Bright Single-Photon Sources Based on Anti-Reflection Coated Deterministic Quantum Dot Microlenses

Directory of Open Access Journals (Sweden)

Peter Schnauber

2015-12-01

Full Text Available We report on enhancing the photon-extraction efficiency (PEE of deterministic quantum dot (QD microlenses via anti-reflection (AR coating. The AR-coating deposited on top of the curved microlens surface is composed of a thin layer of Ta2O5, and is found to effectively reduce back-reflection of light at the semiconductor-vacuum interface. A statistical analysis of spectroscopic data reveals, that the AR-coating improves the light out-coupling of respective microlenses by a factor of 1.57 ± 0.71, in quantitative agreement with numerical calculations. Taking the enhancement factor into account, we predict improved out-coupling of light with a PEE of up to 50%. The quantum nature of emission from QDs integrated into AR-coated microlenses is demonstrated via photon auto-correlation measurements revealing strong suppression of two-photon emission events with g(2(0 = 0.05 ± 0.02. As such, these bright non-classical light sources are highly attractive with respect to applications in the field of quantum cryptography.

Proceedings of Waseda international symposium on fundamental physics. New perspectives in quantum physics

International Nuclear Information System (INIS)

Ohba, Ichiro; Aizawa, Yoji; Daishido, Tsuneaki; Kurihara, Susumu; Maeda, Kei-ichi; Nakazato, Hiromichi; Tasaki, Shuichi; Yuasa, Kazuya

2003-11-01

Waseda International Symposium on Fundamental Physics - New Perspectives in Quantum Physics - was held on November 12-15, 2002 at International Conference Hall (IBUKA HALL), Waseda University, Tokyo, Japan. This symposium was organized to provide an opportunity to verify fundamental physics attainments and to discuss new prospectives in quantum physics in the 21st century. These themes of the symposium were reexamined from all aspects in terms of important key words of the symposium, fundamental quantum theory, quantum coherence and decoherence, quantum chaos, time symmetry breaking, Bose-Einstein condensation and quantum information and computation. Separate abstracts were presented for 12 of the papers in this report. The remaining 40 were considered outside the subject scope of INIS. (J.P.N.)

The internal waves and Rayleigh-Taylor instability in compressible quantum plasmas

International Nuclear Information System (INIS)

Lu, H. L.; Qiu, X. M.

2011-01-01

In this paper, we investigate the quantum effect on internal waves and Rayleigh-Taylor (RT) instability in compressible quantum plasmas. First of all, let us consider the case of the limit of short wavelength perturbations. In the case, the dispersion relation including quantum and compressibility effects and the RT instability growth rate can be derived using Wentzel-Kramers-Brillouin method. The results show that the internal waves can propagate along the transverse direction due to the quantum effect, which was first pointed out by Bychkov et al.[Phys. Lett. A 372, 3042 (2008)], and the coupling between it and compressibility effect, which is found out in this paper. Then, without making the approximation assumption of short wavelength limit, we examine the linearized perturbation equation following Qiu et al.'s solving process [Phys. Plasmas 10, 2956 (2003)]. It is found that the quantum effect always stabilizes the RT instability in either incompressible or compressible quantum plasmas. Moreover, in the latter case, the coupling between it and compressibility effect makes this stabilization further enhance.

Proceedings of the international colloquium on modern quantum field theory II

International Nuclear Information System (INIS)

Das, S.R.; Mandal, G.; Mukhi, S.; Wadia, S.R.

1995-01-01

In the second International Colloquium on Modern Quantum Field Theory an attempt was made to cover a broad spectrum of topics in theoretical physics that included string theory, quantum gravity, statistical mechanics, condensed matter theory, complexity, lattice gauge theory and epistemological aspects of quantum mechanics. Papers relevant to INIS in the published proceedings are indexed separately

International Conference on Quantum Science and Applications (ICQSA-2016)

International Nuclear Information System (INIS)

Algin, A.; Arik, M.; Gavrilik, A. M.

2016-01-01

This special volume of Journal of Physics: Conference Series is dedicated to the proceedings of “International Conference on Quantum Science and Applications (ICQSA-2016)”. The conference was organized by the Centre for Quantum Research and Applications at Eskisehir Osmangazi University, Eskisehir, Turkey. It was held in Eskisehir Osmangazi University Congress and Culture Centre during May 25-27, 2016 http://icqsa2016.ogu.edu.tr. It gathered actively 143 participants from different disciplines in natural and applied sciences coming from 16 different countries from all over the word. It was the first international conference in its content on the scientific research fields of quantum science and applications in Turkey. It also consisted of 12 plenary lectures and 119 contributed oral presentations covering interdisciplinary fields of research. The ICQSA-2016 conference focused on recent modern theoretical and experimental developments of quantum science in multi-disciplinary aspects of areas of mathematics, physics, statistics, chemistry, biology, computer science, electronics, informatics, medicine, education, etc. It served as an interaction platform for students, researchers, public, and private sector delegates for sharing new scientific and technological ideas on quantum applications in science and technology. The topics of the conference were: Quantum theory and quantum computing, quantum information theory and its applications, quantum statistics and its applications, quantum thermodynamics, quantum cryptography, classical and quantum symmetries, quantum calculus in science, engineering, medicine, education, etc., classical and quantum integrable systems, modeling and numerical methods in quantum systems, other modern mathematical methods in science and technology. Each of the submitted papers for this special volume of the proceedings of ICQSA-2016 has been reviewed by external referees. There are 36 accepted papers. Besides, it is worth pointing out

International Conference on Coherence and Quantum Optics

CERN Document Server

RECENT DEVELOPMENTS IN QUANTUM OPTICS

1993-01-01

This volume is composed of papers (invited and contributed) presented at the International Conference on Coherence and Quantum Optics held at the University of Hyderabad January 5-January 10, 1991. It has been organized by Professor Girish Agarwal and his colleagues at the School of Physics, University of Hyderabad, Hyder­ abad, India under partial support from the Department of Science and Technology, Government of India, International Center for Theoretical Physics, Trieste, Italy and the National Science Foundation, USA. Without the untiring efforts of Prof. Girish Agarwal and the members of his quantum office group, the Conference and the present volume would not have been possible. Some extraordinary circumstances resulted in a delay of the publication of the present volume. Our sincere apologies to all the authors. We deeply regret the inconvenience caused due to the delay. A debt of gratitude is due to Ms. Kim Bella for the excellent typing job of the different versions and the final version of the ma...

NATO Advanced Study Institute on International Summer School on Chaotic Dynamics and Transport in Classical and Quantum Systems

CERN Document Server

Collet, P; Métens, S; Neishtadt, A; Zaslavsky, G; Chaotic Dynamics and Transport in Classical and Quantum Systems

2005-01-01

This book offers a modern updated review on the most important activities in today dynamical systems and statistical mechanics by some of the best experts in the domain. It gives a contemporary and pedagogical view on theories of classical and quantum chaos and complexity in hamiltonian and ergodic systems and their applications to anomalous transport in fluids, plasmas, oceans and atom-optic devices and to control of chaotic transport. The book is issued from lecture notes of the International Summer School on "Chaotic Dynamics and Transport in Classical and Quantum Systems" held in Cargèse (Corsica) 18th to the 30th August 2003. It reflects the spirit of the School to provide lectures at the post-doctoral level on basic concepts and tools. The first part concerns ergodicity and mixing, complexity and entropy functions, SRB measures, fractal dimensions and bifurcations in hamiltonian systems. Then, models of dynamical evolutions of transport processes in classical and quantum systems have been largely expla...

Quantum groups and quantum homogeneous spaces

International Nuclear Information System (INIS)

Kulish, P.P.

1994-01-01

The usefulness of the R-matrix formalism and the reflection equations is demonstrated on examples of the quantum group covariant algebras (quantum homogeneous spaces): quantum Minkowski space-time, quantum sphere and super-sphere. The irreducible representations of some covariant algebras are constructed. The generalization of the reflection equation to super case is given and the existence of the quasiclassical limits is pointed out. (orig.)

Nonimaging light concentration using total internal reflection films.

Science.gov (United States)

Ouellette, G; Waltham, C E; Drees, R M; Poon, A; Schubank, R; Whitehead, L A

1992-05-01

We present a method of fabricating nonimaging light concentrators from total internal reflection film. A prototype has been made and tested and found to operate in agreement with predictions of ray-tracing codes. The performance of the prototype is comparable with that of concentrators made from specular reflecting materials.

Entanglement entropy in quantum spin chains with broken reflection symmetry

International Nuclear Information System (INIS)

Kadar, Zoltan; Zimboras, Zoltan

2010-01-01

We investigate the entanglement entropy of a block of L sites in quasifree translation-invariant spin chains concentrating on the effect of reflection-symmetry breaking. The Majorana two-point functions corresponding to the Jordan-Wigner transformed fermionic modes are determined in the most general case; from these, it follows that reflection symmetry in the ground state can only be broken if the model is quantum critical. The large L asymptotics of the entropy are calculated analytically for general gauge-invariant models, which have, until now, been done only for the reflection-symmetric sector. Analytical results are also derived for certain nongauge-invariant models (e.g., for the Ising model with Dzyaloshinskii-Moriya interaction). We also study numerically finite chains of length N with a nonreflection-symmetric Hamiltonian and report that the reflection symmetry of the entropy of the first L spins is violated but the reflection-symmetric Calabrese-Cardy formula is recovered asymptotically. Furthermore, for noncritical reflection-symmetry-breaking Hamiltonians, we find an anomaly in the behavior of the saturation entropy as we approach the critical line. The paper also provides a concise but extensive review of the block-entropy asymptotics in translation-invariant quasifree spin chains with an analysis of the nearest-neighbor case and the enumeration of the yet unsolved parts of the quasifree landscape.

Effects of low charge carrier wave function overlap on internal quantum efficiency in GaInN quantum wells

Energy Technology Data Exchange (ETDEWEB)

Netzel, Carsten; Hoffmann, Veit; Wernicke, Tim; Knauer, Arne; Weyers, Markus [Ferdinand-Braun-Institut fuer Hoechstfrequenztechnik, Gustav-Kirchhoff-Strasse 4, 12489 Berlin (Germany); Kneissl, Michael [Ferdinand-Braun-Institut fuer Hoechstfrequenztechnik, Gustav-Kirchhoff-Strasse 4, 12489 Berlin (Germany); Institut fuer Festkoerperphysik, Technische Universitaet Berlin, Hardenbergstrasse 36, 10623 Berlin (Germany)

2010-07-15

To determine relevant processes affecting the internal quantum efficiency in GaInN quantum well structures, we have studied the temperature and excitation power dependent photoluminescence intensity for quantum wells with different well widths on (0001) c-plane GaN and for quantum wells on nonpolar (11-20) a-plane GaN. In thick polar quantum wells, the quantum confined Stark effect (QCSE) causes a stronger intensity decrease with increasing temperature as long as the radiative recombination dominates. At higher temperatures, when the nonradiative recombination becomes more important, thick polar quantum wells feature a lower relative intensity decrease than thinner polar or nonpolar quantum wells. Excitation power dependent photoluminescence points to a transition from a recombination of excitons to a bimolecular recombination of uncorrelated charge carriers for thick polar quantum wells in the same temperature range. This transition might contribute to the limitation of nonradiative recombination by a reduced diffusivity of charge carriers. (copyright 2010 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

Harnessing Multiple Internal Reflections to Design Highly Absorptive Acoustic Metasurfaces

Science.gov (United States)

Shen, Chen; Cummer, Steven A.

2018-05-01

The rapid development of metasurfaces has enabled numerous intriguing applications with acoustically thin sheets. Here we report the theory and experimental realization of a nonresonant sound-absorbing strategy using metasurfaces by harnessing multiple internal reflections. We theoretically and numerically show that the higher-order diffraction of thin gradient-index metasurfaces is tied to multiple internal reflections inside the unit cells. Highly absorbing acoustic metasurfaces can be realized by enforcing multiple internal reflections together with a small amount of loss. A reflective gradient-index acoustic metasurface is designed based on the theory, and we further experimentally verify the performance using a three-dimensional printed prototype. Measurements show over 99% energy absorption at the peak frequency and a 95% energy absorption bandwidth of around 600 Hz. The proposed mechanism provides an alternative route for sound absorption without the necessity of high absorption of the individual unit cells.

Quantum threshold reflection is not a consequence of a region of the long-range attractive potential with rapidly varying de Broglie wavelength

Science.gov (United States)

Petersen, Jakob; Pollak, Eli; Miret-Artes, Salvador

2018-04-01

Quantum threshold reflection is a well-known quantum phenomenon which prescribes that at threshold, except for special circumstances, a quantum particle scattering from any potential, even if attractive at long range, will be reflected with unit probability. In the past, this property had been associated with the so-called badlands region of the potential, where the semiclassical description of the scattering fails due to a rapid spatial variation of the de Broglie wavelength. This badlands region occurs far from the strong interaction region of the potential and has therefore been used to "explain" the quantum reflection phenomenon. In this paper we show that the badlands region of the interaction potential is immaterial. The extremely long wavelength of the scattered particle at threshold is much longer than the spatial extension of the badlands region, which therefore does not affect the scattering. For this purpose, we review and generalize the proof for the existence of quantum threshold reflection to stress that it is only a consequence of continuity and boundary conditions. The nonlocal character of the scattering implies that the whole interaction potential is involved in the phenomenon. We then provide a detailed numerical study of the threshold scattering of a particle by a Morse potential and an Eckart potential, especially in the time domain. We compare exact quantum computations with incoherent results obtained from a classical Wigner approximation. This study shows that close to threshold the time-dependent amplitude of the scattered particle is negligible in the badlands region and is the same whether the potential has a reflecting wall as in the Morse potential or a steplike structure as in the Eckart smooth step potential. The mean flight time of the particle is not shortened due to a local reflection from the badlands region or due to the lower density of the wave function at short distances. This study should serve to definitely rule out the

Nonlocal transformation of the internal quantum particle structure

Directory of Open Access Journals (Sweden)

Alexey Yu. Samarin

2016-09-01

Full Text Available The analysis of the integral wave equation, having path integral kernel, has resulted, that collapse phenomenon is based on the nonlocal transformation of the internal structure of a quantum particle, considering in the form of the matter fields collection. This nonlocality allows to escape the contradiction between the reduction quantum mechanics postulate and special relativity. It is shown, that the wave function transformation, corresponding to von Neumann's reduction, has the deterministic nature and the quantum mechanics stochasticity is a consequence of a macroscopic measurer presence in the measuring process. Besides it is demonstrated, that the decogerence phenomenon has the same mechanism of the wave function transformation. EPR-type experiment is described in detail and the possibility of the faster-then light communication is proved, as well the possible rules of thumb of this communication are proposed.

Quantum coherence in the reflection of above barrier wavepackets

Science.gov (United States)

Petersen, Jakob; Pollak, Eli

2018-02-01

The quantum phenomenon of above barrier reflection is investigated from a time-dependent perspective using Gaussian wavepackets. The transition path time distribution, which in principle is experimentally measurable, is used to study the mean flight times ⟨t⟩R and ⟨t⟩T associated with the reflection and the transmission over the barrier paying special attention to their dependence on the width of the barrier. Both flight times, and their difference Δt, exhibit two distinct regimes depending on the ratio of the spatial width of the incident wavepacket and the length of the barrier. When the ratio is larger than unity, the reflection and transmission dynamics are coherent and dominated by the resonances above the barrier. The flight times ⟨t⟩R/T and the flight time difference Δt oscillate as a function of the barrier width (almost in phase with the transmission probability). These oscillations reflect a momentum filtering effect related to the coherent superposition of the reflected and transmitted waves. For a ratio less than unity, the barrier reflection and transmission dynamics are incoherent and the oscillations are absent. The barrier width which separates the coherent and incoherent regimes is identified analytically. The oscillatory structure of the time difference Δt as a function of the barrier width in the coherent regime is absent when considered in terms of the Wigner phase time delays for reflection and transmission. We conclude that the Wigner phase time does not correctly describe the temporal properties of above barrier reflection. We also find that the structure of the reflected and transmitted wavepackets depends on the coherence of the process. In the coherent regime, the wavepackets can have an overlapping peak structure, but the peaks are not fully resolved. In the incoherent regime, the wavepackets split in time into distinct separated Gaussian like waves, each one reflecting the number of times the wavepacket crosses the barrier

Internal Reflection Sensor for the Cone Penetrometer. Innovative Technology Summary Report

International Nuclear Information System (INIS)

None

2001-01-01

The Internal Reflection Sensor, developed by EIC Laboratories, Inc. as a cone penetrometer based technology, provides real-time detection of subsurface non-aqueous phase liquids (NAPLs). The internal reflection element is positioned against the wall of the cone penetrometer probe such that its sensing face is in contact with the soil or groundwater as the cone is pushed into the subsurface. When NAPL is present and in contact with the sensing face, the internally reflected light is diminished. This results in a decrease in the signal output by the detector - a positive indicator of NAPL presence

PREFACE: International Conference on Quantum Simulators and Design, Hiroshima, Japan, 3 6 December 2006

Science.gov (United States)

Akai, Hisazumi; Oguchi, Tamio

2007-09-01

This special issue of Journal of Physics: Condensed Matter comprises selected papers from the 1st International Conference on Quantum Simulators and Design (QSD2006) held in Hiroshima, Japan, 3-6 December 2006. This conference was organized under the auspices of the Development of New Quantum Simulators and Quantum Design Grant-in-Aid for Scientific Research on Priority Areas, Ministry of Education, Culture, Sports, Science and Technology of Japan (MEXT), and Hiroshima University Quantum design is a computational approach to the development of new materials with specified properties and functionalities. The basic ingredient is the use of quantum simulations to design a material that meets a given specification of properties and functionalities. For this to be successful, the quantum simulation should be highly reliable and be applicable to systems of realistic size. A central interest is, therefore, the development of new methods of quantum simulation and quantum design. This includes methods beyond the local density approximation of density functional theory (LDA), order-N methods, methods dealing with excitations and reactions, and so on, as well as the application of these methods to the design of new materials and devices. The field of quantum design has developed rapidly in the past few years and this conference provides an international forum for experimental and theoretical researchers to exchange ideas. A total of 183 delegates from 8 countries participated in the conference. There were 18 invited talks, 16 oral presentations and 100 posters. There were many new ideas and we foresee dramatic progress in the coming years. The 2nd International Conference on Quantum Simulators and Design will be held in Tokyo, Japan, 31 May-3 June 2008.

15th International Conference on Non-Hermitian Hamiltonians in Quantum Physics

CERN Document Server

Passante, Roberto; Trapani, Camillo

2016-01-01

This book presents the Proceedings of the 15th International Conference on Non-Hermitian Hamiltonians in Quantum Physics, held in Palermo, Italy, from 18 to 23 May 2015. Non-Hermitian operators, and non-Hermitian Hamiltonians in particular, have recently received considerable attention from both the mathematics and physics communities. There has been a growing interest in non-Hermitian Hamiltonians in quantum physics since the discovery that PT-symmetric Hamiltonians can have a real spectrum and thus a physical relevance. The main subjects considered in this book include: PT-symmetry in quantum physics, PT-optics, Spectral singularities and spectral techniques, Indefinite-metric theories, Open quantum systems, Krein space methods, and Biorthogonal systems and applications. The book also provides a summary of recent advances in pseudo-Hermitian Hamiltonians and PT-symmetric Hamiltonians, as well as their applications in quantum physics and in the theory of open quantum systems.

Quantum-Circuit Refrigerator

Science.gov (United States)

MöTtöNen, Mikko; Tan, Kuan Y.; Masuda, Shumpei; Partanen, Matti; Lake, Russell E.; Govenius, Joonas; Silveri, Matti; Grabert, Hermann

Quantum technology holds great potential in providing revolutionizing practical applications. However, fast and precise cooling of the functional quantum degrees of freedom on demand remains a major challenge in many solid-state implementations, such as superconducting circuits. We demonstrate direct cooling of a superconducting resonator mode using voltage-controllable quantum tunneling of electrons in a nanoscale refrigerator. In our first experiments on this type of a quantum-circuit refrigerator, we measure the drop in the mode temperature by electron thermometry at a resistor which is coupled to the resonator mode through ohmic losses. To eliminate unwanted dissipation, we remove the probe resistor and directly observe the power spectrum of the resonator output in agreement with the so-called P(E) theory. We also demonstrate in microwave reflection experiments that the internal quality factor of the resonator can be tuned by orders of magnitude. In the future, our refrigerator can be integrated with different quantum electric devices, potentially enhancing their performance. For example, it may prove useful in the initialization of superconducting quantum bits and in dissipation-assisted quantum annealing. We acknowledge European Research Council Grant SINGLEOUT (278117) and QUESS (681311) for funding.

Optically controlled reflection modulator using GaAs-AlGaAs n-i-p-i/multiple-quantum-well structures

Science.gov (United States)

Law, K.-K.; Simes, R. J.; Coldren, L. A.; Gossard, A. C.; Maserjian, J.

1989-01-01

An optically controlled reflection modulator has been demonstrated that consists of a combination of a GaAs-AlGaAs n-i-p-i doping structure with a multiple-quantum-well structures on top of a distributed Bragg reflector, all grown by MBE. A modulation of approximately 60 percent is obtained on the test structure, corresponding to a differential change of absorption coefficient in the quantum wells of approximately 7500/cm. Changes in reflectance can be observed with a control beam power as low as 1.5 microW. This device structure has the potential of being developed as an optically addressed spatial light modulator for optical information processing.

Small-displacement sensing system based on multiple total internal reflections in heterodyne interferometry.

Science.gov (United States)

Wang, Shinn-Fwu; Chiu, Ming-Hung; Chen, Wei-Wu; Kao, Fu-Hsi; Chang, Rong-Seng

2009-05-01

A small-displacement sensing system based on multiple total internal reflections in heterodyne interferometry is proposed. In this paper, a small displacement can be obtained only by measuring the variation in phase difference between s- and p-polarization states for the total internal reflection effect. In order to improve the sensitivity, we increase the number of total internal reflections by using a parallelogram prism. The theoretical resolution of the method is better than 0.417 nm. The method has some merits, e.g., high resolution, high sensitivity, and real-time measurement. Also, its feasibility is demonstrated.

From a particle in a box to the uncertainty relation in a quantum dot and to reflecting walls for relativistic fermions

International Nuclear Information System (INIS)

Al-Hashimi, M.H.; Wiese, U.-J.

2012-01-01

We consider a 1-parameter family of self-adjoint extensions of the Hamiltonian for a particle confined to a finite interval with perfectly reflecting boundary conditions. In some cases, one obtains negative energy states which seem to violate the Heisenberg uncertainty relation. We use this as a motivation to derive a generalized uncertainty relation valid for an arbitrarily shaped quantum dot with general perfectly reflecting walls in d dimensions. In addition, a general uncertainty relation for non-Hermitian operators is derived and applied to the non-Hermitian momentum operator in a quantum dot. We also consider minimal uncertainty wave packets in this situation, and we prove that the spectrum depends monotonically on the self-adjoint extension parameter. In addition, we construct the most general boundary conditions for semiconductor heterostructures such as quantum dots, quantum wires, and quantum wells, which are characterized by a 4-parameter family of self-adjoint extensions. Finally, we consider perfectly reflecting boundary conditions for relativistic fermions confined to a finite volume or localized on a domain wall, which are characterized by a 1-parameter family of self-adjoint extensions in the (1+1)-d and (2+1)-d cases, and by a 4-parameter family in the (3+1)-d and (4+1)-d cases. - Highlights: ► Finite volume Heisenberg uncertainty relation. ► General self-adjoint extensions for relativistic fermions. ► New prospective for the problem of particle in a box.

Internal quantum efficiency in yellow-amber light emitting AlGaN-InGaN-GaN heterostructures

Energy Technology Data Exchange (ETDEWEB)

Ngo, Thi Huong; Gil, Bernard; Valvin, Pierre [Laboratoire Charles Coulomb – UMR 5221, CNRS and University Montpellier, Case courier 074, 34095 Montpellier Cedex 5 (France); Damilano, Benjamin; Lekhal, Kaddour; De Mierry, Philippe [CRHEA-CNRS Centre de Recherche sur l' Hétéro-Epitaxie et ses Applications, Centre National de la Recherche Scientifique, rue Bernard Gregory, 06560 Valbonne (France)

2015-09-21

We determine the internal quantum efficiency of strain-balanced AlGaN-InGaN-GaN hetero-structures designed for yellow-amber light emission, by using a recent model based on the kinetics of the photoluminescence decay initiated by Iwata et al. [J. Appl. Phys. 117, 075701 (2015)]. Our results indicate that low temperature internal quantum efficiencies sit in the 50% range and we measure that adding an AlGaN layer increases the internal quantum efficiency from 50% up to 57% with respect to the GaN-InGaN case. More dramatic, it almost doubles from 2.5% up to 4.3% at room temperature.

International Workshop on "Intersubband Transitions in Quantum Wells : Physics and Applications"

CERN Document Server

Su, Yan-Kuin

1998-01-01

The International Workshop on "Intersubband Transitions in Quantum Wells:: Physics and Applications," was held at National Cheng Kung University, in Tainan, Taiwan, December 15-18, 1997. The objective of the Workshop is to facilitate the presentation and discussion of the recent results in theoretical, experimental, and applied aspects of intersubband transitions in quantum wells and dots. The program followed the tradition initiated at the 1991 conference in Cargese-France, the 1993 conference in Whistler, B. C. Canada, and the 1995 conference in Kibbutz Ginosar, Israel. Intersubband transitions in quantum wells and quantum dots have attracted considerable attention in recent years, mainly due to the promise of various applications in the mid- and far-infrared regions (2-30 J. lm). Over 40 invited and contributed papers were presented in this four-day workshop, with topics covered most aspects of the intersubband transition phenomena including: the basic intersubband transition processes, multiquantum well i...

Temperature-reflection I

DEFF Research Database (Denmark)

McGady, David A.

2017-01-01

-temperature path integrals for quantum field theories (QFTs) should be T-reflection invariant. Because multi-particle partition functions are equal to Euclidean path integrals for QFTs, we expect them to be T-reflection invariant. Single-particle partition functions though are often not invariant under T......In this paper, we revisit the claim that many partition functions are invariant under reflecting temperatures to negative values (T-reflection). The goal of this paper is to demarcate which partition functions should be invariant under T-reflection, and why. Our main claim is that finite...... that T-reflection is unrelated to time-reversal. Finally, we study the interplay between T-reflection and perturbation theory in the anharmonic harmonic oscillator in quantum mechanics and in Yang-Mills in four-dimensions. This is the first in a series of papers on temperature-reflections....

Total internal reflection second-harmonic generation: probing the alkane water interface

International Nuclear Information System (INIS)

Conboy, J.C.; Daschbach, J.L.; Richmond, G.L.

1994-01-01

Total internal reflection Second-Harmonic Generation (SHG) has been used to study a series of neat n-alkane/water interfaces. Polarization and incident angular-dependent measurements of the SH response show good agreement with theoretical predictions. Analysis of the incident and polarization angular-dependent SH response allows for determination of the nonlinear optical properties of molecules comprising the interfacial region. Based on Kleinman symmetry, the measured surface nonlinear susceptibilities suggest a high degree of interfacial order for octane and decane with less order indicated by the odd carbon n-alkanes examined, heptane and nonane. The SH response in reflection and transmission has been measured under a Total Internal Reflection (TIR) of the fundamental. The measured nonlinear susceptibilities in each case are found to be identical. (orig.)

International Mindedness through the Looking Glass: Reflections on a Concept

Science.gov (United States)

Castro, Paloma; Lundgren, Ulla; Woodin, Jane

2015-01-01

The aim of this article is to report and reflect on a research project involving the conceptualization of the term "International Mindedness", which is used across a range of International Baccalaureate (IB) global and local contexts. The research process involved both a critical analysis of IB official documents and a literature review…

Quantum capacity of quantum black holes

Science.gov (United States)

Adami, Chris; Bradler, Kamil

2014-03-01

The fate of quantum entanglement interacting with a black hole has been an enduring mystery, not the least because standard curved space field theory does not address the interaction of black holes with matter. We discuss an effective Hamiltonian of matter interacting with a black hole that has a precise analogue in quantum optics and correctly reproduces both spontaneous and stimulated Hawking radiation with grey-body factors. We calculate the quantum capacity of this channel in the limit of perfect absorption, as well as in the limit of a perfectly reflecting black hole (a white hole). We find that the white hole is an optimal quantum cloner, and is isomorphic to the Unruh channel with positive quantum capacity. The complementary channel (across the horizon) is entanglement-breaking with zero capacity, avoiding a violation of the quantum no-cloning theorem. The black hole channel on the contrary has vanishing capacity, while its complement has positive capacity instead. Thus, quantum states can be reconstructed faithfully behind the black hole horizon, but not outside. This work sheds new light on black hole complementarity because it shows that black holes can both reflect and absorb quantum states without violating the no-cloning theorem, and makes quantum firewalls obsolete.

Phase transitions and reflection positivity for a class of quantum lattice systems

International Nuclear Information System (INIS)

Perez, J.F.; Wreszinski, W.F.

1980-08-01

A form reflection positivity in planes containing sites is proved for a class of quantum lattice systems. Two apllications to typical models are given: a proof of phase transition of ferromagnetic type by the method of infrared bounds for hhe Fisher-stabilized Ising antiferromagnet in an external magnetic field with parallel and tranverse components, and a proof of a phase transition of antiferromagnetic type for the same model with no stabilization by a suitable version of the Peierls argument. The spherical model is also discussed in an appendix. (Author) [pt

Precise shape reconstruction by active pattern in total-internal-reflection-based tactile sensor.

Science.gov (United States)

Saga, Satoshi; Taira, Ryosuke; Deguchi, Koichiro

2014-03-01

We are developing a total-internal-reflection-based tactile sensor in which the shape is reconstructed using an optical reflection. This sensor consists of silicone rubber, an image pattern, and a camera. It reconstructs the shape of the sensor surface from an image of a pattern reflected at the inner sensor surface by total internal reflection. In this study, we propose precise real-time reconstruction by employing an optimization method. Furthermore, we propose to use active patterns. Deformation of the reflection image causes reconstruction errors. By controlling the image pattern, the sensor reconstructs the surface deformation more precisely. We implement the proposed optimization and active-pattern-based reconstruction methods in a reflection-based tactile sensor, and perform reconstruction experiments using the system. A precise deformation experiment confirms the linearity and precision of the reconstruction.

PREFACE: Proceedings of the 2nd International Conference on Quantum Simulators and Design (Tokyo, Japan, 31 May-3 June 2008) Proceedings of the 2nd International Conference on Quantum Simulators and Design (Tokyo, Japan, 31 May-3 June 2008)

Science.gov (United States)

Akai, Hisazumi; Tsuneyuki, Shinji

2009-02-01

This special issue of Journal of Physics: Condensed Matter comprises selected papers from the proceedings of the 2nd International Conference on Quantum Simulators and Design (QSD2008) held in Tokyo, Japan, between 31 May and 3 June 2008. This conference was organized under the auspices of the Development of New Quantum Simulators and Quantum Design Grant-in-Aid for Scientific Research on Priority Areas, Ministry of Education, Culture, Sports, Science and Technology of Japan (MEXT). The conference focused on the development of first principles electronic structure calculations and their applications. The aim was to provide an opportunity for discussion on the progress in computational materials design and, in particular, the development of quantum simulators and quantum design. Computational materials design is a computational approach to the development of new materials. The essential ingredient is the use of quantum simulators to design a material that meets a given specification of properties and functionalities. For this to be successful, the quantum simulator should be very reliable and be applicable to systems of realistic size. During the conference, new methods of quantum simulation and quantum design were discussed including methods beyond the local density approximation of density functional theory, order-N methods, methods dealing with excitations and reactions, and the application of these methods to the design of novel materials, devices and systems. The conference provided an international forum for experimental and theoretical researchers to exchange ideas. A total of 220 delegates from eight countries participated in the conference. There were 13 invited talks, ten oral presentations and 120 posters. The 3rd International Conference on Quantum Simulators and Design will be held in Germany in the autumn of 2011.

Proceedings of quantum field theory, quantum mechanics, and quantum optics

International Nuclear Information System (INIS)

Dodonov, V.V.; Man; ko, V.I.

1991-01-01

This book contains papers presented at the XVIII International Colloquium on Group Theoretical Methods in Physics held in Moscow on June 4-9, 1990. Topics covered include; applications of algebraic methods in quantum field theory, quantum mechanics, quantum optics, spectrum generating groups, quantum algebras, symmetries of equations, quantum physics, coherent states, group representations and space groups

Internalization of targeted quantum dots by brain capillary endothelial cells in vivo.

Science.gov (United States)

Paris-Robidas, Sarah; Brouard, Danny; Emond, Vincent; Parent, Martin; Calon, Frédéric

2016-04-01

Receptors located on brain capillary endothelial cells forming the blood-brain barrier are the target of most brain drug delivery approaches. Yet, direct subcellular evidence of vectorized transport of nanoformulations into the brain is lacking. To resolve this question, quantum dots were conjugated to monoclonal antibodies (Ri7) targeting the murine transferrin receptor. Specific transferrin receptor-mediated endocytosis of Ri7-quantum dots was first confirmed in N2A and bEnd5 cells. After intravenous injection in mice, Ri7-quantum dots exhibited a fourfold higher volume of distribution in brain tissues, compared to controls. Immunofluorescence analysis showed that Ri7-quantum dots were sequestered throughout the cerebral vasculature 30 min, 1 h, and 4 h post injection, with a decline of signal intensity after 24 h. Transmission electron microscopic studies confirmed that Ri7-quantum dots were massively internalized by brain capillary endothelial cells, averaging 37 ± 4 Ri7-quantum dots/cell 1 h after injection. Most quantum dots within brain capillary endothelial cells were observed in small vesicles (58%), with a smaller proportion detected in tubular structures or in multivesicular bodies. Parenchymal penetration of Ri7-quantum dots was extremely low and comparable to control IgG. Our results show that systemically administered Ri7-quantum dots complexes undergo extensive endocytosis by brain capillary endothelial cells and open the door for novel therapeutic approaches based on brain endothelial cell drug delivery. © The Author(s) 2015.

Piezomodulated reflectivity on CdMnTe/CdTe quantum well structures as a new standard characterization method

Energy Technology Data Exchange (ETDEWEB)

Kurtz, E.; Schmitt, K.; Hommel, D.; Waag, A.; Bicknell-Tassius, R.N.; Landwehr, G. (Physikalisches Inst., Univ. Wuerzburg (Germany))

1993-01-30

Piezomodulated reflectivity (PZR) measurements are reported for the first time as a standard characterization method for CdMnTe/CdTe single (SQW) and multiple (MQW) quantum wells grown by molecular beam epitaxy on CdTe substrates 1 mm thick. Previously, modulation spectroscopy studies of II-VI structures required thin substrates which needed special preparation. In this paper we present studies of optical properties of CdMnTe/CdTe SQWs and MWQs using the PZR technique. The samples, mounted on a sinusoidally driven piezoelectric transducer are subjected to an alternating strain. Exploiting ''lock-in'' techniques, the first derivative of the reflectivity is measured directly. Specific electronic transitions, e.g. excitons, are well resolved in the modulated spectrum and can be easily identified. This makes PZR a very sensitive and powerful tool for the characterization of quantum well structures, and a useful complement to other standard techniques such as photoluminescence and excitation spectroscopy. (orig.).

Quantum spill-out in few-nanometer metal gaps: Effect on gap plasmons and reflectance from ultrasharp groove arrays

DEFF Research Database (Denmark)

Skjølstrup, Enok Johannes Haahr; Søndergaard, Thomas; Pedersen, Thomas Garm

2018-01-01

Plasmons in ultranarrow metal gaps are highly sensitive to the electron density profile at the metal surfaces. Using a quantum mechanical approach and assuming local response, we study the effects of electron spill-out on gap plasmons and reflectance from ultrasharp metal grooves.We demonstrate...... the reflectance from arrays of ultrasharp metal grooves. These findings are explained in terms of enhanced gap plasmon absorption taking place inside the gap 1–2 °A from the walls and delocalization near the groove bottom. Reflectance calculations taking spill-out into account are shown to be in much better...

Role of the substrate reflectance and surface-bulk treatments in CsI quantum efficiency

CERN Document Server

Singh, B K; Nitti, M A; Valentini, A

2003-01-01

We have experimentally investigated the following aspects related to the quantum efficiency of CsI photocathodes: the type of substrate, the film thickness and the effect of a 'bulk treatment' during the film growth. We discovered that, using a high reflectivity aluminium substrate, the photoemission of very thin CsI film is enhanced. Our study also revealed that photocathodes become less sensitive to moisture when a negative bias voltage is applied to the substrate during the film deposition process.

An Arduino-Based Experiment Designed to Clarify the Transition to Total Internal Reflection

Science.gov (United States)

Atkin, Keith

2018-01-01

The topic of refraction and reflection of light at the boundary of transparent media is a fundamentally important one. The special case of total internal reflection is however commonly misrepresented in elementary textbooks. This paper addresses the problem and describes an experimental procedure for measuring and displaying reflected and…

Attenuated total internal reflection infrared microspectroscopic imaging using a large-radius germanium internal reflection element and a linear array detector.

Science.gov (United States)

Patterson, Brian M; Havrilla, George J

2006-11-01

The number of techniques and instruments available for Fourier transform infrared (FT-IR) microspectroscopic imaging has grown significantly over the past few years. Attenuated total internal reflectance (ATR) FT-IR microspectroscopy reduces sample preparation time and has simplified the analysis of many difficult samples. FT-IR imaging has become a powerful analytical tool using either a focal plane array or a linear array detector, especially when coupled with a chemometric analysis package. The field of view of the ATR-IR microspectroscopic imaging area can be greatly increased from 300 x 300 microm to 2500 x 2500 microm using a larger internal reflection element of 12.5 mm radius instead of the typical 1.5 mm radius. This gives an area increase of 70x before aberrant effects become too great. Parameters evaluated include the change in penetration depth as a function of beam displacement, measurements of the active area, magnification factor, and change in spatial resolution over the imaging area. Drawbacks such as large file size will also be discussed. This technique has been successfully applied to the FT-IR imaging of polydimethylsiloxane foam cross-sections, latent human fingerprints, and a model inorganic mixture, which demonstrates the usefulness of the method for pharmaceuticals.

Effect of the refraction factor of a plastic fiber shell on the internal reflection coefficient

International Nuclear Information System (INIS)

Pkrksypkin, A.I.; Ponomarev, L.I.

1992-01-01

Results of pilot studies of the effect of refraction factor of plastic fiber shell on the coefficient of light internal reflection in the fiber are presented. It is pointed, that the shell does not absorb the light, but effects the surface layer of the fiber centre so, that dependence of the coefficient of internal reflection on refraction factor of the shell may be described using Fresnel formulae. It is shown, that coefficient of internal reflection decreases with the increase of refraction factor. Technique to determine volume length of scintillation light absorption in the fiber is suggested

Quantum Fest 2016 International Conference on Quantum Phenomena, Quantum Control and Quantum Optics

International Nuclear Information System (INIS)

2017-01-01

The Quantum Fest is a periodic annual festival on Quantum Phenomena, Quantum Control and Geometry of Quantum States, organized by the Center for Research and Advanced Studies (Cinvestav by its acronym in Spanish) and Unidad Profesional Interdisciplinaria en Ingeniería y Tecnologías Avanzadas del Instituto Politécnico Nacional (UPIITA-IPN) in México City, Mexico. The aim of this meeting is to bring together students and researchers which are engaged in the subjects of the festival, from both theoretical and experimental approaches, in order to get lively discussions and to enable a closer contact between them.The Quantum Fest was celebrated for the first time in the Physics Department of Cinvestav (2010), since then it has been hosted in Cinvestav, UPIITA-IPN and the Tecnológico de Monterrey, Campus Estado de México (ITESM-CEM).The Quantum Fest 2016 is the seventh edition of the festival, it took place from October 17 to 21 in the Sala de Usos Múltiples, Edificio I of UPIITA-IPN, and was addressed to join the celebration of the first eighty years of the Instituto Politécnico Nacional as well as the first twenty years of the Unidad Profesional Interdisciplinaria en Ingeniería y Tecnologías Avanzadas del Instituto Politécnico Nacional. We would like to thank the willing of the UPIITA-IPN to offer its facilities as the venue of the festival; all its help provided to simplify the logistics and organization of the conference has been welcomed and is acknowledged.The topics addressed at the short courses of the Quantum Fest 2016 were time asymmetric quantum mechanics, quantum resonances, models of quantum field theory in metamaterials, singular potentials and self-adjoint extensions, nonclassical states of light, Hardy functions and Hilbert space operators.The Lecturers of Quantum Fest 2016 were:Manuel Gadella (Valladolid University, Spain)Maribel Loaiza (Department of Mathematics, Cinvestav, Mexico)Luis Miguel Nieto (Valladolid University, Spain)Oscar Rosas

Phonon-assisted exciton formation in ZnO/(Zn, Mg)O single quantum wells grown on C-plane oriented substrates

International Nuclear Information System (INIS)

Béaur, L.; Bretagnon, T.; Guillet, T.; Brimont, C.; Gallart, M.; Gil, B.; Gilliot, P.; Morhain, C.

2013-01-01

We report on absorption phenomena in ZnO/(Zn, Mg)O quantum wells grown along the c-axis by molecular beam epitaxy. The optical properties of such quantum wells are affected by a huge internal electric field. For wide quantum wells the absorption is driven by Quantum Confined Stark Effect. Phonon-assisted formation of excitons is observed in the case of thin quantum wells. The physical origin of these hot excitons is determined by using both low temperature (T=10 K) photoluminescence excitation spectroscopy and reflectivity measurements. -- Highlights: ► High structural quality ZnO/(Zn, Mg)O quantum wells are growth along the polar c-direction. ► Indirect phonon-assisted formation of excitons in the thin single quantum wells. ► Strong internal electric field present in polar heterostructures prevents the observation of hot excitons

Internal quantum efficiency and tunable colour temperature in monolithic white InGaN/GaN LED

Science.gov (United States)

Titkov, Ilya E.; Yadav, Amit; Zerova, Vera L.; Zulonas, Modestas; Tsatsulnikov, Andrey F.; Lundin, Wsevolod V.; Sakharov, Alexey V.; Rafailov, Edik U.

2014-03-01

Internal Quantum Efficiency (IQE) of two-colour monolithic white light emitting diode (LED) was measured by temperature dependant electro-luminescence (TDEL) and analysed with modified rate equation based on ABC model. External, internal and injection efficiencies of blue and green quantum wells were analysed separately. Monolithic white LED contained one green InGaN QW and two blue QWs being separated by GaN barrier. This paper reports also the tunable behaviour of correlated colour temperature (CCT) in pulsed operation mode and effect of self-heating on device performance.

Quantum Entropy of Black Hole with Internal Global Monopole

Institute of Scientific and Technical Information of China (English)

HAN Yi-Wen; YANG Shu-Zheng; LIU Wen-Biao

2005-01-01

Using the generalized uncertainty relation, the new equation of state density is obtained, and then the entropy of black hole with an internal global monopole is discussed. The divergence that appears in black hole entropy calculation through original brick-wall model is overcome. The result of the direct proportion between black hole entropy and its event horizon area is drawn and given. The result shows that the black hole entropy must be the entropy of quantum state near the event horizon.

Internal reflection spectroscopic analysis of sulphide mineral surfaces

International Nuclear Information System (INIS)

Kaoma, J.

1989-01-01

To establish the reason for flotation of sulfide minerals in the absence of any conventional collector, internal reflection spectroscopic analysis (IRS) of their surfaces was conducted. sulfur, sulfates, thiosulfates, and hydrocarbonates have been detected on the surface of as-grand sulfide minerals. On sodium sulfide-treated surfaces, both sulfur and polysulfide have also been found to be present. From these findings, the flotation of sulfide minerals without collectors is discussed. (author). 26 refs

Quantum Walk in Terms of Quantum Bernoulli Noise and Quantum Central Limit Theorem for Quantum Bernoulli Noise

Directory of Open Access Journals (Sweden)

Caishi Wang

2018-01-01

Full Text Available As a unitary quantum walk with infinitely many internal degrees of freedom, the quantum walk in terms of quantum Bernoulli noise (recently introduced by Wang and Ye shows a rather classical asymptotic behavior, which is quite different from the case of the usual quantum walks with a finite number of internal degrees of freedom. In this paper, we further examine the structure of the walk. By using the Fourier transform on the state space of the walk, we obtain a formula that links the moments of the walk’s probability distributions directly with annihilation and creation operators on Bernoulli functionals. We also prove some other results on the structure of the walk. Finally, as an application of these results, we establish a quantum central limit theorem for the annihilation and creation operators themselves.

Integrating sphere based reflectance measurements for small-area semiconductor samples

Science.gov (United States)

Saylan, S.; Howells, C. T.; Dahlem, M. S.

2018-05-01

This article describes a method that enables reflectance spectroscopy of small semiconductor samples using an integrating sphere, without the use of additional optical elements. We employed an inexpensive sample holder to measure the reflectance of different samples through 2-, 3-, and 4.5-mm-diameter apertures and applied a mathematical formulation to remove the bias from the measured spectra caused by illumination of the holder. Using the proposed method, the reflectance of samples fabricated using expensive or rare materials and/or low-throughput processes can be measured. It can also be incorporated to infer the internal quantum efficiency of small-area, research-level solar cells. Moreover, small samples that reflect light at large angles and develop scattering may also be measured reliably, by virtue of an integrating sphere insensitive to directionalities.

Total internal reflection tomography of small objects

International Nuclear Information System (INIS)

Chen Xudong

2008-01-01

The multiple signal classification (MUSIC) imaging method is applied to determine the locations of a collection of small anisotropic spherical scatterers in the framework of the total internal reflection tomography. Multiple scattering between scatterers is considered and the inverse scattering problem is nonlinear, which, however, is solved by the proposed fast analytical approach where no associated forward problem is iteratively evaluated. The paper also discusses the role of the polarization of incidence waves, the incidence angle, the separation of scatterers from the surface of the substrate, and the level of noise on the resolution of imaging.

