressible Navier-Stokes equations was recently proved for ideal polytropic gas (see Huang et al. [15, 22] and Ma [31]), but there is few result for general gases including ideal polytropic gas. We prove that if the solution to the corresponding Euler system of general gas satisfying (1.4) is piecewise constant with a contact discontinuity, then there exist smooth solutions to Navier-Stokes equations which converge to the inviscid solutions at a rate of κ14 as the heat-conductivity coeff cient κtends to zero. The key is to construct a viscous contact wave of general gas suitable to our proof (see Section 2). Notice that we have no need to restrict the strength of the contact discontinuity to be small.

  8. Networks of dissipative systems compositional certification of stability, performance, and safety

    CERN Document Server

    Arcak, Murat; Packard, Andrew

    2016-01-01

    This book addresses a major problem for today’s large-scale networked systems: certification of the required stability and performance properties using analytical and computational models. On the basis of illustrative case studies, it demonstrates the applicability of theoretical methods to biological networks, vehicle fleets, and Internet congestion control. Rather than tackle the network as a whole —an approach that severely limits the ability of existing methods to cope with large numbers of physical components— the book develops a compositional approach that derives network-level guarantees from key structural properties of the components and their interactions. The foundational tool in this approach is the established dissipativity theory, which is reviewed in the first chapter and supplemented with modern computational techniques. The book blends this theory with the authors’ recent research efforts at a level that is accessible to graduate students and practising engineers familiar with only th...

  9. Global classical solutions for partially dissipative hyperbolic system of balance laws

    CERN Document Server

    Xu, Jiang

    2012-01-01

    This work is concerned with ($N$-component) hyperbolic system of balance laws in arbitrary space dimensions. Under entropy dissipative assumption and the Shizuta-Kawashima algebraic condition, a general theory on the well-posedness of classical solutions in the framework of Chemin-Lerner's spaces with critical regularity is established. To do this, we first explore the functional space theory and develop an elementary fact that indicates the relation between homogeneous and inhomogeneous Chemin-Lerner's spaces. Then this fact allows to prove the local well-posedness for general data and global well-posedness for small data by using the Fourier frequency-localization argument. Finally, we apply the new existence theory to a specific fluid model-the compressible Euler equations with damping, and obtain the corresponding results in critical spaces.

  10. Periodic Point, Endpoint, and Convergence Theorems for Dissipative Set-Valued Dynamic Systems with Generalized Pseudodistances in Cone Uniform and Uniform Spaces

    Directory of Open Access Journals (Sweden)

    Kazimierz Włodarczyk

    2010-01-01

    Full Text Available In cone uniform and uniform spaces, we introduce the three kinds of dissipative set-valued dynamic systems with generalized pseudodistances and not necessarily lower semicontinuous entropies, we study the convergence of dynamic processes and generalized sequences of iterations of these dissipative dynamic systems, and we establish conditions guaranteeing the existence of periodic points and endpoints of these dissipative dynamic systems and the convergence to these periodic points and endpoints of dynamic processes and generalized sequences of iterations of these dissipative dynamic systems. The paper includes examples.

  11. Robust quantum correlations in out-of-equilibrium matter-light systems

    Science.gov (United States)

    Acevedo, O. L.; Quiroga, L.; Rodríguez, F. J.; Johnson, N. F.

    2015-09-01

    High precision macroscopic quantum control in interacting light-matter systems remains a significant goal toward novel information processing and ultra-precise metrology. We show that the out-of-equilibrium behavior of a paradigmatic light-matter system (Dicke model) reveals two successive stages of enhanced quantum correlations beyond the traditional schemes of near-adiabatic and sudden quenches. The first stage features magnification of matter-only and light-only entanglement and squeezing due to effective nonlinear self-interactions. The second stage results from a highly entangled light-matter state, with enhanced superradiance and signatures of chaotic and highly quantum states. We show that these new effects scale up consistently with matter system size, and are reliable even in dissipative environments.

  12. Characterization of Unruh channel in the context of open quantum systems

    Science.gov (United States)

    Banerjee, Subhashish; Kumar Alok, Ashutosh; Omkar, S.; Srikanth, R.

    2017-02-01

    In this work, we study an important facet of field theories in curved space-time, viz. the Unruh effect, by making use of ideas of statistical mechanics and quantum foundations. Aspects of decoherence and dissipation, natural artifacts of open quantum systems, along with foundational issues such as the trade-off between coherence and mixing as well as various aspects of quantum correlations are investigated in detail for the Unruh effect. We show how the Unruh effect can be quantified mathematically by the Choi matrix approach. We study how environmentally induced decoherence modifies the effect of the Unruh channel. The differing effects of a dissipative or non-dissipative environment are noted. Further, useful parameters characterizing channel performance such as gate and channel fidelity are applied here to the Unruh channel, both with and without external influences. Squeezing, which is known to play an important role in the context of particle creation, is shown to be a useful resource in a number of scenarios.