Quantum-well enhancement of the Goos-Hänchen shift for p-polarized beams in a two prism configuration

DEFF Research Database (Denmark)

Broe, Jacob; Keller, Ole

2002-01-01

It is predicted that the Goos-Hänchen effect can be resonantly enhanced by placing a metallic quantum well (ultrathin film) at the dielectric-vacuum (air) interface. We study the enhancement of the phenomenon, as it appears in frustrated total internal reflection with p-polarized light, both...... by depositing quantum wells on the glass-vacuum interfaces to obtain a better spatial photon localization....

Uptake, retention and internalization of quantum dots in Daphnia is influenced by particle surface functionalization

Energy Technology Data Exchange (ETDEWEB)

Feswick, A., E-mail: afeswick@yahoo.ca [Center for Environmental and Human Toxicology, University of Florida, PO Box 110885, Gainesville, FL 32611 (United States); Canadian Rivers Institute, University of New Brunswick, PO Box 5050, Saint John NB, CA (United States); Griffitt, R.J., E-mail: joe.griffitt@usm.edu [Department of Coastal Sciences, University of Southern Mississippi, 703 East Beach Drive, Ocean Springs, MS 39564 (United States); Siebein, K., E-mail: kerry.siebein@nist.gov [Major Analytical Instrumentation Center, University of Florida, PO Box 116400, Gainesville, FL 32611 (United States); Barber, D.S., E-mail: barberd@vetmed.ufl.edu [Center for Environmental and Human Toxicology, University of Florida, PO Box 110885, Gainesville, FL 32611 (United States)

2013-04-15

Highlights: ► Daphnia underwent a waterborne exposure of PEG, NH{sub 2} and COOH functionalized quantum dot nanoparticles. ► There was preferential retention of COOH nanoparticles. ► TEM demonstrated that NH{sub 2} and COOH nanoparticles were internalized in cells adjacent to the GI tract. ► This cellular internalization was confirmed using energy dispersive spectroscopy. -- Abstract: Nanomaterials are a diverse group of compounds whose inevitable release into the environment warrants study of the fundamental processes that govern the ingestion, uptake and accumulation in aquatic organisms. Nanomaterials have the ability to transfer to higher trophic levels in aquatic ecosystems, and recent evidence suggests that the surface chemistry of both the nanoparticle and biological membrane can influence uptake kinetics. Therefore, our study investigates the effect of surface functionalization on uptake, internalization and depuration in Daphnia spp. Uncharged (polyethylene glycol; PEG), positively charged (amino-terminated: NH{sub 2}) and negatively charged (carboxyl-modified; COOH) cadmium selenide/zinc sulfide quantum dots were used to monitor ingestion, uptake and depuration of nanometals in Daphnia magna and Ceriodaphnia dubia over 24 h of exposure. These studies demonstrated that particles with higher negative charge (COOH quantum dots) were taken up to a greater extent by Daphnia (259.17 ± 17.70 RFU/20 Daphnia) than either the NH{sub 2} (150.01 ± 18.91) or PEG quantum dots (95.17 ± 9.78), however this is likely related to the functional groups attached to the nanoparticles as there were no real differences in zeta potential. Whole body fluorescence associates well with fluorescent microscopic images obtained at the 24 h timepoint. Confocal and electron microscopic analysis clearly demonstrated that all three types of quantum dots could cross the intestinal epithelial barrier and be translocated to other cells. Upon cessation of exposure, elimination of

Significant internal quantum efficiency enhancement of GaN/AlGaN multiple quantum wells emitting at ~350 nm via step quantum well structure design

KAUST Repository

Wu, Feng; Sun, Haiding; Ajia, Idris A.; Roqan, Iman S.; Zhang, Daliang; Dai, Jiangnan; Chen, Changqing; Feng, Zhe Chuan; Li, Xiaohang

2017-01-01

Significant internal quantum efficiency (IQE) enhancement of GaN/AlGaN multiple quantum wells (MQWs) emitting at similar to 350 nm was achieved via a step quantum well (QW) structure design. The MQW structures were grown on AlGaN/AlN/sapphire templates by metal-organic chemical vapor deposition (MOCVD). High resolution x-ray diffraction (HR-XRD) and scanning transmission electron microscopy (STEM) were performed, showing sharp interface of the MQWs. Weak beam dark field imaging was conducted, indicating a similar dislocation density of the investigated MQWs samples. The IQE of GaN/AlGaN MQWs was estimated by temperature dependent photoluminescence (TDPL). An IQE enhancement of about two times was observed for the GaN/AlGaN step QW structure, compared with conventional QW structure. Based on the theoretical calculation, this IQE enhancement was attributed to the suppressed polarization-induced field, and thus the improved electron-hole wave-function overlap in the step QW.

Significant internal quantum efficiency enhancement of GaN/AlGaN multiple quantum wells emitting at ~350 nm via step quantum well structure design

KAUST Repository

Wu, Feng

2017-05-03

Significant internal quantum efficiency (IQE) enhancement of GaN/AlGaN multiple quantum wells (MQWs) emitting at similar to 350 nm was achieved via a step quantum well (QW) structure design. The MQW structures were grown on AlGaN/AlN/sapphire templates by metal-organic chemical vapor deposition (MOCVD). High resolution x-ray diffraction (HR-XRD) and scanning transmission electron microscopy (STEM) were performed, showing sharp interface of the MQWs. Weak beam dark field imaging was conducted, indicating a similar dislocation density of the investigated MQWs samples. The IQE of GaN/AlGaN MQWs was estimated by temperature dependent photoluminescence (TDPL). An IQE enhancement of about two times was observed for the GaN/AlGaN step QW structure, compared with conventional QW structure. Based on the theoretical calculation, this IQE enhancement was attributed to the suppressed polarization-induced field, and thus the improved electron-hole wave-function overlap in the step QW.

Foreword [International conference on algebra, analysis and quantum probability

International Nuclear Information System (INIS)

2016-01-01

The present volume of the Journal of Physics: Conference Series represents contributions from participants of the International Conference ’’Algebra, Analysis and Quantum Probability” (Tashkent, 10-12 September 2015) organized by the Institute of Mathematics and the Faculty of Mechanics and Mathematics of the National University of Uzbekistan (NUUz) in collaboration with University Putra Malaysia (UPM) and International Islamic University Malaysia (IIUM). The Conference is dedicated to the 100th anniversary of one of the outstanding scientists of Uzbekistan, the founder of the Tashkent scientific school of functional analysis, who has initiated the investigations on operator algebras and quantum probability theory in Uzbekistan - Professor Tashmukhamed Alievich Sarymsakov (10 Sept. 1915 - 19 Dec. 1995). Among the mathematical community Professor T. A. Sarymsakov is widely known for his research in the fields of probability theory, functional analysis, general topology and their applications. A gifted teacher and skilful organizer he had a beneficial effect on the development of many new mathematicians in Uzbekistan. Professor T.A. Sarymsakov, an outstanding organizer of science in Uzbekistan, was one of the founders of the Uzbekistan Academy of Sciences, where from 1943 he was a member and Vice President, and from 1946 to 1952 president of the Academy of Sciences. Professor Sarymsakov successfully combined his fruitful scientific research with teaching and social work. During 1943-1944, 1952-1958 and 1971-1983 he was the rector of Tashkent State University (now the National University of Uzbekistan). He has made a significant contribution to the development of higher education in Uzbekistan, serving from 1959 to 1960 as the Chairman of the State Committee, and from 1960 to 1971 as the Minister of Higher and Secondary Special Education of Uzbekistan. The main objective of the scientific conference was to facilitate communication and collaboration between

Corrugated Quantum Well Infrared Photodetector Focal Plane Array Test Results

Science.gov (United States)

Goldberg, A.; Choi, K. K.; Das, N. C.; La, A.; Jhabvala, M.

1999-01-01

The corrugated quantum-well infrared photodetector (C-QWIP) uses total internal reflection to couple normal incident light into the optically active quantum wells. The coupling efficiency has been shown to be relatively independent of the pixel size and wavelength thus making the C-QWIP a candidate for detectors over the entire infrared spectrum. The broadband coupling efficiency of the C-QWIP makes it an ideal candidate for multiwavelength detectors. We fabricated and tested C-QWIP focal plane arrays (FPAs) with cutoff wavelengths of 11.2 and 16.2 micrometers. Each FPA has 256 x 256 pixels that are bump-bonded to a direct injection readout circuit. Both FPAs provided infrared imagery with good aesthetic attributes. For the 11.2-micrometers FPA, background-limited performance (BLIP) was observed at 60 K with f/3 optics. For the 16.2-micrometers FPA, BLIP was observed at 38 K. Besides the reduction of dark current in C-QWIP structures, the measured internal quantum efficiency (eta) remains to be high. The values for responsivity and quantum efficiency obtained from the FPA results agree well with those measured for single devices.

Quantum reference frames and quantum transformations

International Nuclear Information System (INIS)

Toller, M.

1997-01-01

A quantum frame is defined by a material object following the laws of quantum mechanics. The present paper studies the relations between quantum frames, which are described by some generalization of the Poincare' group. The possibility of using a suitable quantum group is examined, but some arguments are given which show that a different mathematical structure is necessary. Some simple examples in lower-dimensional space-times are treated. They indicate the necessity of taking into account some ''internal'' degrees of freedom of the quantum frames, that can be disregarded in a classical treatment

An International Experience for Social Work Students: Self-Reflection through Poetry and Journal Writing Exercises

Science.gov (United States)

Furman, Rich; Coyne, Ann; Negi, Nalini Junko

2008-01-01

This descriptive article explores the uses of poetry and journaling exercises as means of helping students develop their self-reflective capacities within the context of international social work. First, self-reflection and its importance to social work practice and education is discussed. Second, the importance of self-reflection in international…

Quantum random walks using quantum accelerator modes

International Nuclear Information System (INIS)

Ma, Z.-Y.; Burnett, K.; D'Arcy, M. B.; Gardiner, S. A.

2006-01-01

We discuss the use of high-order quantum accelerator modes to achieve an atom optical realization of a biased quantum random walk. We first discuss how one can create coexistent quantum accelerator modes, and hence how momentum transfer that depends on the atoms' internal state can be achieved. When combined with microwave driving of the transition between the states, a different type of atomic beam splitter results. This permits the realization of a biased quantum random walk through quantum accelerator modes

Block-free optical quantum Banyan network based on quantum state fusion and fission

International Nuclear Information System (INIS)

Zhu Chang-Hua; Meng Yan-Hong; Quan Dong-Xiao; Zhao Nan; Pei Chang-Xing

2014-01-01

Optical switch fabric plays an important role in building multiple-user optical quantum communication networks. Owing to its self-routing property and low complexity, a banyan network is widely used for building switch fabric. While, there is no efficient way to remove internal blocking in a banyan network in a classical way, quantum state fusion, by which the two-dimensional internal quantum states of two photons could be combined into a four-dimensional internal state of a single photon, makes it possible to solve this problem. In this paper, we convert the output mode of quantum state fusion from spatial-polarization mode into time-polarization mode. By combining modified quantum state fusion and quantum state fission with quantum Fredkin gate, we propose a practical scheme to build an optical quantum switch unit which is block free. The scheme can be extended to building more complex units, four of which are shown in this paper. (general)

Live Imaging of Cellular Internalization of Single Colloidal Particle by Combined Label-Free and Fluorescence Total Internal Reflection Microscopy.

Science.gov (United States)

Byrne, Gerard D; Vllasaliu, Driton; Falcone, Franco H; Somekh, Michael G; Stolnik, Snjezana

2015-11-02

In this work we utilize the combination of label-free total internal reflection microscopy and total internal reflectance fluorescence (TIRM/TIRF) microscopy to achieve a simultaneous, live imaging of single, label-free colloidal particle endocytosis by individual cells. The TIRM arm of the microscope enables label free imaging of the colloid and cell membrane features, while the TIRF arm images the dynamics of fluorescent-labeled clathrin (protein involved in endocytosis via clathrin pathway), expressed in transfected 3T3 fibroblasts cells. Using a model polymeric colloid and cells with a fluorescently tagged clathrin endocytosis pathway, we demonstrate that wide field TIRM/TIRF coimaging enables live visualization of the process of colloidal particle interaction with the labeled cell structure, which is valuable for discerning the membrane events and route of colloid internalization by the cell. We further show that 500 nm in diameter model polystyrene colloid associates with clathrin, prior to and during its cellular internalization. This association is not apparent with larger, 1 μm in diameter colloids, indicating an upper particle size limit for clathrin-mediated endocytosis.

The open quantum Brownian motions

International Nuclear Information System (INIS)

Bauer, Michel; Bernard, Denis; Tilloy, Antoine

2014-01-01

Using quantum parallelism on random walks as the original seed, we introduce new quantum stochastic processes, the open quantum Brownian motions. They describe the behaviors of quantum walkers—with internal degrees of freedom which serve as random gyroscopes—interacting with a series of probes which serve as quantum coins. These processes may also be viewed as the scaling limit of open quantum random walks and we develop this approach along three different lines: the quantum trajectory, the quantum dynamical map and the quantum stochastic differential equation. We also present a study of the simplest case, with a two level system as an internal gyroscope, illustrating the interplay between the ballistic and diffusive behaviors at work in these processes. Notation H z : orbital (walker) Hilbert space, C Z in the discrete, L 2 (R) in the continuum H c : internal spin (or gyroscope) Hilbert space H sys =H z ⊗H c : system Hilbert space H p : probe (or quantum coin) Hilbert space, H p =C 2 ρ t tot : density matrix for the total system (walker + internal spin + quantum coins) ρ-bar t : reduced density matrix on H sys : ρ-bar t =∫dxdy ρ-bar t (x,y)⊗|x〉 z 〈y| ρ-hat t : system density matrix in a quantum trajectory: ρ-hat t =∫dxdy ρ-hat t (x,y)⊗|x〉 z 〈y|. If diagonal and localized in position: ρ-hat t =ρ t ⊗|X t 〉 z 〈X t | ρ t : internal density matrix in a simple quantum trajectory X t : walker position in a simple quantum trajectory B t : normalized Brownian motion ξ t , ξ t † : quantum noises (paper)

Internal-wave reflection from uniform slopes: higher harmonics and Coriolis effects

Directory of Open Access Journals (Sweden)

T. Gerkema

2006-01-01

Full Text Available Weakly nonlinear reflection of internal waves from uniform slopes produces higher harmonics and mean fields; the expressions are here derived for constant stratification and with Coriolis effects fully included, i.e. the horizontal component of the earth rotation vector (referred to as 'non-traditional'' is taken into account. Uniformity in one of the horizontal directions is assumed. It is shown that solutions can be as readily derived with as without ; hence there is no need to make the so-called Traditional Approximation. Examples of reflecting internal-wave beams are presented for super-inertial, inertial and sub-inertial frequencies. The problem of resonant and non-resonant forcing of the second harmonic is studied for single plane waves; unlike under the Traditional Approximation, the problem of reflection from a horizontal bottom no longer forms a singular case. Non-traditional effects are favourable to resonant forcing at near-tidal rather than near-inertial frequencies, and generally increase the intensity of the second harmonic. Strong stratification tends to suppress non-traditional effects, but a near-total suppression is only attained for high values of stratification that are characteristic of the seasonal thermocline; in most parts of the ocean, non-traditional effects can therefore be expected to be important.

Quantum master equation for collisional dynamics of massive particles with internal degrees of freedom

International Nuclear Information System (INIS)

Smirne, Andrea; Vacchini, Bassano

2010-01-01

We address the microscopic derivation of a quantum master equation in Lindblad form for the dynamics of a massive test particle with internal degrees of freedom, interacting through collisions with a background ideal gas. When either internal or center-of-mass degrees of freedom can be treated classically, previously established equations are obtained as special cases. If in an interferometric setup the internal degrees of freedom are not detected at the output, the equation can be recast in the form of a generalized Lindblad structure, which describes non-Markovian effects. The effect of internal degrees of freedom on center-of-mass decoherence is considered in this framework.

International workshop on interfacial effects in quantum engineering systems (IEQES-96). Book of abstracts

International Nuclear Information System (INIS)

1996-01-01

In the international workshop on 'interfacial effects in quantum engineering systems (IEQES-96)' organized by Nuclear Engineering Research Laboratory, the University of Tokyo and held on August 21-23, 1996, 108 items were discussed in following 3 sessions. In the first session, on interfacial effects in fusion energy systems, 29 items on Plasma-surface interactions in fusion devices and 14 items on blanket breeder-hydrogen isotope interactions were investigated. In the second session, 38 items on interfacial effects in fission energy systems were discussed. Furthermore, in the third session, 27 items of quantum beam-material interactions were investigated. (G.K.)

Trapping of microwave radiation in hollow polypyrrole microsphere through enhanced internal reflection: A novel approach

Science.gov (United States)

Panigrahi, Ritwik; Srivastava, Suneel K.

2015-01-01

In present work, spherical core (polystyrene, PS)/shell (polypyrrole, PPy) has been synthesized via in situ chemical oxidative copolymerization of pyrrole (Py) on the surface of sulfonated PS microsphere followed by the formation of hollow polypyrrole (HPPy) shell by dissolving PS inner core in THF. Thereafter, we first time established that such fabricated novel art of morphology acts as a conducting trap in absorbing electromagnetic (EM) wave by internal reflection. Further studies have been extended on the formation of its silver nanocomposites HPPy/Ag to strengthen our contention on this novel approach. Our investigations showed that electromagnetic interference (EMI) shielding efficiency (SE) of HPPy (34.5-6 dB) is significantly higher compared to PPy (20-5 dB) in the frequency range of 0.5-8 GHz due to the trapping of EM wave by internal reflection. We also observed that EMI shielding is further enhanced to 59-23 in 10 wt% Ag loaded HPPy/Ag-10. This is attributed to the simultaneous contribution of internal reflection as well as reflection from outer surface. Such high EMI shielding capacity using conducting polymers are rarely reported.

Quantum phase transition with dissipative frustration

Science.gov (United States)

Maile, D.; Andergassen, S.; Belzig, W.; Rastelli, G.

2018-04-01

We study the quantum phase transition of the one-dimensional phase model in the presence of dissipative frustration, provided by an interaction of the system with the environment through two noncommuting operators. Such a model can be realized in Josephson junction chains with shunt resistances and resistances between the chain and the ground. Using a self-consistent harmonic approximation, we determine the phase diagram at zero temperature which exhibits a quantum phase transition between an ordered phase, corresponding to the superconducting state, and a disordered phase, corresponding to the insulating state with localized superconducting charge. Interestingly, we find that the critical line separating the two phases has a nonmonotonic behavior as a function of the dissipative coupling strength. This result is a consequence of the frustration between (i) one dissipative coupling that quenches the quantum phase fluctuations favoring the ordered phase and (ii) one that quenches the quantum momentum (charge) fluctuations leading to a vanishing phase coherence. Moreover, within the self-consistent harmonic approximation, we analyze the dissipation induced crossover between a first and second order phase transition, showing that quantum frustration increases the range in which the phase transition is second order. The nonmonotonic behavior is reflected also in the purity of the system that quantifies the degree of correlation between the system and the environment, and in the logarithmic negativity as an entanglement measure that encodes the internal quantum correlations in the chain.

Direct observation of the Andreev reflection of a quasiparticle beam by quantum turbulence in superfluid 3He-B

International Nuclear Information System (INIS)

Bradley, D.I.; Fisher, S.N.; Guenault, A.M.; Lowe, M.R.; Pickett, G.R.; Rahm, A.

2003-01-01

A beam of quasiparticles from a black-body radiator is directed at a localized region of quantum turbulence generated by a vibrating wire resonator driven at super-critical velocity. We are able to measure directly the fraction of the incident quasiparticle beam which is retro-reflected from the turbulence by Andreev processes. Combining these measurements with previous measurements on the spatial extent of the turbulence may allow us to infer the vortex line density

Calculation of the tunneling time using the extended probability of the quantum histories approach

International Nuclear Information System (INIS)

Rewrujirek, Jiravatt; Hutem, Artit; Boonchui, Sutee

2014-01-01

The dwell time of quantum tunneling has been derived by Steinberg (1995) [7] as a function of the relation between transmission and reflection times τ t and τ r , weighted by the transmissivity and the reflectivity. In this paper, we reexamine the dwell time using the extended probability approach. The dwell time is calculated as the weighted average of three mutually exclusive events. We consider also the scattering process due to a resonance potential in the long-time limit. The results show that the dwell time can be expressed as the weighted sum of transmission, reflection and internal probabilities.

Single-Shot Quantum Nondemolition Detection of Individual Itinerant Microwave Photons

Science.gov (United States)

Besse, Jean-Claude; Gasparinetti, Simone; Collodo, Michele C.; Walter, Theo; Kurpiers, Philipp; Pechal, Marek; Eichler, Christopher; Wallraff, Andreas

2018-04-01

Single-photon detection is an essential component in many experiments in quantum optics, but it remains challenging in the microwave domain. We realize a quantum nondemolition detector for propagating microwave photons and characterize its performance using a single-photon source. To this aim, we implement a cavity-assisted conditional phase gate between the incoming photon and a superconducting artificial atom. By reading out the state of this atom in a single shot, we reach an external (internal) photon-detection fidelity of 50% (71%), limited by transmission efficiency between the source and the detector (75%) and the coherence properties of the qubit. By characterizing the coherence and average number of photons in the field reflected off the detector, we demonstrate its quantum nondemolition nature. We envisage applications in generating heralded remote entanglement between qubits and for realizing logic gates between propagating microwave photons.

DIRC dreams: research directions for the next generation of internally reflected imaging counters

International Nuclear Information System (INIS)

Ratcliff, Blair N.; Spanier, Stefan

1999-01-01

Some conceptual design features of the total internally reflecting, imaging Cherenkov counter (DIRC) are described. Limits of the DIRC approach to particle identification, and a few features of alternative DIRC designs, are briefly explored

«Land of Confusion»: Quantum Physic In IR Theory?

Directory of Open Access Journals (Sweden)

Tatiana A. Alekseeva

2016-01-01

Full Text Available The article deals with the "Quantum mind"hypothesis which has been elaborated in recent works of Alexander Wendt. It is ultimately significant to analyze this hypothesis and to expand on its difficulties and possible inconsistencies given Wendt's credentials in IR theorizing. It allows us to develop a new approach and promising research program on the basis of the hypothesis and its critical reflection. Wendt's quantum physicalism (or holism implies serious philosophical injury and outstanding usage of different science disciplines' apparatus including physics, biology, and psychology. Thought-provoking approach of Wendt boosts researching efforts within the field of political philosophy, world politics and international relations. The main feature of the hypothesis is the idea of quantum nature in social and political processes which appears to be the consequence of epistemological authority of current science. Alexander Wendt proposes several explanations for quantum foundations within the political and social processes including wide-known "agent-structure" dilemma. According to him, invisibility of social structures does not lead to denial of its existence. Firstly, social structures emerge from the space of possibilities and are not directly dependant on material factors. Secondly, invisibility and its acceptance in different areas are parts of science clarification in many areas including quantum physics. The article discuses how quantum physics principles such as particle-wave dualism, superposition and size absoluteness can be useful in social and political studies. This allows us to demonstrate the given hypothesi' potential in research field of social sciences with regard to international relations and world politics.

Design of coherent quantum observers for linear quantum systems

International Nuclear Information System (INIS)

Vuglar, Shanon L; Amini, Hadis

2014-01-01

Quantum versions of control problems are often more difficult than their classical counterparts because of the additional constraints imposed by quantum dynamics. For example, the quantum LQG and quantum H ∞ optimal control problems remain open. To make further progress, new, systematic and tractable methods need to be developed. This paper gives three algorithms for designing coherent quantum observers, i.e., quantum systems that are connected to a quantum plant and their outputs provide information about the internal state of the plant. Importantly, coherent quantum observers avoid measurements of the plant outputs. We compare our coherent quantum observers with a classical (measurement-based) observer by way of an example involving an optical cavity with thermal and vacuum noises as inputs. (paper)

Waiting time distribution revealing the internal spin dynamics in a double quantum dot

Science.gov (United States)

Ptaszyński, Krzysztof

2017-07-01

Waiting time distribution and the zero-frequency full counting statistics of unidirectional electron transport through a double quantum dot molecule attached to spin-polarized leads are analyzed using the quantum master equation. The waiting time distribution exhibits a nontrivial dependence on the value of the exchange coupling between the dots and the gradient of the applied magnetic field, which reveals the oscillations between the spin states of the molecule. The zero-frequency full counting statistics, on the other hand, is independent of the aforementioned quantities, thus giving no insight into the internal dynamics. The fact that the waiting time distribution and the zero-frequency full counting statistics give a nonequivalent information is associated with two factors. Firstly, it can be explained by the sensitivity to different timescales of the dynamics of the system. Secondly, it is associated with the presence of the correlation between subsequent waiting times, which makes the renewal theory, relating the full counting statistics and the waiting time distribution, no longer applicable. The study highlights the particular usefulness of the waiting time distribution for the analysis of the internal dynamics of mesoscopic systems.

ELiXIR—Solid-State Luminaire With Enhanced Light Extraction by Internal Reflection

Science.gov (United States)

Allen, Steven C.; Steckl, Andrew J.

2007-06-01

A phosphor-converted light-emitting diode (pcLED) luminaire featuring enhanced light extraction by internal reflection (ELiXIR) with efficacy of 60 lm/W producing 18 lumens of yellowish green light at 100 mA is presented. The luminaire consists of a commercial blue high power LED, a polymer hemispherical shell lens with interior phosphor coating, and planar aluminized reflector. High extraction efficiency of the phosphor-converted light is achieved by separating the phosphor from the LED and using internal reflection to steer the light away from lossy reflectors and the LED package and out of the device. At 10 and 500 mA, the luminaire produces 2.1 and 66 lumens with efficacies of 80 and 37 lm/W, respectively. Technological improvements over existing commercial LEDs, such as more efficient pcLED packages or, alternatively, higher efficiency green or yellow for color mixing, will be essential to achieving 150 200 lm/W solid-state lighting. Advances in both areas are demonstrated.

Intrinsic quantum computation

International Nuclear Information System (INIS)

Crutchfield, James P.; Wiesner, Karoline

2008-01-01

We introduce ways to measure information storage in quantum systems, using a recently introduced computation-theoretic model that accounts for measurement effects. The first, the quantum excess entropy, quantifies the shared information between a quantum process's past and its future. The second, the quantum transient information, determines the difficulty with which an observer comes to know the internal state of a quantum process through measurements. We contrast these with von Neumann entropy and quantum entropy rate and provide a closed-form expression for the latter for the class of deterministic quantum processes

Analysis of the external and internal quantum efficiency of multi-emitter, white organic light emitting diodes

Science.gov (United States)

Furno, Mauro; Rosenow, Thomas C.; Gather, Malte C.; Lüssem, Björn; Leo, Karl

2012-10-01

We report on a theoretical framework for the efficiency analysis of complex, multi-emitter organic light emitting diodes (OLEDs). The calculation approach makes use of electromagnetic modeling to quantify the overall OLED photon outcoupling efficiency and a phenomenological description for electrical and excitonic processes. From the comparison of optical modeling results and measurements of the total external quantum efficiency, we obtain reliable estimates of internal quantum yield. As application of the model, we analyze high-efficiency stacked white OLEDs and comment on the various efficiency loss channels present in the devices.

Quantum beats from the coherent interaction of hole states with surface state in near-surface quantum well

Energy Technology Data Exchange (ETDEWEB)

Khan, Salahuddin; Jayabalan, J., E-mail: jjaya@rrcat.gov.in; Chari, Rama; Pal, Suparna [Laser Physics Applications Section, Raja Ramanna Centre for Advanced Technology, Indore 452013 (India); Porwal, Sanjay; Sharma, Tarun Kumar; Oak, S. M. [Semiconductor Physics and Devices Lab., Solid State Laser Division, Raja Ramanna Centre for Advanced Technology, Indore 452013 (India)

2014-08-18

We report tunneling assisted beating of carriers in a near-surface single GaAsP/AlGaAs quantum well using transient reflectivity measurement. The observed damped oscillating signal has a period of 120 ± 6 fs which corresponds to the energy difference between lh1 and hh2 hole states in the quantum well. Comparing the transient reflectivity signal at different photon energies and with a buried quantum well sample, we show that the beating is caused by the coherent coupling between surface state and the hole states (lh1 and hh2) in the near-surface quantum well. The dependence of decay of coherence of these tunneling carriers on the excitation fluence is also reported. This observation on the coherent tunneling of carrier is important for future quantum device applications.

Quantum beats from the coherent interaction of hole states with surface state in near-surface quantum well

International Nuclear Information System (INIS)

Khan, Salahuddin; Jayabalan, J.; Chari, Rama; Pal, Suparna; Porwal, Sanjay; Sharma, Tarun Kumar; Oak, S. M.

2014-01-01

We report tunneling assisted beating of carriers in a near-surface single GaAsP/AlGaAs quantum well using transient reflectivity measurement. The observed damped oscillating signal has a period of 120 ± 6 fs which corresponds to the energy difference between lh1 and hh2 hole states in the quantum well. Comparing the transient reflectivity signal at different photon energies and with a buried quantum well sample, we show that the beating is caused by the coherent coupling between surface state and the hole states (lh1 and hh2) in the near-surface quantum well. The dependence of decay of coherence of these tunneling carriers on the excitation fluence is also reported. This observation on the coherent tunneling of carrier is important for future quantum device applications.

Effect of surface plasmon polaritons on the sensitivity of refractive index measurement using total internal reflection method

International Nuclear Information System (INIS)

Roshan Entezar, S.

2015-01-01

The phase difference between two p-polarized and s-polarized plane waves which are reflected under total internal reflection from the base of a prism with a thin metal coating is studied. Typically such a quantity can be used to measure the refractive index of a test material using the total internal reflection method. It is shown that due to the excitation of surface plasmon polaritons at the interface between the tested dielectric material and the thin metal layer, the p-polarized light experiences a large phase shift which enlarges the phase difference between the p-polarized and the s-polarized waves. As a result, the sensitivity of refractive index measurement increases and the error in determining the refractive index decreases. - Highlights: • Phase difference of totally internally reflected p and s polarized beams is studied. • Excitation of the surface wave increases the phase shift of the p-polarized light. • The sensitivity of refractive index measurement increases by using a coated prism. • The error in determining the refractive index decreases using the coated prism

Silicon Quantum Dots for Quantum Information Processing

Science.gov (United States)

2013-11-01

S. Lai, C. Tahan, A. Morello and A. S. Dzurak, Electron Spin lifetimes in multi-valley sil- icon quantum dots, S3NANO Winter School Few spin solid...lifetimes in multi-valley sil- icon quantum dots, International Workshop on Silicon Quantum Electronics, Grenoble, France, February 2012 (Poster). C...typically plunger gates), PMMA A5 is spun at 5000 rpm for 30 seconds, resulting in a 280 nm resist thickness. The resists are baked for 90 seconds at 180

Seismic reflection imaging, accounting for primary and multiple reflections

Science.gov (United States)

Wapenaar, Kees; van der Neut, Joost; Thorbecke, Jan; Broggini, Filippo; Slob, Evert; Snieder, Roel

2015-04-01

Imaging of seismic reflection data is usually based on the assumption that the seismic response consists of primary reflections only. Multiple reflections, i.e. waves that have reflected more than once, are treated as primaries and are imaged at wrong positions. There are two classes of multiple reflections, which we will call surface-related multiples and internal multiples. Surface-related multiples are those multiples that contain at least one reflection at the earth's surface, whereas internal multiples consist of waves that have reflected only at subsurface interfaces. Surface-related multiples are the strongest, but also relatively easy to deal with because the reflecting boundary (the earth's surface) is known. Internal multiples constitute a much more difficult problem for seismic imaging, because the positions and properties of the reflecting interfaces are not known. We are developing reflection imaging methodology which deals with internal multiples. Starting with the Marchenko equation for 1D inverse scattering problems, we derived 3D Marchenko-type equations, which relate reflection data at the surface to Green's functions between virtual sources anywhere in the subsurface and receivers at the surface. Based on these equations, we derived an iterative scheme by which these Green's functions can be retrieved from the reflection data at the surface. This iterative scheme requires an estimate of the direct wave of the Green's functions in a background medium. Note that this is precisely the same information that is also required by standard reflection imaging schemes. However, unlike in standard imaging, our iterative Marchenko scheme retrieves the multiple reflections of the Green's functions from the reflection data at the surface. For this, no knowledge of the positions and properties of the reflecting interfaces is required. Once the full Green's functions are retrieved, reflection imaging can be carried out by which the primaries and multiples are

Differential calculus on quantum spaces and quantum groups

International Nuclear Information System (INIS)

Zumino, B.

1992-01-01

A review of recent developments in the quantum differential calculus. The quantum group GL q (n) is treated by considering it as a particular quantum space. Functions on SL q (n) are defined as a subclass of functions on GL q (n). The case of SO q (n) is also briefly considered. These notes cover part of a lecture given at the XIX International Conference on Group Theoretic Methods in Physics, Salamanca, Spain 1992

Superresolution confocal technology for displacement measurements based on total internal reflection

International Nuclear Information System (INIS)

Kuang Cuifang; Hao Xiang; Wang Tingting; Liu Xu; Ali, M. Yakut

2010-01-01

In order to achieve a higher axial resolution for displacement measurement, a novel method is proposed based on total internal reflection filter and confocal microscope principle. A theoretical analysis of the basic measurement principles is presented. The analysis reveals that the proposed confocal detection scheme is effective in enhancing the resolution of nonlinearity of the reflectance curve greatly. In addition, a simple prototype system has been developed based on the theoretical analysis and a series of experiments have been performed under laboratory conditions to verify the system feasibility, accuracy, and stability. The experimental results demonstrate that the axial resolution in displacement measurements is better than 1 nm in a range of 200 nm which is threefold better than that can be achieved using the plane reflector.

Superresolution confocal technology for displacement measurements based on total internal reflection.

Science.gov (United States)

Kuang, Cuifang; Ali, M Yakut; Hao, Xiang; Wang, Tingting; Liu, Xu

2010-10-01

In order to achieve a higher axial resolution for displacement measurement, a novel method is proposed based on total internal reflection filter and confocal microscope principle. A theoretical analysis of the basic measurement principles is presented. The analysis reveals that the proposed confocal detection scheme is effective in enhancing the resolution of nonlinearity of the reflectance curve greatly. In addition, a simple prototype system has been developed based on the theoretical analysis and a series of experiments have been performed under laboratory conditions to verify the system feasibility, accuracy, and stability. The experimental results demonstrate that the axial resolution in displacement measurements is better than 1 nm in a range of 200 nm which is threefold better than that can be achieved using the plane reflector.

Toy models of crossed Andreev reflection

International Nuclear Information System (INIS)

Melin, R; Jirari, H; Peysson, S

2003-01-01

We propose toy models of crossed Andreev reflection in multiterminal hybrid structures containing out-of-equilibrium conductors. We apply the description to two possible experiments: (i) to a device containing a large quantum dot inserted in a crossed Andreev reflection circuit, and (ii) to a device containing an Aharonov-Bohm loop inserted in a crossed Andreev reflection circuit

Reflection Positive Stochastic Processes Indexed by Lie Groups

Science.gov (United States)

Jorgensen, Palle E. T.; Neeb, Karl-Hermann; Ólafsson, Gestur

2016-06-01

Reflection positivity originates from one of the Osterwalder-Schrader axioms for constructive quantum field theory. It serves as a bridge between euclidean and relativistic quantum field theory. In mathematics, more specifically, in representation theory, it is related to the Cartan duality of symmetric Lie groups (Lie groups with an involution) and results in a transformation of a unitary representation of a symmetric Lie group to a unitary representation of its Cartan dual. In this article we continue our investigation of representation theoretic aspects of reflection positivity by discussing reflection positive Markov processes indexed by Lie groups, measures on path spaces, and invariant gaussian measures in spaces of distribution vectors. This provides new constructions of reflection positive unitary representations.

Effect of barrier height and indium composition on the internal quantum efficiency of (In)AlGaN multiple quantum well structures

Energy Technology Data Exchange (ETDEWEB)

Ledentsov, Nikolay Jr.; Reich, Christoph; Mehnke, Frank; Kuhn, Christian; Wernicke, Tim; Kolbe, Tim; Lobo Ploch, Neysha; Rass, Jens [Institute of Solid State Physics, Technische Universitaet Berlin (Germany); Kueller, Viola [Ferdinand-Braun-Institut, Berlin (Germany); Kneissl, Michael [Institute of Solid State Physics, Technische Universitaet Berlin (Germany); Ferdinand-Braun-Institut, Berlin (Germany)

2013-07-01

We studied (In)AlGaN multiple quantum wells (MQWs) emitting in the UV-B spectral region with photoluminescence and electroluminescence spectroscopy. The internal quantum efficiency (IQE) was determined by temperature dependent measurements (5 K-300 K). The quantum confined Stark effect (QCSE) was investigated by studying the shift of the emission energy with increasing excitation power density. In the first series, Al{sub 0.27}Ga{sub 0.73}N MQWs with different Al{sub x}Ga{sub 1-x}N barriers (0.32

Total internal reflection fluorescence (TIRF) microscopy for real-time imaging of nanoparticle-cell plasma membrane interaction

DEFF Research Database (Denmark)

Parhamifar, Ladan; Moghimi, Seyed Moien

2012-01-01

Nanoparticulate systems are widely used for site-specific drug and gene delivery as well as for medical imaging. The mode of nanoparticle-cell interaction may have a significant effect on the pathway of nanoparticle internalization and subsequent intracellular trafficking. Total internal reflection...

Reflections on Quantum Data Hiding

Science.gov (United States)

Winter, Andreas

Quantum data hiding, originally invented as a limitation on local operations and classical communications (LOCC) in distinguishing globally orthogonal states, is actually a phenomenon arising generically in statistics whenever comparing a `strong' set of measurements (i.e., decision rules) with a `weak' one. The classical statistical analogue of this would be secret sharing, in which two perfectly distinguishable multi-partite hypotheses appear to be indistinguishable when accessing only a marginal. The quantum versions are richer in that for example LOCC allows for state tomography, so the states cannot be come perfectly indistinguishable but only nearly so, and hence the question is one of efficiency. I will discuss two concrete examples and associated sets of problems: 1. Gaussian operations and classical computation (GOCC): Not very surprisingly, GOCC cannot distinguish optimally even two coherent states of a single mode. Here we find states, each a mixture of multi-mode coherent states, which are almost perfectly distinguishable by suitable measurements, by when restricted to GOCC, i.e. linear optics and post-processing, the states appear almost identical. The construction is random and relies on coding arguments. Open questions include whether there one can give a constructive version of the argument, and whether for instance even thermal states can be used, or how efficient the hiding is. 2. Local operation and classical communication (LOCC): It is well-known that in a bipartite dxd-system, asymptotically logd bits can be hidden. Here we show for the first time, using the calculus of min-entropies, that this is asymptotically optimal. In fact, we get bounds on the data hiding capacity of any preparation system; these are however not always tight. While it is known that data hiding by separable states is possible (i.e. the state preparation can be done by LOCC), it is open whether the optimal information efficiency of (asymptotically) log d bits can be

Smooth and rough Proteus mirabilis lipopolysaccharides studied by total internal reflection ellipsometry

International Nuclear Information System (INIS)

Gleńska-Olender, J.; Dworecki, K.; Sęk, S.; Kwinkowski, M.; Kaca, W.

2013-01-01

Total internal reflection ellipsometry (TIRE), a label-free optical detection technique for studying interactions between biomolecules, was used to examine the adsorption of various forms of lipopolysaccharides (LPSs) isolated from Proteus mirabilis S1959, R110, and R45 strains on a gold surface. The thickness of the adsorbed layers was determined by TIRE, with the average values for S1959, R110, and R45 LPS layers being 78 ± 5, 39 ± 3, and 12 ± 2 nm, respectively. The thickness of LPS layers corresponds to the presence and length of O-specific parts in P. mirabilis LPS molecules. Atomic force microscopy was used as a complementary technique for visualizing lipopolysaccharides on the surface. Force measurements seem to confirm the data obtained from TIRE experiments. - Highlights: • Proteus mirabilis lipopolysaccharides were adsorbed on the gold surface. • Thickness of adsorbed layers was determined by total internal reflection ellipsometry. • Atomic force microscopy was used to visualize lipopolysaccharide build-up on gold surface. • Time is important in the evolution of biomolecular film thickness created on gold surface

Smooth and rough Proteus mirabilis lipopolysaccharides studied by total internal reflection ellipsometry

Energy Technology Data Exchange (ETDEWEB)

Gleńska-Olender, J., E-mail: joannaglenska@wp.pl [Institute of Biology, Jan Kochanowski University, 25-406 Kielce (Poland); Świętokrzyski Biobank, Regional Science and Technology Center, 26-060 Chęciny (Poland); Dworecki, K. [Institute of Physics, Jan Kochanowski University, 25-406 Kielce (Poland); Sęk, S. [Department of Chemistry, University of Warsaw, 02-093 Warsaw (Poland); Kwinkowski, M.; Kaca, W. [Institute of Biology, Jan Kochanowski University, 25-406 Kielce (Poland)

2013-12-02

Total internal reflection ellipsometry (TIRE), a label-free optical detection technique for studying interactions between biomolecules, was used to examine the adsorption of various forms of lipopolysaccharides (LPSs) isolated from Proteus mirabilis S1959, R110, and R45 strains on a gold surface. The thickness of the adsorbed layers was determined by TIRE, with the average values for S1959, R110, and R45 LPS layers being 78 ± 5, 39 ± 3, and 12 ± 2 nm, respectively. The thickness of LPS layers corresponds to the presence and length of O-specific parts in P. mirabilis LPS molecules. Atomic force microscopy was used as a complementary technique for visualizing lipopolysaccharides on the surface. Force measurements seem to confirm the data obtained from TIRE experiments. - Highlights: • Proteus mirabilis lipopolysaccharides were adsorbed on the gold surface. • Thickness of adsorbed layers was determined by total internal reflection ellipsometry. • Atomic force microscopy was used to visualize lipopolysaccharide build-up on gold surface. • Time is important in the evolution of biomolecular film thickness created on gold surface.

Preface [EmQM15: 3. international symposium on emergent quantum mechanics

International Nuclear Information System (INIS)

2016-01-01

These proceedings comprise the invited lectures of the third international symposium on Emergent Quantum Mechanics (EmQM15), which was held at the Vienna University of Technology in Vienna, Austria, 23-25 October 2015. The symposium convened at the Festsaal and the adjacent Boeckl-Saal of the Technical University, and was devoted to the open exploration of the quantum state as a reality. The resurgence of interest in ontological quantum theory, including both deterministic and indeterministic approaches, challenges long held assumptions and focuses on the following questions: Is the world local or nonlocal? What is the nature of quantum nonlocality? If nonlocal, i.e., superluminal, influences exist then why can't they be used for superluminal signaling and communication? How is the role of the scientific observer/agent to be accounted for in realistic approaches to quantum theory? How could recent developments in the field of space-time as an emergent phenomenon advance new insight at this research frontier? What new experiments might contribute to new understanding? These and related questions were addressed in the context also of a possible deeper level theory for quantum mechanics that interconnects three fields of knowledge: emergence, the quantum, and information. Could there appear a revised image of physical reality from recognizing new links between emergence, the quantum, and information? The symposium provided a forum for considering (i) current theoretical and conceptual obstacles which need to be overcome as well as (ii) promising developments and research opportunities on the way towards realistic quantum mechanics. Contributions were invited that present current advances in both standard as well as unconventional approaches. The EmQM15 symposium was co-organized by Gerhard Grössing (Austrian Institute for Nonlinear Studies (AINS), Vienna), and by Jan Walleczek (Fetzer Franklin Fund, USA, and Phenoscience Laboratories, Berlin). After two

DIRC Dreams Redux: Research Directions for the Next Generation of Internally Reflected Imaging Counters

Energy Technology Data Exchange (ETDEWEB)

Ratcliff, Blair N

2001-09-18

Some general conceptual design features of total internally reflecting, imaging Cherenkov counters (DIRCs) are described. Limits of the DIRC approach to particle identification and a few features of alternative DIRC designs are briefly explored.

Sine-Gordon quantum field theory on the half-line with quantum boundary degrees of freedom

International Nuclear Information System (INIS)

Baseilhac, P.; Koizumi, K.

2003-01-01

The sine-Gordon model on the half-line with a dynamical boundary introduced by Delius and one of the authors is considered at quantum level. Classical boundary conditions associated with classical integrability are shown to be preserved at quantum level too. Non-local conserved charges are constructed explicitly in terms of the field and boundary operators. We solve the intertwining equation associated with a certain coideal subalgebra of U q (sl 2 -bar) generated by these non-local charges. The corresponding solution is shown to satisfy quantum boundary Yang-Baxter equations. Up to an exact relation between the quantization length of the boundary quantum mechanical system and the sine-Gordon coupling constant, we conjecture the soliton/antisoliton reflection matrix and bound states reflection matrices. The structure of the boundary state is then considered, and shown to be divided in two sectors. Also, depending on the sine-Gordon coupling constant a finite set of boundary bound states are identified. Taking the analytic continuation of the coupling, the corresponding boundary sinh-Gordon model is briefly discussed. In particular, the particle reflection factor enjoys weak-strong coupling duality

Improving Collaborative Planning and Reflection Practices at International Baccalaureate Diploma Schools in Amman

Science.gov (United States)

Saa'd AlDin, Kawther

2014-01-01

In 2010, the International Baccalaureate (IB) Organization mandated that all its schools, including Diploma (DP) schools, adhere to the collaborative planning and reflection requirements, which emphasized the importance of integrating its theory of knowledge (TOK) core component into all disciplines. Many schools officials and educations in Amman…

Do people ruminate because they haven't digested their goals? The relations of rumination and reflection to goal internalization and ambivalence

DEFF Research Database (Denmark)

Thomsen, Dorthe Kirkegaard; Tønnesvang, Jan; Schnieber, Anette

2011-01-01

In three studies it was investigated whether rumination was related to less internalized self-regulation and goals and whether reflection was related to more internalized self-regulation and goals. In all studies students completed questionnaires measuring rumination, reflection, and internalizat...

Microplate-compatible total internal reflection fluorescence microscopy for receptor pharmacology

Science.gov (United States)

Chen, Minghan; Zaytseva, Natalya V.; Wu, Qi; Li, Min; Fang, Ye

2013-05-01

We report the use of total internal reflection fluorescence (TIRF) microscopy for analyzing receptor pharmacology and the development of a microplate-compatible TIRF imaging system. Using stably expressed green fluorescence protein tagged β2-adrenergic receptor as the reporter, we found that the activation of different receptors results in distinct kinetic signatures of the TIRF intensity of cells. These TIRF signatures closely resemble the characteristics of their respective label-free dynamic mass redistribution signals in the same cells. This suggests that TIRF in microplate can be used for profiling and screening drugs.

DIRC, the internally reflecting ring imaging Cherenkov detector for BABAR

International Nuclear Information System (INIS)

Adam, I.; Aston, D.

1997-11-01

The DIRC is a new type of Cherenkov imaging device that will be used for the first time in the BABAR detector at the asymmetric B-factory, PEP-II. It is based on total internal reflection and uses long, rectangular bars made from synthetic fused silica as Cherenkov radiator and light guide. The principles of the DIRC ring imaging Cherenkov technique are explained and results from the prototype program are presented. Its choice for the BABAR detector particle identification system is motivated, followed by a discussion of the quartz radiator properties and the detector design

Creating Comic Books in Nigeria: International Reflections on Literacy, Creativity, and Student Engagement

Science.gov (United States)

Bitz, Michael; Emejulu, Obiajulu

2016-01-01

This article is an international reflection on literacy, creativity, and student engagement. The authors collaborated to help Nigerian youths and their teachers develop, design, and share original comic books. By leveraging student engagement for literacy learning, the authors highlighted the crucial role of creativity in the classroom. The…

PREFACE: 6th International Workshop on Pseudo-Hermitian Hamiltonians in Quantum Physics

Science.gov (United States)

Fring, Andreas; Jones, Hugh; Znojil, Miloslav

2008-06-01

Attempts to understand the quantum mechanics of non-Hermitian Hamiltonian systems can be traced back to the early days, one example being Heisenberg's endeavour to formulate a consistent model involving an indefinite metric. Over the years non-Hermitian Hamiltonians whose spectra were believed to be real have appeared from time to time in the literature, for instance in the study of strong interactions at high energies via Regge models, in condensed matter physics in the context of the XXZ-spin chain, in interacting boson models in nuclear physics, in integrable quantum field theories as Toda field theories with complex coupling constants, and also very recently in a field theoretical scenario in the quantization procedure of strings on an AdS5 x S5 background. Concrete experimental realizations of these types of systems in the form of optical lattices have been proposed in 2007. In the area of mathematical physics similar non-systematic results appeared sporadically over the years. However, intensive and more systematic investigation of these types of non- Hermitian Hamiltonians with real eigenvalue spectra only began about ten years ago, when the surprising discovery was made that a large class of one-particle systems perturbed by a simple non-Hermitian potential term possesses a real energy spectrum. Since then regular international workshops devoted to this theme have taken place. This special issue is centred around the 6th International Workshop on Pseudo-Hermitian Hamiltonians in Quantum Physics held in July 2007 at City University London. All the contributions contain significant new results or alternatively provide a survey of the state of the art of the subject or a critical assessment of the present understanding of the topic and a discussion of open problems. Original contributions from non-participants were also invited. Meanwhile many interesting results have been obtained and consensus has been reached on various central conceptual issues in the

Total Internal Reflection Fluorescence Microscopy Imaging-Guided Confocal Single-Molecule Fluorescence Spectroscopy

OpenAIRE

Zheng, Desheng; Kaldaras, Leonora; Lu, H. Peter

2013-01-01

We have developed an integrated spectroscopy system combining total internal reflection fluorescence microscopy imaging with confocal single-molecule fluorescence spectroscopy for two-dimensional interfaces. This spectroscopy approach is capable of both multiple molecules simultaneously sampling and in situ confocal fluorescence dynamics analyses of individual molecules of interest. We have demonstrated the calibration with fluorescent microspheres, and carried out single-molecule spectroscop...

Reflection-type hologram for atoms

International Nuclear Information System (INIS)

Shimizu, Fujio; Fujita, Jun-ichi

2002-01-01

A cold metastable neon atomic beam was manipulated with a reflective amplitude hologram that was encoded on a silicon surface. A black-and-white pattern of atoms was reconstructed on a microchannel plate detector. The hologram used the enhanced quantum reflection developed by authors and was made of a two-dimensional array of rectangular low and high reflective cells. The surface of the high reflective cell was composed of regularly spaced roof-shaped ridges, while the low reflective cell was simply a flat surface. The hologram was the first demonstration of reflective atom-optical elements that used universal interaction between a neutral atom and solid surface

High quantum efficiency annular backside silicon photodiodes for reflectance pulse oximetry in wearable wireless body sensors

International Nuclear Information System (INIS)

Duun, Sune; Haahr, Rasmus G; Hansen, Ole; Birkelund, Karen; Thomsen, Erik V

2010-01-01

The development of annular photodiodes for use in a reflectance pulse oximetry sensor is presented. Wearable and wireless body sensor systems for long-term monitoring require sensors that minimize power consumption. We have fabricated large area 2D ring-shaped silicon photodiodes optimized for minimizing the optical power needed in reflectance pulse oximetry. To simplify packaging, backside photodiodes are made which are compatible with assembly using surface mounting technology without pre-packaging. Quantum efficiencies up to 95% and area-specific noise equivalent powers down to 30 fW Hz -1/2 cm -1 are achieved. The photodiodes are incorporated into a wireless pulse oximetry sensor system embedded in an adhesive patch presented elsewhere as 'The Electronic Patch'. The annular photodiodes are fabricated using two masked diffusions of first boron and subsequently phosphor. The surface is passivated with a layer of silicon nitride also serving as an optical filter. As the final process, after metallization, a hole in the center of the photodiode is etched using deep reactive ion etch.

Imaging Hybrid Photon Detectors with a Reflective Photocathode

CERN Document Server

Ferenc, D

2000-01-01

Modern epitaxially grown photocathodes, like GaAsP, bring a very high inherent quantum efficiency, but are rather expensive due to the complicated manufacturing and mounting process. We argue that such photocathodes could be used in reflective mode, in order to avoid the risky and expensive removal of the epitaxial growth substrate. Besides that the quantum efficiency should increase considerably. In this paper we present results of the development of large imaging Hybrid Photon Detectors (HPDs), particularly designed for such reflective photocathodes.

33rd International Conference on the Physics of Semiconductors

International Nuclear Information System (INIS)

2017-01-01

Preface to the Proceedings of the 33rd International Conference on the Physics of Semiconductors, Beijing, 2016 Shaoyun Huang 1 , Yingjie Xing 1 , Yang Ji 2 , Dapeng Yu 3 , and Hongqi Xu 1 1 Beijing Key Laboratory of Quantum Devices, Key Laboratory for the Physics and Chemistry of Nanodevices and Department of Electronics, Peking University, Beijing 100871, China 2 SKLSM, Institute of Semiconductors, Chinese Academy of Sciences, Beijing 100083, China 3 State Key Laboratory for Mesoscopic Physics, Department of Physics, Peking University, Beijing 100871, China From July 31 st to August 5 th , 2016, the 33rd International Conference on the Physics of Semiconductors (ICPS 2016) was held in Beijing, China, with a great success. The International Conference on the Physics of Semiconductors began in the 1950’s and is a premier biennial meeting for reporting all aspects of semiconductor physics including electronic, structural, optical, magnetic and transport properties. Reflecting the state of the art developments in semiconductor physics, ICPS 2016 served as an international forum for scholars, researchers, and specialists across the globe to discuss future research directions and technological advancements. The main topics of ICPS 2016 included: • Material growth, structural properties and characterization, phonons • Wide-bandgap semiconductors • Narrow-bandgap semiconductors • Carbon: nanotubes and graphene • 2D Materials beyond graphene • Organic semiconductors • Topological states of matter, topological Insulators and Weyl semimetals • Transport in heterostructures • Quantum Hall effects • Spintronics and spin phenomena • Electron devices and applications • Optical properties, optoelectronics, solar cells • Quantum optics, nanophotonics • Quantum information • Other topics in semiconductor physics and devices • Special topic: Majorana fermions in solid state (paper)

Extremely high absolute internal quantum efficiency of photoluminescence in co-doped GaN:Zn,Si

Science.gov (United States)

Reshchikov, M. A.; Willyard, A. G.; Behrends, A.; Bakin, A.; Waag, A.

2011-10-01

We report on the fabrication of GaN co-doped with silicon and zinc by metalorganic vapor phase epitaxy and a detailed study of photoluminescence in this material. We observe an exceptionally high absolute internal quantum efficiency of blue photoluminescence in GaN:Zn,Si. The value of 0.93±0.04 has been obtained from several approaches based on rate equations.

Symbolic Uses of Evaluation in the International Aid Sector: Arguments for Critical Reflection

Science.gov (United States)

McNulty, James

2012-01-01

Significant progress has been made in recent years to improve the quality of the evaluation of international aid. Increasingly, this includes an interest in improving the way evaluations are used to improve policies and programmes. However, the prevalence of symbolic use--a phenomenon that is often mentioned but rarely studied--reflects an…

Specific Features of Reflection of Information Regarding Lease Operations in the National and International Standards

Directory of Open Access Journals (Sweden)

Nikolenko Nataliya V.

2013-12-01

Full Text Available The article identifies the degree of correspondence of the national Provisions (Standard of Business Accounting (PSBA Lease with the international standard and provides recommendations with respect to their closing up. On the results of the study the author provides specific features of international and national standards – the existing IFRS 17 Lease and national PSBA 14 Lease by the following components: definition of lease, its classification and reflection in accounting. Also the text of PSBA 31 Financial Expenditures is supplemented with provisions on capitalisation of financial expenditures prospectively, which would allow avoidance of correction of the balance of the retained income and provision of comparative information for previous periods. The article provides an algorithm of division of lease for accounting purposes on the basis of international standards. Its use would ensure correctness of reflection of lease operations in accounting and would serve as a basis for development of methodical provisions with respect to accounting. By the result of the study the author forms definition of the qualification asset as an asset which requires considerable time for its creation, preparation for target use, sales or acquisition of the ownership right. Capitalisation of such expenditures would allow non-reduction of the accounting income and also would provide a possibility to reflect financial expenditures in accordance with their economic essence.

Beyond ‘Innocents Abroad’: Reflecting on Sustainability Issues During International Study Trips

Directory of Open Access Journals (Sweden)

Anne H. Reilly

2016-12-01

Full Text Available With ecosystems and populations in many regions threatened by rapid development, sustainability is a critical component for businesses in mature markets and emerging economies alike. The International Association of Jesuit Business Schools notes that global sustainability involves a broad set of interconnected issues ranging from environmental preservation to social justice to desirable production and consumption patterns. Jesuit business schools are uniquely positioned to address sustainability issues with their focus on teaching managerial content in tandem with corporate social responsibility. Further, the Ignatian Pedagogy Paradigm of experience, reflection, and action would suggest that business students may benefit from reflective observation in support of learning about sustainability. In this paper, we examine the international study trip as an opportunity for students to learn about sustainability, with results suggesting that student understanding about the broad sustainability domain may be enhanced through the study abroad experience. We discuss how two classes of primarily American MBA students traveling to emerging markets (one class to Santiago, Chile and one class to Johannesburg, South Africa were able to connect local business practices with economic and social as well as environmental sustainability issues, enhancing both student engagement and learning outcomes. Further, these students’ sustainability experiences while in an unfamiliar environment provided the opportunity to apply the potentially transformative experience, reflection, and action components of the Ignatian Pedagogy Paradigm. Compared to similar graduate business students enrolled in regular classes, we argue that these students discerned deeper connections with the economic, social, and environmental issues of sustainability.

Quantum Worlds

Directory of Open Access Journals (Sweden)

Jeffrey A. Barrett

2016-09-01

Full Text Available http://dx.doi.org/10.5007/1808-1711.2016v20n1p45 Because of the conceptual difficulties it faces, quantum mechanics provides a salient example of how alternative metaphysical commitments may clarify our understanding of a physical theory and the explanations it provides. Here we will consider how postulating alternative quantum worlds in the context of Hugh Everett III’s pure wave mechanics may serve to explain determinate measurement records and the standard quantum statistics. We will focus on the properties of such worlds, then briefly consider other metaphysical options available for interpreting pure wave mechanics. These reflections will serve to illustrate both the nature and the limits of naturalized metaphysics.

Obtaining local reflectivity at two-way travel time by filtering acoustic reflection data

NARCIS (Netherlands)

Slob, E.C.; Zhang, L.; Wapenaar, C.P.A.; Mihai Popovici, A.; Fomel, S.

2017-01-01

A modified implementation of Marchenko redatuming leads to a filter that removes internal multiples from reflection data. It produces local reflectivity at two-way travel time. The method creates new primary reflections resulting from emitted events that eliminate internal multiples. We call these

The second quantum revolution

International Nuclear Information System (INIS)

Larousserie, D.

2008-01-01

The development of quantum mechanics has now reached such a level that we can consider its promising applications in various fields as a looming second quantum revolution. The classical computer that relies on logical gates is out, now quantum properties open the way to new machines that will simulate nature's events exactly, this will be possible because both nature and the machine will be quantum. The machine will mimic nature and some problems like high temperature superconductivity that resist any modelling will be reproduced easily and then put within hand reach to be understood. Another application is quantum imaging based on the property of quantum entanglement. In the case of 2 entangled particle beams, the measurement of the properties of one beam fixes the values on the other beam. In other words, in case of entangled fluctuations, the measurement of the fluctuations on one beam fixes the value of the fluctuations on the other beam and by subtracting them on the second beam, we get a more accurate result: we have made the background noise disappear. Another application, that has already entered our daily life, is the generation of random numbers in a simple way: quantum mechanics states that a photon has a probability of 50 % to be reflected by a semi-reflecting plate and be detected, this experimental setting is a perfect toss play. The most known application of quantum mechanics is cryptography to assure the security of information transfer. Various systems have proved its efficiency but this technology is hampered by the damping of the signal in optical fibers and is reliable on distances shorter than a few hundreds kilometers. (A.C.)

Determination of continuous complex refractive index dispersion of biotissue based on internal reflection

Science.gov (United States)

Deng, Zhichao; Wang, Jin; Ye, Qing; Sun, Tengqian; Zhou, Wenyuan; Mei, Jianchun; Zhang, Chunping; Tian, Jianguo

2016-01-01

The complex refractive index dispersion (CRID), which contains the information on the refractive index dispersion and extinction coefficient spectra, is an important optical parameter of biotissue. However, it is hard to perform the CRID measurement on biotissues due to their high scattering property. Continuous CRID measurement based on internal reflection (CCRIDM-IR) is introduced. By using a lab-made apparatus, internal reflectance spectra of biotissue samples at multiple incident angles were detected, from which the continuous CRIDs were calculated based on the Fresnel formula. Results showed that in 400- to 750-nm range, hemoglobin solution has complicated dispersion and extinction coefficient spectra, while other biotissues have normal dispersion properties, and their extinction coefficients do not vary much with different wavelengths. The normal dispersion can be accurately described by several coefficients of dispersion equations (Cauchy equation, Cornu equation, and Conrady equation). To our knowledge, this is the first time that the continuous CRID of scattering biotissue over a continuous spectral region is measured, and we hereby have proven that CCRIDM-IR is a good method for continuous CRID research of biotissue.

Growth of a delta-doped silicon layer by molecular beam epitaxy on a charge-coupled device for reflection-limited ultraviolet quantum efficiency

Science.gov (United States)

Hoenk, Michael E.; Grunthaner, Paula J.; Grunthaner, Frank J.; Terhune, R. W.; Fattahi, Masoud; Tseng, Hsin-Fu

1992-01-01

Low-temperature silicon molecular beam epitaxy is used to grow a delta-doped silicon layer on a fully processed charge-coupled device (CCD). The measured quantum efficiency of the delta-doped backside-thinned CCD is in agreement with the reflection limit for light incident on the back surface in the spectral range of 260-600 nm. The 2.5 nm silicon layer, grown at 450 C, contained a boron delta-layer with surface density of about 2 x 10 exp 14/sq cm. Passivation of the surface was done by steam oxidation of a nominally undoped 1.5 nm Si cap layer. The UV quantum efficiency was found to be uniform and stable with respect to thermal cycling and illumination conditions.

Dynamics of quantum discord in a quantum critical environment

International Nuclear Information System (INIS)

Xi Zhengjun; Li Yongming; Lu Xiaoming; Sun Zhe

2011-01-01

We study the dynamics of quantum discord (QD) of two qubits independently coupled to an Ising spin chain in a transverse field, which exhibits a quantum phase transition. For this model, we drive the corresponding Kraus operators, obtain the analytic results of QD and compare the dynamics of QD with the dynamics of relative entropy of entanglement nearby the critical point. It is shown that the impact of the quantum criticality environment on QD can be concentrated in a very narrow region nearby the critical point, so it supplies an efficient way to detect the critical points. In the vicinity of the critical point, the evolution of QD is shown to be more complicated than that of entanglement. Furthermore, we find that separable states can also be used to reflect the quantum criticality of the environment.

Quantum Variational Calculus

OpenAIRE

Malinowska , Agnieszka B.; Torres , Delfim

2014-01-01

International audience; Introduces readers to the treatment of the calculus of variations with q-differences and Hahn difference operators Provides the reader with the first extended treatment of quantum variational calculus Shows how the techniques described can be applied to economic models as well as other mathematical systems This Brief puts together two subjects, quantum and variational calculi by considering variational problems involving Hahn quantum operators. The main advantage of it...

From Einstein-Podolsky-Rosen paradox to quantum nonlocality: experimental investigation of quantum correlations

Science.gov (United States)

Xu, Jin-Shi; Li, Chuan-Feng; Guo, Guang-Can

2016-11-01

In 1935, Einstein, Podolsky and Rosen published their influential paper proposing a now famous paradox (the EPR paradox) that threw doubt on the completeness of quantum mechanics. Two fundamental concepts: entanglement and steering, were given in the response to the EPR paper by Schrodinger, which both reflect the nonlocal nature of quantum mechanics. In 1964, John Bell obtained an experimentally testable inequality, in which its violation contradicts the prediction of local hidden variable models and agrees with that of quantum mechanics. Since then, great efforts have been made to experimentally investigate the nonlocal feature of quantum mechanics and many distinguished quantum properties were observed. In this work, along with the discussion of the development of quantum nonlocality, we would focus on our recent experimental efforts in investigating quantum correlations and their applications with optical systems, including the study of entanglement-assisted entropic uncertainty principle, Einstein-Podolsky-Rosen steering and the dynamics of quantum correlations.

PREFACE: The 5th International Symposium in Quantum Theory and Symmetries (QTS5)

Science.gov (United States)

Arratia, O.; Calzada, J. A.; Gómez-Cubillo, F.; Negro, J.; del Olmo, M. A.

2008-02-01

This volume of Journal of Physics: Conference Series contains the Proceedings of the 5th International Symposium in Quantum Theory and Symmetries (QTS5), held in Valladolid, Spain, 22-28 July 2007. This is the fifth of a series of conferences previously held in Goslar (Germany) 1999, QTS1; Cracow (Poland) 2001, QTS2; Cincinnati (USA) 2003, QTS3, and Varna (Bulgaria) 2005, QTS4. The QTS5 symposium gathered 181 participants from 39 countries working in different fields on Theoretical Physics. The spirit of the QTS conference series is to join researchers in a wide variety of topics in Theoretical Physics, as a way to make accessible recent results and the new lines of different fields. The QTS5 conference offered the following list of topics: Symmetries in String Theory, Quantum Gravity and related Symmetries in Quantum Field Theories, Conformal and Related Field Theories, Lattice and Noncommutative Theories, Gauge Theories Quantum Computing, Information and Control Foundations of Quantum Theory Quantum Optics, Coherent States, Wigner Functions Dynamical and Integrable Systems Symmetries in Condensed Matter and Statistical Physics Symmetries in Particle Physics, Nuclear, Atomic and Molecular Nonlinear Quantum Mechanics Time Asymmetric Quantum Mechanics SUSY Quantum Mechanics, PT symmetries and pseudo-Hamiltonians Mathematical Methods for Symmetries and Quantum Theories Symmetries in Chemistry Biology and other Sciences Papers accepted for publication in the present issue are based on the contributions from the participants in the QTS5 conference after a peer review process. In addition, a special issue of Journal Physics A: Mathematical and Theoretical contains contributions from plenary speakers, some participants as well as contributions from other authors whose works fit into the topics of the conference. The organization of the conference had the following pattern. In the morning there were five plenary or general sessions for all the participants, which aimed to

Signatures of bifurcation on quantum correlations: Case of the quantum kicked top.

Science.gov (United States)

Bhosale, Udaysinh T; Santhanam, M S

2017-01-01

Quantum correlations reflect the quantumness of a system and are useful resources for quantum information and computational processes. Measures of quantum correlations do not have a classical analog and yet are influenced by classical dynamics. In this work, by modeling the quantum kicked top as a multiqubit system, the effect of classical bifurcations on measures of quantum correlations such as the quantum discord, geometric discord, and Meyer and Wallach Q measure is studied. The quantum correlation measures change rapidly in the vicinity of a classical bifurcation point. If the classical system is largely chaotic, time averages of the correlation measures are in good agreement with the values obtained by considering the appropriate random matrix ensembles. The quantum correlations scale with the total spin of the system, representing its semiclassical limit. In the vicinity of trivial fixed points of the kicked top, the scaling function decays as a power law. In the chaotic limit, for large total spin, quantum correlations saturate to a constant, which we obtain analytically, based on random matrix theory, for the Q measure. We also suggest that it can have experimental consequences.

Preparation of reflective CsI photocathodes with reproducible high quantum efficiency

Science.gov (United States)

Maier-Komor, P.; Bauer, B. B.; Friese, J.; Gernhäuser, R.; Kienle, P.; Körner, H. J.; Montermann, G.; Zeitelhack, K.

1995-02-01

CsI as a solid UV-photocathode material has many promising applications in fast gaseous photon detectors. They are proposed in large area Ring Imaging CHerenkov (RICH) devices in forthcoming experiments at various high-energy particle accelerators. A high photon-to-electron conversion efficiency is a basic requirement for the successful operation of these devices. High reproducible quantum efficiencies could be achieved with CsI layers prepared by electron beam evaporation from a water-cooled copper crucible. CsI films were deposited in the thickness range of 30 to 500 μg/cm 2. Absorption coefficients and quantum efficiencies were measured in the wavelength region of 150 nm to 250 nm. The influence of various evaporation parameters on the quantum efficiency were investigated.

Preparation of reflective CsI photocathodes with reproducible high quantum efficiency

Energy Technology Data Exchange (ETDEWEB)

Maier-Komor, P. [Technische Univ. Muenchen, Garching (Germany). Physik-Department; Bauer, B.B. [Technische Univ. Muenchen, Garching (Germany). Physik-Department; Friese, J. [Technische Univ. Muenchen, Garching (Germany). Physik-Department; Gernhaeuser, R. [Technische Univ. Muenchen, Garching (Germany). Physik-Department; Kienle, P. [Technische Univ. Muenchen, Garching (Germany). Physik-Department; Koerner, H.J. [Technische Univ. Muenchen, Garching (Germany). Physik-Department; Montermann, G. [Technische Univ. Muenchen, Garching (Germany). Physik-Department; Zeitelhack, K. [Technische Univ. Muenchen, Garching (Germany). Physik-Department

1995-08-01

CsI as a solid UV-photocathode material has many promising applications in fast gaseous photon detectors. They are proposed in large area Ring Imaging CHerenkov (RICH) devices in forthcoming experiments at various high-energy particle accelerators. A high photon-to-electron conversion efficiency is a basic requirement for the successful operation of these devices. High reproducible quantum efficiencies could be achieved with CsI layers prepared by electron beam evaporation from a water-cooled copper crucible. CsI films were deposited in the thickness range of 30 to 500 {mu}g/cm{sup 2}. Absorption coefficients and quantum efficiencies were measured in the wavelength region of 150 nm to 250 nm. The influence of various evaporation parameters on the quantum efficiency were investigated. (orig.).

Generalized quantum groups

International Nuclear Information System (INIS)

Leivo, H.P.

1992-01-01

The algebraic approach to quantum groups is generalized to include what may be called an anyonic symmetry, reflecting the appearance of phases more general than ±1 under transposition. (author). 6 refs

Quantum trajectories in complex space: One-dimensional stationary scattering problems

International Nuclear Information System (INIS)

Chou, C.-C.; Wyatt, Robert E.

2008-01-01

One-dimensional time-independent scattering problems are investigated in the framework of the quantum Hamilton-Jacobi formalism. The equation for the local approximate quantum trajectories near the stagnation point of the quantum momentum function is derived, and the first derivative of the quantum momentum function is related to the local structure of quantum trajectories. Exact complex quantum trajectories are determined for two examples by numerically integrating the equations of motion. For the soft potential step, some particles penetrate into the nonclassical region, and then turn back to the reflection region. For the barrier scattering problem, quantum trajectories may spiral into the attractors or from the repellers in the barrier region. Although the classical potentials extended to complex space show different pole structures for each problem, the quantum potentials present the same second-order pole structure in the reflection region. This paper not only analyzes complex quantum trajectories and the total potentials for these examples but also demonstrates general properties and similar structures of the complex quantum trajectories and the quantum potentials for one-dimensional time-independent scattering problems

All-optical microscope autofocus based on an electrically tunable lens and a totally internally reflected IR laser.

Science.gov (United States)

Bathe-Peters, M; Annibale, P; Lohse, M J

2018-02-05

Microscopic imaging at high spatial-temporal resolution over long time scales (minutes to hours) requires rapid and precise stabilization of the microscope focus. Conventional and commercial autofocus systems are largely based on piezoelectric stages or mechanical objective actuators. Objective to sample distance is either measured by image analysis approaches or by hardware modules measuring the intensity of reflected infrared light. We propose here a truly all-optical microscope autofocus taking advantage of an electrically tunable lens and a totally internally reflected infrared probe beam. We implement a feedback-loop based on the lateral position of a totally internally reflected infrared laser on a quadrant photodetector, as an indicator of the relative defocus. We show here how to treat the combined contributions due to mechanical defocus and deformation of the tunable lens. As a result, the sample can be kept in focus without any mechanical movement, at rates up to hundreds of Hertz. The device requires only reflective optics and can be implemented at a fraction of the cost required for a comparable piezo-based actuator.

Internal force corrections with machine learning for quantum mechanics/molecular mechanics simulations.

Science.gov (United States)

Wu, Jingheng; Shen, Lin; Yang, Weitao

2017-10-28

Ab initio quantum mechanics/molecular mechanics (QM/MM) molecular dynamics simulation is a useful tool to calculate thermodynamic properties such as potential of mean force for chemical reactions but intensely time consuming. In this paper, we developed a new method using the internal force correction for low-level semiempirical QM/MM molecular dynamics samplings with a predefined reaction coordinate. As a correction term, the internal force was predicted with a machine learning scheme, which provides a sophisticated force field, and added to the atomic forces on the reaction coordinate related atoms at each integration step. We applied this method to two reactions in aqueous solution and reproduced potentials of mean force at the ab initio QM/MM level. The saving in computational cost is about 2 orders of magnitude. The present work reveals great potentials for machine learning in QM/MM simulations to study complex chemical processes.

Quantum memory Quantum memory

Science.gov (United States)

Le Gouët, Jean-Louis; Moiseev, Sergey

2012-06-01

quest for higher efficiency, better fidelity, broader bandwidth, multimode capacity and longer storage lifetime is pursued in all those approaches, as shown in this special issue. The improvement of quantum memory operation specifically requires in-depth study and control of numerous physical processes leading to atomic decoherence. The present issue reflects the development of rare earth ion doped matrices offering long lifetime superposition states, either as bulk crystals or as optical waveguides. The need for quantum sources and high efficiency detectors at the single photon level is also illustrated. Several papers address the networking of quantum memories either in long-haul cryptography or in the prospect of quantum processing. In this context, much attention has been paid recently to interfacing quantum light with superconducting qubits and with nitrogen-vacancy centers in diamond. Finally, the quantum interfacing of light with matter raises questions on entanglement. The last two papers are devoted to the generation of entanglement by dissipative processes. It is shown that long lifetime entanglement may be built in this way. We hope this special issue will help readers to become familiar with the exciting field of ensemble-based quantum memories and will stimulate them to bring deeper insights and new ideas to this area.

REFLECTIONS ON PRODUCTION INTERNALIZATION AND ITS INTERNATIONAL TRADE IMPLICATIONS

Directory of Open Access Journals (Sweden)

CLIPA RALUCA IRINA

2014-06-01

Full Text Available Vertically-integrated multinational companies place the different stages of production and marketing chain in different countries, looking for advantages such as low production costs, lower taxes, abundant resources and so on, while benefiting from the advantages of economies of scale, control of supplies or outlets. In fact, this vertical integration of multinational companies has led to the expansion of intra-firm trade and "internalized" operations, thus creating their own markets for the vertically-integrated production. Internationally active firms operate in a way that replaces the different functions of an open market with internal transactions, i.e. intra-firm transactions, whenever internal transaction costs are lower than the open-market ones. The direct consequence over international trade is the increase of intra-firm share of trade flows to one third of world trade, those companies making a suppression of international market segments that act in favour of an internal market. The creation of a multinational market and the enhancement of intra-firm trade have profound quantitative and qualitative implications on the composition, geographic orientation and dynamics of international trade. This paper deals with the issue of production internalization, with an overview of the main contributions made to the theory of internalization, while tackling its relative dimension. However, we intend to highlight the implications of this phenomenon on international trade. The work methodology falls within the range of qualitative approaches: logical argumentation, critical theoretical analysis.

Suppression of the internal electric field effects in ZnO/Zn0.7Mg0.3O quantum wells by ion-implantation induced intermixing

International Nuclear Information System (INIS)

Davis, J A; Dao, L V; Wen, X; Ticknor, C; Hannaford, P; Coleman, V A; Tan, H H; Jagadish, C; Koike, K; Sasa, S; Inoue, M; Yano, M

2008-01-01

Strong suppression of the effects caused by the internal electric field in ZnO/ZnMgO quantum wells following ion-implantation and rapid thermal annealing, is revealed by photoluminescence, time-resolved photoluminescence, and band structure calculations. The implantation and annealing induces Zn/Mg intermixing, resulting in graded quantum well interfaces. This reduces the quantum-confined Stark shift and increases electron-hole wavefunction overlap, which significantly reduces the exciton lifetime and increases the oscillator strength

Molecular quantum mechanical gradients within the polarizable embedding approach—Application to the internal vibrational Stark shift of acetophenone

DEFF Research Database (Denmark)

List, Nanna Holmgaard; Beerepoot, Maarten; Olsen, Jógvan Magnus Haugaard

2015-01-01

for the quantum region, covering (multiconfigurational) self-consistent-field and Kohn–Sham density functional theory. As the first application of the implementation, we consider the internal vibrational Stark effect of the C=O group of acetophenone in different solvents and derive its vibrational linear Stark...

Quantum Optical Multiple Scattering

DEFF Research Database (Denmark)

Ott, Johan Raunkjær

. In the first part we use a scattering-matrix formalism combined with results from random-matrix theory to investigate the interference of quantum optical states on a multiple scattering medium. We investigate a single realization of a scattering medium thereby showing that it is possible to create entangled...... states by interference of squeezed beams. Mixing photon states on the single realization also shows that quantum interference naturally arises by interfering quantum states. We further investigate the ensemble averaged transmission properties of the quantized light and see that the induced quantum...... interference survives even after disorder averaging. The quantum interference manifests itself through increased photon correlations. Furthermore, the theoretical description of a measurement procedure is presented. In this work we relate the noise power spectrum of the total transmitted or reflected light...

Quantum state-resolved gas/surface reaction dynamics probed by reflection absorption infrared spectroscopy

Energy Technology Data Exchange (ETDEWEB)

Chen Li [Department of Dynamics at Surfaces, Max Planck Institute for Biophysical Chemistry, Am Fassberg 11, Goettingen (Germany); Ueta, Hirokazu; Beck, Rainer D. [Laboratoire de Chimie Physique Moleculaire, Ecole Polytechnique Federale de Lausanne (Switzerland); Bisson, Regis [Aix-Marseille Universite, PIIM, CNRS, UMR 7345, 13397 Marseille (France)

2013-05-15

We report the design and characterization of a new molecular-beam/surface-science apparatus for quantum state-resolved studies of gas/surface reaction dynamics combining optical state-specific reactant preparation in a molecular beam by rapid adiabatic passage with detection of surface-bound reaction products by reflection absorption infrared spectroscopy (RAIRS). RAIRS is a non-invasive infrared spectroscopic detection technique that enables online monitoring of the buildup of reaction products on the target surface during reactant deposition by a molecular beam. The product uptake rate obtained by calibrated RAIRS detection yields the coverage dependent state-resolved reaction probability S({theta}). Furthermore, the infrared absorption spectra of the adsorbed products obtained by the RAIRS technique provide structural information, which help to identify nascent reaction products, investigate reaction pathways, and determine branching ratios for different pathways of a chemisorption reaction. Measurements of the dissociative chemisorption of methane on Pt(111) with this new apparatus are presented to illustrate the utility of RAIRS detection for highly detailed studies of chemical reactions at the gas/surface interface.

Bicovariant quantum algebras and quantum Lie algebras

International Nuclear Information System (INIS)

Schupp, P.; Watts, P.; Zumino, B.

1993-01-01

A bicovariant calculus of differential operators on a quantum group is constructed in a natural way, using invariant maps from Fun(G q ) to U q g, given by elements of the pure braid group. These operators - the 'reflection matrix' Y= triple bond L + SL - being a special case - generate algebras that linearly close under adjoint actions, i.e. they form generalized Lie algebras. We establish the connection between the Hopf algebra formulation of the calculus and a formulation in compact matrix form which is quite powerful for actual computations and as applications we find the quantum determinant and an orthogonality relation for Y in SO q (N). (orig.)

Variable-angle total internal reflection fluorescence microscopy of intact cells of Arabidopsis thaliana

Directory of Open Access Journals (Sweden)

Kim Myung K

2011-09-01

Full Text Available Abstract Background Total internal reflection fluorescence microscopy (TIRFM is a powerful tool for observing fluorescently labeled molecules on the plasma membrane surface of animal cells. However, the utility of TIRFM in plant cell studies has been limited by the fact that plants have cell walls, thick peripheral layers surrounding the plasma membrane. Recently, a new technique known as variable-angle epifluorescence microscopy (VAEM was developed to circumvent this problem. However, the lack of a detailed analysis of the optical principles underlying VAEM has limited its applications in plant-cell biology. Results Here, we present theoretical and experimental evidence supporting the use of variable-angle TIRFM in observations of intact plant cells. We show that when total internal reflection occurs at the cell wall/cytosol interface with an appropriate angle of incidence, an evanescent wave field of constant depth is produced inside the cytosol. Results of experimental TIRFM observations of the dynamic behaviors of phototropin 1 (a membrane receptor protein and clathrin light chain (a vesicle coat protein support our theoretical analysis. Conclusions These findings demonstrate that variable-angle TIRFM is appropriate for quantitative live imaging of cells in intact tissues of Arabidopsis thaliana.

The capacity of black holes to transmit quantum information

International Nuclear Information System (INIS)

Brádler, Kamil; Adami, Christoph

2014-01-01

We study the properties of the quantum information transmission channel that emerges from the quantum dynamics of particles interacting with a black hole horizon. We calculate the quantum channel capacity in two limiting cases where a single-letter capacity is known to exist: the limit of perfectly reflecting and perfectly absorbing black holes. We find that the perfectly reflecting black hole channel is closely related to the Unruh channel and that its capacity is non-vanishing, allowing for the perfect reconstruction of quantum information outside of the black hole horizon. We also find that the complementary channel (transmitting entanglement behind the horizon) is entanglement-breaking in this case, with vanishing capacity. We then calculate the quantum capacity of the black hole channel in the limit of a perfectly absorbing black hole and find that this capacity vanishes, while the capacity of the complementary channel is non-vanishing instead. Rather than inviting a new crisis for quantum physics, this finding instead is in accordance with the quantum no-cloning theorem, because it guarantees that there are no space-like surfaces that contain both the sender’s quantum state and the receiver’s reconstructed quantum state

The capacity of black holes to transmit quantum information

Energy Technology Data Exchange (ETDEWEB)

Brádler, Kamil [Department of Astronomy and Physics, Saint Mary’s University,Halifax, Nova Scotia, B3H 3C3 (Canada); Adami, Christoph [Department of Physics and Astronomy, Michigan State University,East Lansing, MI 48824 (United States)

2014-05-21

We study the properties of the quantum information transmission channel that emerges from the quantum dynamics of particles interacting with a black hole horizon. We calculate the quantum channel capacity in two limiting cases where a single-letter capacity is known to exist: the limit of perfectly reflecting and perfectly absorbing black holes. We find that the perfectly reflecting black hole channel is closely related to the Unruh channel and that its capacity is non-vanishing, allowing for the perfect reconstruction of quantum information outside of the black hole horizon. We also find that the complementary channel (transmitting entanglement behind the horizon) is entanglement-breaking in this case, with vanishing capacity. We then calculate the quantum capacity of the black hole channel in the limit of a perfectly absorbing black hole and find that this capacity vanishes, while the capacity of the complementary channel is non-vanishing instead. Rather than inviting a new crisis for quantum physics, this finding instead is in accordance with the quantum no-cloning theorem, because it guarantees that there are no space-like surfaces that contain both the sender’s quantum state and the receiver’s reconstructed quantum state.

Quantum networks based on cavity QED

Energy Technology Data Exchange (ETDEWEB)

Ritter, Stephan; Bochmann, Joerg; Figueroa, Eden; Hahn, Carolin; Kalb, Norbert; Muecke, Martin; Neuzner, Andreas; Noelleke, Christian; Reiserer, Andreas; Uphoff, Manuel; Rempe, Gerhard [Max-Planck-Institut fuer Quantenoptik, Hans-Kopfermann-Strasse 1, 85748 Garching (Germany)

2014-07-01

Quantum repeaters require an efficient interface between stationary quantum memories and flying photons. Single atoms in optical cavities are ideally suited as universal quantum network nodes that are capable of sending, storing, retrieving, and even processing quantum information. We demonstrate this by presenting an elementary version of a quantum network based on two identical nodes in remote, independent laboratories. The reversible exchange of quantum information and the creation of remote entanglement are achieved by exchange of a single photon. Quantum teleportation is implemented using a time-resolved photonic Bell-state measurement. Quantum control over all degrees of freedom of the single atom also allows for the nondestructive detection of flying photons and the implementation of a quantum gate between the spin state of the atom and the polarization of a photon upon its reflection from the cavity. Our approach to quantum networking offers a clear perspective for scalability and provides the essential components for the realization of a quantum repeater.

Graphene quantum dots

CERN Document Server

Güçlü, Alev Devrim; Korkusinski, Marek; Hawrylak, Pawel

2014-01-01

This book reflects the current status of theoretical and experimental research of graphene based nanostructures, in particular quantum dots, at a level accessible to young researchers, graduate students, experimentalists and theorists. It presents the current state of research of graphene quantum dots, a single or few monolayer thick islands of graphene. It introduces the reader to the electronic and optical properties of graphite, intercalated graphite and graphene, including Dirac fermions, Berry's phase associated with sublattices and valley degeneracy, covers single particle properties of

Quantum state engineering in hybrid open quantum systems

OpenAIRE

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

2015-01-01

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 disp...

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.

Autocompensating quantum cryptography

International Nuclear Information System (INIS)

Bethune, Donald S.; Risk, William P.

2002-01-01

Quantum cryptographic key distribution (QKD) uses extremely faint light pulses to carry quantum information between two parties (Alice and Bob), allowing them to generate a shared, secret cryptographic key. Autocompensating QKD systems automatically and passively compensate for uncontrolled time-dependent variations of the optical fibre properties by coding the information as a differential phase between orthogonally polarized components of a light pulse sent on a round trip through the fibre, reflected at mid-course using a Faraday mirror. We have built a prototype system based on standard telecom technology that achieves a privacy-amplified bit generation rate of ∼1000 bits s -1 over a 10 km optical fibre link. Quantum cryptography is an example of an application that, by using quantum states of individual particles to represent information, accomplishes a practical task that is impossible using classical means. (author)

Exploiting total internal reflection geometry for efficient optical modulation of terahertz light

Directory of Open Access Journals (Sweden)

Xudong Liu

2016-10-01

Full Text Available Efficient methods to modulate terahertz (THz light are essential for realizing rapid THz imaging and communication applications. Here we report a novel THz modulator which utilizes the evanescent wave in a total internal reflection setup coupled with a conductive interface to enhance the attenuation efficiency of THz light. This approach makes it possible to achieve close to 100% modulation with a small interface conductivity of 12 mS. The frequency dependence of this technique is linked to the optical properties of the materials: a material with close to frequency independent conductivity that is also controllable will result in an achromatic modulation response, and the device performance can be optimized further by tuning the internal reflection angle. In this work, we focus on applying the technique in the terahertz frequency range. Using an LED array with a pump intensity of 475 mW/cm2 to produce carriers in a silicon wafer, we have achieved a modulation depth of up to 99.9% in a broad frequency range of 0.1 THz–0.8 THz. The required pumping power for the generation of the required free carriers is low because the sheet conductivity needed is far less than required for traditional transmission techniques. Consequently, the device can be modulated by an LED making it a very practical, low cost, and scalable solution for THz modulation.

Quantum foundations in the light of quantum cryptography

International Nuclear Information System (INIS)

Brassard, G.; Fuchs, C.A.

2005-01-01

Full text: Consider the two great physical theories of the twentieth century: relativity and quantum mechanics. Einstein derived relativity from very simple principles such as: 'The speed of light in empty space is independent of the speed of its source' and 'Physics should appear the same in all inertial reference frames'. By contrast, the foundation of quantum mechanics is built on a set of rather strange, disjointed and ad hoc axioms. Why is that? Must quantum mechanics be inherently less elegant than relativity? Or is it rather that the current axioms of quantum mechanics reflect at best the history that led to its discovery by too many people (compared to one person for relativity), over too long a period of time? The purpose of this talk is to argue that a better foundation for quantum mechanics lies within the teachings of quantum information science. We postulate that the truly fundamental laws of nature concern information, not waves or particles. For example, it has been proven, from the current axioms of quantum mechanics, that 'nature allows for the unconditionally secure transmission of confidential information', but 'nature does not allow for unconditionally secure bit commitment' (these are standard classical cryptographic primitives). We propose to turn the table around, start from these two theorems and possibly a few others, upgrade them as axioms, and ask how much of quantum mechanics they can derive. This provocative talk is meant as an eye-opener: we shall ask far more questions than we shall resolve. (author)

Distribution of quantum information between an atom and two photons

International Nuclear Information System (INIS)

Weber, Bernhard

2008-01-01

The construction of networks consisting of optically interconnected processing units is a promising way to scale up quantum information processing systems. To store quantum information, single trapped atoms are among the most proven candidates. By placing them in high finesse optical resonators, a bidirectional information exchange between the atoms and photons becomes possible with, in principle, unit efficiency. Such an interface between stationary and ying qubits constitutes a possible node of a future quantum network. The results presented in this thesis demonstrate the prospects of a quantum interface consisting of a single atom trapped within the mode of a high-finesse optical cavity. In a two-step process, we distribute entanglement between the stored atom and two subsequently emitted single photons. The long atom trapping times achieved in the system together with the high photon collection efficiency of the cavity make the applied protocol in principle deterministic, allowing for the creation of an entangled state at the push of a button. Running the protocol on this quasi-stationary quantum interface, the internal state of the atom is entangled with the polarization state of a single emitted photon. The entanglement is generated by driving a vacuum-stimulated Raman adiabatic passage between states of the coupled atom-cavity system. In a second process, the atomic part of the entangled state is mapped onto a second emitted photon using a similar technique and resulting in a polarization-entangled two-photon state. To verify and characterize the photon-photon entanglement, we measured a violation of a Bell inequality and performed a full quantum state tomography. The results prove the prior atom-photon entanglement and demonstrate a quantum information transfer between the atom and the two emitted photons. This reflects the advantages of a high-finesse cavity as a quantum interface in future quantum networks. (orig.)

Distribution of quantum information between an atom and two photons

Energy Technology Data Exchange (ETDEWEB)

Weber, Bernhard

2008-11-03

The construction of networks consisting of optically interconnected processing units is a promising way to scale up quantum information processing systems. To store quantum information, single trapped atoms are among the most proven candidates. By placing them in high finesse optical resonators, a bidirectional information exchange between the atoms and photons becomes possible with, in principle, unit efficiency. Such an interface between stationary and ying qubits constitutes a possible node of a future quantum network. The results presented in this thesis demonstrate the prospects of a quantum interface consisting of a single atom trapped within the mode of a high-finesse optical cavity. In a two-step process, we distribute entanglement between the stored atom and two subsequently emitted single photons. The long atom trapping times achieved in the system together with the high photon collection efficiency of the cavity make the applied protocol in principle deterministic, allowing for the creation of an entangled state at the push of a button. Running the protocol on this quasi-stationary quantum interface, the internal state of the atom is entangled with the polarization state of a single emitted photon. The entanglement is generated by driving a vacuum-stimulated Raman adiabatic passage between states of the coupled atom-cavity system. In a second process, the atomic part of the entangled state is mapped onto a second emitted photon using a similar technique and resulting in a polarization-entangled two-photon state. To verify and characterize the photon-photon entanglement, we measured a violation of a Bell inequality and performed a full quantum state tomography. The results prove the prior atom-photon entanglement and demonstrate a quantum information transfer between the atom and the two emitted photons. This reflects the advantages of a high-finesse cavity as a quantum interface in future quantum networks. (orig.)