  13. The entropy dissipation method for spatially inhomogeneous reaction-diffusion-type systems

    KAUST Repository

    Di Francesco, M.

    2008-12-08

    We study the long-time asymptotics of reaction-diffusion-type systems that feature a monotone decaying entropy (Lyapunov, free energy) functional. We consider both bounded domains and confining potentials on the whole space for arbitrary space dimensions. Our aim is to derive quantitative expressions for (or estimates of) the rates of convergence towards an (entropy minimizing) equilibrium state in terms of the constants of diffusion and reaction and with respect to conserved quantities. Our method, the so-called entropy approach, seeks to quantify convergence to equilibrium by using functional inequalities, which relate quantitatively the entropy and its dissipation in time. The entropy approach is well suited to nonlinear problems and known to be quite robust with respect to model variations. It has already been widely applied to scalar diffusion-convection equations, and the main goal of this paper is to study its generalization to systems of partial differential equations that contain diffusion and reaction terms and admit fewer conservation laws than the size of the system. In particular, we successfully apply the entropy approach to general linear systems and to a nonlinear example of a reaction-diffusion-convection system arising in solid-state physics as a paradigm for general nonlinear systems. © 2008 The Royal Society.

  14. A semi-analytical direct optimal control solution for strongly excited and dissipative Hamiltonian systems

    Science.gov (United States)

    Ying, Zu-guang; Luo, Yin-miao; Zhu, Wei-qiu; Ni, Yi-qing; Ko, Jan-ming

    2012-04-01

    A semi-analytical direct optimal control solution for strongly excited and dissipative Hamiltonian systems is proposed based on the extended Hamiltonian principle, the Hamilton-Jacobi-Bellman (HJB) equation and its variational integral equation, and the finite time element approximation. The differential extended Hamiltonian equations for structural vibration systems are replaced by the variational integral equation, which can preserve intrinsic system structure. The optimal control law dependent on the value function is determined by the HJB equation so as to satisfy the overall optimality principle. The partial differential equation for the value function is converted into the integral equation with variational weighting. Then the successive solution of optimal control with system state is designed. The two variational integral equations are applied to sequential time elements and transformed into the algebraic equations by using the finite time element approximation. The direct optimal control on each time element is obtained respectively by solving the algebraic equations, which is unconstrained by the system state observed. The proposed control algorithm is applicable to linear and nonlinear systems with the quadratic performance index, and takes into account the effects of external excitations measured on control. Numerical examples are given to illustrate the optimal control effectiveness.

  15. Quantum liquids in correlated systems

    Science.gov (United States)

    Kusminskiy, Silvia Viola

    Particular aspects of two different relevant systems in contemporary Condensed Matter Physics are studied: heavy fermion materials and the newly discovered graphene (an atom thick layer of graphite), specifically its bilayer. On one hand, the physics of heavy fermion materials under strong external magnetic fields is analyzed from a mean field point of view. The evolution of the heavy fermion ground state under the application of a magnetic field is investigated. A richer version of the usual hybridization mean field theory is presented, which allows for hybridization in both the singlet and triplet channels and incorporates a self-consistent Weiss field. It is shown that for a magnetic field strength B⋆, at a filling-dependent fraction of the zero-field hybridization gap, the spin up quasiparticle band becomes fully polarized---an event marked by a sudden jump in the magnetic susceptibility. The system exhibits a kind of quantum rigidity in which the susceptibility (and several other physical observables) are insensitive to further increases in field strength. This behavior ends abruptly with the collapse of the hybridization order parameter in a first-order transition to the normal metallic state. It is argued that the feature at B⋆ corresponds to the "metamagnetic transition" in YbRh2Si2. These results are in good agreement with recent experimental measurements. For the case of the graphene bilayer, the effect of electron-electron interactions on the properties of a graphene bilayer is studied within the Hartree-Fock-Thomas-Fermi theory. It is found that the electronic compressibility is rather different from those of either the two-dimensional electron gas or ordinary semiconductors. An inherent competition between the contributions coming from intra-band exchange interactions and inter-band interactions leads to a non-monotonic behavior of the compressibility as a function of carrier density. Also analyzed is the effect of the interactions on the

  16. Measurements of nanoresonator-qubit interactions in a hybrid quantum electromechanical system

    Science.gov (United States)

    Rouxinol, F.; Hao, Y.; Brito, F.; Caldeira, A. O.; Irish, E. K.; LaHaye, M. D.