PREFACE Quantum Groups, Quantum Foundations and Quantum Information: a Festschrift for Tony Sudbery

Science.gov (United States)

Weigert, Stefan

2010-11-01

On 29 July 2008, Professor Anthony Thomas Sudbery - known as Tony to his friends and colleagues - celebrated his 65th birthday. To mark this occasion and to honour Tony's scientific achievements, a 2-day Symposion was held at the University of York on 29-30 September 2008 under the sponsorship of the Institute of Physics and the London Mathematical Society. The breadth of Tony's research interests was reflected in the twelve invited lectures by A Beige, I Bengtsson, K Brown, N Cerf, E Corrigan, J Ladyman, A J Macfarlane, S Majid, C Manogue, S Popescu, J Ryan and R W Tucker. This Festschrift, also made possible by the generosity of the IOP and the LMS, reproduces the majority of these contributions together with other invited papers. Tony obtained his PhD from the University of Cambridge in 1970. His thesis, written under the guidance of Alan Macfarlane, is entitled Some aspects of chiral su(3) × su(3) symmetry in hadron dynamics. He arrived in York in 1971 with his wife Rodie, two young daughters, a lively mind and a very contemporary shock of hair. He was at that stage interested in mathematical physics and so was classed as an applied mathematician in the departmental division in place at that time. But luckily Tony did not fit into this category. His curiosity is combined with a good nose for problems and his capacity for knocking off conjectures impressed us all. Within a short time of his arrival he was writing papers on group theory, complex analysis and combinatorics, while continuing to work on quantum mechanics. His important paper on quaternionic analysis is an example of the imagination and elegance of his ideas. By developing a derivative, he replaced the relatively obscure analytical theory of quaternions by one informed by modern complex analysis. Other interests emerged, centred round the quantum: quantum mechanics and its foundations, quantum groups and quantum information. He didn't just dabble in these areas but mastered them, gaining a national

Equivalent Method of Solving Quantum Efficiency of Reflection-Mode Exponential Doping GaAs Photocathode

International Nuclear Information System (INIS)

Jun, Niu; Zhi, Yang; Ben-Kang, Chang

2009-01-01

The mathematical expression of the electron diffusion and drift length L DE of exponential doping photocathode is deduced. In the quantum efficiency equation of the reffection-mode uniform doping cathode, substituting L DE for L D , the equivalent quantum efficiency equation of the reffection-mode exponential doping cathode is obtained. By using the equivalent equation, theoretical simulation and experimental analysis shows that the equivalent index formula and formula-doped cathode quantum efficiency results in line. The equivalent equation avoids complicated calculation, thereby simplifies the process of solving the quantum efficiency of exponential doping photocathode

Quantum effects in strong fields

International Nuclear Information System (INIS)

Roessler, Lars

2014-01-01

This work is devoted to quantum effects for photons in spatially inhomogeneous fields. Since the purely analytical solution of the corresponding equations is an unsolved problem even today, a main aspect of this work is to use the worldline formalism for scalar QED to develop numerical algorithms for correlation functions beyond perturbative constructions. In a first step we take a look at the 2-Point photon correlation function, in order to understand effects like vacuum polarization or quantum reflection. For a benchmark test of the numerical algorithm we reproduce analytical results in a constant magnetic background. For inhomogeneous fields we calculate for the first time local refractive indices of the quantum vacuum. In this way we find a new de-focusing effect of inhomogeneous magnetic fields. Furthermore the numerical algorithm confirms analytical results for quantum reflection obtained within the local field approximation. In a second step we take a look at higher N-Point functions, with the help of our numerical algorithm. An interesting effect at the level of the 3-Point function is photon splitting. First investigations show that the Adler theorem remains also approximately valid for inhomogeneous fields.

Quantum random number generator

Science.gov (United States)

Soubusta, Jan; Haderka, Ondrej; Hendrych, Martin

2001-03-01

Since reflection or transmission of a quantum particle on a beamsplitter is inherently random quantum process, a device built on this principle does not suffer from drawbacks of neither pseudo-random computer generators or classical noise sources. Nevertheless, a number of physical conditions necessary for high quality random numbers generation must be satisfied. Luckily, in quantum optics realization they can be well controlled. We present an easy random number generator based on the division of weak light pulses on a beamsplitter. The randomness of the generated bit stream is supported by passing the data through series of 15 statistical test. The device generates at a rate of 109.7 kbit/s.

Giersch International Symposion 2016 : Week 1 : Experimental Search for Quantum Gravity

CERN Document Server

Experimental Search for Quantum Gravity

2018-01-01

This book summarizes recent developments in the research area of quantum gravity phenomenology. A series of short and nontechnical essays lays out the prospects of various experimental possibilities and their current status. Finding observational evidence for the quantization of space-time was long thought impossible. In the last decade however, new experimental design and technological advances have changed the research landscape and opened new perspectives on quantum gravity. Formerly dominated by purely theoretical constructions, quantum gravity now has a lively phenomenology to offer. From high precision measurements using macroscopic quantum oscillators to new analysis methods of the cosmic microwave background, no stone is being left unturned in the experimental search for quantum gravity. This book sheds new light on the connection of astroparticle physics with the quantum gravity problem. Gravitational waves and their detection are covered. It illustrates findings from the interconnection between gene...

Entanglement characteristics of subharmonic modes reflected from a cavity for type-II second-harmonic generation

International Nuclear Information System (INIS)

Zhai Zehui; Li Yongming; Gao Jiangrui

2004-01-01

Quantum fluctuation and quantum entanglement of the pump fields reflected from an optical cavity for type-II second-harmonic generation are theoretically analyzed. The correlation spectra of quadrature components between the reflected subharmonic fields are interpreted in terms of pump parameter, intracavity losses, and normalized frequency. High correlation of both amplitude and phase quadratures can be accessed in a triple resonant cavity before the pitchfork bifurcation occurs. The two reflected subharmonic fields are in an entangled state with quantum correlation of phase quadratures and anticorrelation of amplitude quadratures. The proposed system can be exploited as a source for generating entangled states of continuous variables

Quantum mechanical suppression of chaos

International Nuclear Information System (INIS)

Bluemel, R.; Smilansky, U.

1990-01-01

The relation between determinism and predictability is the central issue in the study of 'deterministic chaos'. Much knowledge has been accumulated in the past 10 years about the chaotic dynamics of macroscopic (classical) systems. The implications of chaos in the microscopic quantum world is examined, in other words, how to reconcile the correspondence principle with the inherent uncertainties which reflect the wave nature of quantum dynamics. Recent atomic physics experiments demonstrate clearly that chaos is relevant to the microscopic world. In particular, such experiments emphasise the urgent need to clarify the genuine quantum mechanism which imposes severe limitations on quantum dynamics, and renders it so very different from its classical counterpart. (author)

Twistor Cosmology and Quantum Space-Time

International Nuclear Information System (INIS)

Brody, D.C.; Hughston, L.P.

2005-01-01

The purpose of this paper is to present a model of a 'quantum space-time' in which the global symmetries of space-time are unified in a coherent manner with the internal symmetries associated with the state space of quantum-mechanics. If we take into account the fact that these distinct families of symmetries should in some sense merge and become essentially indistinguishable in the unified regime, our framework may provide an approximate description of or elementary model for the structure of the universe at early times. The quantum elements employed in our characterisation of the geometry of space-time imply that the pseudo-Riemannian structure commonly regarded as an essential feature in relativistic theories must be dispensed with. Nevertheless, the causal structure and the physical kinematics of quantum space-time are shown to persist in a manner that remains highly analogous to the corresponding features of the classical theory. In the case of the simplest conformally flat cosmological models arising in this framework, the twistorial description of quantum space-time is shown to be effective in characterising the various physical and geometrical properties of the theory. As an example, a sixteen-dimensional analogue of the Friedmann-Robertson-Walker cosmologies is constructed, and its chronological development is analysed in some detail. More generally, whenever the dimension of a quantum space-time is an even perfect square, there exists a canonical way of breaking the global quantum space-time symmetry so that a generic point of quantum space-time can be consistently interpreted as a quantum operator taking values in Minkowski space. In this scenario, the breakdown of the fundamental symmetry of the theory is due to a loss of quantum entanglement between space-time and internal quantum degrees of freedom. It is thus possible to show in a certain specific sense that the classical space-time description is an emergent feature arising as a consequence of a

Quantum mechanics from classical statistics

International Nuclear Information System (INIS)

Wetterich, C.

2010-01-01

Quantum mechanics can emerge from classical statistics. A typical quantum system describes an isolated subsystem of a classical statistical ensemble with infinitely many classical states. The state of this subsystem can be characterized by only a few probabilistic observables. Their expectation values define a density matrix if they obey a 'purity constraint'. Then all the usual laws of quantum mechanics follow, including Heisenberg's uncertainty relation, entanglement and a violation of Bell's inequalities. No concepts beyond classical statistics are needed for quantum physics - the differences are only apparent and result from the particularities of those classical statistical systems which admit a quantum mechanical description. Born's rule for quantum mechanical probabilities follows from the probability concept for a classical statistical ensemble. In particular, we show how the non-commuting properties of quantum operators are associated to the use of conditional probabilities within the classical system, and how a unitary time evolution reflects the isolation of the subsystem. As an illustration, we discuss a classical statistical implementation of a quantum computer.

Meaning, Internalization, and Externalization: Toward a Fuller Understanding of the Process of Reflection and Its Role in the Construction of the Self

Science.gov (United States)

Le Cornu, Alison

2009-01-01

The study of the process of reflection has a dignified history. However, few have linked reflection to the development of the self in such a way that the form of reflection is understood to influence the resultant type of self. This article explores the process of reflection using a framework of meaning making, internalization, and externalization…

Formalization of Quantum Protocols using Coq

Directory of Open Access Journals (Sweden)

Jaap Boender

2015-11-01

Full Text Available Quantum Information Processing, which is an exciting area of research at the intersection of physics and computer science, has great potential for influencing the future development of information processing systems. The building of practical, general purpose Quantum Computers may be some years into the future. However, Quantum Communication and Quantum Cryptography are well developed. Commercial Quantum Key Distribution systems are easily available and several QKD networks have been built in various parts of the world. The security of the protocols used in these implementations rely on information-theoretic proofs, which may or may not reflect actual system behaviour. Moreover, testing of implementations cannot guarantee the absence of bugs and errors. This paper presents a novel framework for modelling and verifying quantum protocols and their implementations using the proof assistant Coq. We provide a Coq library for quantum bits (qubits, quantum gates, and quantum measurement. As a step towards verifying practical quantum communication and security protocols such as Quantum Key Distribution, we support multiple qubits, communication and entanglement. We illustrate these concepts by modelling the Quantum Teleportation Protocol, which communicates the state of an unknown quantum bit using only a classical channel.

Influence of dislocation density on internal quantum efficiency of GaN-based semiconductors

Directory of Open Access Journals (Sweden)

Jiadong Yu

2017-03-01

Full Text Available By considering the effects of stress fields coming from lattice distortion as well as charge fields coming from line charges at edge dislocation cores on radiative recombination of exciton, a model of carriers’ radiative and non-radiative recombination has been established in GaN-based semiconductors with certain dislocation density. Using vector average of the stress fields and the charge fields, the relationship between dislocation density and the internal quantum efficiency (IQE is deduced. Combined with related experimental results, this relationship is fitted well to the trend of IQEs of bulk GaN changing with screw and edge dislocation density, meanwhile its simplified form is fitted well to the IQEs of AlGaN multiple quantum well LEDs with varied threading dislocation densities but the same light emission wavelength. It is believed that this model, suitable for different epitaxy platforms such as MOCVD and MBE, can be used to predict to what extent the luminous efficiency of GaN-based semiconductors can still maintain when the dislocation density increases, so as to provide a reasonable rule of thumb for optimizing the epitaxial growth of GaN-based devices.

Quantum crystallography: A perspective.

Science.gov (United States)

Massa, Lou; Matta, Chérif F

2018-06-30

Extraction of the complete quantum mechanics from X-ray scattering data is the ultimate goal of quantum crystallography. This article delivers a perspective for that possibility. It is desirable to have a method for the conversion of X-ray diffraction data into an electron density that reflects the antisymmetry of an N-electron wave function. A formalism for this was developed early on for the determination of a constrained idempotent one-body density matrix. The formalism ensures pure-state N-representability in the single determinant sense. Applications to crystals show that quantum mechanical density matrices of large molecules can be extracted from X-ray scattering data by implementing a fragmentation method termed the kernel energy method (KEM). It is shown how KEM can be used within the context of quantum crystallography to derive quantum mechanical properties of biological molecules (with low data-to-parameters ratio). © 2017 Wiley Periodicals, Inc. © 2017 Wiley Periodicals, Inc.

Luminescence of quantum-well exciton polaritons from microstructured AlxGa1-xAs-GaAs multiple quantum wells

Science.gov (United States)

Kohl, M.; Heitmann, D.; Grambow, P.; Ploog, K.

1988-06-01

Periodic multiple-quantum-well wires have been prepared by etching five-layer quantum-well structures through a holographically prepared mask. The periodicity was 380 nm, the lateral confinement 180 nm, and the quantum-well width 13, nm. The luminescence from these microstructured systems in the frequency regime of the one-electron-one-heavy-hole transition was strongly polarized with the electric field perpendicular to the periodic structure. This effect was caused by the resonantly enhanced emission of quantum-well-exciton (QWE) polaritons. Excitation of QWE polaritons was also observed in reflection measurements on the microstructured samples.

Recombination dynamics and internal quantum efficiency in InGaN

International Nuclear Information System (INIS)

Murotani, Hideaki; Andoh, Hiroya; Tsukamoto, Takehiko; Sugiura, Toko; Yamada, Yoichi; Tabata, Takuya; Honda, Yoshio; Yamaguchi, Masahito; Amano, Hiroshi

2014-01-01

Recombination dynamics and internal quantum efficiency (IQE) of green luminescent InGaN nanowires with different crystalline qualities have been studied by means photoluminescence (PL) and time-resolved PL spectroscopy. Temperature- and excitation-power-density-dependent PL spectroscopy enabled to evaluate the IQE as a function of excitation power density. The shape of the efficiency curves at low temperature strongly depended on the magnitude of nonradiative recombination processes. This leads to the misestimation of the IQE in the lower quality nanowire. In addition, the PL decay curves were well described by a double exponential function both at 6 and 300 K. The PL decay time of the faster component was affected by nonradiative recombination processes even at low temperature. This indicated that the radiative recombination lifetime cannot be estimated from the PL decay time in the lower quality nanowire. (copyright 2014 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

Fixed point algebras for easy quantum groups

DEFF Research Database (Denmark)

Gabriel, Olivier; Weber, Moritz

2016-01-01

Compact matrix quantum groups act naturally on Cuntz algebras. The first author isolated certain conditions under which the fixed point algebras under this action are Kirchberg algebras. Hence they are completely determined by their K-groups. Building on prior work by the second author,we prove...... that free easy quantum groups satisfy these conditions and we compute the K-groups of their fixed point algebras in a general form. We then turn to examples such as the quantum permutation group S+ n,the free orthogonal quantum group O+ n and the quantum reflection groups Hs+ n. Our fixed point......-algebra construction provides concrete examples of free actions of free orthogonal easy quantum groups,which are related to Hopf-Galois extensions....

A survey of quantum Lyapunov control methods.

Science.gov (United States)

Cong, Shuang; Meng, Fangfang

2013-01-01

The condition of a quantum Lyapunov-based control which can be well used in a closed quantum system is that the method can make the system convergent but not just stable. In the convergence study of the quantum Lyapunov control, two situations are classified: nondegenerate cases and degenerate cases. For these two situations, respectively, in this paper the target state is divided into four categories: the eigenstate, the mixed state which commutes with the internal Hamiltonian, the superposition state, and the mixed state which does not commute with the internal Hamiltonian. For these four categories, the quantum Lyapunov control methods for the closed quantum systems are summarized and analyzed. Particularly, the convergence of the control system to the different target states is reviewed, and how to make the convergence conditions be satisfied is summarized and analyzed.

Indirect absorption spectroscopy using quantum cascade lasers: mid-infrared refractometry and photothermal spectroscopy.

Science.gov (United States)

Pfeifer, Marcel; Ruf, Alexander; Fischer, Peer

2013-11-04

We record vibrational spectra with two indirect schemes that depend on the real part of the index of refraction: mid-infrared refractometry and photothermal spectroscopy. In the former, a quantum cascade laser (QCL) spot is imaged to determine the angles of total internal reflection, which yields the absorption line via a beam profile analysis. In the photothermal measurements, a tunable QCL excites vibrational resonances of a molecular monolayer, which heats the surrounding medium and changes its refractive index. This is observed with a probe laser in the visible. Sub-monolayer sensitivities are demonstrated.

Optimal dynamics for quantum-state and entanglement transfer through homogeneous quantum systems

International Nuclear Information System (INIS)

Banchi, L.; Apollaro, T. J. G.; Cuccoli, A.; Vaia, R.; Verrucchi, P.

2010-01-01

The capability of faithfully transmit quantum states and entanglement through quantum channels is one of the key requirements for the development of quantum devices. Different solutions have been proposed to accomplish such a challenging task, which, however, require either an ad hoc engineering of the internal interactions of the physical system acting as the channel or specific initialization procedures. Here we show that optimal dynamics for efficient quantum-state and entanglement transfer can be attained in generic quantum systems with homogeneous interactions by tuning the coupling between the system and the two attached qubits. We devise a general procedure to determine the optimal coupling, and we explicitly implement it in the case of a channel consisting of a spin-(1/2)XY chain. The quality of quantum-state and entanglement transfer is found to be very good and, remarkably, almost independent of the channel length.

Quantum centipedes: collective dynamics of interacting quantum walkers

International Nuclear Information System (INIS)

Krapivsky, P L; Luck, J M; Mallick, K

2016-01-01

We consider the quantum centipede made of N fermionic quantum walkers on the one-dimensional lattice interacting by means of the simplest of all hard-bound constraints: the distance between two consecutive fermions is either one or two lattice spacings. This composite quantum walker spreads ballistically, just as the simple quantum walk. However, because of the interactions between the internal degrees of freedom, the distribution of its center-of-mass velocity displays numerous ballistic fronts in the long-time limit, corresponding to singularities in the empirical velocity distribution. The spectrum of the centipede and the corresponding group velocities are analyzed by direct means for the first few values of N . Some analytical results are obtained for arbitrary N by exploiting an exact mapping of the problem onto a free-fermion system. We thus derive the maximal velocity describing the ballistic spreading of the two extremal fronts of the centipede wavefunction, including its non-trivial value in the large- N limit. (paper)

3D study of a bi facial polycrystalline photovoltaic cell under constant magnetic field and determination of the parameters of recombination from internal quantum yield

International Nuclear Information System (INIS)

ZOUMA Bernard

2010-01-01

The work presented in this thesis deals with the problem of the quality of polycrystalline silicon solar cells. This work has been done on square surface columnar grains of the bi facial solar cell. This study ends in the determination of the quality of bi facial solar cells from their recombination parameters. We propose an useful technique to determine these recombination parameters from the algorithm calculation that is based on the internal quantum efficiency. A set of dimensional approach like the three-dimensional model of the solar cell that allows taking into account the grain size and grain boundaries recombination velocity. The emitter contribution and the terrestrial magnetic field influence are taken into account too. While lighted, the emitter region becomes a recombination zone of the electron from the base region. We have obtained a new exhaustive analytical expression of the internal quantum efficiency. This theoretical efficiency is a function of the recombination parameters and it is used to fit the experimental curves of the internal quantum efficiency versus the wavelength. The results are in a good agreement with the experimental values.(Author) [fr

Microwave quantum logic gates for trapped ions.

Science.gov (United States)

Ospelkaus, C; Warring, U; Colombe, Y; Brown, K R; Amini, J M; Leibfried, D; Wineland, D J

2011-08-10

Control over physical systems at the quantum level is important in fields as diverse as metrology, information processing, simulation and chemistry. For trapped atomic ions, the quantized motional and internal degrees of freedom can be coherently manipulated with laser light. Similar control is difficult to achieve with radio-frequency or microwave radiation: the essential coupling between internal degrees of freedom and motion requires significant field changes over the extent of the atoms' motion, but such changes are negligible at these frequencies for freely propagating fields. An exception is in the near field of microwave currents in structures smaller than the free-space wavelength, where stronger gradients can be generated. Here we first manipulate coherently (on timescales of 20 nanoseconds) the internal quantum states of ions held in a microfabricated trap. The controlling magnetic fields are generated by microwave currents in electrodes that are integrated into the trap structure. We also generate entanglement between the internal degrees of freedom of two atoms with a gate operation suitable for general quantum computation; the entangled state has a fidelity of 0.76(3), where the uncertainty denotes standard error of the mean. Our approach, which involves integrating the quantum control mechanism into the trapping device in a scalable manner, could be applied to quantum information processing, simulation and spectroscopy.

Quantum walk with one variable absorbing boundary

International Nuclear Information System (INIS)

Wang, Feiran; Zhang, Pei; Wang, Yunlong; Liu, Ruifeng; Gao, Hong; Li, Fuli

2017-01-01

Quantum walks constitute a promising ingredient in the research on quantum algorithms; consequently, exploring different types of quantum walks is of great significance for quantum information and quantum computation. In this study, we investigate the progress of quantum walks with a variable absorbing boundary and provide an analytical solution for the escape probability (the probability of a walker that is not absorbed by the boundary). We simulate the behavior of escape probability under different conditions, including the reflection coefficient, boundary location, and initial state. Moreover, it is also meaningful to extend our research to the situation of continuous-time and high-dimensional quantum walks. - Highlights: • A novel scheme about quantum walk with variable boundary is proposed. • The analytical results of the survival probability from the absorbing boundary. • The behavior of survival probability under different boundary conditions. • The influence of different initial coin states on the survival probability.

Entropy inequalities from reflection positivity

International Nuclear Information System (INIS)

Casini, H

2010-01-01

We investigate the question of whether the entropy and the Renyi entropies of the vacuum state reduced to a region of space can be represented in terms of correlators in quantum field theory. In this case, the positivity relations for the correlators are mapped into inequalities for the entropies. We write them using a real-time version of reflection positivity, which can be generalized to general quantum systems. Using this generalization we can prove an infinite sequence of inequalities which are obeyed by the Renyi entropies of integer index. There is one independent inequality involving any number of different subsystems. In quantum field theory the inequalities acquire a simple geometrical form and are consistent with the integer index Renyi entropies being given by vacuum expectation values of twisting operators in the Euclidean formulation. Several possible generalizations and specific examples are analyzed

Unusual conversations: A reflection on the mechanics of internationally engaged public scholarship

Directory of Open Access Journals (Sweden)

Jonathan Damiani

2016-09-01

Full Text Available This article analyses the civic engagement pathways of researchers from the Asia-Pacific and the United States in an effort to see how the principles of what American  scholars consider publicly engaged research and creative practice are being enacted in research sites across the globe. The purpose of this ongoing project is to focus on finding ways of connecting American scholars with a network of higher education and research institutions that hold a commitment and passion for social responsibility and civic engagement as it impacts education, research and service for community development overseas. The narrative includes the voices and perspectives of colleagues dedicated to engaged scholarship from across the new region in which I work (the Asia-Pacific, alongside the voices of some of Imagining America’s (IA 2014 National Conference participants. These conversations serve as a critical reflection on the mechanics of doing public scholarship overseas and frame a new model of internationally engaged scholarship. Keywords: Internationally engaged public scholarship, unusual conversations

Refractive Index Imaging of Cells with Variable-Angle Near-Total Internal Reflection (TIR) Microscopy.

Science.gov (United States)

Bohannon, Kevin P; Holz, Ronald W; Axelrod, Daniel

2017-10-01

The refractive index in the interior of single cells affects the evanescent field depth in quantitative studies using total internal reflection (TIR) fluorescence, but often that index is not well known. We here present method to measure and spatially map the absolute index of refraction in a microscopic sample, by imaging a collimated light beam reflected from the substrate/buffer/cell interference at variable angles of incidence. Above the TIR critical angle (which is a strong function of refractive index), the reflection is 100%, but in the immediate sub-critical angle zone, the reflection intensity is a very strong ascending function of incidence angle. By analyzing the angular position of that edge at each location in the field of view, the local refractive index can be estimated. In addition, by analyzing the steepness of the edge, the distance-to-substrate can be determined. We apply the technique to liquid calibration samples, silica beads, cultured Chinese hamster ovary cells, and primary culture chromaffin cells. The optical technique suffers from decremented lateral resolution, scattering, and interference artifacts. However, it still provides reasonable results for both refractive index (~1.38) and for distance-to-substrate (~150 nm) for the cells, as well as a lateral resolution to about 1 µm.

Quantum parameter estimation in the Unruh–DeWitt detector model

Energy Technology Data Exchange (ETDEWEB)

Hao, Xiang, E-mail: xhao@phas.ubc.ca [School of Mathematics and Physics, Suzhou University of Science and Technology, Suzhou, Jiangsu 215011 (China); Pacific Institute of Theoretical Physics, Department of Physics and Astronomy, University of British Columbia, 6224 Agriculture Rd., Vancouver B.C., Canada V6T 1Z1 (Canada); Wu, Yinzhong [School of Mathematics and Physics, Suzhou University of Science and Technology, Suzhou, Jiangsu 215011 (China)

2016-09-15

Relativistic effects on the precision of quantum metrology for particle detectors, such as two-level atoms are studied. The quantum Fisher information is used to estimate the phase sensitivity of atoms in non-inertial motions or in gravitational fields. The Unruh–DeWitt model is applicable to the investigation of the dynamics of a uniformly accelerated atom weakly coupled to a massless scalar vacuum field. When a measuring device is in the same relativistic motion as the atom, the dynamical behavior of quantum Fisher information as a function of Rindler proper time is obtained. It is found out that monotonic decrease in phase sensitivity is characteristic of dynamics of relativistic quantum estimation. The origin of the decay of quantum Fisher information is the thermal bath that the accelerated detector finds itself in due to the Unruh effect. To improve relativistic quantum metrology, we reasonably take into account two reflecting plane boundaries perpendicular to each other. The presence of the reflecting boundary can shield the detector from the thermal bath in some sense.

Effects of InGaN barriers with low indium content on internal quantum efficiency of blue InGaN multiple quantum wells

International Nuclear Information System (INIS)

Lai, Wang; Jia-Xing, Wang; Wei, Zhao; Xiang, Zou; Yi, Luo

2010-01-01

Blue In 0.2 Ga 0.8 N multiple quantum wells (MQWs) with In x Ga 1–x N (x = 0.01–0.04) barriers are grown by metal organic vapour phase epitaxy. The internal quantum efficiencies (IQEs) of these MQWs are studied in a way of temperature-dependent photoluminescence spectra. Furthermore, a 2-channel Arrhenius model is used to analyse the nonradiative recombination centres (NRCs). It is found that by adopting the InGaN barrier beneath the lowest well, it is possible to reduce the strain hence the NRCs in InGaN MQWs. By optimizing the thickness and the indium content of the InGaN barriers, the IQEs of InGaN/InGaN MQWs can be increased by about 2.5 times compared with conventional InGaN/GaN MQWs. On the other hand, the incorporation of indium atoms into the intermediate barriers between adjacent wells does not improve IQE obviously. In addition, the indium content of the intermediate barriers should match with that of the lowest barrier to avoid relaxation. (condensed matter: structure, thermal and mechanical properties)

Moessbauer neutrinos in quantum mechanics and quantum field theory

International Nuclear Information System (INIS)

Kopp, Joachim

2009-01-01

We demonstrate the correspondence between quantum mechanical and quantum field theoretical descriptions of Moessbauer neutrino oscillations. First, we compute the combined rate Γ of Moessbauer neutrino emission, propagation, and detection in quantum field theory, treating the neutrino as an internal line of a tree level Feynman diagram. We include explicitly the effect of homogeneous line broadening due to fluctuating electromagnetic fields in the source and detector crystals and show that the resulting formula for Γ is identical to the one obtained previously [1] for the case of inhomogeneous line broadening. We then proceed to a quantum mechanical treatment of Moessbauer neutrinos and show that the oscillation, coherence, and resonance terms from the field theoretical result can be reproduced if the neutrino is described as a superposition of Lorentz-shaped wave packet with appropriately chosen energies and widths. On the other hand, the emission rate and the detection cross section, including localization and Lamb-Moessbauer terms, cannot be predicted in quantum mechanics and have to be put in by hand.

Molecular quantum mechanical gradients within the polarizable embedding approach—Application to the internal vibrational Stark shift of acetophenone

International Nuclear Information System (INIS)

List, Nanna Holmgaard; Jensen, Hans Jørgen Aagaard; Kongsted, Jacob; Beerepoot, Maarten T. P.; Gao, Bin; Ruud, Kenneth; Olsen, Jógvan Magnus Haugaard

2015-01-01

We present an implementation of analytical quantum mechanical molecular gradients within the polarizable embedding (PE) model to allow for efficient geometry optimizations and vibrational analysis of molecules embedded in large, geometrically frozen environments. We consider a variational ansatz for the quantum region, covering (multiconfigurational) self-consistent-field and Kohn–Sham density functional theory. As the first application of the implementation, we consider the internal vibrational Stark effect of the C=O group of acetophenone in different solvents and derive its vibrational linear Stark tuning rate using harmonic frequencies calculated from analytical gradients and computed local electric fields. Comparisons to PE calculations employing an enlarged quantum region as well as to a non-polarizable embedding scheme show that the inclusion of mutual polarization between acetophenone and water is essential in order to capture the structural modifications and the associated frequency shifts observed in water. For more apolar solvents, a proper description of dispersion and exchange–repulsion becomes increasingly important, and the quality of the optimized structures relies to a larger extent on the quality of the Lennard-Jones parameters

Molecular quantum mechanical gradients within the polarizable embedding approach—Application to the internal vibrational Stark shift of acetophenone

Energy Technology Data Exchange (ETDEWEB)

List, Nanna Holmgaard, E-mail: nhl@sdu.dk; Jensen, Hans Jørgen Aagaard; Kongsted, Jacob [Department of Physics, Chemistry and Pharmacy, University of Southern Denmark, Campusvej 55, Odense M, Odense DK-5230 Denmark (Denmark); Beerepoot, Maarten T. P.; Gao, Bin; Ruud, Kenneth [Centre for Theoretical and Computational Chemistry, Department of Chemistry, University of Tromsø–The Arctic University of Norway, N-9037 Tromsø (Norway); Olsen, Jógvan Magnus Haugaard [Department of Physics, Chemistry and Pharmacy, University of Southern Denmark, Campusvej 55, Odense M, Odense DK-5230 Denmark (Denmark); Laboratory of Computational Chemistry and Biochemistry, Ecole Polytechnique Fédérale de Lausanne, CH-1015 Lausanne (Switzerland)

2015-01-21

We present an implementation of analytical quantum mechanical molecular gradients within the polarizable embedding (PE) model to allow for efficient geometry optimizations and vibrational analysis of molecules embedded in large, geometrically frozen environments. We consider a variational ansatz for the quantum region, covering (multiconfigurational) self-consistent-field and Kohn–Sham density functional theory. As the first application of the implementation, we consider the internal vibrational Stark effect of the C=O group of acetophenone in different solvents and derive its vibrational linear Stark tuning rate using harmonic frequencies calculated from analytical gradients and computed local electric fields. Comparisons to PE calculations employing an enlarged quantum region as well as to a non-polarizable embedding scheme show that the inclusion of mutual polarization between acetophenone and water is essential in order to capture the structural modifications and the associated frequency shifts observed in water. For more apolar solvents, a proper description of dispersion and exchange–repulsion becomes increasingly important, and the quality of the optimized structures relies to a larger extent on the quality of the Lennard-Jones parameters.

Quantum interaction. Proceedings

International Nuclear Information System (INIS)

Bruza, Peter; Rijsbergen, Keith van

2009-01-01

This book constitutes the refereed proceedings of the Third International Symposium on Quantum Interaction, QI 2009, held in Saarbruecken, Germany, in March 2009. The 21 revised full papers presented together with the 3 position papers were carefully reviewed and selected from numerous submissions. The papers show the cross-disciplinary nature of quantum interaction covering topics such as computation, cognition, decision theory, information retrieval, information systems, social interaction, computational linguistics and finance. (orig.)

Quantum interaction. Proceedings

Energy Technology Data Exchange (ETDEWEB)

Bruza, Peter [Queensland Univ. of Technology, Brisbane (Australia). Faculty of Science and Technology; Sofge, Donald [Navy Center for Applied Research in Artificial Intelligence, Washington, DC (United States). Naval Research Lab.; Lawless, William [Paine Coll., Augusta, GA (United States); Rijsbergen, Keith van [Glasgow Univ. (United Kingdom). Dept. of Computing Science; Klusch, Matthias (eds.) [German Research Center for Artificial Intelligence, Saarbruecken (Germany)

2009-07-01

This book constitutes the refereed proceedings of the Third International Symposium on Quantum Interaction, QI 2009, held in Saarbruecken, Germany, in March 2009. The 21 revised full papers presented together with the 3 position papers were carefully reviewed and selected from numerous submissions. The papers show the cross-disciplinary nature of quantum interaction covering topics such as computation, cognition, decision theory, information retrieval, information systems, social interaction, computational linguistics and finance. (orig.)

Room-temperature near-field reflection spectroscopy of single quantum wells

DEFF Research Database (Denmark)

Langbein, Wolfgang Werner; Hvam, Jørn Marcher; Madsen, Steen

1997-01-01

. This technique suppresses efficiently the otherwise dominating far-field background and reduces topographic artifacts. We demonstrate its performance on a thin, strained near-surface CdS/ZnS single quantum well at room temperature. The optical structure of these topographically flat samples is due to Cd...

Nonlinear quantum dynamics in diatomic molecules: Vibration, rotation and spin

International Nuclear Information System (INIS)

Yang, Ciann-Dong; Weng, Hung-Jen

2012-01-01

Highlights: ► This paper reveals the internal nonlinear dynamics embedded in a molecular quantum state. ► Analyze quantum molecular dynamics in a deterministic way, while preserving the consistency with probability interpretation. ► Molecular vibration–rotation interaction and spin–orbital coupling are considered simultaneously. ► Spin is just the remnant angular motion when orbital angular momentum is zero. ► Spin is the “zero dynamics” of nonlinear quantum dynamics. - Abstract: For a given molecular wavefunction Ψ, the probability density function Ψ ∗ Ψ is not the only information that can be extracted from Ψ. We point out in this paper that nonlinear quantum dynamics of a diatomic molecule, completely consistent with the probability prediction of quantum mechanics, does exist and can be derived from the quantum Hamilton equations of motion determined by Ψ. It can be said that the probability density function Ψ ∗ Ψ is an external representation of the quantum state Ψ, while the related Hamilton dynamics is an internal representation of Ψ, which reveals the internal mechanism underlying the externally observed random events. The proposed internal representation of Ψ establishes a bridge between nonlinear dynamics and quantum mechanics, which allows the methods and tools already developed by the former to be applied to the latter. Based on the quantum Hamilton equations of motion derived from Ψ, vibration, rotation and spin motions of a diatomic molecule and the interactions between them can be analyzed simultaneously. The resulting dynamic analysis of molecular motion is compared with the conventional probability analysis and the consistency between them is demonstrated.

Isoperiodic classical systems and their quantum counterparts

International Nuclear Information System (INIS)

Asorey, M.; Carinena, J.F.; Marmo, G.; Perelomov, A.

2007-01-01

One-dimensional isoperiodic classical systems have been first analyzed by Abel. Abel's characterization can be extended for singular potentials and potentials which are not defined on the whole real line. The standard shear equivalence of isoperiodic potentials can also be extended by using reflection and inversion transformations. We provide a full characterization of isoperiodic rational potentials showing that they are connected by translations, reflections or Joukowski transformations. Upon quantization many of these isoperiodic systems fail to exhibit identical quantum energy spectra. This anomaly occurs at order O(h 2 ) because semiclassical corrections of energy levels of order O(h) are identical for all isoperiodic systems. We analyze families of systems where this quantum anomaly occurs and some special systems where the spectral identity is preserved by quantization. Conversely, we point out the existence of isospectral quantum systems which do not correspond to isoperiodic classical systems

Distribution of electron density and internal rotation in phospha-alkenes according to data from quantum-chemical calculations by the MNDO method

International Nuclear Information System (INIS)

Boldeskul, I.E.; Pen'kovskii, V.V.; Povolotskii, M.I.

1988-01-01

A quantum-chemical investigation of the characteristics of the phosphorus-carbon bond and the internal rotation around it in phospha-alkenes has been carried out in the MNDO approximation. The results of the calculation have been compared with experimental dynamic 1 H NMR data

Quantum information processing with trapped ions

International Nuclear Information System (INIS)

Haeffner, H.; Haensel, W.; Rapol, U.; Koerber, T.; Benhelm, J.; Riebe, M.; Chek-al-Kar, D.; Schmidt-Kaler, F.; Becher, C.; Roos, C.; Blatt, R.

2005-01-01

Single Ca + ions and crystals of Ca + ions are confined in a linear Paul trap and are investigated for quantum information processing. Here we report on recent experimental advancements towards a quantum computer with such a system. Laser-cooled trapped ions are ideally suited systems for the investigation and implementation of quantum information processing as one can gain almost complete control over their internal and external degrees of freedom. The combination of a Paul type ion trap with laser cooling leads to unique properties of trapped cold ions, such as control of the motional state down to the zero-point of the trapping potential, a high degree of isolation from the environment and thus a very long time available for manipulations and interactions at the quantum level. The very same properties make single trapped atoms and ions well suited for storing quantum information in long lived internal states, e.g. by encoding a quantum bit (qubit) of information within the coherent superposition of the S 1/2 ground state and the metastable D 5/2 excited state of Ca + . Recently we have achieved the implementation of simple algorithms with up to 3 qubits on an ion-trap quantum computer. We will report on methods to implement single qubit rotations, the realization of a two-qubit universal quantum gate (Cirac-Zoller CNOT-gate), the deterministic generation of multi-particle entangled states (GHZ- and W-states), their full tomographic reconstruction, the realization of deterministic quantum teleportation, its quantum process tomography and the encoding of quantum information in decoherence-free subspaces with coherence times exceeding 20 seconds. (author)

History dependent quantum random walks as quantum lattice gas automata

Energy Technology Data Exchange (ETDEWEB)

Shakeel, Asif, E-mail: asif.shakeel@gmail.com, E-mail: dmeyer@math.ucsd.edu, E-mail: plove@haverford.edu; Love, Peter J., E-mail: asif.shakeel@gmail.com, E-mail: dmeyer@math.ucsd.edu, E-mail: plove@haverford.edu [Department of Physics, Haverford College, Haverford, Pennsylvania 19041 (United States); Meyer, David A., E-mail: asif.shakeel@gmail.com, E-mail: dmeyer@math.ucsd.edu, E-mail: plove@haverford.edu [Department of Mathematics, University of California/San Diego, La Jolla, California 92093-0112 (United States)

2014-12-15

Quantum Random Walks (QRW) were first defined as one-particle sectors of Quantum Lattice Gas Automata (QLGA). Recently, they have been generalized to include history dependence, either on previous coin (internal, i.e., spin or velocity) states or on previous position states. These models have the goal of studying the transition to classicality, or more generally, changes in the performance of quantum walks in algorithmic applications. We show that several history dependent QRW can be identified as one-particle sectors of QLGA. This provides a unifying conceptual framework for these models in which the extra degrees of freedom required to store the history information arise naturally as geometrical degrees of freedom on the lattice.

The Over-Barrier Resonant States and Multi-Channel Scattering in Multiple Quantum Wells

Directory of Open Access Journals (Sweden)

A Polupanov

2016-09-01

Full Text Available We demonstrate an explicit numerical method for accurate calculation of the scattering matrix and its poles, and apply this method to describe the multi-channel scattering in the multiple quantum-wells structures. The S-matrix is continued analytically to the unphysical region of complex energy values. Results of calculations show that there exist one or more S-matrix poles, corresponding to the over-barrier resonant states critical for the effect of the absolute reflection of holes in the energy range where only the heavy ones may propagate over barriers in a structure. Light- and heavy-hole states are described by the Luttinger Hamiltonian matrix. In contrast to the single quantum-well case, at some parameters of a multiple quantum-wells structure the number of S-matrix poles may exceed that of the absolute reflection peaks, and at different values of parameters the absolute reflection peak corresponds to different resonant states. The imaginary parts of the S-matrix poles and hence the lifetimes of resonant states as well as the widths of resonant peaks of absolute reflection depend drastically on the quantum-well potential depth. In the case of shallow quantum wells there is in fact a long-living over-barrier resonant hole state.

Particles and nuclei, letters; Proceedings of the international workshop 'Quantum Physics and Communication'

International Nuclear Information System (INIS)

Ivanov, V.V.

2003-01-01

The present collection of letters from JINR, Dubna, contains ten separate records on the microscopic entropy and nonlocality, conditional density matrix: systems and subsystems in quantum mechanics, physics of quantum computation, flipping qubits, quantum zeno effect for N-level Friedrichs model, universal hybrid quantum processors, formation of the SU(3)-polarization states in atom-quantum electromagnetic field system under condition of the Bose-Einstein condensate existence, periodical sequences (trajectories) of outcomes of atomic state measurement on exit from the micromaser cavity, an algebraic method to solve the Tavis-Cummings problem, quantum teleportation of nuclear matter and its investigation

Intradot spin-flip Andreev reflection tunneling through a ferromagnet-quantum dot-superconductor system with ac field

International Nuclear Information System (INIS)

Song Hongyan; Zhou Shiping

2008-01-01

We investigate Andreev reflection (AR) tunneling through a ferromagnet-quantum dot-superconductor (F-QD-S) system in the presence of an external ac field. The intradot spin-flip scattering in the QD is involved. Using the nonequilibrium Green function and BCS quasiparticle spectrum for superconductor, time-averaged AR conductance is formulated. The competition between the intradot spin-flip scattering and photon-assisted tunneling dominates the resonant behaviors of the time-averaged AR conductance. For weak intradot spin-flip scattering strengths, the AR conductance shows a series of equal interval resonant levels. However, the single-peak at main resonant level develops into a well-resolved double-peak resonance at a strong intradot spin-flip scattering strength. Remarkable, multiple-photon-assisted tunneling that generates photonic sideband peaks with a variable interval has been found. In addition, the AR conductance-bias voltage characteristic shows a transition between the single-peak to double-peak resonance as the ratio of the two tunneling strengths varies

Optimizing the internal quantum efficiency of GaInN SQW structures for green light emitters

International Nuclear Information System (INIS)

Fuhrmann, D.; Rossow, U.; Netzel, C.; Bremers, H.; Hangleiter, A.; Ade, G.; Hinze, P.

2006-01-01

Ga x In 1-x N/GaN single quantum well (QW) structures emitting in the range of 450 nm to 620 nm have been grown by MOVPE. Temperature and excitation power dependent photoluminescence (PL) was used to determine the internal quantum efficiency (IQE) for these structures. For the blue emitting QWs high IQE values on the order of 60% were achieved. Due to a reduced growth temperature, reduced growth rate and increased V/III ratio we obtained QWs with good morphology and high In content above 25%. Thinner QWs with high In content showed a clear improvement of IQE compared to QW-structures with larger thickness but smaller In-content emitting at the same wavelength. Between λ peak =460 nm and 530 nm we observed a slight reduction in IQE with values of 58% at 490 nm and 40% at 525 nm. But towards λ peak =620 nm IQE decreased due to the electric field induced separation of the electron and hole wavefunction down to 1%. (copyright 2006 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

Calorimetric Measurement for Internal Conversion Efficiency of Photovoltaic Cells/Modules Based on Electrical Substitution Method

Science.gov (United States)

Saito, Terubumi; Tatsuta, Muneaki; Abe, Yamato; Takesawa, Minato

2018-02-01

We have succeeded in the direct measurement for solar cell/module internal conversion efficiency based on a calorimetric method or electrical substitution method by which the absorbed radiant power is determined by replacing the heat absorbed in the cell/module with the electrical power. The technique is advantageous in that the reflectance and transmittance measurements, which are required in the conventional methods, are not necessary. Also, the internal quantum efficiency can be derived from conversion efficiencies by using the average photon energy. Agreements of the measured data with the values estimated from the nominal values support the validity of this technique.

Quantum linear Boltzmann equation

International Nuclear Information System (INIS)

Vacchini, Bassano; Hornberger, Klaus

2009-01-01

We review the quantum version of the linear Boltzmann equation, which describes in a non-perturbative fashion, by means of scattering theory, how the quantum motion of a single test particle is affected by collisions with an ideal background gas. A heuristic derivation of this Lindblad master equation is presented, based on the requirement of translation-covariance and on the relation to the classical linear Boltzmann equation. After analyzing its general symmetry properties and the associated relaxation dynamics, we discuss a quantum Monte Carlo method for its numerical solution. We then review important limiting forms of the quantum linear Boltzmann equation, such as the case of quantum Brownian motion and pure collisional decoherence, as well as the application to matter wave optics. Finally, we point to the incorporation of quantum degeneracies and self-interactions in the gas by relating the equation to the dynamic structure factor of the ambient medium, and we provide an extension of the equation to include internal degrees of freedom.

A Quantum Non-Demolition Parity measurement in a mixed-species trapped-ion quantum processor

Science.gov (United States)

Marinelli, Matteo; Negnevitsky, Vlad; Lo, Hsiang-Yu; Flühmann, Christa; Mehta, Karan; Home, Jonathan

2017-04-01

Quantum non-demolition measurements of multi-qubit systems are an important tool in quantum information processing, in particular for syndrome extraction in quantum error correction. We have recently demonstrated a protocol for quantum non-demolition measurement of the parity of two beryllium ions by detection of a co-trapped calcium ion. The measurement requires a sequence of quantum gates between the three ions, using mixed-species gates between beryllium hyperfine qubits and a calcium optical qubit. Our work takes place in a multi-zone segmented trap setup in which we have demonstrated high fidelity control of both species and multi-well ion shuttling. The advantage of using two species of ion is that we can individually manipulate and read out the state of each ion species without disturbing the internal state of the other. The methods demonstrated here can be used for quantum error correcting codes as well as quantum metrology and are key ingredients for realizing a hybrid universal quantum computer based on trapped ions. Mixed-species control may also enable the investigation of new avenues in quantum simulation and quantum state control. left the group and working in a company now.

Continuous-wave spatial quantum correlations of light induced by multiple scattering

DEFF Research Database (Denmark)

Smolka, Stephan; Ott, Johan Raunkjær; Huck, Alexander

2012-01-01

and reflectance. Utilizing frequency-resolved quantum noise measurements, we observe that the strength of the spatial quantum correlation function can be controlled by changing the quantum state of an incident bright squeezed-light source. Our results are found to be in excellent agreement with the developed......We present theoretical and experimental results on spatial quantum correlations induced by multiple scattering of nonclassical light. A continuous-mode quantum theory is derived that enables determining the spatial quantum correlation function from the fluctuations of the total transmittance...... theory and form a basis for future research on, e. g., quantum interference of multiple quantum states in a multiple scattering medium....

Numerical renormalization group calculation of impurity internal energy and specific heat of quantum impurity models

Science.gov (United States)

Merker, L.; Costi, T. A.

2012-08-01

We introduce a method to obtain the specific heat of quantum impurity models via a direct calculation of the impurity internal energy requiring only the evaluation of local quantities within a single numerical renormalization group (NRG) calculation for the total system. For the Anderson impurity model we show that the impurity internal energy can be expressed as a sum of purely local static correlation functions and a term that involves also the impurity Green function. The temperature dependence of the latter can be neglected in many cases, thereby allowing the impurity specific heat Cimp to be calculated accurately from local static correlation functions; specifically via Cimp=(∂Eionic)/(∂T)+(1)/(2)(∂Ehyb)/(∂T), where Eionic and Ehyb are the energies of the (embedded) impurity and the hybridization energy, respectively. The term involving the Green function can also be evaluated in cases where its temperature dependence is non-negligible, adding an extra term to Cimp. For the nondegenerate Anderson impurity model, we show by comparison with exact Bethe ansatz calculations that the results recover accurately both the Kondo induced peak in the specific heat at low temperatures as well as the high-temperature peak due to the resonant level. The approach applies to multiorbital and multichannel Anderson impurity models with arbitrary local Coulomb interactions. An application to the Ohmic two-state system and the anisotropic Kondo model is also given, with comparisons to Bethe ansatz calculations. The approach could also be of interest within other impurity solvers, for example, within quantum Monte Carlo techniques.

PREFACE: The 5th International Symposium on Quantum Theory and Symmetries (QTS5)

Science.gov (United States)

Gadella, M.; Izquierdo, J. M.; Kuru, S.; Negro, J.; del Olmo, M. A.

2008-08-01

This special issue of Journal of Physics A: Mathematical and Theoretical appears on the occasion of the 5th International Symposium on Quantum Theory and Symmetries (QTS5), held in Valladolid, Spain, from 22-28 July 2007. This is the fith in a series of conferences previously held in Goslar (Germany) 1999, QTS1; Cracow (Poland) 2001, QTS2; Cincinnati (USA) 2003, QTS3; and Varna (Bulgaria) 2005, QTS4. The QTS5 symposium gathered 181 participants from 39 countries working in different fields of theoretical physics. The spirit of the QTS conference series is to join researchers in a wide variety of topics in theoretical physics, as a way of making accessible recent results and the new lines of different fields. This is based on the feeling that it is good for a physicist to have a general overview as well as expertise in his/her own field. There are many other conferences devoted to specific topics, which are of interest to gain deeper insight in many technical aspects and that are quite suitable for discussions due to their small size. However, we believe that general conferences like this are interesting and worth keeping. We like the talks, in both plenary and parallel sessions, which are devoted to specific topics, to be prepared so as to be accessible to any researcher in any branch of theoretical physics. We think that this objective is compatible with rigour and high standards. As is well known, similar methods and techniques can be useful for many problems in different fields. We hope that this has been appreciated during the sessions of the QTS5 conference. The QTS5 conference offered the following list of topics: 1. Symmetries in string theory, quantum gravity and related topics 2. Symmetries in quantum field theories, conformal and related field theories, lattice and noncommutative theories, gauge theories 3.Quantum computing, information and control 4. Foundations of quantum theory 5. Quantum optics, coherent states, Wigner functions 6. Dynamical and

Constructivism Goes Quantum

Directory of Open Access Journals (Sweden)

Tatiana A. Alekseeva

2016-01-01

Full Text Available The article deals with the evolution of constructivist paradigm of international relations. The issue is of utmost importance in terms of the search for theoretical alternatives in the IR thinking. First, we are giving basic introduction of constructivism on the basis of historical and hermeneutical approaches. There is no doubt that the paradigm has faced different theoretical challenges and a lot of critics which has to be addressed. The authors reconsider some constructivist theories and notions in Alexander Wendt's works and the way Wendt tried to reinforce and reassure the constructivist paradigm. This allows us to claim that quantum turn in recent Wendt's work was almost inevitable. Second, the article attempts to answer a question whether the fundamentals of quantum physics are relevant when speaking about social and political processes. At first glance, quantum physics approach has nothing in common with the theory of politics and the theory of international relations. However, there are some grounds to believe that certain problem issues of the political science and IR theory are not deadlocks. In the second part of the article we use the unleashed and underestimated potential of analytical philosophy. To conclude, we believe that today there are more questions than answers but the quantum paradigm is expected to be the important part of the political studies and IR theory as well.

Fractional Quantum Hall States in a Ge Quantum Well.

Science.gov (United States)

Mironov, O A; d'Ambrumenil, N; Dobbie, A; Leadley, D R; Suslov, A V; Green, E

2016-04-29

Measurements of the Hall and dissipative conductivity of a strained Ge quantum well on a SiGe/(001)Si substrate in the quantum Hall regime are reported. We analyze the results in terms of thermally activated quantum tunneling of carriers from one internal edge state to another across saddle points in the long-range impurity potential. This shows that the gaps for different filling fractions closely follow the dependence predicted by theory. We also find that the estimates of the separation of the edge states at the saddle are in line with the expectations of an electrostatic model in the lowest spin-polarized Landau level (LL), but not in the spin-reversed LL where the density of quasiparticle states is not high enough to accommodate the carriers required.

Classification of quantum relativistic orientable objects

Energy Technology Data Exchange (ETDEWEB)

Gitman, D M [Instituto de Fisica, Universidade de Sao Paulo, Caixa Postal 66318-CEP, 05315-970, Sao Paulo, SP (Brazil); Shelepin, A L, E-mail: gitman@dfn.if.usp.br, E-mail: alex@shelepin.msk.ru [Moscow Institute of Radio Engineering, Electronics and Automation, Prospect Vernadskogo, 78, 117454 Moscow (Russian Federation)

2011-01-15

Extending our previous work 'Fields on the Poincare group and quantum description of orientable objects' (Gitman and Shelepin 2009 Eur. Phys. J. C 61 111-39), we consider here a classification of orientable relativistic quantum objects in 3+1 dimensions. In such a classification, one uses a maximal set of ten commuting operators (generators of left and right transformations) in the space of functions on the Poincare group. In addition to the usual six quantum numbers related to external symmetries (given by left generators), there appear additional quantum numbers related to internal symmetries (given by right generators). Spectra of internal and external symmetry operators are interrelated, which, however, does not contradict the Coleman-Mandula no-go theorem. We believe that the proposed approach can be useful for the description of elementary spinning particles considered as orientable objects. In particular, it gives a group-theoretical interpretation of some facts of the existing phenomenological classification of spinning particles.

Classification of quantum relativistic orientable objects

International Nuclear Information System (INIS)

Gitman, D M; Shelepin, A L

2011-01-01

Extending our previous work 'Fields on the Poincare group and quantum description of orientable objects' (Gitman and Shelepin 2009 Eur. Phys. J. C 61 111-39), we consider here a classification of orientable relativistic quantum objects in 3+1 dimensions. In such a classification, one uses a maximal set of ten commuting operators (generators of left and right transformations) in the space of functions on the Poincare group. In addition to the usual six quantum numbers related to external symmetries (given by left generators), there appear additional quantum numbers related to internal symmetries (given by right generators). Spectra of internal and external symmetry operators are interrelated, which, however, does not contradict the Coleman-Mandula no-go theorem. We believe that the proposed approach can be useful for the description of elementary spinning particles considered as orientable objects. In particular, it gives a group-theoretical interpretation of some facts of the existing phenomenological classification of spinning particles.

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

QED. Another rapidly growing research field (although its origin can be traced to the beginning of the 1980s) is the quantum control of evolution at the microscopic level. These examples show that quantum non-stationary systems continue to be a living and very interesting part of quantum physics, uniting researchers from many different areas. Thus it is no mere chance that several special scientific meetings devoted to these topics have been organized recently. One was the international seminar 'Time-Dependent Phenomena in Quantum Mechanics' organized by Manfred Kleber and Tobias Kramer in 2007 at Blaubeuren, Germany. The proceedings of that event were published in 2008 as volume 99 of Journal of Physics: Conference Series. Another recent meeting was the International Workshop on Quantum Non-Stationary Systems, held on 19-23 October 2009 at the International Center for Condensed Matter Physics (ICCMP) in Brasilia, Brazil. It was organized and directed by Victor Dodonov (Institute of Physics, University of Brasilia, Brazil), Vladimir Man'ko (P N Lebedev Physical Institute, Moscow, Russia) and Salomon Mizrahi (Physics Department, Federal University of Sao Carlos, Brazil). This event was accompanied by a satellite workshop 'Quantum Dynamics in Optics and Matter', organized by Salomon Mizrahi and Victor Dodonov on 25-26 October 2009 at the Physics Department of the Federal University of Sao Carlos, Brazil. These two workshops, supported by the Brazilian federal agencies CAPES and CNPq and the local agencies FAP-DF and FAPESP, were attended by more than 120 participants from 16 countries. Almost 50 invited talks and 20 poster presentations covered a wide area of research in quantum mechanics, quantum optics and quantum information. This special issue of CAMOP/Physica Scripta contains contributions presented by some invited speakers and participants of the workshop in Brasilia. Although they do not cover all of the wide spectrum of problems related to quantum non

BRICS and Quantum Information Processing

DEFF Research Database (Denmark)

Schmidt, Erik Meineche

1998-01-01

BRICS is a research centre and international PhD school in theoretical computer science, based at the University of Aarhus, Denmark. The centre has recently become engaged in quantum information processing in cooperation with the Department of Physics, also University of Aarhus. This extended...... abstract surveys activities at BRICS with special emphasis on the activities in quantum information processing....

Numerical analysis of the big bounce in loop quantum cosmology

International Nuclear Information System (INIS)

Laguna, Pablo

2007-01-01

Loop quantum cosmology (LQC) homogeneous models with a massless scalar field show that the big-bang singularity can be replaced by a big quantum bounce. To gain further insight on the nature of this bounce, we study the semidiscrete loop quantum gravity Hamiltonian constraint equation from the point of view of numerical analysis. For illustration purposes, we establish a numerical analogy between the quantum bounces and reflections in finite difference discretizations of wave equations triggered by the use of nonuniform grids or, equivalently, reflections found when solving numerically wave equations with varying coefficients. We show that the bounce is closely related to the method for the temporal update of the system and demonstrate that explicit time-updates in general yield bounces. Finally, we present an example of an implicit time-update devoid of bounces and show back-in-time, deterministic evolutions that reach and partially jump over the big-bang singularity

Quantum electrodynamics of strong fields

International Nuclear Information System (INIS)

Greiner, W.

1983-01-01

Quantum Electrodynamics of Strong Fields provides a broad survey of the theoretical and experimental work accomplished, presenting papers by a group of international researchers who have made significant contributions to this developing area. Exploring the quantum theory of strong fields, the volume focuses on the phase transition to a charged vacuum in strong electric fields. The contributors also discuss such related topics as QED at short distances, precision tests of QED, nonperturbative QCD and confinement, pion condensation, and strong gravitational fields In addition, the volume features a historical paper on the roots of quantum field theory in the history of quantum physics by noted researcher Friedrich Hund

Perfect quantum multiple-unicast network coding protocol

Science.gov (United States)

Li, Dan-Dan; Gao, Fei; Qin, Su-Juan; Wen, Qiao-Yan

2018-01-01

In order to realize long-distance and large-scale quantum communication, it is natural to utilize quantum repeater. For a general quantum multiple-unicast network, it is still puzzling how to complete communication tasks perfectly with less resources such as registers. In this paper, we solve this problem. By applying quantum repeaters to multiple-unicast communication problem, we give encoding-decoding schemes for source nodes, internal ones and target ones, respectively. Source-target nodes share EPR pairs by using our encoding-decoding schemes over quantum multiple-unicast network. Furthermore, quantum communication can be accomplished perfectly via teleportation. Compared with existed schemes, our schemes can reduce resource consumption and realize long-distance transmission of quantum information.

Reflection Negative Kernels and Fractional Brownian Motion

Directory of Open Access Journals (Sweden)

Palle E. T. Jorgensen

2018-06-01

Full Text Available In this article we study the connection of fractional Brownian motion, representation theory and reflection positivity in quantum physics. We introduce and study reflection positivity for affine isometric actions of a Lie group on a Hilbert space E and show in particular that fractional Brownian motion for Hurst index 0 < H ≤ 1 / 2 is reflection positive and leads via reflection positivity to an infinite dimensional Hilbert space if 0 < H < 1 / 2 . We also study projective invariance of fractional Brownian motion and relate this to the complementary series representations of GL 2 ( R . We relate this to a measure preserving action on a Gaussian L 2 -Hilbert space L 2 ( E .

How diverse are physics instructors’ attitudes and approaches to teaching undergraduate level quantum mechanics?

International Nuclear Information System (INIS)

Siddiqui, Shabnam; Singh, Chandralekha

2017-01-01

Understanding instructors’ attitudes and approaches to teaching undergraduate-level quantum mechanics can be helpful in developing effective instructional tools to help students learn quantum mechanics. Here we discuss the findings from a survey in which 12 university faculty members reflected on various issues related to undergraduate-level quantum mechanics teaching and learning. Topics included faculty members’ thoughts on the goals of a college quantum mechanics course, general challenges in teaching the subject matter, students’ preparation for the course, views about foundational issues and the difficulty in teaching certain topics, reflection on their own learning of quantum mechanics when they were students versus how they teach it to their students and the extent to which they incorporate contemporary topics into their courses. The findings related to instructors’ attitudes and approaches discussed here can be useful in improving teaching and learning of quantum mechanics. (paper)

Quantum state transfer and network engineering

International Nuclear Information System (INIS)

Nikolopoulos, Georgios M.; Jex, Igor

2014-01-01

Presents the basics of large-scale quantum information processing and networking. Covers most aspects of the problems of state transfer and quantum network engineering. Reflects the interdisciplinary nature of the field. Presents various theoretical approaches as well as possible implementations and related experiments. Faithful communication is a necessary precondition for large-scale quantum information processing and networking, irrespective of the physical platform. Thus, the problems of quantum-state transfer and quantum-network engineering have attracted enormous interest over the last years, and constitute one of the most active areas of research in quantum information processing. The present volume introduces the reader to fundamental concepts and various aspects of this exciting research area, including links to other related areas and problems. The implementation of state-transfer schemes and the engineering of quantum networks are discussed in the framework of various quantum optical and condensed matter systems, emphasizing the interdisciplinary character of the research area. Each chapter is a review of theoretical or experimental achievements on a particular topic, written by leading scientists in the field. The volume aims at both newcomers as well as experienced researchers.

Two Quantum Polytropic Cycles

Science.gov (United States)

Arias-Hernández, L. A.; Morales-Serrano, A. F.

2002-11-01

In this work we follow the Bender et al paper [1] to study the quantum analogues of the Stirling and Ericsson polytropic cycles. In the context of the classical thermodynamics, the Stirling and Ericsson cycles correspond to reversible heat engines with two isothermal processes joined by two polytropic branches which occur in a device called regenerator. If this device is an ideal one, the efficiency of these cycles is the Carnot efficiency. Here, we introduce the quantum analogues of the Stirling and Ericsson cycles, the first one based on a double square potential well with a finite potential barrier, since in this system the tunnel effect could be the analogue to the regeneration classical process, therefore the isochoric quantum branches would really correspond to an internal energy storage, and the last one with an unknown system where the isobaric quantum processes don't induce changes in its quantum state. With these systems the quantum engines have cycles consisting of polytropic and isothermal quantum processes analogues to the corresponding classical processes. We show that in both cases the quantum cycles have an efficiency given by ηCQM = 1 - EC/EH, which is the same expression for the quantum analogue of the Carnot cycle studied by Bender.

Casimir-Polder shifts on quantum levitation states

Science.gov (United States)

Crépin, P.-P.; Dufour, G.; Guérout, R.; Lambrecht, A.; Reynaud, S.

2017-03-01

An ultracold atom above a horizontal mirror experiences quantum reflection from the attractive Casimir-Polder interaction, which holds it against gravity and leads to quantum levitation states. We analyze this system by using a Liouville transformation of the Schrödinger equation and a Langer coordinate adapted to problems with a classical turning point. Reflection on the Casimir-Polder attractive well is replaced by reflection on a repulsive wall, and the problem is then viewed as an ultracold atom trapped inside a cavity with gravity and Casimir-Polder potentials acting, respectively, as top and bottom mirrors. We calculate numerically Casimir-Polder shifts of the energies of the cavity resonances and propose an approximate treatment which is precise enough to discuss spectroscopy experiments aimed at tests of the weak-equivalence principle on antihydrogen. We also discuss the lifetimes by calculating complex energies associated with cavity resonances.

Quantum interaction. Selected papers

Energy Technology Data Exchange (ETDEWEB)

Atmanspacher, Harald [Eidgenoessische Technische Hochschule, Zurich (Switzerland); Haven, Emmanuel [Leicester Univ. (United Kingdom). School of Management; Kitto, Kirsty [Queensland Univ. of Technology, Brisbane, QLD (Australia); Raine, Derek (ed.) [Leicester Univ. (United Kingdom). Centre for Interdisciplinary Science

2014-07-01

This book constitutes the refereed proceedings of the 7th International Conference on Quantum Interaction, QI 2013, held in Leicester, UK, in July 2013. The 31 papers presented in this book were carefully selected from numerous submissions. The papers cover various topics on quantum interaction and revolve around four themes: information processing/retrieval/semantic representation and logic; cognition and decision making; finance/economics and social structures and biological systems.

Quantum interaction. Selected papers

International Nuclear Information System (INIS)

Atmanspacher, Harald; Haven, Emmanuel; Raine, Derek

2014-01-01

This book constitutes the refereed proceedings of the 7th International Conference on Quantum Interaction, QI 2013, held in Leicester, UK, in July 2013. The 31 papers presented in this book were carefully selected from numerous submissions. The papers cover various topics on quantum interaction and revolve around four themes: information processing/retrieval/semantic representation and logic; cognition and decision making; finance/economics and social structures and biological systems.

Quantum Phase Extraction in Isospectral Electronic Nanostructures

Energy Technology Data Exchange (ETDEWEB)

Moon, Christopher

2010-04-28

Quantum phase is not a direct observable and is usually determined by interferometric methods. We present a method to map complete electron wave functions, including internal quantum phase information, from measured single-state probability densities. We harness the mathematical discovery of drum-like manifolds bearing different shapes but identical resonances, and construct quantum isospectral nanostructures possessing matching electronic structure but divergent physical structure. Quantum measurement (scanning tunneling microscopy) of these 'quantum drums' [degenerate two-dimensional electron states on the Cu(111) surface confined by individually positioned CO molecules] reveals that isospectrality provides an extra topological degree of freedom enabling robust quantum state transplantation and phase extraction.

Emergence of liquid crystalline order in the lowest Landau level of a quantum Hall system with internal anisotropy

Science.gov (United States)

Ciftja, Orion

2018-05-01

It has now become evident that interplay between internal anisotropy parameters (such as electron mass anisotropy and/or anisotropic coupling of electrons to the substrate) and electron-electron correlation effects can create a rich variety of possibilities especially in quantum Hall systems. The electron mass anisotropy or material substrate effects (for example, the piezoelectric effect in GaAs) can lead to an effective anisotropic interaction potential between electrons. For lack of knowledge of realistic ab-initio potentials that may describe such effects, we adopt a phenomenological approach and assume that an anisotropic Coulomb interaction potential mimics the internal anisotropy of the system. In this work we investigate the emergence of liquid crystalline order at filling factor ν = 1/6 of the lowest Landau level, a state very close to the point where a transition from the liquid to the Wigner solid happens. We consider small finite systems of electrons interacting with an anisotropic Coulomb interaction potential and study the energy stability of an anisotropic liquid crystalline state relative to its isotropic Fermi-liquid counterpart. Quantum Monte Carlo simulation results in disk geometry show stabilization of liquid crystalline order driven by an anisotropic Coulomb interaction potential at all values of the interaction anisotropy parameter studied.

Discrete Lorentzian quantum gravity

NARCIS (Netherlands)

Loll, R.

2000-01-01

Just as for non-abelian gauge theories at strong coupling, discrete lattice methods are a natural tool in the study of non-perturbative quantum gravity. They have to reflect the fact that the geometric degrees of freedom are dynamical, and that therefore also the lattice theory must be formulated

Quantum-like behavior without quantum physics I : Kinematics of neural-like systems.

Science.gov (United States)

Selesnick, S A; Rawling, J P; Piccinini, Gualtiero

2017-09-01

Recently there has been much interest in the possible quantum-like behavior of the human brain in such functions as cognition, the mental lexicon, memory, etc., producing a vast literature. These studies are both empirical and theoretical, the tenets of the theory in question being mainly, and apparently inevitably, those of quantum physics itself, for lack of other arenas in which quantum-like properties are presumed to obtain. However, attempts to explain this behavior on the basis of actual quantum physics going on at the atomic or molecular level within some element of brain or neuronal anatomy (other than the ordinary quantum physics that underlies everything), do not seem to survive much scrutiny. Moreover, it has been found empirically that the usual physics-like Hilbert space model seems not to apply in detail to human cognition in the large. In this paper we lay the groundwork for a theory that might explain the provenance of quantum-like behavior in complex systems whose internal structure is essentially hidden or inaccessible. The approach is via the logic obeyed by these systems which is similar to, but not identical with, the logic obeyed by actual quantum systems. The results reveal certain effects in such systems which, though quantum-like, are not identical to the kinds of quantum effects found in physics. These effects increase with the size of the system.

Effects of quantum well growth temperature on the recombination efficiency of InGaN/GaN multiple quantum wells that emit in the green and blue spectral regions

Energy Technology Data Exchange (ETDEWEB)

Hammersley, S.; Dawson, P. [School of Physics and Astronomy, Photon Science Institute, University of Manchester, Manchester M13 9PL (United Kingdom); Kappers, M. J.; Massabuau, F. C.-P.; Sahonta, S.-L.; Oliver, R. A.; Humphreys, C. J. [Department of Materials Science and Metallurgy, University of Cambridge, 27 Charles Babbage Road, Cambridge CB3 0FS (United Kingdom)

2015-09-28

InGaN-based light emitting diodes and multiple quantum wells designed to emit in the green spectral region exhibit, in general, lower internal quantum efficiencies than their blue-emitting counter parts, a phenomenon referred to as the “green gap.” One of the main differences between green-emitting and blue-emitting samples is that the quantum well growth temperature is lower for structures designed to emit at longer wavelengths, in order to reduce the effects of In desorption. In this paper, we report on the impact of the quantum well growth temperature on the optical properties of InGaN/GaN multiple quantum wells designed to emit at 460 nm and 530 nm. It was found that for both sets of samples increasing the temperature at which the InGaN quantum well was grown, while maintaining the same indium composition, led to an increase in the internal quantum efficiency measured at 300 K. These increases in internal quantum efficiency are shown to be due reductions in the non-radiative recombination rate which we attribute to reductions in point defect incorporation.

Effects of quantum well growth temperature on the recombination efficiency of InGaN/GaN multiple quantum wells that emit in the green and blue spectral regions

International Nuclear Information System (INIS)

Hammersley, S.; Dawson, P.; Kappers, M. J.; Massabuau, F. C.-P.; Sahonta, S.-L.; Oliver, R. A.; Humphreys, C. J.

2015-01-01

InGaN-based light emitting diodes and multiple quantum wells designed to emit in the green spectral region exhibit, in general, lower internal quantum efficiencies than their blue-emitting counter parts, a phenomenon referred to as the “green gap.” One of the main differences between green-emitting and blue-emitting samples is that the quantum well growth temperature is lower for structures designed to emit at longer wavelengths, in order to reduce the effects of In desorption. In this paper, we report on the impact of the quantum well growth temperature on the optical properties of InGaN/GaN multiple quantum wells designed to emit at 460 nm and 530 nm. It was found that for both sets of samples increasing the temperature at which the InGaN quantum well was grown, while maintaining the same indium composition, led to an increase in the internal quantum efficiency measured at 300 K. These increases in internal quantum efficiency are shown to be due reductions in the non-radiative recombination rate which we attribute to reductions in point defect incorporation

Experimental status of quaternionic quantum mechanics

International Nuclear Information System (INIS)

Brumby, S.P.; Joshi, G.C.

1995-01-01

Analysis of the logical foundations of quantum mechanics indicates the possibility of constructing a theory using quaternionic Hilbert spaces. Whether this mathematical structure reflects reality is a matter for experiment to decide. The only direct search for quaternionic quantum mechanics yet carried out is reviewed and is proposed to look for quaternionic effects in correlated multi-particle systems. It is also discussed how such experiments might distinguish between the several quaternionic models proposed in the literature. 21 refs

Nonpolarizing beam splitter designed by frustrated total internal reflection inside a glass cube.

Science.gov (United States)

Xu, Xueke; Shao, Jianda; Fan, Zhengxiu

2006-06-20

A method for the design of an all-dielectric nonpolarizing prism beam splitter utilizing the principle of frustrated total internal reflection is reported. The nonpolarizing condition for a prism beam splitter is discussed, and some single layer design examples are elaborated. The concept can be applied to a wide range of wavelengths and arbitrary transmittance values, and with the help of a computer design program examples of 400-700 nm, T(p)=T(s)=0.5+/-0.01, with incident angles of 45 degrees and 62 degrees are given. In addition, the sensitivity and application of the design are also discussed.

Minimal computational-space implementation of multiround quantum protocols

International Nuclear Information System (INIS)

Bisio, Alessandro; D'Ariano, Giacomo Mauro; Perinotti, Paolo; Chiribella, Giulio

2011-01-01

A single-party strategy in a multiround quantum protocol can be implemented by sequential networks of quantum operations connected by internal memories. Here, we provide an efficient realization in terms of computational-space resources.

Reconstruction of abstract quantum theory

International Nuclear Information System (INIS)

Drieschner, M.; Goernitz, T.; von Weizsaecker, C.F.

1988-01-01

Understanding quantum theory as a general theory of prediction, we reconstruct abstract quantum theory. Abstract means the general frame of quantum theory, without reference to a three-dimensional position space, to concepts like particle or field, or to special laws of dynamics. Reconstruction is the attempt to do this by formulating simple and plausible postulates on prediction in order to derive the basic concepts of quantum theory from them. Thereby no law of classical physics is presupposed which would then have to be quantized. We briefly discuss the relationship of theory and interpretation in physics and the fundamental role of time as a basic concept for physics. Then a number of assertions are given, formulated as succinctly as possible in order to make them easily quotable and comparable. The assertations are arranged in four groups: heuristic principles, verbal definitions of some terms, three basic postulates, and consequences. The three postulates of separable alternatives, indeterminism, and kinematics are the central points of this work. These brief assertions are commented upon, and their relationship with the interpretation of quantum theory is discussed. Also given are an outlook on the further development into concrete quantum theory and some philosophical reflections

Optical manifestation of magnetoexcitons in near-surface quantum wells

Energy Technology Data Exchange (ETDEWEB)

Flores-Desirena, B.; Perez-Rodriguez, F

2003-05-15

The optical response of excitons in quantum wells, close to the sample boundary and under the action of a strong magnetic field perpendicular to their plane, is investigated theoretically. Solving the system of coupled equations for the coherent electron-hole interband amplitude and the electromagnetic field, reflectivity spectra for such nanostructures are calculated. The effect of the interaction of magnetoexcitons with the sample surface on the resonance structure of reflectivity spectra is analyzed. These optical spectra are also affected by the phase change of the electromagnetic wave as it propagates in the cap layer, overlying the quantum well.

Common-path configuration in total internal reflection digital holography microscopy.

Science.gov (United States)

Calabuig, Alejandro; Matrecano, Marcella; Paturzo, Melania; Ferraro, Pietro

2014-04-15

Total Internal Reflection Digital Holographic Microscopy (TIRDHM) is recognized to be a powerful tool for retrieving quantitative phase images of cell-substrate interfaces, adhesions, and tissue structures close to the prism surface. In this Letter, we develop an improved TIRDHM system, taking advantage of a refractive index mismatch between the prism and the sample substrate, to allow phase-shifting DH with just a single-beam interferometric configuration. Instead of the traditional off-axis method, phase-shift method is used to retrieve amplitude and phase images in coherent light and TIR modality. Essentially, the substrate-prism interface acts like a beam splitter generating a reference beam, where the phase-shift dependence on the incident angle is exploited in this common-path configuration. With the aim to demonstrate the technique's validity, some experiments are performed to establish the advantage of this compact and simple configuration, in which the reference arm in the setup is avoided.

Quantum correlations of coupled superconducting two-qubit system in various cavity environments

International Nuclear Information System (INIS)

Yu, Yanxia; Fu, Guolan; Guo, L.P.; Pan, Hui; Wang, Z.S.

2013-01-01

Highlights: •We investigate dynamic evolutions of quantum and classical correlations for coupled superconducting system with various cavity environments. •We show that the quantum discord continues to reflect quantum information. •A transition of quantum discord is founded between classical loss and quantum increasing of correlations for a purely dephasing mode. •We show that the environment-dependent models can delay the loss of quantum discord. •We find that the results depend strongly on the initial angle. -- Abstract: Dynamic evolutions of quantum discord, concurrence, and classical correlation are investigated in coupled superconducting system with various cavity environments, focusing on the two-qubit system at an initially entangling X-state and Y-state. We find that for a smaller photon number, the quantum discord, concurrence and classical correlation show damped oscillations for all different decay modes. Differently from the sudden death or the dark and bright periods emerging in evolving processing of the concurrence and classical correlation, however, the quantum discord decreases gradually to zero. The results reveal that the quantum entanglement and classical correlation are lost, but the quantum discord continues to reflect quantum information in the same evolving period. For a larger photon number, the oscillations disappear. It is surprised that there exists a transition of quantum discord between classical loss and quantum increasing of correlations for a purely dephasing mode. For a larger photon number in the Y-state, the transition disappears. Moreover, we show that the environment-dependent models can delay the loss of quantum discord. The results depend strongly on the initial angle, which provide a clue to control the quantum gate of superconducting circuit

Trapping of microwave radiation in hollow polypyrrole microsphere through enhanced internal reflection: A novel approach

OpenAIRE

Ritwik Panigrahi; Suneel K. Srivastava

2015-01-01

In present work, spherical core (polystyrene, PS)/shell (polypyrrole, PPy) has been synthesized via in situ chemical oxidative copolymerization of pyrrole (Py) on the surface of sulfonated PS microsphere followed by the formation of hollow polypyrrole (HPPy) shell by dissolving PS inner core in THF. Thereafter, we first time established that such fabricated novel art of morphology acts as a conducting trap in absorbing electromagnetic (EM) wave by internal reflection. Further studies have bee...

Gaussian Hypothesis Testing and Quantum Illumination.

Science.gov (United States)

Wilde, Mark M; Tomamichel, Marco; Lloyd, Seth; Berta, Mario

2017-09-22

Quantum hypothesis testing is one of the most basic tasks in quantum information theory and has fundamental links with quantum communication and estimation theory. In this paper, we establish a formula that characterizes the decay rate of the minimal type-II error probability in a quantum hypothesis test of two Gaussian states given a fixed constraint on the type-I error probability. This formula is a direct function of the mean vectors and covariance matrices of the quantum Gaussian states in question. We give an application to quantum illumination, which is the task of determining whether there is a low-reflectivity object embedded in a target region with a bright thermal-noise bath. For the asymmetric-error setting, we find that a quantum illumination transmitter can achieve an error probability exponent stronger than a coherent-state transmitter of the same mean photon number, and furthermore, that it requires far fewer trials to do so. This occurs when the background thermal noise is either low or bright, which means that a quantum advantage is even easier to witness than in the symmetric-error setting because it occurs for a larger range of parameters. Going forward from here, we expect our formula to have applications in settings well beyond those considered in this paper, especially to quantum communication tasks involving quantum Gaussian channels.

Emergence of quantum mechanics from classical statistics

International Nuclear Information System (INIS)

Wetterich, C

2009-01-01

The conceptual setting of quantum mechanics is subject to an ongoing debate from its beginnings until now. The consequences of the apparent differences between quantum statistics and classical statistics range from the philosophical interpretations to practical issues as quantum computing. In this note we demonstrate how quantum mechanics can emerge from classical statistical systems. We discuss conditions and circumstances for this to happen. Quantum systems describe isolated subsystems of classical statistical systems with infinitely many states. While infinitely many classical observables 'measure' properties of the subsystem and its environment, the state of the subsystem can be characterized by the expectation values of only a few probabilistic observables. They define a density matrix, and all the usual laws of quantum mechanics follow. No concepts beyond classical statistics are needed for quantum physics - the differences are only apparent and result from the particularities of those classical statistical systems which admit a quantum mechanical description. In particular, we show how the non-commuting properties of quantum operators are associated to the use of conditional probabilities within the classical system, and how a unitary time evolution reflects the isolation of the subsystem.

Second-harmonic imaging of semiconductor quantum dots

DEFF Research Database (Denmark)

Østergaard, John Erland; Bozhevolnyi, Sergey I.; Pedersen, Kjeld

2000-01-01

Resonant second-harmonic generation is observed at room temperature in reflection from self-assembled InAlGaAs quantum dots grown on a GaAs (001) substrate. The detected second-harmonic signal peaks at a pump wavelength of similar to 885 nm corresponding to the quantum-dot photoluminescence maximum....... In addition, the second-harmonic spectrum exhibits another smaller but well-pronounced peak at 765 nm not found in the linear experiments. We attribute this peak to the generation of second-harmonic radiation in the AlGaAs spacer layer enhanced by the local symmetry at the quantum-dot interface. We further...

Macroscopic quantum systems and gravitational phenomena

International Nuclear Information System (INIS)

Pikovski, I.

2014-01-01

Low-energy quantum systems are studied theoretically in light of possible experiments to test the interplay between quantum theory and general relativity. The research focus in this thesis is on quantum systems which can be controlled with very high precision and which allow for tests of quantum theory at novel scales in terms of mass and size. The pulsed regime of opto-mechanics is explored and it is shown how short optical pulses can be used to prepare and characterize quantum states of a massive mechanical resonator, and how some phenomenological models of quantum gravity can be probed. In addition, quantum interferometry with photons and matter-waves in the presence of gravitational time dilation is considered. It is shown that time dilation causes entanglement between internal states and the center-of-mass position and that it leads to decoherence of all composite quantum systems. The results of the thesis show that the interplay between quantum theory and general relativity affects even low-energy quantum systems and that it offers novel phenomena which can be probed in experiments. (author) [de

VII International Symposium and Young Scientists School “Modern Problems of Laser Physics”

International Nuclear Information System (INIS)

2017-01-01

General Information This volume of the Journal is devoted to the VII International Symposium and Young Scientists School “Modern Problems of Laser Physics” (MPLP-2016). I was held in Novosibirsk Akademgorodok, Russia, 22–28 August 2016. Akademgorodok is the well-known Siberian Scientific Centre of Russian Academy of Sciences (RAS). It was founded in 1957. Since that time it is the place of many international scientific meetings, because it reflects the unique and fruitful symbiosis of many research institutions and Novosibirsk State University at one territory. Since the first MPLP meeting in 1995 the Symposium usually gathers scientists from many countries, carrying out their investigations at the forefront of laser physics, quantum metrology and high-resolution spectroscopy, physics of ultracold atoms, molecules and ions, atom optics, ultrafast phenomena and attoscience, quantum optics and information, nonlinear optics and applications of laser radiation from THz to UV radiation ranges in medicine, geophysics, chemistry and microbiology. Traditionally the Symposium is the place where scientists can discuss new trends in modern laser physics, generate new ideas as well as initiate further collaborations. (paper)

Mechanical Resonators for Quantum Optomechanics Experiments at Room Temperature.

Science.gov (United States)

Norte, R A; Moura, J P; Gröblacher, S

2016-04-08

All quantum optomechanics experiments to date operate at cryogenic temperatures, imposing severe technical challenges and fundamental constraints. Here, we present a novel design of on-chip mechanical resonators which exhibit fundamental modes with frequencies f and mechanical quality factors Q_{m} sufficient to enter the optomechanical quantum regime at room temperature. We overcome previous limitations by designing ultrathin, high-stress silicon nitride (Si_{3}N_{4}) membranes, with tensile stress in the resonators' clamps close to the ultimate yield strength of the material. By patterning a photonic crystal on the SiN membranes, we observe reflectivities greater than 99%. These on-chip resonators have remarkably low mechanical dissipation, with Q_{m}∼10^{8}, while at the same time exhibiting large reflectivities. This makes them a unique platform for experiments towards the observation of massive quantum behavior at room temperature.

Anthropology and the peasant class: the pertinence of the persistent. Anthropological reflections on peasant internationalism

Directory of Open Access Journals (Sweden)

Raúl Hernán Contreras Román

2015-12-01

Full Text Available The present article develops an initial discussion on the persistence of the peasant class in anthropology as an awkward object, which since it has become asubject for the discipline has  obliged anthropologists to re-examine their disciplinary identity and re-think their theoretical  bases. We start from the idea that both the emergence and the decline of peasant studies in the discipline have corresponded with localizable social, intellectual and political contexts. For this  reason we present the current struggle of peasant internationalism, represented by the international movement Vía Campesina, for food sovereignty and international recognition of the  rights of peasant men and women. These struggles are considered to constitute a politically novel space which has the potential to generate political opportunities for peasant claims in the face of  neoliberal despoliation. Finally, we reflect on how these struggles again present the peasant class as an awkward object for anthropology and demand anthropological discussion of the subject.

Quantum work in the Bohmian framework

Science.gov (United States)

Sampaio, R.; Suomela, S.; Ala-Nissila, T.; Anders, J.; Philbin, T. G.

2018-01-01

At nonzero temperature classical systems exhibit statistical fluctuations of thermodynamic quantities arising from the variation of the system's initial conditions and its interaction with the environment. The fluctuating work, for example, is characterized by the ensemble of system trajectories in phase space and, by including the probabilities for various trajectories to occur, a work distribution can be constructed. However, without phase-space trajectories, the task of constructing a work probability distribution in the quantum regime has proven elusive. Here we use quantum trajectories in phase space and define fluctuating work as power integrated along the trajectories, in complete analogy to classical statistical physics. The resulting work probability distribution is valid for any quantum evolution, including cases with coherences in the energy basis. We demonstrate the quantum work probability distribution and its properties with an exactly solvable example of a driven quantum harmonic oscillator. An important feature of the work distribution is its dependence on the initial statistical mixture of pure states, which is reflected in higher moments of the work. The proposed approach introduces a fundamentally different perspective on quantum thermodynamics, allowing full thermodynamic characterization of the dynamics of quantum systems, including the measurement process.

Topological quantum field theories in terms of coloured graphs associated to quantum groups

International Nuclear Information System (INIS)

Karowski, M.

1993-01-01

Apart from obvious mathematical applications the investigation is motivated by the problem of braid group statistics in physics. Statistics is one of the central concepts in many body quantum systems. Consider a system of two identical particles located at x 1 and x 2 in R d with Schroedinger wave function ψ(x 1 , x 2 ). Under the exchange of particles with these coordinates one usually has Bose or Fermi statistics in case ψ(x 2 , x 1 )=±ψ(x-1,x T 2). For a quick access to the problem consider the following classical geometric space-time description of the exchange of position for two identical particles, reflecting itself in two quantum mechanical transformation laws. We briefly review the set-up of topological quantum field theory and present our new formulation in terms of coloured graphs. (orig.)

Repulsive Casimir-Polder potential by a negative reflecting surface

Science.gov (United States)

Yuan, Qi-Zhang

2015-07-01

We present a scheme to generate an all-range long repulsive Casimir-Polder potential between a perfect negative reflecting surface and a ground-state atom. The repulsive potential is stable and does not decay with time. The Casimir-Polder potential is proportional to z-2 at short atom-surface distances and to z-4 at long atom-surface distances. Because of these advantages, this potential can help in building quantum reflectors, quantum levitating devices, and waveguides for matter waves.

PREFACE: 5th International Workshop DICE2010: Space-Time-Matter - Current Issues in Quantum Mechanics and Beyond

Science.gov (United States)

Diósi, Lajos; Elze, Hans-Thomas; Fronzoni, Leone; Halliwell, Jonathan; Prati, Enrico; Vitiello, Giuseppe; Yearsley, James

2011-07-01

These proceedings present the Invited Lectures and Contributed Papers of the Fifth International Workshop on Decoherence, Information, Complexity and Entropy - DICE 2010, held at Castello Pasquini, Castiglioncello (Tuscany), 13-17 September 2010. These proceedings are intended to document the stimulating exchange of ideas at this conference for both the interested public and the wider scientific community, as well as for the participants. The number of participants attending this series of meetings has been growing steadily, which reflects its increasing attraction. Our intention to bring together leading researchers, advanced students, and renowned scholars from various areas in order to stimulate new ideas and their exchange across the borders of specialization seems to bear fruit. In this way, the series of meetings has continued successfully from the beginning with DICE 2002 [1], followed by DICE 2004 [2], DICE 2006 [3], and DICE 2008 [4], uniting more than 100 participants representing almost 30 countries worldwide. It has been a great honour and inspiration to have Professor Luc Montagnier (Nobel Prize for Medicine 2008) from the World Foundation for AIDS Research and Prevention with us, who presented the lecture DNA waves and water (included in this volume). The discussions took place under the wider theme Space-Time-Matter - current issues in quantum mechanics and beyond in the very pleasant and inspiring atmosphere of Castello Pasquini, which - with its beautiful surroundings, overlooking the Tuscany coast - hosted the conference very successfully for the second time. The five-day program was grouped according to the following topics: Gravity and Quantum Mechanics Quantum Coherent Processes in Biology / Many-Body Systems From Quantum Foundations to Particle Physics The Deep Structure of Spacetime Quantum - Relativity - Cosmology A Public Roundtable Discussion formed an integral part of the program under the theme Sull' Onda Della Coerenza" - le nuove

Analysis of thin-film polymers using attenuated total internal reflection-Raman microspectroscopy.

Science.gov (United States)

Tran, Willie; Tisinger, Louis G; Lavalle, Luis E; Sommer, André J

2015-01-01

Two methods commonly employed for molecular surface analysis and thin-film analysis of microscopic areas are attenuated total reflection infrared (ATR-IR) microspectroscopy and confocal Raman microspectroscopy. In the former method, the depth of the evanescent probe beam can be controlled by the wavelength of light, the angle of incidence, or the refractive index of the internal reflection element. Because the penetration depth is proportional to the wavelength of light, one could interrogate a smaller film thickness by moving from the mid-infrared region to the visible region employing Raman spectroscopy. The investigation of ATR Raman microspectroscopy, a largely unexplored technique available to Raman microspectroscopy, was carried out. A Renishaw inVia Raman microscope was externally modified and used in conjunction with a solid immersion lens (SIL) to perform ATR Raman experiments. Thin-film polymer samples were analyzed to explore the theoretical sampling depth for experiments conducted without the SIL, with the SIL, and with the SIL using evanescent excitation. The feasibility of micro-ATR Raman was examined by collecting ATR spectra from films whose thickness measured from 200 to 60 nm. Films of these thicknesses were present on a much thicker substrate, and features from the underlying substrate did not become visible until the thin film reached a thickness of 68 nm.

Single-Molecule Fluorescence Studies of Membrane Transporters Using Total Internal Reflection Microscopy.

Science.gov (United States)

Goudsmits, Joris M H; van Oijen, Antoine M; Slotboom, Dirk J

2017-01-01

Cells are delineated by a lipid bilayer that physically separates the inside from the outer environment. Most polar, charged, or large molecules require proteins to reduce the energetic barrier for passage across the membrane and to achieve transport rates that are relevant for life. Here, we describe techniques to visualize the functioning of membrane transport proteins with fluorescent probes at the single-molecule level. First, we explain how to produce membrane-reconstituted transporters with fluorescent labels. Next, we detail the construction of a microfluidic flow cell to image immobilized proteoliposomes on a total internal reflection fluorescence microscope. We conclude by describing the methods that are needed to analyze fluorescence movies and obtain useful single-molecule data. © 2017 Elsevier Inc. All rights reserved.

Recent additions to fundament aspects of quantum mechanics

International Nuclear Information System (INIS)

Flamm, D.

1991-01-01

Problems like those of Schroedinger's can comprise quantum systems as classical systems, the measurement process and reality. After a reviewing the history of interpretation of quantum mechanics it is shown how a generalized algebraic quantum theory (e.g. G.G. Emch 1986) can tackle these problems and paradoxes. This theory treats systems with infinite degrees of freedom and open systems. It is applicable both to quantum as to classical systems and thus to the measurement process with its irreversibility. The usual linear Schroedinger equation is replaced by a non-linear one where the nonlinear terms reflect the interaction of the system with its environment or with the measuring apparatus. (Quittner) To appear also in 'Naturwissenschaft und Weltbild', 1992

Single cell adhesion strength assessed with variable-angle total internal reflection fluorescence microscopy

Directory of Open Access Journals (Sweden)

Marcelina Cardoso Dos Santos

2017-06-01

Full Text Available We propose a new strategy to evaluate adhesion strength at the single cell level. This approach involves variable-angle total internal reflection fluorescence microscopy to monitor in real time the topography of cell membranes, i.e. a map of the membrane/substrate separation distance. According to the Boltzmann distribution, both potential energy profile and dissociation energy related to the interactions between the cell membrane and the substrate were determined from the membrane topography. We have highlighted on glass substrates coated with poly-L-lysine and fibronectin, that the dissociation energy is a reliable parameter to quantify the adhesion strength of MDA-MB-231 motile cells.