    2016-09-01

    Experiments to probe the basic quantum properties of motional degrees of freedom of mechanical systems have developed rapidly over the last decade. One promising approach is to use hybrid electromechanical systems incorporating superconducting qubits and microwave circuitry. However, a critical challenge facing the development of these systems is to achieve strong coupling between mechanics and qubits while simultaneously reducing coupling of both the qubit and mechanical mode to the environment. Here we report measurements of a qubit-coupled mechanical resonator system consisting of an ultra-high-frequency nanoresonator and a long coherence-time superconducting transmon qubit, embedded in a superconducting coplanar waveguide cavity. It is demonstrated that the nanoresonator and transmon have commensurate energies and transmon coherence times are one order of magnitude larger than for all previously reported qubit-coupled nanoresonators. Moreover, we show that numerical simulations of this new hybrid quantum system are in good agreement with spectroscopic measurements and suggest that the nanoresonator in our device resides at low thermal occupation number, near its ground state, acting as a dissipative bath seen by the qubit. We also outline how this system could soon be developed as a platform for implementing more advanced experiments with direct relevance to quantum information processing and quantum thermodynamics, including the study of nanoresonator quantum noise properties, reservoir engineering, and nanomechanical quantum state generation and detection.

  17. Excess entropy production in quantum system: Quantum master equation approach

    OpenAIRE

    Nakajima, Satoshi; Tokura, Yasuhiro

    2016-01-01

    For open systems described by the quantum master equation (QME), we investigate the excess entropy production under quasistatic operations between nonequilibrium steady states. The average entropy production is composed of the time integral of the instantaneous steady entropy production rate and the excess entropy production. We define average entropy production rate using the average energy and particle currents, which are calculated by using the full counting statistics with QME. The excess...

  18. A Decentralized Event-Triggered Dissipative Control Scheme for Systems With Multiple Sensors to Sample the System Outputs.

    Science.gov (United States)

    Zhang, Xian-Ming; Han, Qing-Long

    2016-12-01

    This paper is concerned with decentralized event-triggered dissipative control for systems with the entries of the system outputs having different physical properties. Depending on these different physical properties, the entries of the system outputs are grouped into multiple nodes. A number of sensors are used to sample the signals from different nodes. A decentralized event-triggering scheme is introduced to select those necessary sampled-data packets to be transmitted so that communication resources can be saved significantly while preserving the prescribed closed-loop performance. First, in order to organize the decentralized data packets transmitted from the sensor nodes, a data packet processor (DPP) is used to generate a new signal to be held by the zero-order-hold once the signal stored by the DPP is updated at some time instant. Second, under the mechanism of the DPP, the resulting closed-loop system is modeled as a linear system with an interval time-varying delay. A sufficient condition is derived such that the closed-loop system is asymptotically stable and strictly (Q0,S0,R0) -dissipative, where Q0,S0 , and R0 are real matrices of appropriate dimensions with Q0 and R0 symmetric. Third, suitable output-based controllers can be designed based on solutions to a set of a linear matrix inequality. Finally, two examples are given to demonstrate the effectiveness of the proposed method.

  19. Reaching equilibrium: the role of dissipation in analogous systems, within a thermodynamic-like perspective

    Science.gov (United States)

    Bonanno, A.; Camarca, M.; Sapia, P.

    2012-11-01

    Isomorphic problems play an acknowledged pedagogical role in the physics teaching/learning process. In this context, we describe a unified approach to a wide class of physical systems formally analogous to the well-known ‘two-capacitor system’. The proposed learning path, specifically addressed to university students, provides the opportunity to introduce a unitary graphical representation that is very suitable to describe the system energy evolution, as well as allowing the highlighting of the mutually exclusive roles of dissipation and reversibility when the system approaches its equilibrium conditions (where ‘equilibrium’ must be interpreted in its most general meaning, either as ‘static equilibrium’ or as ‘steady state’). Moreover, a new quantitative modeling is introduced for two representative systems, in order to show that the energy ‘missed’ during the equilibrium achievement is just equal to the negative work an external agent should make to let the system reach its final state quasi-statically and reversibly.

  20. Noise management to achieve superiority in quantum information systems

    Science.gov (United States)

    Nemoto, Kae; Devitt, Simon; Munro, William J.

    2017-06-01

    Quantum information systems are expected to exhibit superiority compared with their classical counterparts. This superiority arises from the quantum coherences present in these quantum systems, which are obviously absent in classical ones. To exploit such quantum coherences, it is essential to control the phase information in the quantum state. The phase is analogue in nature, rather than binary. This makes quantum information technology fundamentally different from our classical digital information technology. In this paper, we analyse error sources and illustrate how these errors must be managed for the system to achieve the required fidelity and a quantum superiority. This article is part of the themed issue 'Quantum technology for the 21st century'.