The pure phases, the irreducible quantum fields, and dynamical symmetry breaking in Symanzik--Nelson positive quantum field theories

International Nuclear Information System (INIS)

Frohlich, J.

1976-01-01

We prove that a Symanzik--Nelson positive quantum field theory, i.e., a quantum field theory derived from a Euclidean field theory, has a unique decomposition into pure phases which preserves Symanzik--Nelson positivity and Poincare covariance. We derive useful sufficient conditions for the breakdown of an internal symmetry of such a theory in its pure phases, for the self-adjointness and nontrivially (in the sense of Borchers classes) of its quantum fields, and the existence of time-ordered and retarded products. All these general results are then applied to the P (phi) 2 and the phi 3 4 quantum field models

On the quantum dynamical foundations of collision terms

International Nuclear Information System (INIS)

Nemes, M.C.; Toledo Piza, A.F.R. de

1981-08-01

Collision terms are non-unitary corrections usually added to mean field descriptions in order to describe dissipative effects. Derivations of collision terms usually include assumptions which lack an explicit connection with a fully quantum dynamical description. Quantum dynamical foundations of collision terms are examined: they are shown to reflect the dynamics of quantum correlations. A careful study of the non-unitary aspects of the evolution of quantum correlations leads naturally to an unambiguous definition of a collision term. This collision term is shown to obey a non-linear pre-master equation, whose derivation is fully quantum-mechanical. Moreover, it is shown that quantum correlations also yield an unitary correction to the mean field description, which could be absorbed in a suitable redefinition of the mean field. Formal expressions for these corrections are derived and their connection with memory effects exhibited explicitely. The typical time of evaluation of quantum correlations allows for an analytical expression for the 'lifetime of mean field descriptions'. Finally, a quantum mechanical point of view for 'irreversibility' in deep inelastic is discussed. (Author) [pt

Basic quantum irreversibility in neutron interferometry

International Nuclear Information System (INIS)

Rauch, H

2009-01-01

The transition between the quantum and classical world is a topical problem in quantum physics, which can be investigated by neutron interferometric methods. Here we discuss unavoidable quantum losses as they appear in neutron phase-echo and spin rotation experiments and we show how entanglement effects in a single-particle system demonstrate quantum contextuality, i.e. an entanglement between external and internal degrees of freedom in single-particle systems. This contextuality phenomenon also shows that a quantum system carries much more information than usually extracted. In all cases of an interaction, parasitic beams are produced which cannot be recombined completely with the original beam. This means that a complete reconstruction of the original state is, in principle, impossible which causes a kind of intrinsic irreversibility. Even small interaction potentials can have huge effects when they are applied in quantum Zeno-like experiments. The path towards advanced neutron quantum optics will be discussed.

Quantum hall effect. A perspective

International Nuclear Information System (INIS)

Aoki, Hideo

2006-01-01

Novel concepts and phenomena are emerging recently in the physics of quantum Hall effect. This article gives an overview, which starts from the fractional quantum Hall system viewed as an extremely strongly correlated system, and move on to present various phenomena involving internal degrees of freedom (spin and layer), non-equilibrium and optical properties, and finally the spinoff to anomalous Hall effect and the rotating Bose-Einstein condensate. (author)

A full quantum analysis of the Stern–Gerlach experiment using the evolution operator method: analyzing current issues in teaching quantum mechanics

International Nuclear Information System (INIS)

Benítez Rodríguez, E; Aguilar, L M Arévalo; Martínez, E Piceno

2017-01-01

To the quantum mechanics specialists community it is a well-known fact that the famous original Stern–Gerlach experiment (SGE) produces entanglement between the external degrees of freedom (position) and the internal degree of freedom (spin) of silver atoms. Despite this fact, almost all textbooks on quantum mechanics explain this experiment using a semiclassical approach, where the external degrees of freedom are considered classical variables, the internal degree is treated as a quantum variable, and Newton's second law is used to describe the dynamics. In the literature there are some works that analyze this experiment in its full quantum mechanical form. However, astonishingly, to the best of our knowledge the original experiment, where the initial states of the spin degree of freedom are randomly oriented coming from the oven, has not been analyzed yet in the available textbooks using the Schrödinger equation (to the best of our knowledge there is only one paper that treats this case: Hsu et al (2011 Phys. Rev. A 83 012109)). Therefore, in this contribution we use the time-evolution operator to give a full quantum mechanics analysis of the SGE when the initial state of the internal degree of freedom is completely random, i.e. when it is a statistical mixture. Additionally, as the SGE and the development of quantum mechanics are heavily intermingled, we analyze some features and drawbacks in the current teaching of quantum mechanics. We focus on textbooks that use the SGE as a starting point, based on the fact that most physicist do not use results from physics education research, and comment on traditional pedagogical attitudes in the physics community. (paper)

Reflection equation algebras, coideal subalgebras, and their centres

NARCIS (Netherlands)

Kolb, S.; Stokman, J.V.

2009-01-01

Reflection equation algebras and related U-q(g)-comodule algebras appear in various constructions of quantum homogeneous spaces and can be obtained via transmutation or equivalently via twisting by a cocycle. In this paper we investigate algebraic and representation theoretic properties of such so

Quantum nondemolition measurement saturates fidelity trade-off

International Nuclear Information System (INIS)

Mista, L.; Filip, R.

2005-01-01

Full text: A general quantum measurement on an unknown quantum state enables us to estimate what the state originally was. Simultaneously, the measurement has a destructive effect on a measured quantum state which is reflected by the decrease of the output fidelity. We show for any d-level system that quantum non-demolition measurement controlled by a suitably prepared ancilla is a measurement in which the decrease of the output fidelity is minimal. The ratio between the estimation fidelity and the output fidelity can be continuously controlled by the preparation of the ancilla. Different measurement strategies on the ancilla to gain maximum estimation fidelity are analyzed. A feasible scheme of such a measurement for atomic and optical 2-level systems based on basic controlled-NOT gate is discussed. (author)

The algebraic versus geometric approach to quantum field theory

International Nuclear Information System (INIS)

Schroer, B.

1990-06-01

Some recent developments in algebraic QFT are reviewed and confronted with results obtained by geometric methods. In particular a critical evaluation of the present status of the quantum symmetry discussion is given and the possible relation of the (Gepner-Witten) modularity in conformal QFT 2 and the Tomita modularity (existence of quantum reflections) of the algebraic approach is commented on. (author) 34 refs

Quantum solitons

Energy Technology Data Exchange (ETDEWEB)

Abram, I [Centre National d' Etudes des Telecommunications (CNET), 196 Avenue Henri Ravera, F-92220 Bagneux (France)

1999-02-01

results in an improvement in the bit-error rate of the transmission. The fact that squeezing does not survive attenuation does not matter in this case, since it is alive during the nonlinear interaction when it is needed. Another possible application of squeezed solitons would be in switching devices and logic gates based on soliton interactions, such as the fibre-end devices for signal processing in telecommunications developed by Mohamed Islam at AT and T in the US in the early 1990s. The use of number-squeezing would allow collisions between solitons to be controlled to high precision, thus significantly reducing the error rate of these devices. Solitons and quantum information It might also be possible to use solitons in the processing of quantum information. Quantum information is an emerging field of physics that takes advantage of phenomena that are particular to quantum mechanics such as uncertainty, superposition and entanglement to code, transmit or process information (see Physics World March 1998). Recent highlights in this field include quantum cryptography (which can be used to achieve unconditionally secure key distribution) and quantum computing, which considerably speeds up the solution of problems that are exponentially difficult. These problems include the factorization of large numbers and searches of large databases. Although most proposals for processing quantum information to date concentrate on single-photon or single-spin implementations, optical solitons may offer an alternative that is easier to handle experimentally, yet still provides many of the basic quantum features that are displayed by single quanta. This could lead to new paradigms for computation and communications. In particular, the existence of quantum correlations in the fluctuations of the spectral and temporal sidebands of the solitons turns them into macroscopic quantum objects with internal entanglement. If these internal quantum correlations can be tailored into prescribed

Knots, topology and quantum field theories

International Nuclear Information System (INIS)

Lusanna, L.

1989-01-01

The title of the workshop, Knots, Topology and Quantum Field Theory, accurate reflected the topics discussed. There have been important developments in mathematical and quantum field theory in the past few years, which had a large impact on physicist thinking. It is historically unusual and pleasing that these developments are taking place as a result of an intense interaction between mathematical physicists and mathematician. On the one hand, topological concepts and methods are playing an increasingly important lead to novel mathematical concepts: for instance, the study of quantum groups open a new chapter in the deformation theory of Lie algebras. These developments at present will lead to new insights into the theory of elementary particles and their interactions. In essence, the talks dealt with three, broadly defined areas of theoretical physics. One was topological quantum field theories, the other the problem of quantum groups and the third one certain aspects of more traditional field theories, such as, for instance, quantum gravity. These topics, however, are interrelated and the general theme of the workshop defies rigid classification; this was evident from the cross references to be found in almo all the talks

Coherence protection in coupled quantum systems

Science.gov (United States)

Cammack, H. M.; Kirton, P.; Stace, T. M.; Eastham, P. R.; Keeling, J.; Lovett, B. W.

2018-02-01

The interaction of a quantum system with its environment causes decoherence, setting a fundamental limit on its suitability for quantum information processing. However, we show that if the system consists of coupled parts with different internal energy scales then the interaction of one part with a thermal bath need not lead to loss of coherence from the other. Remarkably, we find that the protected part can remain coherent for longer when the coupling to the bath becomes stronger or the temperature is raised. Our theory will enable the design of decoherence-resistant hybrid quantum computers.

Quantum fluctuations of a fullerene cage modulate its internal magnetic environment.

Science.gov (United States)

Kawatsu, Tsutomu; Tachikawa, Masanori

2018-01-17

To investigate the effect of quantum fluctuations on the magnetic environment inside a C 60 fullerene cage, we have calculated the nuclear magnetic shielding constant of protons in H 2 @C 60 and HD@C 60 systems by on-the-fly ab initio path integral simulation, including both thermal and nuclear quantum effects. The most dominant upfield from an isolated hydrogen molecule occurs due to the diamagnetic current of the C 60 cage, which is partly cancelled by the paramagnetic current, where the paramagnetic contribution is enlarged by the zero-point vibrational fluctuation of the C 60 carbon backbone structure via a widely distributed HOMO-LUMO gap. This quantum modulation mechanism of the nuclear magnetic shielding constant is newly proposed. Because this quantum effect is independent of the difference between H 2 and HD, the H 2 /HD isotope shift occurs in spite of the C 60 cage. The nuclear magnetic constants computed for H 2 @C 60 and HD@C 60 are 32.047 and 32.081 ppm, respectively, which are in reasonable agreement with the corresponding values of 32.19 and 32.23 ppm estimated from the experimental values of the chemical shifts.

How Is Buddhism Relevant to Career Counseling in an International High School in Hong Kong? A Counsellor's Reflection

Science.gov (United States)

Ng, Vinci; Yuen, Mantak

2015-01-01

This paper reflects upon the relevance of Buddhism to counselling in general and to career counseling in particular by discussing a program implemented at an international school in Hong Kong. The authors provide an analysis of the pertinent literature related to relevant concepts within Buddhism. This topic has not yet been adequately researched…

Randomness and locality in quantum mechanics

International Nuclear Information System (INIS)

Bub, J.

1976-01-01

This paper considers the problem of representing the statistical states of a quantum mechanical system by measures on a classical probability space. The Kochen and Specker theorem proves the impossibility of embedding the possibility structure of a quantum mechanical system into a Boolean algebra. It is shown that a hidden variable theory involves a Boolean representation which is not an embedding, and that such a representation cannot recover the quantum statistics for sequential probabilities without introducing a randomization process for the hidden variables which is assumed to apply only on measurement. It is suggested that the relation of incompatability is to be understood as a type of stochastic independence, and that the indeterminism of a quantum mechanical system is engendered by the existence of independent families of properties. Thus, the statistical relations reflect the possibility structure of the system: the probabilities are logical. The hidden variable thesis is influenced by the Copenhagen interpretation of quantum mechanics, i.e. by some version of the disturbance theory of measurement. Hence, the significance of the representation problem is missed, and the completeness of quantum mechanics is seen to turn on the possibility of recovering the quantum statistics by a hidden variable scheme which satisfies certain physically motivated conditions, such as locality. Bell's proof that no local hidden variable theory can reproduce the statistical relations of quantum mechanics is considered. (Auth.)

Basic quantum theory and measurement from the viewpoint of local quantum physics

International Nuclear Information System (INIS)

Schroer, Bert

1999-04-01

Several aspects of the manifestation of the causality principle in LQP (local quantum physics) are reviewed or presented. Particular emphasis is given to those properties which are typical for LQP in the sense that they do go beyond the structure of general quantum theory and even escape the Lagrangian quantization methods of standard QFT. The most remarkable are those relating causality to the modular Tomita-Takesaki theory, since they bring in the basic concepts of antiparticles, charge superselections as well as internal and external (geometric and hidden) symmetries. (author)

International Conference on Quantum Mathematical Physics : a Bridge between Mathematics and Physics

CERN Document Server

Kleiner, Johannes; Röken, Christian; Tolksdorf, Jürgen

2016-01-01

Quantum physics has been highly successful for more than 90 years. Nevertheless, a rigorous construction of interacting quantum field theory is still missing. Moreover, it is still unclear how to combine quantum physics and general relativity in a unified physical theory. Attacking these challenging problems of contemporary physics requires highly advanced mathematical methods as well as radically new physical concepts. This book presents different physical ideas and mathematical approaches in this direction. It contains a carefully selected cross-section of lectures which took place in autumn 2014 at the sixth conference ``Quantum Mathematical Physics - A Bridge between Mathematics and Physics'' in Regensburg, Germany. In the tradition of the other proceedings covering this series of conferences, a special feature of this book is the exposition of a wide variety of approaches, with the intention to facilitate a comparison. The book is mainly addressed to mathematicians and physicists who are interested in fu...

Quantum opto-mechanics with micromirrors : combining nano-mechanics with quantum optics

International Nuclear Information System (INIS)

Groeblacher, S.

2010-01-01

This work describes more than four years of research on the effects of the radiation-pressure force of light on macroscopic mechanical structures. The basic system studied here is a mechanical oscillator that is highly reflective and part of an optical resonator. It interacts with the optical cavity mode via the radiation-pressure force. Both the dynamics of the mechanical oscillation and the properties of the light field are modified through this interaction. In our experiments we use quantum optical tools (such as homodyning and down-conversion) with the goal of ultimately showing quantum behavior of the mechanical center of mass motion. In this thesis we present several experiments that pave the way towards this goal and when combined should allow the demonstration of the envisioned quantum phenomena, including entanglement, teleportation and Schroeodinger cat states. The study of quantum behavior of truly macroscopic systems is a long outstanding goal, which will help to answer some of the most fundamental questions in quantum physics today: Why is the world around us classical and not quantum? Is there a size- or mass-limit to systems for them to behave according to quantum mechanics? Is quantum theory complete or do we have to extend it to include mechanisms such as decoherence? Can we use the quantum nature of macroscopic objects to, for example, improve the measurement precision of classical apparatuses? The experiments discussed in this thesis include the very first passive radiation-pressure cooling of a mechanical oscillator in a cryogenic optical resonator, as well as the experimental demonstration of radiation-pressure cooling close to the mechanical quantum ground state. Cooling of the mechanical motion is an important pre-condition for observing quantum effects of the mechanical oscillator. In another experiment, we have demonstrated that we are able to enter the strong-coupling regime of the optomechanical system a regime where coherent energy

Cold molecules: Progress in quantum engineering of chemistry and quantum matter

Science.gov (United States)

Bohn, John L.; Rey, Ana Maria; Ye, Jun

2017-09-01

Cooling atoms to ultralow temperatures has produced a wealth of opportunities in fundamental physics, precision metrology, and quantum science. The more recent application of sophisticated cooling techniques to molecules, which has been more challenging to implement owing to the complexity of molecular structures, has now opened the door to the longstanding goal of precisely controlling molecular internal and external degrees of freedom and the resulting interaction processes. This line of research can leverage fundamental insights into how molecules interact and evolve to enable the control of reaction chemistry and the design and realization of a range of advanced quantum materials.

Widefield and total internal reflection fluorescent structured illumination microscopy with scanning galvo mirrors

Science.gov (United States)

Chen, Youhua; Cao, Ruizhi; Liu, Wenjie; Zhu, Dazhao; Zhang, Zhiming; Kuang, Cuifang; Liu, Xu

2018-04-01

We present an alternative approach to realize structured illumination microscopy (SIM), which is capable for live cell imaging. The prototype utilizes two sets of scanning galvo mirrors, a polarization converter and a piezo-platform to generate a fast shifted, s-polarization interfered and periodic variable illumination patterns. By changing the angle of the scanning galvanometer, we can change the position of the spots at the pupil plane of the objective lens arbitrarily, making it easy to switch between widefield and total internal reflection fluorescent-SIM mode and adapting the penetration depth in the sample. Also, a twofold resolution improvement is achieved in our experiments. The prototype offers more flexibility of pattern period and illumination orientation changing than previous systems.

Quantum jumps on Anderson attractors

Science.gov (United States)

Yusipov, I. I.; Laptyeva, T. V.; Ivanchenko, M. V.

2018-01-01

In a closed single-particle quantum system, spatial disorder induces Anderson localization of eigenstates and halts wave propagation. The phenomenon is vulnerable to interaction with environment and decoherence that is believed to restore normal diffusion. We demonstrate that for a class of experimentally feasible non-Hermitian dissipators, which admit signatures of localization in asymptotic states, quantum particle opts between diffusive and ballistic regimes, depending on the phase parameter of dissipators, with sticking about localization centers. In a diffusive regime, statistics of quantum jumps is non-Poissonian and has a power-law interval, a footprint of intermittent locking in Anderson modes. Ballistic propagation reflects dispersion of an ordered lattice and introduces the second timescale for jumps, resulting in non-nonmonotonous probability distribution. Hermitian dephasing dissipation makes localization features vanish, and Poissonian jump statistics along with normal diffusion are recovered.

Uncertainty and complementarity in axiomatic quantum mechanics

International Nuclear Information System (INIS)

Lahti, P.J.

1980-01-01

An investigation of the uncertainty principle and the complementarity principle is carried through. The physical content of these principles and their representation in the conventional Hilbert space formulation of quantum mechanics forms a natural starting point. Thereafter is presented more general axiomatic framework for quantum mechanics, namely, a probability function formulation of the theory. Two extra axioms are stated, reflecting the ideas of the uncertainty principle and the complementarity principle, respectively. The quantal features of these axioms are explicated. (author)

Solvable Quantum Macroscopic Motions and Decoherence Mechanisms in Quantum Mechanics on Nonstandard Space

Science.gov (United States)

Kobayashi, Tsunehiro

1996-01-01

Quantum macroscopic motions are investigated in the scheme consisting of N-number of harmonic oscillators in terms of ultra-power representations of nonstandard analysis. Decoherence is derived from the large internal degrees of freedom of macroscopic matters.

Dilatation effect of ''quantum clocks''

International Nuclear Information System (INIS)

Chylinski, Z.

1981-01-01

The relativistic dilatation effect of the life-time of unstable microparticles combined with quantum symmetry of their description results in the ''quantum-dilatation'' dilemma. It is due to the classical character of the relativity theory which here reveals itself in the classical world-line of the clock necessary in order to deduce the dilatation effect from the Lorentz transformation. It is shown how to solve this dilemma, basing on the relation continuum C 4 . Two types of measurements of time intervals, the direct and indirect one, are analyzed. The former type corresponds to the external space-time continuum, where any direct measurement takes place, and the latter, to the internal relation continuum C 4 , where the internal structures of isolated micro-systems are sunk. (author)

Quantum mechanical streamlines. I - Square potential barrier

Science.gov (United States)

Hirschfelder, J. O.; Christoph, A. C.; Palke, W. E.

1974-01-01

Exact numerical calculations are made for scattering of quantum mechanical particles hitting a square two-dimensional potential barrier (an exact analog of the Goos-Haenchen optical experiments). Quantum mechanical streamlines are plotted and found to be smooth and continuous, to have continuous first derivatives even through the classical forbidden region, and to form quantized vortices around each of the nodal points. A comparison is made between the present numerical calculations and the stationary wave approximation, and good agreement is found between both the Goos-Haenchen shifts and the reflection coefficients. The time-independent Schroedinger equation for real wavefunctions is reduced to solving a nonlinear first-order partial differential equation, leading to a generalization of the Prager-Hirschfelder perturbation scheme. Implications of the hydrodynamical formulation of quantum mechanics are discussed, and cases are cited where quantum and classical mechanical motions are identical.

Energy loss from internal reflection off metal layers on glass

Science.gov (United States)

McDowell, M. W.; Bezuidenhout, D. F.; Klee, H. W.; Theron, E.

1983-12-01

The reflection characteristics of metal layers are considered for the situation where the electromagnetic radiation is incident from the glass side. Theoretical and measured reflectance values are presented which indicate that for some metals the reflection has a strong dependence on the refractive index of the incident medium. Some examples are given of recent cases where the above results were an important consideration in the choice of the metallic reflecting material. These results indicate that aluminium should not be automatically considered the best choice for the visible region nor gold for the infra-red.

Inversion of reflection for the one-dimensional Dirac equation

International Nuclear Information System (INIS)

Clerk, G.L.; Davies, A.J.

1991-01-01

It is a general result of one-dimensional non-relativistic quantum mechanics that the coefficient of reflection (reflected flux) is the same irrespective of the direction of traversing a potential barrier, a result that is independent of the barrier shape. In this note, the authors consider the transmission coefficient instead, and derive a strong result, namely that the transmission amplitude is independent of the direction of barrier traversal. That is, the transmission amplitude has the same complex phase as well as being unchanged in magnitude by changing the barrier around. This process was called inversion of reflection. 2 refs

Entangled states in quantum mechanics

Science.gov (United States)

Ruža, Jānis

2010-01-01

In some circles of quantum physicists, a view is maintained that the nonseparability of quantum systems-i.e., the entanglement-is a characteristic feature of quantum mechanics. According to this view, the entanglement plays a crucial role in the solution of quantum measurement problem, the origin of the “classicality” from the quantum physics, the explanation of the EPR paradox by a nonlocal character of the quantum world. Besides, the entanglement is regarded as a cornerstone of such modern disciplines as quantum computation, quantum cryptography, quantum information, etc. At the same time, entangled states are well known and widely used in various physics areas. In particular, this notion is widely used in nuclear, atomic, molecular, solid state physics, in scattering and decay theories as well as in other disciplines, where one has to deal with many-body quantum systems. One of the methods, how to construct the basis states of a composite many-body quantum system, is the so-called genealogical decomposition method. Genealogical decomposition allows one to construct recurrently by particle number the basis states of a composite quantum system from the basis states of its forming subsystems. These coupled states have a structure typical for entangled states. If a composite system is stable, the internal structure of its forming basis states does not manifest itself in measurements. However, if a composite system is unstable and decays onto its forming subsystems, then the measurables are the quantum numbers, associated with these subsystems. In such a case, the entangled state has a dynamical origin, determined by the Hamiltonian of the corresponding decay process. Possible correlations between the quantum numbers of resulting subsystems are determined by the symmetries-conservation laws of corresponding dynamical variables, and not by the quantum entanglement feature.

Does the Finite Size of Electrons Affect Quantum Noise in Electronic Devices?

International Nuclear Information System (INIS)

Colomés, E; Marian, D; Oriols, X

2015-01-01

Quantum transport is commonly studied with the use of quasi-particle infinite- extended states. This leads to a powerful formalism, the scattering-states theory, able to capture in compact formulas quantities of interest, such as average current, noise, etc.. However, when investigating the spatial size-dependence of quasi-particle wave packets in quantum noise with exchange and tunneling, unexpected new terms appear in the quantum noise expression. For this purpose, the two particle transmission and reflection probabilities for two initial one-particle wave packets (with opposite central momentums) spatially localized at each side of a potential barrier are studied. After the interaction, each wave packet splits into a transmitted and a reflected component. It can be shown that the probability of detecting two (identically injected) electrons at the same side of the barrier is different from zero in very common (single or double barrier) scenarios. This originates an increase of quantum noise which cannot be obtained through the scattering states formalism. (paper)

Quantum Computers and Quantum Computer Languages: Quantum Assembly Language and Quantum C

OpenAIRE

Blaha, Stephen

2002-01-01

We show a representation of Quantum Computers defines Quantum Turing Machines with associated Quantum Grammars. We then create examples of Quantum Grammars. Lastly we develop an algebraic approach to high level Quantum Languages using Quantum Assembly language and Quantum C language as examples.

Quantum language and the migration of scientific concepts

CERN Document Server

Burwell, Jennifer

2018-01-01

How highly abstract quantum concepts were represented in language, and how these concepts were later taken up by philosophers, literary critics, and new-age gurus. The principles of quantum physics -- and the strange phenomena they describe -- are represented most precisely in highly abstract algebraic equations. Why, then, did these mathematically driven concepts compel founders of the field, particularly Erwin Schrödinger, Niels Bohr, and Werner Heisenberg, to spend so much time reflecting on ontological, epistemological, and linguistic concerns? What is it about quantum concepts that appeals to latter-day Eastern mystics, poststructuralist critics, and get-rich-quick schemers? How did their interpretations and misinterpretations of quantum phenomena reveal their own priorities? In this book, Jennifer Burwell examines these questions and considers what quantum phenomena -- in the context of the founders' debates over how to describe them -- reveal about the relationship between everyday experience, percep...

Advances in quantum chemistry

CERN Document Server

Sabin, John R

2013-01-01

Advances in Quantum Chemistry presents surveys of current topics in this rapidly developing field that has emerged at the cross section of the historically established areas of mathematics, physics, chemistry, and biology. It features detailed reviews written by leading international researchers. This volume focuses on the theory of heavy ion physics in medicine.Advances in Quantum Chemistry presents surveys of current topics in this rapidly developing field that has emerged at the cross section of the historically established areas of mathematics, physics, chemistry, and biology. It features

Quantum Jarzynski equality of measurement-based work extraction.

Science.gov (United States)

Morikuni, Yohei; Tajima, Hiroyasu; Hatano, Naomichi

2017-03-01

Many studies of quantum-size heat engines assume that the dynamics of an internal system is unitary and that the extracted work is equal to the energy loss of the internal system. Both assumptions, however, should be under scrutiny. In the present paper, we analyze quantum-scale heat engines, employing the measurement-based formulation of the work extraction recently introduced by Hayashi and Tajima [M. Hayashi and H. Tajima, arXiv:1504.06150]. We first demonstrate the inappropriateness of the unitary time evolution of the internal system (namely, the first assumption above) using a simple two-level system; we show that the variance of the energy transferred to an external system diverges when the dynamics of the internal system is approximated to a unitary time evolution. Second, we derive the quantum Jarzynski equality based on the formulation of Hayashi and Tajima as a relation for the work measured by an external macroscopic apparatus. The right-hand side of the equality reduces to unity for "natural" cyclic processes but fluctuates wildly for noncyclic ones, exceeding unity often. This fluctuation should be detectable in experiments and provide evidence for the present formulation.

Quantum walk with a four-dimensional coin

International Nuclear Information System (INIS)

Hamilton, Craig S; Gabris, Aurel; Jex, Igor; Barnett, Stephen M

2011-01-01

We examine the physical implementation of a discrete time quantum walk with a four-dimensional coin. Our quantum walker is a photon moving repeatedly through a time delay loop, with time being our position space. The quantum coin is implemented using the internal states of the photon: the polarization and two of the orbital angular momentum states. We demonstrate how to implement this physically and what components would be needed. We then illustrate some of the results that could be obtained by performing the experiment.

Quantum dynamics of classical stochastic systems

Energy Technology Data Exchange (ETDEWEB)

Casati, G

1983-01-01

It is shown that one hand Quantum Mechanics introduces limitations to the manifestations of chaotic motion resulting, for the case of the periodically kicked rotator, in the limitation of energy growth; also, as it is confirmed by numerical experiments, phenomena like the exponential instability of orbits, inherent to strongly chaotic systems, are absent here and therefore Quantum Mechanics appear to be more stable and predictable than Classical Mechanics. On the other hand, we have seen that nonrecurrent behavior may arise in Quantum Systems and it is connected to the presence of singular continuous spectrum. We conjecture that the classical chaotic behavior is reflected, at least partially, in the nature of the spectrum and the singular-continuity of the latter may possess a self-similar structure typical of classical chaos.

Benchmarking of HEU mental annuli critical assemblies with internally reflected graphite cylinder

Directory of Open Access Journals (Sweden)

Xiaobo Liu

2017-01-01

Full Text Available Three experimental configurations of critical assemblies, performed in 1963 at the Oak Ridge Critical Experiment Facility, which are assembled using three different diameter HEU annuli (15-9 inches, 15-7 inches and 13-7 inches metal annuli with internally reflected graphite cylinder are evaluated and benchmarked. The experimental uncertainties which are 0.00057, 0.00058 and 0.00057 respectively, and biases to the benchmark models which are − 0.00286, − 0.00242 and − 0.00168 respectively, were determined, and the experimental benchmark keff results were obtained for both detailed and simplified models. The calculation results for both detailed and simplified models using MCNP6-1.0 and ENDF/B-VII.1 agree well to the benchmark experimental results within difference less than 0.2%. The benchmarking results were accepted for the inclusion of ICSBEP Handbook.

On reflection algebras and twisted Yangians

International Nuclear Information System (INIS)

Doikou, Anastasia

2005-01-01

It is well known that integrable models associated to rational R matrices give rise to certain non-Abelian symmetries known as Yangians. Analogously boundary symmetries arise when general but still integrable boundary conditions are implemented, as originally argued by Delius, Mackay, and Short from the field theory point of view, in the context of the principal chiral model on the half-line. In the present study we deal with a discrete quantum mechanical system with boundaries, that is the N site gl(n) open quantum spin chain. In particular, the open spin chain with two distinct types of boundary condition known as soliton preserving and soliton nonpreserving is considered. For both types of boundaries we present a unified framework for deriving the corresponding boundary nonlocal charges directly at the quantum level. The nonlocal charges are simply coproduct realizations of particular boundary quantum algebras called boundary or twisted Yangians, depending on the choice of boundary conditions. Finally, with the help of linear intertwining relations between the solutions of the reflection equation and the generators of the boundary or twisted Yangians we are able to exhibit the exact symmetry of the open spin chain, namely we show that a number of the boundary nonlocal charges are in fact conserved quantities

Parental reflective functioning as a moderator of child internalizing difficulties in the context of child sexual abuse.

Science.gov (United States)

Ensink, Karin; Bégin, Michaël; Normandin, Lina; Fonagy, Peter

2017-11-01

The objective was to examine pathways from child sexual abuse (CSA) and maternal mentalizing to child internalizing and externalizing difficulties and to test a model of MRF as a moderator of the relationships between CSA and child difficulties. The sample was comprised of 154 mothers and children aged 2-12 where 64 children had experienced CSA. To assess parental mentalizing the Parental Development Interview was rated with the Parental Reflective Functioning Scale. Child internalizing and externalizing difficulties were assessed with the Child Behavior Checklist (CBCL). Results indicate that there were significant inverse relationships between maternal mentalizing and child internalizing and externalizing difficulties. When maternal mentalizing was considered together with CSA, only maternal mentalizing was a significant predictor of child difficulties. Furthermore, maternal mentalizing moderated the relationship between CSA and child internalizing difficulties. These findings provide evidence of the importance of the parents' mentalizing stance for psychiatric symptoms of children aged 2-12, as well as children's recovery from CSA. The clinical implications of the findings are discussed. Copyright © 2017 Elsevier B.V. All rights reserved.

The Stratonovich formulation of quantum feedback network rules

Science.gov (United States)

Gough, John E.

2016-12-01

We express the rules for forming quantum feedback networks using the Stratonovich form of quantum stochastic calculus rather than the Itō or SLH (J. E. Gough and M. R. James, "Quantum feedback networks: Hamiltonian formulation," Commun. Math. Phys. 287, 1109 (2009), J. E. Gough and M. R. James, "The Series product and its application to quantum feedforward and feedback networks," IEEE Trans. Autom. Control 54, 2530 (2009)) form. Remarkably the feedback reduction rule implies that we obtain the Schur complement of the matrix of Stratonovich coupling operators where we short out the internal input/output coefficients.

[Discussion on quantum entanglement theory and acupuncture].

Science.gov (United States)

Wang, Jun; Wu, Bin; Chen, Sheng

2017-11-12

The quantum entanglement is a new discovery of modern physics and has drawn a widely attention in the world. After learning the quantum entanglement, the authors have found that many characteristics of quantum are reflected in TCM, acupuncture theory and clinical practice. For example, the quantum entanglement phenomenon is mutually verified with the holism, yinyang doctrine, the theory of primary, secondary, root and knot in TCM, etc. It can be applied to interpret the clinical situations which is difficult to be explained in clinical practice, such as the instant effect of acupuncture, multi-point stimulation in one disorder and the points with specific effects. On the basis of the discovery above, the quantum entanglement theory achieved the mutual treatment among the relatives in acupuncture clinical practice and the therapeutic effects were significant. The results suggest that the coupling relationship in quantum entanglement presents between the diseases and the acupoints in the direct relative. The authors believe that the discovery in this study contributes to the exploration on the approaches to the acupuncture treatment in clinical practice and enrich the ideas on the disease prevention.

Celebrating international collaboration: reflections on the first Virtual International Practice Development Conference

Directory of Open Access Journals (Sweden)

Moira Stephens

2016-11-01

Full Text Available This article reports on the first Virtual International Practice Development Conference, held in May 2015 to celebrate International Nurses Day. The article describes key aspects of its planning, offers a flavour of the event itself and sets out an evaluation, including learning points and recommendations to assist with planning similar events in the future. Central to our learning are: The need for practice developers to grasp skills in technology associated with virtual space The need to embrace virtual space itself as another means by which creative and communicative spaces can be established for active learning and practice development activities The potential advantages that international virtual engagement has over face-to-face national or international engagement The delivery of this virtual event made a significant international contribution to global practice development activity within the International Practice Development Collaborative and to enabling practice developers to connect and celebrate on a more global basis. Implications for practice: Virtual space technology skills can assist with sharing and translating practice development research, innovations and critical commentary Virtual space can provide an adjunct to creative and communicative learning spaces Global networking opportunities can be developed and enhanced through the use of virtual space technology Practice developers need to role model the use of virtual technologies

Reflection, radiation, and interference near the black hole horizon

International Nuclear Information System (INIS)

Kuchiev, M.Yu.

2004-01-01

The event horizon of black holes is capable of reflection: there is a finite probability for any particle that approaches the horizon to bounce back. The albedo of the horizon depends on the black hole temperature and the energy of the incoming particle. The reflection shares its physical origins with the Hawking process of radiation; both of them arise as consequences of the mixing of the incoming and outgoing waves that takes place due to quantum processes on the event horizon

Predictable quantum efficient detector based on n-type silicon photodiodes

Science.gov (United States)

Dönsberg, Timo; Manoocheri, Farshid; Sildoja, Meelis; Juntunen, Mikko; Savin, Hele; Tuovinen, Esa; Ronkainen, Hannu; Prunnila, Mika; Merimaa, Mikko; Tang, Chi Kwong; Gran, Jarle; Müller, Ingmar; Werner, Lutz; Rougié, Bernard; Pons, Alicia; Smîd, Marek; Gál, Péter; Lolli, Lapo; Brida, Giorgio; Rastello, Maria Luisa; Ikonen, Erkki

2017-12-01

The predictable quantum efficient detector (PQED) consists of two custom-made induced junction photodiodes that are mounted in a wedged trap configuration for the reduction of reflectance losses. Until now, all manufactured PQED photodiodes have been based on a structure where a SiO2 layer is thermally grown on top of p-type silicon substrate. In this paper, we present the design, manufacturing, modelling and characterization of a new type of PQED, where the photodiodes have an Al2O3 layer on top of n-type silicon substrate. Atomic layer deposition is used to deposit the layer to the desired thickness. Two sets of photodiodes with varying oxide thicknesses and substrate doping concentrations were fabricated. In order to predict recombination losses of charge carriers, a 3D model of the photodiode was built into Cogenda Genius semiconductor simulation software. It is important to note that a novel experimental method was developed to obtain values for the 3D model parameters. This makes the prediction of the PQED responsivity a completely autonomous process. Detectors were characterized for temperature dependence of dark current, spatial uniformity of responsivity, reflectance, linearity and absolute responsivity at the wavelengths of 488 nm and 532 nm. For both sets of photodiodes, the modelled and measured responsivities were generally in agreement within the measurement and modelling uncertainties of around 100 parts per million (ppm). There is, however, an indication that the modelled internal quantum deficiency may be underestimated by a similar amount. Moreover, the responsivities of the detectors were spatially uniform within 30 ppm peak-to-peak variation. The results obtained in this research indicate that the n-type induced junction photodiode is a very promising alternative to the existing p-type detectors, and thus give additional credibility to the concept of modelled quantum detector serving as a primary standard. Furthermore, the manufacturing of

Accounting for Interference, Scattering, and Electrode Absorption to Make Accurate Internal Quantum Efficiency Measurements in Organic and Other Thin Solar Cells

KAUST Repository

Burkhard, George F.; Hoke, Eric T.; McGehee, Michael D.

2010-01-01

Accurately measuring internal quantum efficiency requires knowledge of absorption in the active layer of a solar cell. The experimentally accessible total absorption includes significant contributions from the electrodes and other nonactive layers. We suggest a straightforward method for calculating the active layer contribution that minimizes error by subtracting optically-modeled electrode absorption from experimentally measured total absorption. (Figure Presented) © 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Accounting for Interference, Scattering, and Electrode Absorption to Make Accurate Internal Quantum Efficiency Measurements in Organic and Other Thin Solar Cells

KAUST Repository

Burkhard, George F.

2010-05-31

Accurately measuring internal quantum efficiency requires knowledge of absorption in the active layer of a solar cell. The experimentally accessible total absorption includes significant contributions from the electrodes and other nonactive layers. We suggest a straightforward method for calculating the active layer contribution that minimizes error by subtracting optically-modeled electrode absorption from experimentally measured total absorption. (Figure Presented) © 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

CubeSat quantum communications mission

Energy Technology Data Exchange (ETDEWEB)

Oi, Daniel K.L. [University of Strathclyde, SUPA Department of Physics, Glasgow (United Kingdom); University of Strathclyde, Strathclyde Space Institute, Glasgow (United Kingdom); Ling, Alex [National University of Singapore, Centre for Quantum Technologies, Singapore (Singapore); National University of Singapore, Dept. of Physics, Singapore (Singapore); Vallone, Giuseppe; Villoresi, Paolo [Universita degli Studi di Padova, Dipartimento di Ingegneria dell' Informazione, Padova (Italy); Greenland, Steve; Kerr, Emma [University of Strathclyde, Advanced Space Concepts Laboratory, Mechanical and Aerospace Engineering, Glasgow (United Kingdom); Macdonald, Malcolm [Technology and Innovation Centre, Scottish Centre of Excellence in Satellite Applications, Glasgow (United Kingdom); Weinfurter, Harald [Ludwig-Maximilians-Universitaet, Department fuer Physik, Munich (Germany); Kuiper, Hans [Delft University of Technology, Space Systems Engineering, Aerospace Engineering, Delft (Netherlands); Charbon, Edoardo [AQUA, EPFL, Lausanne (Switzerland); Delft University of Technology, Delft (Netherlands); Ursin, Rupert [Vienna Austrian Academy of Sciences, Institute for Quantum Optics and Quantum Information, Vienna (Austria)

2017-12-15

Quantum communication is a prime space technology application and offers near-term possibilities for long-distance quantum key distribution (QKD) and experimental tests of quantum entanglement. However, there exists considerable developmental risks and subsequent costs and time required to raise the technological readiness level of terrestrial quantum technologies and to adapt them for space operations. The small-space revolution is a promising route by which synergistic advances in miniaturization of both satellite systems and quantum technologies can be combined to leap-frog conventional space systems development. Here, we outline a recent proposal to perform orbit-to-ground transmission of entanglement and QKD using a CubeSat platform deployed from the International Space Station (ISS). This ambitious mission exploits advances in nanosatellite attitude determination and control systems (ADCS), miniaturised target acquisition and tracking sensors, compact and robust sources of single and entangled photons, and high-speed classical communications systems, all to be incorporated within a 10 kg 6 litre mass-volume envelope. The CubeSat Quantum Communications Mission (CQuCoM) would be a pathfinder for advanced nanosatellite payloads and operations, and would establish the basis for a constellation of low-Earth orbit trusted-nodes for QKD service provision. (orig.)

CubeSat quantum communications mission

International Nuclear Information System (INIS)

Oi, Daniel K.L.; Ling, Alex; Vallone, Giuseppe; Villoresi, Paolo; Greenland, Steve; Kerr, Emma; Macdonald, Malcolm; Weinfurter, Harald; Kuiper, Hans; Charbon, Edoardo; Ursin, Rupert

2017-01-01

Quantum communication is a prime space technology application and offers near-term possibilities for long-distance quantum key distribution (QKD) and experimental tests of quantum entanglement. However, there exists considerable developmental risks and subsequent costs and time required to raise the technological readiness level of terrestrial quantum technologies and to adapt them for space operations. The small-space revolution is a promising route by which synergistic advances in miniaturization of both satellite systems and quantum technologies can be combined to leap-frog conventional space systems development. Here, we outline a recent proposal to perform orbit-to-ground transmission of entanglement and QKD using a CubeSat platform deployed from the International Space Station (ISS). This ambitious mission exploits advances in nanosatellite attitude determination and control systems (ADCS), miniaturised target acquisition and tracking sensors, compact and robust sources of single and entangled photons, and high-speed classical communications systems, all to be incorporated within a 10 kg 6 litre mass-volume envelope. The CubeSat Quantum Communications Mission (CQuCoM) would be a pathfinder for advanced nanosatellite payloads and operations, and would establish the basis for a constellation of low-Earth orbit trusted-nodes for QKD service provision. (orig.)

Influence of excitonic effects on luminescence quantum yield in silicon

Energy Technology Data Exchange (ETDEWEB)

Sachenko, A.V.; Kostylyov, V.P.; Vlasiuk, V.M. [V. Lashkaryov Institute of Semiconductor Physics, NAS of Ukraine, 41 prospect Nauky, 03028 Kyiv (Ukraine); Sokolovskyi, I.O., E-mail: isokolovskyi@mun.ca [V. Lashkaryov Institute of Semiconductor Physics, NAS of Ukraine, 41 prospect Nauky, 03028 Kyiv (Ukraine); Department of Physics and Physical Oceanography, Memorial University of Newfoundland, St. John' s, NL, A1B 3X7 Canada (Canada); Evstigneev, M. [Department of Physics and Physical Oceanography, Memorial University of Newfoundland, St. John' s, NL, A1B 3X7 Canada (Canada)

2017-03-15

Nonradiative exciton lifetime in silicon is determined by comparison of the experimental and theoretical curves of bulk minority charge carriers lifetime on doping and excitation levels. This value is used to analyze the influence of excitonic effects on internal luminescence quantum yield at room temperature, taking into account both nonradiative and radiative exciton lifetimes. A range of Shockley-Hall-Reed lifetimes is found, where excitonic effects lead to an increase of internal luminescence quantum yield.

Quantum Computers and Quantum Computer Languages: Quantum Assembly Language and Quantum C Language

OpenAIRE

Blaha, Stephen

2002-01-01

We show a representation of Quantum Computers defines Quantum Turing Machines with associated Quantum Grammars. We then create examples of Quantum Grammars. Lastly we develop an algebraic approach to high level Quantum Languages using Quantum Assembly language and Quantum C language as examples.

Quantum walks, quantum gates, and quantum computers

International Nuclear Information System (INIS)

Hines, Andrew P.; Stamp, P. C. E.

2007-01-01

The physics of quantum walks on graphs is formulated in Hamiltonian language, both for simple quantum walks and for composite walks, where extra discrete degrees of freedom live at each node of the graph. It is shown how to map between quantum walk Hamiltonians and Hamiltonians for qubit systems and quantum circuits; this is done for both single-excitation and multiexcitation encodings. Specific examples of spin chains, as well as static and dynamic systems of qubits, are mapped to quantum walks, and walks on hyperlattices and hypercubes are mapped to various gate systems. We also show how to map a quantum circuit performing the quantum Fourier transform, the key element of Shor's algorithm, to a quantum walk system doing the same. The results herein are an essential preliminary to a Hamiltonian formulation of quantum walks in which coupling to a dynamic quantum environment is included

Semi-quantum Secure Direct Communication Scheme Based on Bell States

Science.gov (United States)

Xie, Chen; Li, Lvzhou; Situ, Haozhen; He, Jianhao

2018-06-01

Recently, the idea of semi-quantumness has been often used in designing quantum cryptographic schemes, which allows some of the participants of a quantum cryptographic scheme to remain classical. One of the reasons why this idea is popular is that it allows a quantum information processing task to be accomplished by using quantum resources as few as possible. In this paper, we extend the idea to quantum secure direct communication(QSDC) by proposing a semi-quantum secure direct communication scheme. In the scheme, the message sender, Alice, encodes each bit into a Bell state |φ+> = 1/{√2}(|00> +|11> ) or |{Ψ }+> = 1/{√ 2}(|01> +|10> ), and the message receiver, Bob, who is classical in the sense that he can either let the qubit he received reflect undisturbed, or measure the qubit in the computational basis |0>, |1> and then resend it in the state he found. Moreover, the security analysis of our scheme is also given.

Coherent transport through interacting quantum dots

Energy Technology Data Exchange (ETDEWEB)

Hiltscher, Bastian

2012-10-05

the linear-conductance regime. The second work deals with the ratio of coherent processes in transport through quantum dots. To this end, a quantum dot is embedded in one of the arms of an Aharonov-Bohm interferometer. In former theoretical as well as experimental works it has been observed that an important source of decoherence are cotunneling processes that flip the dot's spin. In order to elucidate the role of spin in more detail, we assume one of the leads to be ferromagnetic and the other one to be normal. The main motivations of our work are the two questions: (1) What fraction of the total current through a single-level quantum dot weakly coupled to the electrodes is coherent? (2) How and under which circumstances can this fraction be extracted from a current measurement in an Aharonov-Bohm setup? The measurable quantity in such an experiment is the magnetic-flux dependent ratio of the total current. It turns out that the answers of the two questions strongly depend on the dot level position, the polarization of the ferromagnet, and the transport direction. Especially the flux-dependent and the coherent ratios are not necessarily the same. The main motivation of the third work is to identify crossed Andreev reflection in quantum dots, that is, a Cooper pair splits into two single electrons, which are transferred into different quantum dots in one coherent process. We consider a setup, where two quantum dots are tunnel coupled to the same superconductor and each dot is additionally coupled to a normal conductor. In previous works a bias voltage has been applied between the superconductor and the normal conductors. Then, three processes sustain transport. Beside crossed Andreev reflection also local Andreev reflection, where both electrons of the Cooper pair tunnel into the same dot, and single-particle tunneling occur. This complicates the identification of crossed Andreev reflection. Therefore, we propose the transport mechanism of adiabatic pumping in

Coherent transport through interacting quantum dots

International Nuclear Information System (INIS)

Hiltscher, Bastian

2012-01-01

the linear-conductance regime. The second work deals with the ratio of coherent processes in transport through quantum dots. To this end, a quantum dot is embedded in one of the arms of an Aharonov-Bohm interferometer. In former theoretical as well as experimental works it has been observed that an important source of decoherence are cotunneling processes that flip the dot's spin. In order to elucidate the role of spin in more detail, we assume one of the leads to be ferromagnetic and the other one to be normal. The main motivations of our work are the two questions: (1) What fraction of the total current through a single-level quantum dot weakly coupled to the electrodes is coherent? (2) How and under which circumstances can this fraction be extracted from a current measurement in an Aharonov-Bohm setup? The measurable quantity in such an experiment is the magnetic-flux dependent ratio of the total current. It turns out that the answers of the two questions strongly depend on the dot level position, the polarization of the ferromagnet, and the transport direction. Especially the flux-dependent and the coherent ratios are not necessarily the same. The main motivation of the third work is to identify crossed Andreev reflection in quantum dots, that is, a Cooper pair splits into two single electrons, which are transferred into different quantum dots in one coherent process. We consider a setup, where two quantum dots are tunnel coupled to the same superconductor and each dot is additionally coupled to a normal conductor. In previous works a bias voltage has been applied between the superconductor and the normal conductors. Then, three processes sustain transport. Beside crossed Andreev reflection also local Andreev reflection, where both electrons of the Cooper pair tunnel into the same dot, and single-particle tunneling occur. This complicates the identification of crossed Andreev reflection. Therefore, we propose the transport mechanism of adiabatic pumping in the

Dirac's equation and the nature of quantum field theory

International Nuclear Information System (INIS)

Plotnitsky, Arkady

2012-01-01

This paper re-examines the key aspects of Dirac's derivation of his relativistic equation for the electron in order advance our understanding of the nature of quantum field theory. Dirac's derivation, the paper argues, follows the key principles behind Heisenberg's discovery of quantum mechanics, which, the paper also argues, transformed the nature of both theoretical and experimental physics vis-à-vis classical physics and relativity. However, the limit theory (a crucial consideration for both Dirac and Heisenberg) in the case of Dirac's theory was quantum mechanics, specifically, Schrödinger's equation, while in the case of quantum mechanics, in Heisenberg's version, the limit theory was classical mechanics. Dirac had to find a new equation, Dirac's equation, along with a new type of quantum variables, while Heisenberg, to find new theory, was able to use the equations of classical physics, applied to different, quantum-mechanical variables. In this respect, Dirac's task was more similar to that of Schrödinger in his work on his version of quantum mechanics. Dirac's equation reflects a more complex character of quantum electrodynamics or quantum field theory in general and of the corresponding (high-energy) experimental quantum physics vis-à-vis that of quantum mechanics and the (low-energy) experimental quantum physics. The final section examines this greater complexity and its implications for fundamental physics.

The Quantum Socket: Wiring for Superconducting Qubits - Part 2

Science.gov (United States)

Bejanin, J. H.; McConkey, T. G.; Rinehart, J. R.; Bateman, J. D.; Earnest, C. T.; McRae, C. H.; Rohanizadegan, Y.; Shiri, D.; Mariantoni, M.; Penava, B.; Breul, P.; Royak, S.; Zapatka, M.; Fowler, A. G.

Quantum computing research has reached a level of maturity where quantum error correction (QEC) codes can be executed on linear arrays of superconducting quantum bits (qubits). A truly scalable quantum computing architecture, however, based on practical QEC algorithms, requires nearest neighbor interaction between qubits on a two-dimensional array. Such an arrangement is not possible with techniques that rely on wire bonding. To address this issue, we have developed the quantum socket, a device based on three-dimensional wires that enables the control of superconducting qubits on a two-dimensional grid. In this talk, we present experimental results characterizing this type of wiring. We will show that the quantum socket performs exceptionally well for the transmission and reflection of microwave signals up to 10 GHz, while minimizing crosstalk between adjacent wires. Under realistic conditions, we measured an S21 of -5 dB at 6 GHz and an average crosstalk of -60 dB. We also describe time domain reflectometry results and arbitrary pulse transmission tests, showing that the quantum socket can be used to control superconducting qubits.

Quantum degeneracy effect on performance of irreversible Otto cycle with ideal Bose gas

International Nuclear Information System (INIS)

Wu Feng; Chen Lingen; Sun Fengrui; Wu Chih; Guo Fangzhong; Li Qing

2006-01-01

An Otto cycle working with an ideal Bose gas is called a Bose Otto cycle. The internal irreversibility of the cycle is included in the factors of internal irreversibility degree. The quantum degeneracy effect on the performance of the cycle is investigated based on quantum statistical mechanics and thermodynamics. Variations of the maximum work output ratio R W and the efficiency ratio y with temperature ratio τ are examined, which reveal the influence of the quantum degeneracy of the working substance on the performance of a Bose Otto cycle. It is shown that the results obtained herein are valid under both classical and quantum ideal gas conditions

Fluctuations of Internal Transmittance in Security of Measurement-Device-Independent Quantum Key Distribution with an Untrusted Source*

International Nuclear Information System (INIS)

Wang Yang; Bao Wan-Su; Chen Rui-Ke; Zhou Chun; Jiang Mu-Sheng; Li Hong-Wei

2017-01-01

Measurement-device-independent quantum key distribution (MDI-QKD) is immune to detector side channel attacks, which is a crucial security loophole problem in traditional QKD. In order to relax a key assumption that the sources are trusted in MDI-QKD, an MDI-QKD protocol with an untrusted source has been proposed. For the security of MDI-QKD with an untrusted source, imperfections in the practical experiment should also be taken into account. In this paper, we analyze the effects of fluctuations of internal transmittance on the security of a decoy-state MDI-QKD protocol with an untrusted source. Our numerical results show that both the secret key rate and the maximum secure transmission distance decrease when taken fluctuations of internal transmittance into consideration. Especially, they are more sensitive when Charlie’s mean photon number per pulse is smaller. Our results emphasize that the stability of correlative optical devices is important for practical implementations . (paper)

Detecting strain wave propagation through quantum dots by pump-probe spectroscopy: A theoretical analysis

International Nuclear Information System (INIS)

Huneke, J; Kuhn, T; Axt, V M

2010-01-01

The influence of strain waves traveling across a quantum dot structure on its optical response is studied for two different situations: First, a strain wave is created by the optical excitation of a single quantum dot near a surface which, after reflection at the surface, reenters the dot; second, a phonon wave packet is emitted by the excitation of a nearby second dot and then travels across the quantum dot. Pump-probe type excitations are simulated for quantum dots in the strong confinement limit. We show that the optical signals allow us to monitor crossing strain waves for both structures in the real-time response as well as in the corresponding pump-probe spectra. In the time-derivative of the phase of the polarization a distinct trace reflects the instantaneous shifts of the transition energy during the passage while in the spectra pronounced oscillations reveal the passage of the strain waves.

High accuracy subwavelength distance measurements: A variable-angle standing-wave total-internal-reflection optical microscope

International Nuclear Information System (INIS)

Haynie, A.; Min, T.-J.; Luan, L.; Mu, W.; Ketterson, J. B.

2009-01-01

We describe an extension of the total-internal-reflection microscopy technique that permits direct in-plane distance measurements with high accuracy (<10 nm) over a wide range of separations. This high position accuracy arises from the creation of a standing evanescent wave and the ability to sweep the nodal positions (intensity minima of the standing wave) in a controlled manner via both the incident angle and the relative phase of the incoming laser beams. Some control over the vertical resolution is available through the ability to scan the incoming angle and with it the evanescent penetration depth.

Probing quantum and thermal noise in an interacting many-body system

DEFF Research Database (Denmark)

Hofferberth, S.; Lesanovsky, Igor; Schumm, Thorsten

2008-01-01

of the shot-to-shot variations of interference-fringe contrast for pairs of independently created one-dimensional Bose condensates. Analysing different system sizes, we observe the crossover from thermal to quantum noise, reflected in a characteristic change in the distribution functions from poissonian......The probabilistic character of the measurement process is one of the most puzzling and fascinating aspects of quantum mechanics. In many-body systems quantum-mechanical noise reveals non-local correlations of the underlying many-body states. Here, we provide a complete experimental analysis....... Furthermore, our experiments constitute the first analysis of the full distribution of quantum noise in an interacting many-body system....

When quantum mechanics interacts with cognitive science

NARCIS (Netherlands)

Blutner, R.

2010-01-01

I reflect on several aspects of the general claim that a quantum-like approach to Cognitive Science is advantageous over classical approaches. The classical approaches refer to the symbolic approaches including models using a classical (Kolmogorov) probability calculus. The general claim seems to be

Lectures on Quantum Mechanics

CERN Document Server

Basdevant, Jean-Louis

2007-01-01

Beautifully illustrated and engagingly written, Lectures on Quantum Mechanics presents theoretical physics with a breathtaking array of examples and anecdotes. Basdevant's style is clear and stimulating, in the manner of a brisk classroom lecture that students can follow with ease and enjoyment. Here is a sample of the book's style, from the opening of Chapter 1: "If one were to ask a passer-by to quote a great formula of physics, chances are that the answer would be 'E = mc2'. Nevertheless, the formula 'E=hV' which was written in the same year 1905 by the same Albert Einstein, and which started quantum theory, concerns their daily life considerably more. In fact, of the three watershed years for physics toward the beginning of the 20th century - 1905: the Special Relativity of Einstein, Lorentz and Poincaré; 1915: the General Relativity of Einstein, with its extraordinary reflections on gravitation, space and time; and 1925: the full development of Quantum Mechanics - it is surely the last which has the mos...

InAs quantum wires on InP substrate for VCSEL applications

OpenAIRE

Lamy , Jean-Michel; Paranthoën , Cyril; Levallois , Christophe; Nakkar , Abdulhadi; Folliot , Hervé; Dehaese , Olivier; Le Corre , Alain; Loualiche , Slimane; Castany , Olivier; Dupont , Laurent

2008-01-01

International audience; Quantum dash based vertical cavity surface emitting lasers (VCSEL) on InP substrate are presented. Single and close stacking layers were successfully grown with molecular beam epitaxy. Optimized quantum dash layers exhibit a strong polarized 1.55 µm photoluminescence along the [1-10] crystallographic axis. Continuous wave laser emission is demonstrated at room temperature for the first time on a quantum dash VCSEL structure on InP susbtrate. The quantum dash VCSEL lase...

A review of the quantum current standard

International Nuclear Information System (INIS)

Kaneko, Nobu-Hisa; Nakamura, Shuji; Okazaki, Yuma

2016-01-01

The electric current, voltage, and resistance standards are the most important standards related to electricity and magnetism. Of these three standards, only the ampere, which is the unit of electric current, is an International System of Units (SI) base unit. However, even with modern technology, relatively large uncertainty exists regarding the generation and measurement of current. As a result of various innovative techniques based on nanotechnology and novel materials, new types of junctions for quantum current generation and single-electron current sources have recently been proposed. These newly developed methods are also being used to investigate the consistency of the three quantum electrical effects, i.e. the Josephson, quantum Hall, and single-electron tunneling effects, which are also known as ‘the quantum metrology triangle’. This article describes recent research and related developments regarding current standards and quantum-metrology-triangle experiments. (topical review)

Using of Quantum Dots in Biology and Medicine.

Science.gov (United States)

Pleskova, Svetlana; Mikheeva, Elza; Gornostaeva, Ekaterina

2018-01-01

Quantum dots are nanoparticles, which due to their unique physical and chemical (first of all optical) properties, are promising in biology and medicine. There are many ways for quantum dots synthesis, both in the form of nanoislands self-forming on the surfaces, which can be used as single-photon emitters in electronics for storing information, and in the form of colloidal quantum dots for diagnostic and therapeutic purposes in living systems. The paper describes the main methods of quantum dots synthesis and summarizes medical and biological ways of their use. The main emphasis is laid on the ways of quantum dots surface modification. Influence of the size and form of nanoparticles, charge on the surfaces of quantum dots, and cover type on the efficiency of internalization by cells and cell compartments is shown. The main mechanisms of penetration are considered.

A novel usage of hydrogen treatment to improve the indium incorporation and internal quantum efficiency of green InGaN/GaN multiple quantum wells simultaneously

International Nuclear Information System (INIS)

Ren, Peng; Zhang, Ning; Xue, Bin; Liu, Zhe; Wang, Junxi; Li, Jinmin

2016-01-01

The challenge for improving the internal quantum efficiency (IQE) of InGaN-based light emitting diodes (LED) in the green light range is referred to as the ‘green gap’. However the IQE of InGaN-based LEDs often drops when the emission peak wavelength is adjusted through reducing the growth temperature. Although hydrogen (H 2 ) can improve surface morphology, it reduces the indium incorporation significantly. Here, a novel usage of H 2 treatment on the GaN barrier before the InGaN quantum well is demonstrated to enhance indium incorporation efficiency and improve the IQE simultaneously for the first time. The mechanism behind it is systematically investigated and explained in detail. The possible reason for this phenomenon is the strain relieving function by the undulant GaN barrier surface after H 2 treatment. Test measurements show that applying 0.2 min H 2 treatment on the barrier would reduce defects and enhance indium incorporation, which would improve the localization effect and finally lead to a higher IQE. Although further increasing the treatment time to 0.4 min incorporates more indium atoms, the IQE decreases at the expense of more defects and a larger polarization field than the 0.2 min sample. (paper)

Plasmon resonance-induced photoluminescence enhancement of CdTe/Cds quantum dots thin films

Energy Technology Data Exchange (ETDEWEB)

Wang, Hongyu [Nanjing University of Posts and Telecommunications, Nanjing 210003 (China); National Laboratory of Solid State Microstructure and School of Electronic Science and Engineering, Nanjing University, Nanjing 210093 (China); Xu, Ling, E-mail: xuling@nju.edu.cn [National Laboratory of Solid State Microstructure and School of Electronic Science and Engineering, Nanjing University, Nanjing 210093 (China); Wu, Yangqing; Xu, Jun; Ma, Zhongyuan; Chen, Kunji [National Laboratory of Solid State Microstructure and School of Electronic Science and Engineering, Nanjing University, Nanjing 210093 (China)

2016-11-30

Highlights: • CdTe/CdS quantum dots/Au nano-rods nano-composite films were fabricated. • PL intensity of the quantum dots films was enhanced due to Au nanorods. • Internal quantum efficiency increased due to localized surface plasmon resonance. • The lifetimes of quantum dots films decreased after interaction with Au nano-rods. - Abstract: CdTe/CdS quantum dots/Au nano-rods nano-composite films were fabricated on planar Si substrates. The optical properties of all samples were investigated and the corresponding simulations were studied. It was found that the photoluminescence intensity of the CdTe/CdS quantum dots films was enhanced about 9-fold after the incorporation of Au nano-rods, the internal quantum efficiency increased from 24.3% to 35.2% due to the localized surface plasmon resonance. The time-resolved luminescence decay curves showed that the lifetimes of CdTe/CdS quantum dots films decreased to 2.8 ns after interaction with Au nano-rods. The results of finite-difference time-domain simulation indicated that Au nano-rods induced the localization of electric field, which enhanced the PL intensity of quantum dots films in the vicinity of Au nano-rods.

Total internal reflection sum-frequency generation spectroscopy and dense gold nanoparticles monolayer: a route for probing adsorbed molecules

International Nuclear Information System (INIS)

Tourillon, Gerard; Dreesen, Laurent; Volcke, Cedric; Sartenaer, Yannick; Thiry, Paul A; Peremans, Andre

2007-01-01

We show that sum-frequency generation spectroscopy performed in the total internal reflection configuration (TIR-SFG) combined with a dense gold nanoparticles monolayer allows us to study, with an excellent signal to noise ratio and high signal to background ratio, the conformation of adsorbed molecules. Dodecanethiol (DDT) was used as probe molecules in order to assess the potentialities of the approach. An enhancement of more than one order of magnitude of the SFG signals arising from the adsorbed species is observed with the TIR geometry compared to the external reflection one while the SFG non-resonant contribution remains the same for both configurations. Although further work is required to fully understand the origin of the SFG process on nanoparticles, our work opens new possibilities for studying nanostructures

Multichannel scattering of charge carriers on quantum well heterostructures

CERN Document Server

Galiev, V I; Polupanov, A F; Goldis, E M; Tansli, T L

2002-01-01

An efficient numerical analytical method has been developed for finding continuum spectrum states in quantum well systems with arbitrary potential profiles that are described by coupled Schroedinger equations. Scattering states and S matrix have been built for the case of multichannel scattering in one-dimensional systems with quantum wells and their symmetry properties are obtained and analyzed. The method is applied for studying hole scattering by strained GaInAs-InGaAsP quantum wells. Coefficients of the hole transmission and reflection as well as delay time are calculated as functions of the energy of the incident hole for various values of parameters of structures and values of the momentum

Determination of the absolute internal quantum efficiency of photoluminescence in GaN co-doped with Si and Zn

Science.gov (United States)

Reshchikov, M. A.; Foussekis, M.; McNamara, J. D.; Behrends, A.; Bakin, A.; Waag, A.

2012-04-01

The optical properties of high-quality GaN co-doped with silicon and zinc are investigated by using temperature-dependent continuous-wave and time-resolved photoluminescence measurements. The blue luminescence band is related to the ZnGa acceptor in GaN:Si,Zn, which exhibits an exceptionally high absolute internal quantum efficiency (IQE). An IQE above 90% was calculated for several samples having different concentrations of Zn. Accurate and reliable values of the IQE were obtained by using several approaches based on rate equations. The concentrations of the ZnGa acceptors and free electrons were also estimated from the photoluminescence measurements.

A new exact quantum mechanical propagator

NARCIS (Netherlands)

Wiegel, F.W.; van Andel, P.W.

1987-01-01

The authors derive a closed-form expression for the time-dependent propagator for a quantum mechanical particle which is subject to an external force which is the sum of (i) a reflecting half-plane barrier with a straight edge, and (ii) a harmonic force pointing towards a point of the edge. This new

Yang-Baxter algebras of monodromy matrices in integrable quantum field theories

International Nuclear Information System (INIS)

Vega, H.J. de; Maillet, J.M.; Eichenherr, H.

1984-01-01

We consider a large class of two-dimensional integrable quantum field theories with nonabelian internal symmetry and classical scale invariance. We present a general procedure to determine explicitly the conserved quantum monodromy operator generating infinitely many non-local charges. The main features of our methods are a factorization principle and the use of P, T, and internal symmetries. The monodromy operator is shown to satisfy a Yang-Baxter algebra, the structure constants (i.e. the quantum R-matrix) of which are determined by the two-particle S-matrix of the theory. We apply the method to the chiral SU(N) and the O(2N) Gross-Neveu models. (orig.)

Single-shot quantum nondemolition measurement of a quantum-dot electron spin using cavity exciton-polaritons

Science.gov (United States)

Puri, Shruti; McMahon, Peter L.; Yamamoto, Yoshihisa

2014-10-01

We propose a scheme to perform single-shot quantum nondemolition (QND) readout of the spin of an electron trapped in a semiconductor quantum dot (QD). Our proposal relies on the interaction of the QD electron spin with optically excited, quantum well (QW) microcavity exciton-polaritons. The spin-dependent Coulomb exchange interaction between the QD electron and cavity polaritons causes the phase and intensity response of left circularly polarized light to be different than that of right circularly polarized light, in such a way that the QD electron's spin can be inferred from the response to a linearly polarized probe reflected or transmitted from the cavity. We show that with careful device design it is possible to essentially eliminate spin-flip Raman transitions. Thus a QND measurement of the QD electron spin can be performed within a few tens of nanoseconds with fidelity ˜99.95%. This improves upon current optical QD spin readout techniques across multiple metrics, including speed and scalability.

Quantum critical scaling and fluctuations in Kondo lattice materials

Science.gov (United States)

Yang, Yi-feng; Pines, David; Lonzarich, Gilbert

2017-01-01

We propose a phenomenological framework for three classes of Kondo lattice materials that incorporates the interplay between the fluctuations associated with the antiferromagnetic quantum critical point and those produced by the hybridization quantum critical point that marks the end of local moment behavior. We show that these fluctuations give rise to two distinct regions of quantum critical scaling: Hybridization fluctuations are responsible for the logarithmic scaling in the density of states of the heavy electron Kondo liquid that emerges below the coherence temperature T∗, whereas the unconventional power law scaling in the resistivity that emerges at lower temperatures below TQC may reflect the combined effects of hybridization and antiferromagnetic quantum critical fluctuations. Our framework is supported by experimental measurements on CeCoIn5, CeRhIn5, and other heavy electron materials. PMID:28559308

Near IR Scanning Angle Total Internal Reflection Raman Spectroscopy at Smooth Gold Films

Energy Technology Data Exchange (ETDEWEB)

McKee, Kristopher; Meyer, Matthew; Smith, Emily

2012-04-13

Total internal reflection (TIR) Raman and reflectivity spectra were collected for nonresonant analytes as a function of incident angle at sapphire or sapphire/smooth 50 nm gold interfaces using 785 nm excitation. For both interfaces, the Raman signal as a function of incident angle is well-modeled by the calculated interfacial mean square electric field (MSEF) relative to the incident field times the thickness of the layer being probed in the Raman measurement (D{sub RS}). The Raman scatter was reproducibly enhanced at the interface containing a gold film relative to the sapphire interface by a factor of 4.3–4.6 for aqueous pyridine or 2.2–3.7 for neat nitrobenzene, depending on the analyzed vibrational mode. The mechanism for the increased Raman signal is the enhanced MSEF at incident angles where propagating surface plasmons are excited in the metal film. The background from the TIR prism was reduced by 89–95% with the addition of the gold film, and the percent relative uncertainty in peak area was reduced from 15 to 1.7% for the 1347 cm–1 mode of nitrobenzene. Single monolayers of benzenethiol (S/N = 6.8) and 4-mercaptopyridine (S/N = 16.5) on gold films were measured by TIR Raman spectroscopy with 785 nm excitation (210 mW) without resonant enhancement in 1 min.

Implementing quantum logic gates with gradient ascent pulse engineering: principles and practicalities.

Science.gov (United States)

Rowland, Benjamin; Jones, Jonathan A

2012-10-13

We briefly describe the use of gradient ascent pulse engineering (GRAPE) pulses to implement quantum logic gates in nuclear magnetic resonance quantum computers, and discuss a range of simple extensions to the core technique. We then consider a range of difficulties that can arise in practical implementations of GRAPE sequences, reflecting non-idealities in the experimental systems used.

Colloquium: Non-Markovian dynamics in open quantum systems

Science.gov (United States)

Breuer, Heinz-Peter; Laine, Elsi-Mari; Piilo, Jyrki; Vacchini, Bassano

2016-04-01

The dynamical behavior of open quantum systems plays a key role in many applications of quantum mechanics, examples ranging from fundamental problems, such as the environment-induced decay of quantum coherence and relaxation in many-body systems, to applications in condensed matter theory, quantum transport, quantum chemistry, and quantum information. In close analogy to a classical Markovian stochastic process, the interaction of an open quantum system with a noisy environment is often modeled phenomenologically by means of a dynamical semigroup with a corresponding time-independent generator in Lindblad form, which describes a memoryless dynamics of the open system typically leading to an irreversible loss of characteristic quantum features. However, in many applications open systems exhibit pronounced memory effects and a revival of genuine quantum properties such as quantum coherence, correlations, and entanglement. Here recent theoretical results on the rich non-Markovian quantum dynamics of open systems are discussed, paying particular attention to the rigorous mathematical definition, to the physical interpretation and classification, as well as to the quantification of quantum memory effects. The general theory is illustrated by a series of physical examples. The analysis reveals that memory effects of the open system dynamics reflect characteristic features of the environment which opens a new perspective for applications, namely, to exploit a small open system as a quantum probe signifying nontrivial features of the environment it is interacting with. This Colloquium further explores the various physical sources of non-Markovian quantum dynamics, such as structured environmental spectral densities, nonlocal correlations between environmental degrees of freedom, and correlations in the initial system-environment state, in addition to developing schemes for their local detection. Recent experiments addressing the detection, quantification, and control of

Engineering integrated photonics for heralded quantum gates

Science.gov (United States)

Meany, Thomas; Biggerstaff, Devon N.; Broome, Matthew A.; Fedrizzi, Alessandro; Delanty, Michael; Steel, M. J.; Gilchrist, Alexei; Marshall, Graham D.; White, Andrew G.; Withford, Michael J.

2016-06-01

Scaling up linear-optics quantum computing will require multi-photon gates which are compact, phase-stable, exhibit excellent quantum interference, and have success heralded by the detection of ancillary photons. We investigate the design, fabrication and characterisation of the optimal known gate scheme which meets these requirements: the Knill controlled-Z gate, implemented in integrated laser-written waveguide arrays. We show device performance to be less sensitive to phase variations in the circuit than to small deviations in the coupler reflectivity, which are expected given the tolerance values of the fabrication method. The mode fidelity is also shown to be less sensitive to reflectivity and phase errors than the process fidelity. Our best device achieves a fidelity of 0.931 ± 0.001 with the ideal 4 × 4 unitary circuit and a process fidelity of 0.680 ± 0.005 with the ideal computational-basis process.

Engineering integrated photonics for heralded quantum gates.

Science.gov (United States)

Meany, Thomas; Biggerstaff, Devon N; Broome, Matthew A; Fedrizzi, Alessandro; Delanty, Michael; Steel, M J; Gilchrist, Alexei; Marshall, Graham D; White, Andrew G; Withford, Michael J

2016-06-10

Scaling up linear-optics quantum computing will require multi-photon gates which are compact, phase-stable, exhibit excellent quantum interference, and have success heralded by the detection of ancillary photons. We investigate the design, fabrication and characterisation of the optimal known gate scheme which meets these requirements: the Knill controlled-Z gate, implemented in integrated laser-written waveguide arrays. We show device performance to be less sensitive to phase variations in the circuit than to small deviations in the coupler reflectivity, which are expected given the tolerance values of the fabrication method. The mode fidelity is also shown to be less sensitive to reflectivity and phase errors than the process fidelity. Our best device achieves a fidelity of 0.931 ± 0.001 with the ideal 4 × 4 unitary circuit and a process fidelity of 0.680 ± 0.005 with the ideal computational-basis process.

Optimal reflection-free complex absorbing potentials for quantum propagation of wave packets

International Nuclear Information System (INIS)

Shemer, Oded; Brisker, Daria; Moiseyev, Nimrod

2005-01-01

The conditions for optimal reflection-free complex-absorbing potentials (CAPs) are discussed. It is shown that the CAPs as derived from the smooth-exterior-scaling transformation of the Hamiltonian [J. Phys. B 31, 1431 (1998)] serve as optimal reflection-free CAPs (RF CAPs) in wave-packet propagation calculations of open systems. The initial wave packet, Φ(t=0), can be located in the interaction region (as in half collision experiments) where the CAPs have vanished or in the asymptote where V CAP ≠0. As we show, the optimal CAPs can be introduced also in the region where the physical potential has not vanished. The unavoided reflections due to the use of a finite number of grid points (or basis functions) are discussed. A simple way to reduce the 'edge-grid' reflection effect is described

Quantum interaction. Revised selected papers

International Nuclear Information System (INIS)

Song, Dawei; Zhang, Peng; Wang, Lei; Arafat, Sachi

2011-01-01

This book constitutes the thoroughly refereed post-conference proceedings of the 5th International Symposium on Quantum Interaction, QI 2011, held in Aberdeen, UK, in June 2011. The 26 revised full papers and 6 revised poster papers, presented together with 1 tutorial and 1 invited talk were carefully reviewed and selected from numerous submissions during two rounds of reviewing and improvement. The papers show the cross-disciplinary nature of quantum interaction covering topics such as computation, cognition, mechanics, social interaction, semantic space and information representation and retrieval. (orig.)

Philosophic foundations of quantum mechanics

CERN Document Server

Reichenbach, Hans

1998-01-01

Physics concerns direct analysis of the physical world, while philosophy analyzes knowledge about the physical world. This volume combines both disciplines for a philosophical interpretation of quantum physics - an interpretation free from the imprecision of metaphysics, offering a view of the atomic world and its quantum mechanical results as concrete as the visible everyday world.Written by an internationally renowned philosopher who specialized in symbolic logic and the theory of relativity, this approach consists of three parts. The first section, which requires no background in math or p

Quantum interaction. Revised selected papers

Energy Technology Data Exchange (ETDEWEB)

Song, Dawei; Zhang, Peng; Wang, Lei [Aberdeen Univ. (United Kingdom). School of Computing; Melucci, Massimo [Padua Univ., Padova (Italy). Dept. of Information Engineering; Frommholz, Ingo [Bedfordshire Univ. (United Kingdom); Arafat, Sachi (eds.) [Glasgow Univ. (United Kingdom). School of Computing Science

2011-07-01

This book constitutes the thoroughly refereed post-conference proceedings of the 5th International Symposium on Quantum Interaction, QI 2011, held in Aberdeen, UK, in June 2011. The 26 revised full papers and 6 revised poster papers, presented together with 1 tutorial and 1 invited talk were carefully reviewed and selected from numerous submissions during two rounds of reviewing and improvement. The papers show the cross-disciplinary nature of quantum interaction covering topics such as computation, cognition, mechanics, social interaction, semantic space and information representation and retrieval. (orig.)

Symmetry of intramolecular quantum dynamics

CERN Document Server

Burenin, Alexander V

2012-01-01

The main goal of this book is to give a systematic description of intramolecular quantum dynamics on the basis of only the symmetry principles. In this respect, the book has no analogs in the world literature. The obtained models lead to a simple, purely algebraic, scheme of calculation and are rigorous in the sense that their correctness is limited only to the correct choice of symmetry of the internal dynamics. The book is basically intended for scientists working in the field of molecular spectroscopy, quantum and structural chemistry.

FTL Quantum Models of the Photon and the Electron

International Nuclear Information System (INIS)

Gauthier, Richard F.

2007-01-01

A photon is modeled by an uncharged superluminal quantum moving at 1.414c along an open 45-degree helical trajectory with radius R = λ/2π (where λ is the helical pitch or wavelength). A mostly superluminal spatial model of an electron is composed of a charged pointlike quantum circulating at an extremely high frequency ( 2.5 x 1020 hz) in a closed, double-looped hehcal trajectory whose helical pitch is one Compton wavelength h/mc. The quantum has energy and momentum but not rest mass, so its speed is not limited by c. sThe quantum's speed is superluminal 57% of the time and subluminal 43% of the time, passing through c twice in each trajectory cycle. The quantum's maximum speed in the electron's rest frame is 2.515c and its minimum speed is .707c. The electron model's helical trajectory parameters are selected to produce the electron's spin (ℎ/2π)/2 and approximate (without small QED corrections) magnetic moment e(ℎ/2π)/2m (the Bohr magneton μB) as well as its Dirac equation-related 'jittery motion' angular frequency 2mc2/(ℎ/2π), amplitude (ℎ/2π)/2mc and internal speed c. The two possible helicities of the electron model correspond to the electron and the positron. With these models, an electron is like a closed circulating photon. The electron's inertia is proposed to be related to the electron model's circulating internal Compton momentum mc. The internal superluminalily of the photon model, the internal superluminahty/subluminality of the electron model, and the proposed approach to the electron's inertia as ''momentum at rest'' within the electron, could be relevant to possible mechanisms of superluminal communication and transportation

I, Quantum Robot: Quantum Mind control on a Quantum Computer

OpenAIRE

Zizzi, Paola

2008-01-01

The logic which describes quantum robots is not orthodox quantum logic, but a deductive calculus which reproduces the quantum tasks (computational processes, and actions) taking into account quantum superposition and quantum entanglement. A way toward the realization of intelligent quantum robots is to adopt a quantum metalanguage to control quantum robots. A physical implementation of a quantum metalanguage might be the use of coherent states in brain signals.

2011 Gordon Research Conference on Quantum Control of Light and Matter

International Nuclear Information System (INIS)

Weinacht, Thomas

2011-01-01

Quantum control of light and matter is the quest to steer a physical process to a desirable outcome, employing constructive and destructive interference. Three basic questions address feasibility of quantum control: (1) The problem of controllability, does a control field exist for a preset initial and target state; (2) Synthesis, constructively finding the field that leads to the target; and (3) Optimal Control Theory - optimizing the field that carries out this task. These continue to be the fundamental theoretical questions to be addressed in the conference. How to realize control fields in the laboratory is an ongoing challenge. This task is very diverse viewing the emergence of control scenarios ranging from attoseconds to microseconds. How do the experimental observations reflect on the theoretical framework? The typical arena of quantum control is an open environment where much of the control is indirect. How are control scenarios realized in dissipative open systems? Can new control opportunities emerge? Can one null decoherence effects? An ideal setting for control is ultracold matter. The initial and final state can be defined more precisely. Coherent control unifies many fields of physical science. A lesson learned in one field can reflect on another. Currently quantum information processing has emerged as a primary target of control where the key issue is controlling quantum gate operation. Modern nonlinear spectroscopy has emerged as another primary field. The challenge is to unravel the dynamics of molecular systems undergoing strong interactions with the environment. Quantum optics where non-classical fields are to be generated and employed. Finally, coherent control is the basis for quantum engineering. These issues will be under the limelight of the Gordon conference on Quantum Control of Light and Matter.

How to teach quantum physics to your dog

CERN Document Server

Orzel, Chad

2010-01-01

In this international bestseller, Orzel explains the key theories of quantum physics, taking his dog Emmy's anarchic behaviour as a starting point. Could she use quantum tunnelling to get through the neighbour's fence? How about diffracting round a tree to chase squirrels? From quarks and gluons to Heisenberg's uncertainty principle, this is a uniquely entertaining way to unlock the secrets of the universe.

Duality constructions from quantum state manifolds

Science.gov (United States)

Kriel, J. N.; van Zyl, H. J. R.; Scholtz, F. G.

2015-11-01

The formalism of quantum state space geometry on manifolds of generalised coherent states is proposed as a natural setting for the construction of geometric dual descriptions of non-relativistic quantum systems. These state manifolds are equipped with natural Riemannian and symplectic structures derived from the Hilbert space inner product. This approach allows for the systematic construction of geometries which reflect the dynamical symmetries of the quantum system under consideration. We analyse here in detail the two dimensional case and demonstrate how existing results in the AdS 2 /CF T 1 context can be understood within this framework. We show how the radial/bulk coordinate emerges as an energy scale associated with a regularisation procedure and find that, under quite general conditions, these state manifolds are asymptotically anti-de Sitter solutions of a class of classical dilaton gravity models. For the model of conformal quantum mechanics proposed by de Alfaro et al. [1] the corresponding state manifold is seen to be exactly AdS 2 with a scalar curvature determined by the representation of the symmetry algebra. It is also shown that the dilaton field itself is given by the quantum mechanical expectation values of the dynamical symmetry generators and as a result exhibits dynamics equivalent to that of a conformal mechanical system.

Role of short periodic orbits in quantum maps with continuous openings

Science.gov (United States)

Prado, Carlos A.; Carlo, Gabriel G.; Benito, R. M.; Borondo, F.

2018-04-01

We apply a recently developed semiclassical theory of short periodic orbits to the continuously open quantum tribaker map. In this paradigmatic system the trajectories are partially bounced back according to continuous reflectivity functions. This is relevant in many situations that include optical microresonators and more complicated boundary conditions. In a perturbative regime, the shortest periodic orbits belonging to the classical repeller of the open map—a cantor set given by a region of exactly zero reflectivity—prove to be extremely robust in supporting a set of long-lived resonances of the continuously open quantum maps. Moreover, for steplike functions a significant reduction in the number needed is obtained, similarly to the completely open situation. This happens despite a strong change in the spectral properties when compared to the discontinuous reflectivity case. In order to give a more realistic interpretation of these results we compare with a Fresnel-type reflectivity function.

Teaching the Common Aspects in Mechanical, Electromagnetic and Quantum Waves at Interfaces and Waveguides

Science.gov (United States)

Rojas, R.; Robles, P.

2011-01-01

We discuss common features in mechanical, electromagnetic and quantum systems, supporting identical results for the transmission and reflection coefficients of waves arriving perpendicularly at a plane interface. Also, we briefly discuss the origin of special notions such as refractive index in quantum mechanics, massive photons in wave guides and…

Potts glass reflection of the decoding threshold for qudit quantum error correcting codes

Science.gov (United States)

Jiang, Yi; Kovalev, Alexey A.; Pryadko, Leonid P.

We map the maximum likelihood decoding threshold for qudit quantum error correcting codes to the multicritical point in generalized Potts gauge glass models, extending the map constructed previously for qubit codes. An n-qudit quantum LDPC code, where a qudit can be involved in up to m stabilizer generators, corresponds to a ℤd Potts model with n interaction terms which can couple up to m spins each. We analyze general properties of the phase diagram of the constructed model, give several bounds on the location of the transitions, bounds on the energy density of extended defects (non-local analogs of domain walls), and discuss the correlation functions which can be used to distinguish different phases in the original and the dual models. This research was supported in part by the Grants: NSF PHY-1415600 (AAK), NSF PHY-1416578 (LPP), and ARO W911NF-14-1-0272 (LPP).

Quantum correlations induced by multiple scattering of quadrature squeezed light

DEFF Research Database (Denmark)

Lodahl, Peter

2006-01-01

Propagating quadrature squeezed light through a multiple scattering random medium is found to induce pronounced spatial quantum correlations that have no classical analogue. The correlations are revealed in the number of photons transported through the sample that can be measured from the intensity...... fluctuations of the total transmission or reflection. In contrast, no pronounced spatial quantum correlations appear in the quadrature amplitudes where excess noise above the shot noise level is found....

Hierarchical structures consisting of SiO2 nanorods and p-GaN microdomes for efficiently harvesting solar energy for InGaN quantum well photovoltaic cells.

Science.gov (United States)

Ho, Cheng-Han; Lien, Der-Hsien; Chang, Hung-Chih; Lin, Chin-An; Kang, Chen-Fang; Hsing, Meng-Kai; Lai, Kun-Yu; He, Jr-Hau

2012-12-07

We experimentally and theoretically demonstrated the hierarchical structure of SiO(2) nanorod arrays/p-GaN microdomes as a light harvesting scheme for InGaN-based multiple quantum well solar cells. The combination of nano- and micro-structures leads to increased internal multiple reflection and provides an intermediate refractive index between air and GaN. Cells with the hierarchical structure exhibit improved short-circuit current densities and fill factors, rendering a 1.47 fold efficiency enhancement as compared to planar cells.

How to solve path integrals in quantum mechanics

International Nuclear Information System (INIS)

Grosche, C.

1994-10-01

A systematic classification of Feynman path integrals in quantum mechanics is presented and a table of solvable path integrals is given which reflects the progress made during the last 15 years, including, of course, the main contributions since the invention of the path integral by Feynman in 1942. An outline of the general theory is given which will serve as a quick reference for solving path integrals. Explicit formulae for the so-called basic path integrals are presented on which our general scheme to classify and calculate path integrals in quantum mechanics is based. (orig.)

A new model for quantum games based on the Marinatto–Weber approach

International Nuclear Information System (INIS)

Frąckiewicz, Piotr

2013-01-01

The Marinatto–Weber approach to quantum games is a straightforward way to apply the power of quantum mechanics to classical game theory. In the simplest case, the quantum scheme is that players manipulate their own qubits of a two-qubit state either with the identity 1 or the Pauli operator σ x . However, such a simplification of the scheme raises doubt as to whether it could really reflect a quantum game. In this paper we put forward examples which may constitute arguments against the present form of the Marinatto–Weber scheme. Next, we modify the scheme to eliminate the undesirable properties of the protocol by extending the players’ strategy sets. (paper)

Non-Markovian Investigation of an Autonomous Quantum Heat Engine

Science.gov (United States)

Goyal, Ketan

A systematic study of a quantum heat engine is presented in this thesis. In particular, we study heat conduction through a two-two level composite system, which is then connected to a photon cavity to extract work, forming an autonomous quantum heat engine. The question as to what extent quantum effects such as quantum coherence and correlations impact thermodynamic properties of such a system is addressed. The investigated heat engine has been previously studied using the popular Born-Markovian quantum master equation under weak internal coupling approximation. However, we show that the used approach is quite limited in addressing such problems as it is incapable of correctly accounting for the quantum effects. By using a non-Markovian approach involving hierarchical equations of motion, we show that quantum coherence and correlations between system and environments play a significant role in energy transfer processes of heat conduction and work.

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...

Demonstrating quantum random with single photons

International Nuclear Information System (INIS)

Bronner, Patrick; Strunz, Andreas; Meyn, Jan-Peter; Silberhorn, Christine

2009-01-01

We present an experiment for education which demonstrates random transmission or reflection of heralded single photons on beam splitters. With our set-up, we can realize different quantum random experiments by appropriate settings of polarization rotators. The concept of entanglement is motivated by correlated randomness. The experiments are suitable for undergraduate education and are available as interactive screen experiments.

Registration of T-2 mycotoxin with total internal reflection ellipsometry and QCM impedance methods.

Science.gov (United States)

Nabok, A V; Tsargorodskaya, A; Holloway, A; Starodub, N F; Gojster, O

2007-01-15

A sensitive optical method of total internal reflection ellipsometry (TIRE) in conjunction with immune assay approach was exploited for the registration of T-2 mycotoxin in a wide range of concentrations from 100 microg/ml down to 0.15 ng/ml. Association constants of 1.4x10(6) and 1.9x10(7)mol(-1)s for poly- and monoclonal T-2 antibodies, respectively, were evaluated from TIRE kinetic measurements. According to TIRE data fitting, binding of T-2 molecules to antibodies (at saturation) has resulted in the increase in adsorbed layer thickness of 4-5 nm. The QCM impedance measurements data showed anomalously large mass increase and film softening, most likely, due to the binding of large T-2 aggregates to antibodies.

Single-Ion Implantation for the Development of Si-Based MOSFET Devices with Quantum Functionalities

Directory of Open Access Journals (Sweden)

Jeffrey C. McCallum

2012-01-01

Full Text Available Interest in single-ion implantation is driven in part by research into development of solid-state devices that exhibit quantum behaviour in their electronic or optical characteristics. Here, we provide an overview of international research work on single ion implantation and single ion detection for development of electronic devices for quantum computing. The scope of international research into single ion implantation is presented in the context of our own research in the Centre for Quantum Computation and Communication Technology in Australia. Various single ion detection schemes are presented, and limitations on dopant placement accuracy due to ion straggling are discussed together with pathways for scale-up to multiple quantum devices on the one chip. Possible future directions for ion implantation in quantum computing and communications are also discussed.

Epitaxial lift-off for solid-state cavity quantum electrodynamics

International Nuclear Information System (INIS)

Greuter, Lukas; Najer, Daniel; Kuhlmann, Andreas V.; Starosielec, Sebastian; Warburton, Richard J.; Valentin, Sascha R.; Ludwig, Arne; Wieck, Andreas D.

2015-01-01

We demonstrate an approach to incorporate self-assembled quantum dots into a Fabry-Pérot-like microcavity. Thereby, a 3λ/4 GaAs layer containing quantum dots is epitaxially removed and attached by van der Waals bonding to one of the microcavity mirrors. We reach a finesse as high as 4100 with this configuration limited by the reflectivity of the dielectric mirrors and not by scattering at the semiconductor-mirror interface, demonstrating that the epitaxial lift-off procedure is a promising procedure for cavity quantum electrodynamics in the solid state. As a first step in this direction, we demonstrate a clear cavity-quantum dot interaction in the weak coupling regime with a Purcell factor in the order of 3. Estimations of the coupling strength via the Purcell factor suggest that we are close to the strong coupling regime

Equivalence principle for quantum systems: dephasing and phase shift of free-falling particles

Science.gov (United States)

Anastopoulos, C.; Hu, B. L.

2018-02-01

We ask the question of how the (weak) equivalence principle established in classical gravitational physics should be reformulated and interpreted for massive quantum objects that may also have internal degrees of freedom (dof). This inquiry is necessary because even elementary concepts like a classical trajectory are not well defined in quantum physics—trajectories originating from quantum histories become viable entities only under stringent decoherence conditions. From this investigation we posit two logically and operationally distinct statements of the equivalence principle for quantum systems. Version A: the probability distribution of position for a free-falling particle is the same as the probability distribution of a free particle, modulo a mass-independent shift of its mean. Version B: any two particles with the same velocity wave-function behave identically in free fall, irrespective of their masses. Both statements apply to all quantum states, including those without a classical correspondence, and also for composite particles with quantum internal dof. We also investigate the consequences of the interaction between internal and external dof induced by free fall. For a class of initial states, we find dephasing occurs for the translational dof, namely, the suppression of the off-diagonal terms of the density matrix, in the position basis. We also find a gravitational phase shift in the reduced density matrix of the internal dof that does not depend on the particle’s mass. For classical states, the phase shift has a natural classical interpretation in terms of gravitational red-shift and special relativistic time-dilation.

Time dilation in quantum systems and decoherence

International Nuclear Information System (INIS)

Pikovski, Igor; Zych, Magdalena; Costa, Fabio; Brukner, Časlav

2017-01-01

Both quantum mechanics and general relativity are based on principles that defy our daily intuitions, such as time dilation, quantum interference and entanglement. Because the regimes where the two theories are typically tested are widely separated, their foundational principles are rarely jointly studied. Recent works have found that novel phenomena appear for quantum particles with an internal structure in the presence of time dilation, which can take place at low energies and in weak gravitational fields. Here we briefly review the effects of time dilation on quantum interference and generalize the results to a variety of systems. In addition, we provide an extended study of the basic principles of quantum theory and relativity that are of relevance for the effects and also address several questions that have been raised, such as the description in different reference frames, the role of the equivalence principle and the effective irreversibility of the decoherence. The manuscript clarifies some of the counterintuitive aspects arising when quantum phenomena and general relativistic effects are jointly considered. (paper)

Equivalence of Szegedy's and coined quantum walks

Science.gov (United States)

Wong, Thomas G.

2017-09-01

Szegedy's quantum walk is a quantization of a classical random walk or Markov chain, where the walk occurs on the edges of the bipartite double cover of the original graph. To search, one can simply quantize a Markov chain with absorbing vertices. Recently, Santos proposed two alternative search algorithms that instead utilize the sign-flip oracle in Grover's algorithm rather than absorbing vertices. In this paper, we show that these two algorithms are exactly equivalent to two algorithms involving coined quantum walks, which are walks on the vertices of the original graph with an internal degree of freedom. The first scheme is equivalent to a coined quantum walk with one walk step per query of Grover's oracle, and the second is equivalent to a coined quantum walk with two walk steps per query of Grover's oracle. These equivalences lie outside the previously known equivalence of Szegedy's quantum walk with absorbing vertices and the coined quantum walk with the negative identity operator as the coin for marked vertices, whose precise relationships we also investigate.

Schrödinger's killer app race to build the world's first quantum computer

CERN Document Server

Dowling, Jonathan P

2013-01-01

The race is on to construct the first quantum code breaker, as the winner will hold the key to the entire Internet. From international, multibillion-dollar financial transactions to top-secret government communications, all would be vulnerable to the secret-code-breaking ability of the quantum computer. Written by a renowned quantum physicist closely involved in the U.S. government's development of quantum information science, Schrodinger's Killer App: Race to Build the World's First Quantum Computer presents an inside look at the government's quest to build a quantum computer capable of solvi

Quantum discord and classical correlation signatures of mobility edges in one-dimensional aperiodic single-electron systems

International Nuclear Information System (INIS)

Gong, Longyan; Zhu, Hao; Zhao, Shengmei; Cheng, Weiwen; Sheng, Yubo

2012-01-01

We investigate numerically the quantum discord and the classical correlation in a one-dimensional slowly varying potential model and a one-dimensional Soukoulis–Economou ones, respectively. There are well-defined mobility edges in the slowly varying potential model, while there are discrepancies on mobility edges in the Soukoulis–Economou ones. In the slowly varying potential model, we find that extended and localized states can be distinguished by both the quantum discord and the classical correlation. There are sharp transitions in the quantum discord and the classical correlation at mobility edges. Based on these, we study “mobility edges” in the Soukoulis–Economou model using the quantum discord and the classical correlation, which gives another perspectives for these “mobility edges”. All these provide us good quantities, i.e., the quantum discord and the classical correlation, to reflect mobility edges in these one-dimensional aperiodic single-electron systems. Moreover, our studies propose a consistent interpretation of the discrepancies between previous numerical results about the Soukoulis–Economou model. -- Highlights: ► Quantum discord and classical correlation can signal mobility edges in two models. ► An interpretation for mobility edges in the Soukoulis–Economou model is proposed. ► Quantum discord and classical correlation can reflect well localization properties.

Optical bistability in a single-sided cavity coupled to a quantum channel

Science.gov (United States)

Payravi, M.; Solookinejad, Gh; Jabbari, M.; Nafar, M.; Ahmadi Sangachin, E.

2018-06-01

In this paper, we discuss the long wavelength optical reflection and bistable behavior of an InGaN/GaN quantum dot nanostructure coupled to a single-sided cavity. It is found that due to the presence of a strong coupling field, the reflection coefficient can be controlled at long wavelength, which is essential for adjusting the threshold of reflected optical bistability. Moreover, the phase shift features of the reflection pulse inside an electromagnetically induced transparency window are also discussed.

Liability for nuclear damage: an international perspective. Reflections on the revision of the Vienna Convention

Energy Technology Data Exchange (ETDEWEB)

Lopuski, J

1994-12-31

This book deals with deals of the complex issues of liability and compensation for nuclear damage which have been considered in the course of the work of the IAEA concerning the revision of the Vienna Convention on nuclear liability. It presents, in an orderly way, personal reflections of its author based on his experience gathered in years 1989-1992 when participating in this work. Necessarily it contains in some of its parts references to documents of the IAEA Standing Committee on Nuclear Liability; these documents because of their length could not be reproduced. Consequently these parts may not be fully intelligible for those who have not participated in or closely followed the Committee`s work. The IAEA work on liability for nuclear damage was initiated in the wake of the impact made on the world`s public opinion by the Chernobyl incident and its transboundary effects; issues of international state liability and full compensation have been raised. But humanitarian ideas have quickly been confronted with cold calculations of the cost of financial protection for victims and an open unwillingness of some nuclear states has been manifested. After three years of discussions no wide consensus could be reached on some basic issues, such as: relationship between international state and civil liability regimes, structure of international legislation, concept of nuclear damage, limits of compensation, role of public funds or jurisdiction. The author presents his approach to these controversial issue, trying to provide at the same time a theoretical outline for the future international legislation on nuclear liability. (author).

Liability for nuclear damage: an international perspective. Reflections on the revision of the Vienna Convention

Energy Technology Data Exchange (ETDEWEB)

Lopuski, J.

1993-12-31

This book deals with deals of the complex issues of liability and compensation for nuclear damage which have been considered in the course of the work of the IAEA concerning the revision of the Vienna Convention on nuclear liability. It presents, in an orderly way, personal reflections of its author based on his experience gathered in years 1989-1992 when participating in this work. Necessarily it contains in some of its parts references to documents of the IAEA Standing Committee on Nuclear Liability; these documents because of their length could not be reproduced. Consequently these parts may not be fully intelligible for those who have not participated in or closely followed the Committee`s work. The IAEA work on liability for nuclear damage was initiated in the wake of the impact made on the world`s public opinion by the Chernobyl incident and its transboundary effects; issues of international state liability and full compensation have been raised. But humanitarian ideas have quickly been confronted with cold calculations of the cost of financial protection for victims and an open unwillingness of some nuclear states has been manifested. After three years of discussions no wide consensus could be reached on some basic issues, such as: relationship between international state and civil liability regimes, structure of international legislation, concept of nuclear damage, limits of compensation, role of public funds or jurisdiction. The author presents his approach to these controversial issue, trying to provide at the same time a theoretical outline for the future international legislation on nuclear liability. (author).

Liability for nuclear damage: an international perspective. Reflections on the revision of the Vienna Convention

International Nuclear Information System (INIS)

Lopuski, J.

1993-01-01

This book deals with deals of the complex issues of liability and compensation for nuclear damage which have been considered in the course of the work of the IAEA concerning the revision of the Vienna Convention on nuclear liability. It presents, in an orderly way, personal reflections of its author based on his experience gathered in years 1989-1992 when participating in this work. Necessarily it contains in some of its parts references to documents of the IAEA Standing Committee on Nuclear Liability; these documents because of their length could not be reproduced. Consequently these parts may not be fully intelligible for those who have not participated in or closely followed the Committee's work. The IAEA work on liability for nuclear damage was initiated in the wake of the impact made on the world's public opinion by the Chernobyl incident and its transboundary effects; issues of international state liability and full compensation have been raised. But humanitarian ideas have quickly been confronted with cold calculations of the cost of financial protection for victims and an open unwillingness of some nuclear states has been manifested. After three years of discussions no wide consensus could be reached on some basic issues, such as: relationship between international state and civil liability regimes, structure of international legislation, concept of nuclear damage, limits of compensation, role of public funds or jurisdiction. The author presents his approach to these controversial issue, trying to provide at the same time a theoretical outline for the future international legislation on nuclear liability. (author)

Quantum Erasure: Quantum Interference Revisited

OpenAIRE

Walborn, Stephen P.; Cunha, Marcelo O. Terra; Pádua, Sebastião; Monken, Carlos H.

2005-01-01

Recent experiments in quantum optics have shed light on the foundations of quantum physics. Quantum erasers - modified quantum interference experiments - show that quantum entanglement is responsible for the complementarity principle.

A small-displacement sensor using total internal reflection theory and surface plasmon resonance technology for heterodyne interferometry.

Science.gov (United States)

Wang, Shinn-Fwu

2009-01-01

A small-displacement sensor based on total-internal reflection theory and surface plasmon resonance technology is proposed for use in heterodyne interferometry. A small displacement can be obtained simply by measuring the variation in phase difference between s- and p-polarization states with the small-displacement sensor. The theoretical displacement resolution of the small-displacement sensor can reach 0.45 nm. The sensor has some additional advantages, e.g., a simple optical setup, high resolution, high sensitivity and rapid measurement. Its feasibility is also demonstrated.

Quantum Monte Carlo tunneling from quantum chemistry to quantum annealing

Science.gov (United States)

Mazzola, Guglielmo; Smelyanskiy, Vadim N.; Troyer, Matthias

2017-10-01

Quantum tunneling is ubiquitous across different fields, from quantum chemical reactions and magnetic materials to quantum simulators and quantum computers. While simulating the real-time quantum dynamics of tunneling is infeasible for high-dimensional systems, quantum tunneling also shows up in quantum Monte Carlo (QMC) simulations, which aim to simulate quantum statistics with resources growing only polynomially with the system size. Here we extend the recent results obtained for quantum spin models [Phys. Rev. Lett. 117, 180402 (2016), 10.1103/PhysRevLett.117.180402], and we study continuous-variable models for proton transfer reactions. We demonstrate that QMC simulations efficiently recover the scaling of ground-state tunneling rates due to the existence of an instanton path, which always connects the reactant state with the product. We discuss the implications of our results in the context of quantum chemical reactions and quantum annealing, where quantum tunneling is expected to be a valuable resource for solving combinatorial optimization problems.

Bend-imitating theory and electron scattering in sharply-bent quantum nanowires

International Nuclear Information System (INIS)

Vakhnenko, O.O.

2011-01-01

The concept of bend-imitating description as applied to the one-electron quantum mechanics in sharply-bent ideal electron waveguides and its development into a self consistent theory are presented. In the framework of bend-imitating approach, the investigation of the electron scattering in a doubly-bent 2D quantum wire with S-like bend has been made, and the explicit dependences of the transmission and reflection coefficients on geometrical parameters of a structure, as well as on the electron energy, have been obtained. The total elimination of the mixing between the scattering channels of a S-like bent quantum wire is predicted.

Quantum Nonlocality and Reality

Science.gov (United States)

Bell, Mary; Gao, Shan

2016-09-01

Preface; Part I. John Stewart Bell: The Physicist: 1. John Bell: the Irish connection Andrew Whitaker; 2. Recollections of John Bell Michael Nauenberg; 3. John Bell: recollections of a great scientist and a great man Gian-Carlo Ghirardi; Part II. Bell's Theorem: 4. What did Bell really prove? Jean Bricmont; 5. The assumptions of Bell's proof Roderich Tumulka; 6. Bell on Bell's theorem: the changing face of nonlocality Harvey R. Brown and Christopher G. Timpson; 7. Experimental tests of Bell inequalities Marco Genovese; 8. Bell's theorem without inequalities: on the inception and scope of the GHZ theorem Olival Freire, Jr and Osvaldo Pessoa, Jr; 9. Strengthening Bell's theorem: removing the hidden-variable assumption Henry P. Stapp; Part III. Nonlocality: Illusions or Reality?: 10. Is any theory compatible with the quantum predictions necessarily nonlocal? Bernard d'Espagnat; 11. Local causality, probability and explanation Richard A. Healey; 12. Bell inequality and many-worlds interpretation Lev Vaidman; 13. Quantum solipsism and non-locality Travis Norsen; 14. Lessons of Bell's theorem: nonlocality, yes; action at a distance, not necessarily Wayne C. Myrvold; 15. Bell non-locality, Hardy's paradox and hyperplane dependence Gordon N. Fleming; 16. Some thoughts on quantum nonlocality and its apparent incompatibility with relativity Shan Gao; 17. A reasonable thing that just might work Daniel Rohrlich; 18. Weak values and quantum nonlocality Yakir Aharonov and Eliahu Cohen; Part IV. Nonlocal Realistic Theories: 19. Local beables and the foundations of physics Tim Maudlin; 20. John Bell's varying interpretations of quantum mechanics: memories and comments H. Dieter Zeh; 21. Some personal reflections on quantum non-locality and the contributions of John Bell Basil J. Hiley; 22. Bell on Bohm Sheldon Goldstein; 23. Interactions and inequality Philip Pearle; 24. Gravitation and the noise needed in objective reduction models Stephen L. Adler; 25. Towards an objective

Public Diplomacy and Refugee Relations Reflections of Turkey’s Refugees Relations on the International Media

Directory of Open Access Journals (Sweden)

Ergün Köksoy

2015-11-01

Full Text Available Public diplomacy is described as a new form of relations and communications between countries and societies in the field of international relations with the process of globalisation. The subject of refugees shown among the priority issues can be solved through international cooperation and solidarity with its results affecting all countries and societies, that’s why becoming part of public diplomacy. Asylum seekers and refugee rights are guaranteed by the Universal Declaration of Human Rights and considered to be an area that the international community needs to take the roles and share responsibilities. In this aspect, it is shown as global responsibilities and part of the humanitarian sensibility of countries and societies. In one hand, asylum seekers and refugees are considered to be the subject of the problem and crisis, on the other hand, due to contributing to the human and cultural interaction between the different communities, these are specified as part of public diplomacy. This article discusses the relationship between public diplomacy and refugees relations which provides the interaction between countries and effects the prestige and perception of them. In the study, to reveal the reflections of Turkey’s Refugees Relations on the International Media, three highest-circulation newspapers (“The Guardian”, “Le Monde”, “Der Spiegel” will be choosen from three important EU countries (United Kingdom, France, Germany. These newspapers’ headlines and news content which related to Turkey and Syrian refugees are going to be analized on three-month period. As a result, Turkish public diplomacy and refugee relations and its implications on the international media in the context of Syrian refugees will be evaluated and some recommendations for the future of Turkish public diplomacy and refugee relations will be provided.

Quantum signature in heavy-ion pion production

International Nuclear Information System (INIS)

Buvel, R.L.

1985-01-01

A revised model for pion production in heavy-ion peripheral collisions is presented. The pion-production mechanism investigated here is a two step process involving the formation and subsequent decay of an isobar resonance in the projectile nucleus. The independent-particle shell model with harmonic oscillator states is used to approximate the internal structure of the nucleus. The inclusion of the internal structure of the projectile nucleus led to the discovery of a quantum signature in the pion-production differential cross section. The quantum signature involves a matching condition where the pion-production differential cross section goes to zero for a particular value of the pion kinetic energy. The theory is compared to a recent experiment, but the results of this comparison are inconclusive

Algebraic methods in statistical mechanics and quantum field theory

CERN Document Server

Emch, Dr Gérard G

2009-01-01

This systematic algebraic approach concerns problems involving a large number of degrees of freedom. It extends the traditional formalism of quantum mechanics, and it eliminates conceptual and mathematical difficulties common to the development of statistical mechanics and quantum field theory. Further, the approach is linked to research in applied and pure mathematics, offering a reflection of the interplay between formulation of physical motivations and self-contained descriptions of the mathematical methods.The four-part treatment begins with a survey of algebraic approaches to certain phys

Mathematical aspects of quantum field theories

CERN Document Server

Strobl, Thomas

2015-01-01

Despite its long history and stunning experimental successes, the mathematical foundation of perturbative quantum field theory is still a subject of ongoing research. This book aims at presenting some of the most recent advances in the field, and at reflecting the diversity of approaches and tools invented and currently employed. Both leading experts and comparative newcomers to the field present their latest findings, helping readers to gain a better understanding of not only quantum but also classical field theories. Though the book offers a valuable resource for mathematicians and physicists alike, the focus is more on mathematical developments. This volume consists of four parts: The first Part covers local aspects of perturbative quantum field theory, with an emphasis on the axiomatization of the algebra behind the operator product expansion. The second Part highlights Chern-Simons gauge theories, while the third examines (semi-)classical field theories. In closing, Part 4 addresses factorization homolo...

Metrology of electrical quantum

International Nuclear Information System (INIS)

Camon, A.

1996-01-01

Since 1989 the electrical metrology laboratory of TPYCEA and the low temperature physics department of ICMA have been collaborating in the development of electrical quantum metrology. ICMA has been mainly dedicated to implement the state of the art quantum standards for which its experience on cryogenics, superconductivity and low noise instrumentation was essential. On the other hand TPYCEA concentrated its efforts on the metrological aspects, in which it has great experience. The complimentary knowledge of both laboratories, as well as the advice obtained from several prestigious metrology institutes was the key to successful completion of the two projects so far developed: i) The Josephson voltage standard (1989-1991) ii) The quantum Hall resistance standard (1991-1996) This report contains a description of both projects. Even though we can consider that the two projects are finished from the instrumental and metrological point of view, there is still a strong cooperation between ICMA and TPYCEA on the improvement of these standards, as well as on their international validation

Quantized Hamilton dynamics describes quantum discrete breathers in a simple way

International Nuclear Information System (INIS)

Igumenshchev, Kirill; Prezhdo, Oleg

2011-01-01

We study the localization of energy in a nonlinear coupled system, exhibiting so-called breather modes, using quantized Hamilton dynamics (QHD). Already at the lowest order, which is only twice as complex as classical mechanics, this simple semiclassical method incorporates quantum-mechanical effects. The transition between the localized and delocalized regimes is instantaneous in classical mechanics, while it is gradual due to tunneling in both quantum mechanics and QHD. In contrast to classical mechanics, which predicts an abrupt appearance of breathers, quantum mechanics and QHD show an alternation of localized and delocalized behavior in the transient region. QHD includes zero-point energy that is reflected in a shifted energy asymptote for the localized states, providing another improvement on the classical perspective. By detailed analysis of the distribution and transfer of energy within classical mechanics, QHD, and quantum dynamics, we conclude that QHD is an efficient approach that accounts for moderate quantum effects and can be used to identify quantum breathers in large nonlinear systems.

Quantum nature of the big bang.

Science.gov (United States)

Ashtekar, Abhay; Pawlowski, Tomasz; Singh, Parampreet

2006-04-14

Some long-standing issues concerning the quantum nature of the big bang are resolved in the context of homogeneous isotropic models with a scalar field. Specifically, the known results on the resolution of the big-bang singularity in loop quantum cosmology are significantly extended as follows: (i) the scalar field is shown to serve as an internal clock, thereby providing a detailed realization of the "emergent time" idea; (ii) the physical Hilbert space, Dirac observables, and semiclassical states are constructed rigorously; (iii) the Hamiltonian constraint is solved numerically to show that the big bang is replaced by a big bounce. Thanks to the nonperturbative, background independent methods, unlike in other approaches the quantum evolution is deterministic across the deep Planck regime.

Algebraic Bethe ansatz for 19-vertex models with reflection conditions

International Nuclear Information System (INIS)

Utiel, Wagner

2003-01-01

In this work we solve the 19-vertex models with the use of algebraic Bethe ansatz for diagonal reflection matrices (Sklyanin K-matrices). The eigenvectors, eigenvalues and Bethe equations are given in a general form. Quantum spin chains of spin one derived from the 19-vertex models were also discussed

Ecological optimization of an irreversible quantum Carnot heat engine with spin-1/2 systems

International Nuclear Information System (INIS)

Liu Xiaowei; Chen Lingen; Wu Feng; Sun Fengrui

2010-01-01

A model of a quantum heat engine with heat resistance, internal irreversibility and heat leakage and many non-interacting spin-1/2 systems is established in this paper. The quantum heat engine cycle is composed of two isothermal processes and two irreversible adiabatic processes and is referred to as a spin quantum Carnot heat engine. Based on the quantum master equation and the semi-group approach, equations of some important performance parameters, such as power output, efficiency, entropy generation rate and ecological function (a criterion representing the optimal compromise between exergy output rate and exergy loss rate), for the irreversible spin quantum Carnot heat engine are derived. The optimal ecological performance of the heat engine in the classical limit is analyzed with numerical examples. The effects of internal irreversibility and heat leakage on ecological performance are discussed in detail.

Quantum games as quantum types

Science.gov (United States)

Delbecque, Yannick

In this thesis, we present a new model for higher-order quantum programming languages. The proposed model is an adaptation of the probabilistic game semantics developed by Danos and Harmer [DH02]: we expand it with quantum strategies which enable one to represent quantum states and quantum operations. Some of the basic properties of these strategies are established and then used to construct denotational semantics for three quantum programming languages. The first of these languages is a formalisation of the measurement calculus proposed by Danos et al. [DKP07]. The other two are new: they are higher-order quantum programming languages. Previous attempts to define a denotational semantics for higher-order quantum programming languages have failed. We identify some of the key reasons for this and base the design of our higher-order languages on these observations. The game semantics proposed in this thesis is the first denotational semantics for a lambda-calculus equipped with quantum types and with extra operations which allow one to program quantum algorithms. The results presented validate the two different approaches used in the design of these two new higher-order languages: a first one where quantum states are used through references and a second one where they are introduced as constants in the language. The quantum strategies presented in this thesis allow one to understand the constraints that must be imposed on quantum type systems with higher-order types. The most significant constraint is the fact that abstraction over part of the tensor product of many unknown quantum states must not be allowed. Quantum strategies are a new mathematical model which describes the interaction between classical and quantum data using system-environment dialogues. The interactions between the different parts of a quantum system are described using the rich structure generated by composition of strategies. This approach has enough generality to be put in relation with other

Label free imaging of cell-substrate contacts by holographic total internal reflection microscopy.

Science.gov (United States)

Mandracchia, Biagio; Gennari, Oriella; Marchesano, Valentina; Paturzo, Melania; Ferraro, Pietro

2017-09-01

The study of cell adhesion contacts is pivotal to understand cell mechanics and interaction at substrates or chemical and physical stimuli. We designed and built a HoloTIR microscope for label-free quantitative phase imaging of total internal reflection. Here we show for the first time that HoloTIR is a good choice for label-free study of focal contacts and of cell/substrate interaction as its sensitivity is enhanced in comparison with standard TIR microscopy. Finally, the simplicity of implementation and relative low cost, due to the requirement of less optical components, make HoloTIR a reasonable alternative, or even an addition, to TIRF microscopy for mapping cell/substratum topography. As a proof of concept, we studied the formation of focal contacts of fibroblasts on three substrates with different levels of affinity for cell adhesion. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Combining total internal reflection sum frequency spectroscopy spectral imaging and confocal fluorescence microscopy.

Science.gov (United States)

Allgeyer, Edward S; Sterling, Sarah M; Gunewardene, Mudalige S; Hess, Samuel T; Neivandt, David J; Mason, Michael D

2015-01-27

Understanding surface and interfacial lateral organization in material and biological systems is critical in nearly every field of science. The continued development of tools and techniques viable for elucidation of interfacial and surface information is therefore necessary to address new questions and further current investigations. Sum frequency spectroscopy (SFS) is a label-free, nonlinear optical technique with inherent surface specificity that can yield critical organizational information on interfacial species. Unfortunately, SFS provides no spatial information on a surface; small scale heterogeneities that may exist are averaged over the large areas typically probed. Over the past decade, this has begun to be addressed with the advent of SFS microscopy. Here we detail the construction and function of a total internal reflection (TIR) SFS spectral and confocal fluorescence imaging microscope directly amenable to surface investigations. This instrument combines, for the first time, sample scanning TIR-SFS imaging with confocal fluorescence microscopy.

Observability of Quantum State of Black Hole

CERN Document Server

David, J R; Mandal, G; Wadia, S R; David, Justin R.; Dhar, Avinash; Mandal, Gautam; Wadia, Spenta R.

1997-01-01

We analyze terms subleading to Rutherford in the $S$-matrix between black hole and probes of successively high energies. We show that by an appropriate choice of the probe one can read off the quantum state of the black hole from the S-matrix, staying asymptotically far from the BH all the time. We interpret the scattering experiment as scattering off classical stringy backgrounds which explicitly depend on the internal quantum numbers of the black hole.

Quantum self-controlling free-falling cats

International Nuclear Information System (INIS)

Chryssomalakos, C; Serrano-Ensástiga, E; Hernández-Coronado, H

2015-01-01

In the separation of rotations from internal motions in the n-body problem, there appear some gauge fields which physically represent Coriolis effects. These fields are also present in the “falling cat” problem: at the kinematical level they map changes in the cat's shape to changes in its orientation whereas at the dynamical level they show up as gauge potentials in the Hamiltonian. Classically, the vanishing angular momentum condition allows for the orientation degrees of freedom to decouple from the internal ones and the cat's re-orientation can be accounted for at the kinematical level, partially. In the quantum case the cat's reorientation description requires to be done on dynamical grounds. In this paper we explore the quantum version of the falling cat modelled as a three body problem. (paper)

Loop quantum cosmology: Recent progress

Indian Academy of Sciences (India)

Aspects of the full theory of loop quantum gravity can be studied in a simpler .... group) 1-forms and vector fields and Λ is an SO(3)-matrix indicating the internal ... are p and c which are related to the more familiar scale factor by the relations.

Quantum objective realism

International Nuclear Information System (INIS)

Bednorz, Adam

2015-01-01

The question of whether quantum measurements reflect some underlying objective reality has no generally accepted answer. We show that a description of such reality is possible under natural conditions such as linearity and causality, although in terms of moments and cumulants of finite order and without relativistic invariance. The proposed construction of observations’ probability distribution originates from weak, noninvasive measurements, with detection error replaced by some external finite noise. The noise allows us to construct microscopic objective reality, but remains dynamically decoupled and hence unobservable at the macroscopic level. (paper)

Quantum noise of a Michelson-Sagnac interferometer with a translucent mechanical oscillator

International Nuclear Information System (INIS)

Yamamoto, Kazuhiro; Friedrich, Daniel; Westphal, Tobias; Gossler, Stefan; Danzmann, Karsten; Schnabel, Roman; Somiya, Kentaro; Danilishin, Stefan L.

2010-01-01

Quantum fluctuations in the radiation pressure of light can excite stochastic motions of mechanical oscillators thereby realizing a linear quantum opto-mechanical coupling. When performing a precise measurement of the position of an oscillator, this coupling results in quantum radiation pressure noise. Up to now this effect has not been observed yet. Generally speaking, the strength of radiation pressure noise increases when the effective mass of the oscillator is decreased or when the power of the reflected light is increased. Recently, extremely light SiN membranes (≅100 ng) with high mechanical Q values at room temperature (≥10 6 ) have attracted attention as low thermal noise mechanical oscillators. However, the power reflectance of these membranes is much lower than unity (<0.4 at a wavelength of 1064 nm) which makes the use of advanced interferometer recycling techniques to amplify the radiation pressure noise in a standard Michelson interferometer inefficient. Here, we propose and theoretically analyze a Michelson-Sagnac interferometer that includes the membrane as a common end mirror for the Michelson interferometer part. In this topology, both power and signal recycling can be used even if the reflectance of the membrane is much lower than unity. In particular, signal recycling is a useful tool because it does not involve a power increase at the membrane. We derive the formulas for the quantum radiation pressure noise and the shot noise of an oscillator position measurement and compare them with theoretical models of the thermal noise of a SiN membrane with a fundamental resonant frequency of 75 kHz and an effective mass of125 ng. We find that quantum radiation pressure noise should be observable with a power of 1 W at the central beam splitter of the interferometer and a membrane temperature of 1 K.

Transmission resonances in a semiconductor-superconductor junction quantum interference structure

International Nuclear Information System (INIS)

Takagaki, Y.; Tokura, Y.

1996-01-01

Transport properties in a quantum resonator structure of a normal-conductor endash superconductor (NS) junction are calculated. Quasiparticles in a cavity region undergo multiple reflections due to an abrupt change in the width of the wire and the NS interface. Quantum interference of the reflections modulates the nominal normal reflection probability at the NS boundary. We show that various NS structures can be regarded as the quantum resonator because of the absence of propagation along the NS interface. When the incident energy coincides with the quasibound state energy levels, the zero-voltage conductance exhibits peaks for small voltages applied to the NS junction. The transmission peaks change to dips of nearly perfect reflection when the applied voltage exceeds a critical value. Two branches of the resonance, which are roughly characterized by electron and hole wavelengths, emerge from the individual dip, and the energy difference between them increases with increasing voltage. The electronlike and holelike resonance dips originating from different quasibound states at zero-voltage cross one after another when the voltage approaches the superconducting gap. We find that both crossing and anticrossing can be produced. It is shown that the individual resonance state in the NS system is associated with two zeros and two poles in the complex energy plane. The behavior of the resonance is explained in terms of splitting and merging of the zero-pole pairs. We examine the Green close-quote s function of a one-dimensional NS system in order to find out how the transmission properties are influenced by the scattering from the NS interface. copyright 1996 The American Physical Society

Quantum decision-maker theory and simulation

Science.gov (United States)

Zak, Michail; Meyers, Ronald E.; Deacon, Keith S.

2000-07-01

A quantum device simulating the human decision making process is introduced. It consists of quantum recurrent nets generating stochastic processes which represent the motor dynamics, and of classical neural nets describing the evolution of probabilities of these processes which represent the mental dynamics. The autonomy of the decision making process is achieved by a feedback from the mental to motor dynamics which changes the stochastic matrix based upon the probability distribution. This feedback replaces unavailable external information by an internal knowledge- base stored in the mental model in the form of probability distributions. As a result, the coupled motor-mental dynamics is described by a nonlinear version of Markov chains which can decrease entropy without an external source of information. Applications to common sense based decisions as well as to evolutionary games are discussed. An example exhibiting self-organization is computed using quantum computer simulation. Force on force and mutual aircraft engagements using the quantum decision maker dynamics are considered.

Quantum Control of Graphene Plasmon Excitation and Propagation at Heaviside Potential Steps.

Science.gov (United States)

Wang, Dongli; Fan, Xiaodong; Li, Xiaoguang; Dai, Siyuan; Wei, Laiming; Qin, Wei; Wu, Fei; Zhang, Huayang; Qi, Zeming; Zeng, Changgan; Zhang, Zhenyu; Hou, Jianguo

2018-02-14

Quantum mechanical effects of single particles can affect the collective plasmon behaviors substantially. In this work, the quantum control of plasmon excitation and propagation in graphene is demonstrated by adopting the variable quantum transmission of carriers at Heaviside potential steps as a tuning knob. First, the plasmon reflection is revealed to be tunable within a broad range by varying the ratio γ between the carrier energy and potential height, which originates from the quantum mechanical effect of carrier propagation at potential steps. Moreover, the plasmon excitation by free-space photos can be regulated from fully suppressed to fully launched in graphene potential wells also through adjusting γ, which defines the degrees of the carrier confinement in the potential wells. These discovered quantum plasmon effects offer a unified quantum-mechanical solution toward ultimate control of both plasmon launching and propagating, which are indispensable processes in building plasmon circuitry.

Molecular quantum dynamics. From theory to applications

International Nuclear Information System (INIS)

Gatti, Fabien

2014-01-01

An educational and accessible introduction to the field of molecular quantum dynamics. Illustrates the importance of the topic for broad areas of science: from astrophysics and the physics of the atmosphere, over elementary processes in chemistry, to biological processes. Presents chosen examples of striking applications, highlighting success stories, summarized by the internationally renowned experts. Including a foreword by Lorenz Cederbaum (University Heidelberg, Germany). This book focuses on current applications of molecular quantum dynamics. Examples from all main subjects in the field, presented by the internationally renowned experts, illustrate the importance of the domain. Recent success in helping to understand experimental observations in fields like heterogeneous catalysis, photochemistry, reactive scattering, optical spectroscopy, or femto- and attosecond chemistry and spectroscopy underline that nuclear quantum mechanical effects affect many areas of chemical and physical research. In contrast to standard quantum chemistry calculations, where the nuclei are treated classically, molecular quantum dynamics can cover quantum mechanical effects in their motion. Many examples, ranging from fundamental to applied problems, are known today that are impacted by nuclear quantum mechanical effects, including phenomena like tunneling, zero point energy effects, or non-adiabatic transitions. Being important to correctly understand many observations in chemical, organic and biological systems, or for the understanding of molecular spectroscopy, the range of applications covered in this book comprises broad areas of science: from astrophysics and the physics and chemistry of the atmosphere, over elementary processes in chemistry, to biological processes (such as the first steps of photosynthesis or vision). Nevertheless, many researchers refrain from entering this domain. The book ''Molecular Quantum Dynamics'' offers them an accessible introduction. Although the

Molecular quantum dynamics. From theory to applications

Energy Technology Data Exchange (ETDEWEB)

Gatti, Fabien (ed.) [Montpellier 2 Univ. (France). Inst. Charles Gerhardt - CNRS 5253

2014-09-01

An educational and accessible introduction to the field of molecular quantum dynamics. Illustrates the importance of the topic for broad areas of science: from astrophysics and the physics of the atmosphere, over elementary processes in chemistry, to biological processes. Presents chosen examples of striking applications, highlighting success stories, summarized by the internationally renowned experts. Including a foreword by Lorenz Cederbaum (University Heidelberg, Germany). This book focuses on current applications of molecular quantum dynamics. Examples from all main subjects in the field, presented by the internationally renowned experts, illustrate the importance of the domain. Recent success in helping to understand experimental observations in fields like heterogeneous catalysis, photochemistry, reactive scattering, optical spectroscopy, or femto- and attosecond chemistry and spectroscopy underline that nuclear quantum mechanical effects affect many areas of chemical and physical research. In contrast to standard quantum chemistry calculations, where the nuclei are treated classically, molecular quantum dynamics can cover quantum mechanical effects in their motion. Many examples, ranging from fundamental to applied problems, are known today that are impacted by nuclear quantum mechanical effects, including phenomena like tunneling, zero point energy effects, or non-adiabatic transitions. Being important to correctly understand many observations in chemical, organic and biological systems, or for the understanding of molecular spectroscopy, the range of applications covered in this book comprises broad areas of science: from astrophysics and the physics and chemistry of the atmosphere, over elementary processes in chemistry, to biological processes (such as the first steps of photosynthesis or vision). Nevertheless, many researchers refrain from entering this domain. The book ''Molecular Quantum Dynamics'' offers them an accessible

Quantum information. Teleporation - cryptography - quantum computer

International Nuclear Information System (INIS)

Breuer, Reinhard

2010-01-01

The following topics are dealt with: Reality in the test house, quantum teleportation, 100 years of quantum theory, the reality of quanta, interactionless quantum measurement, rules for quantum computers, quantum computers with ions, spintronics with diamond, the limits of the quantum computers, a view into the future of quantum optics. (HSI)

The experience of being a member of the Student International Community of Practice: a collaborative reflection

Directory of Open Access Journals (Sweden)

Brighide M. Lynch

2015-05-01

Full Text Available Background: In 2010 a community of practice was set up for and by doctoral students engaged in person-centred and practitioner research. After three years, this community became part of a larger international community of practice. Aims and objectives: Captured under the stanzas of a poem and supported by the literature, this paper uses member narratives and creative expressions in a critical reflection on the experience of being a member of the Student International Community of Practice. Conclusions: Membership in the community of practice was experienced as beneficial, providing both support and challenge to enrich the doctoral students’ development as person-centred researchers. Retaining connectivity across an international landscape and finding effective ways to integrate new members into the community presented the greatest challenges. Implications for practice development: • The theoretical foundation and experiential knowledge could assist others considering support structures for the development of person-centred practices • Shared learning and co-creation of knowledge add value to the experience of being a doctoral researcher • Membership fluctuations present challenges to continuity of learning and the maintenance of a safe space with communities of practice. Such fluctuations, however, create chances for community members to experience diverse roles within the group and encourage explicit attention to person-centredness

Quantum groups, non-commutative differential geometry and applications

International Nuclear Information System (INIS)

Schupp, P.; California Univ., Berkeley, CA

1993-01-01

The topic of this thesis is the development of a versatile and geometrically motivated differential calculus on non-commutative or quantum spaces, providing powerful but easy-to-use mathematical tools for applications in physics and related sciences. A generalization of unitary time evolution is proposed and studied for a simple 2-level system, leading to non-conservation of microscopic entropy, a phenomenon new to quantum mechanics. A Cartan calculus that combines functions, forms, Lie derivatives and inner derivations along general vector fields into one big algebra is constructed for quantum groups and then extended to quantum planes. The construction of a tangent bundle on a quantum group manifold and an BRST type approach to quantum group gauge theory are given as further examples of applications. The material is organized in two parts: Part I studies vector fields on quantum groups, emphasizing Hopf algebraic structures, but also introducing a ''quantum geometric'' construction. Using a generalized semi-direct product construction we combine the dual Hopf algebras A of functions and U of left-invariant vector fields into one fully bicovariant algebra of differential operators. The pure braid group is introduced as the commutant of Δ(U). It provides invariant maps A → U and thereby bicovariant vector fields, casimirs and metrics. This construction allows the translation of undeformed matrix expressions into their less obvious quantum algebraic counter parts. We study this in detail for quasitriangular Hopf algebras, giving the determinant and orthogonality relation for the ''reflection'' matrix. Part II considers the additional structures of differential forms and finitely generated quantum Lie algebras -- it is devoted to the construction of the Cartan calculus, based on an undeformed Cartan identity

Quantum mechanics meets cognitive science: explanatory vs descriptive approaches

NARCIS (Netherlands)

Blutner, R.

2010-01-01

We reflect on several aspects of the general claim that a quantum-like approach to Cognitive Science is advantageous over classical approaches. The classical approaches refer to the symbolic approaches including models using a classical (Kolmogorov) probability calculus. The general claim seems to

Quantum space and quantum completeness

Science.gov (United States)

Jurić, Tajron

2018-05-01

Motivated by the question whether quantum gravity can "smear out" the classical singularity we analyze a certain quantum space and its quantum-mechanical completeness. Classical singularity is understood as a geodesic incompleteness, while quantum completeness requires a unique unitary time evolution for test fields propagating on an underlying background. Here the crucial point is that quantum completeness renders the Hamiltonian (or spatial part of the wave operator) to be essentially self-adjoint in order to generate a unique time evolution. We examine a model of quantum space which consists of a noncommutative BTZ black hole probed by a test scalar field. We show that the quantum gravity (noncommutative) effect is to enlarge the domain of BTZ parameters for which the relevant wave operator is essentially self-adjoint. This means that the corresponding quantum space is quantum complete for a larger range of BTZ parameters rendering the conclusion that in the quantum space one observes the effect of "smearing out" the singularity.

Reflection: A Socratic approach.

Science.gov (United States)

Van Seggelen-Damen, Inge C M; Van Hezewijk, René; Helsdingen, Anne S; Wopereis, Iwan G J H

2017-12-01

Reflection is a fuzzy concept. In this article we reveal the paradoxes involved in studying the nature of reflection. Whereas some scholars emphasize its discursive nature, we go further and underline its resemblance to the self-biased dialogue Socrates had with the slave in Plato's Meno . The individual and internal nature of the reflection process creates difficulty for studying it validly and reliably. We focus on methodological issues and use Hans Linschoten's view of coupled systems to identify, analyze, and interpret empirical research on reflection. We argue that researchers and research participants can take on roles in several possible system couplings. Depending on who controls the manipulation of the stimulus, who controls the measuring instrument, who interprets the measurement and the response, different types of research questions can be answered. We conclude that reflection may be validly studied by combining different couplings of experimenter, manipulation, stimulus, participant, measurement, and response.

Quantum correlations in multipartite quantum systems

Science.gov (United States)

Jafarizadeh, M. A.; Heshmati, A.; Karimi, N.; Yahyavi, M.

2018-03-01

Quantum entanglement is the most famous type of quantum correlation between elements of a quantum system that has a basic role in quantum communication protocols like quantum cryptography, teleportation and Bell inequality detection. However, it has already been shown that various applications in quantum information theory do not require entanglement. Quantum discord as a new kind of quantum correlations beyond entanglement, is the most popular candidate for general quantum correlations. In this paper, first we find the entanglement witness in a particular multipartite quantum system which consists of a N-partite system in 2 n -dimensional space. Then we give an exact analytical formula for the quantum discord of this system. At the end of the paper, we investigate the additivity relation of the quantum correlation and show that this relation is satisfied for a N-partite system with 2 n -dimensional space.

High Sensitivity Detection of CdSe/ZnS Quantum Dot-Labeled DNA Based on N-type Porous Silicon Microcavities.

Science.gov (United States)

Lv, Changwu; Jia, Zhenhong; Lv, Jie; Zhang, Hongyan; Li, Yanyu

2017-01-01

N-type macroporous silicon microcavity structures were prepared using electrochemical etching in an HF solution in the absence of light and oxidants. The CdSe/ZnS water-soluble quantum dot-labeled DNA target molecules were detected by monitoring the microcavity reflectance spectrum, which was characterized by the reflectance spectrum defect state position shift resulting from changes to the structures' refractive index. Quantum dots with a high refractive index and DNA coupling can improve the detection sensitivity by amplifying the optical response signals of the target DNA. The experimental results show that DNA combined with a quantum dot can improve the sensitivity of DNA detection by more than five times.

Renormalisation in Quantum Mechanics, Quantum Instantons and Quantum Chaos

OpenAIRE

Jirari, H.; Kröger, H.; Luo, X. Q.; Moriarty, K. J. M.

2001-01-01

We suggest how to construct non-perturbatively a renormalized action in quantum mechanics. We discuss similarties and differences with the standard effective action. We propose that the new quantum action is suitable to define and compute quantum instantons and quantum chaos.

Reduction of the internal electric field in GaN/AlN quantum dots grown on the a-plane of SiC substrates

Energy Technology Data Exchange (ETDEWEB)

Garro, N.; Cros, A.; Budagosky, J.A.; Cantarero, A. [Institut de Ciencia dels Materials, Universitat de Valencia, 46071 Valencia (Spain); Vinattieri, A.; Gurioli, M. [INFM, Dept. of Physics and LENS, Universita di Firenze, Via Sansone 1, 50019 Sesto Fiorentino (Italy); Founta, S.; Mariette, H.; Daudin, B. [CEA-CNRS Group ' ' Nanophysique et Semiconducteurs' ' , Departement de Recherche Fondamentale sur la Matiere Condensee, CEA Grenoble, 17 rue des Martyrs, 38054 Grenoble (France)

2005-11-01

We present a study of the emission of a multi-layer stack of self-assembled GaN/AlN quantum dots grown on the a-plane of 6H-SiC. We look for signatures of the internal electric field in the power dependence of the time-integrated and time-resolved photoluminescence spectra. The lack of a dynamical red-shift reveals that internal electric fields are significantly reduced in these dots. A band on the low energy side of the emission is observed whose intensity quenches fast when increasing the temperature. The polarization selection rules of the emission are examined in order to determine the physical nature of this band. (copyright 2005 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

Nonlinear Dynamics In Quantum Physics -- Quantum Chaos and Quantum Instantons

OpenAIRE

Kröger, H.

2003-01-01

We discuss the recently proposed quantum action - its interpretation, its motivation, its mathematical properties and its use in physics: quantum mechanical tunneling, quantum instantons and quantum chaos.

Quantum dynamics of quantum bits

International Nuclear Information System (INIS)

Nguyen, Bich Ha

2011-01-01

The theory of coherent oscillations of the matrix elements of the density matrix of the two-state system as a quantum bit is presented. Different calculation methods are elaborated in the case of a free quantum bit. Then the most appropriate methods are applied to the study of the density matrices of the quantum bits interacting with a classical pumping radiation field as well as with the quantum electromagnetic field in a single-mode microcavity. The theory of decoherence of a quantum bit in Markovian approximation is presented. The decoherence of a quantum bit interacting with monoenergetic photons in a microcavity is also discussed. The content of the present work can be considered as an introduction to the study of the quantum dynamics of quantum bits. (review)

Size-confined fixed-composition and composition-dependent engineered band gap alloying induces different internal structures in L-cysteine-capped alloyed quaternary CdZnTeS quantum dots

Science.gov (United States)

Adegoke, Oluwasesan; Park, Enoch Y.

2016-06-01

The development of alloyed quantum dot (QD) nanocrystals with attractive optical properties for a wide array of chemical and biological applications is a growing research field. In this work, size-tunable engineered band gap composition-dependent alloying and fixed-composition alloying were employed to fabricate new L-cysteine-capped alloyed quaternary CdZnTeS QDs exhibiting different internal structures. Lattice parameters simulated based on powder X-ray diffraction (PXRD) revealed the internal structure of the composition-dependent alloyed CdxZnyTeS QDs to have a gradient nature, whereas the fixed-composition alloyed QDs exhibited a homogenous internal structure. Transmission electron microscopy (TEM) and dynamic light scattering (DLS) analysis confirmed the size-confined nature and monodispersity of the alloyed nanocrystals. The zeta potential values were within the accepted range of colloidal stability. Circular dichroism (CD) analysis showed that the surface-capped L-cysteine ligand induced electronic and conformational chiroptical changes in the alloyed nanocrystals. The photoluminescence (PL) quantum yield (QY) values of the gradient alloyed QDs were 27-61%, whereas for the homogenous alloyed QDs, the PL QY values were spectacularly high (72-93%). Our work demonstrates that engineered fixed alloying produces homogenous QD nanocrystals with higher PL QY than composition-dependent alloying.

Quantum symmetry in quantum theory

International Nuclear Information System (INIS)

Schomerus, V.

1993-02-01

Symmetry concepts have always been of great importance for physical problems like explicit calculations, classification or model building. More recently, new 'quantum symmetries' ((quasi) quantum groups) attracted much interest in quantum theory. It is shown that all these quantum symmetries permit a conventional formulation as symmetry in quantum mechanics. Symmetry transformations can act on the Hilbert space H of physical states such that the ground state is invariant and field operators transform covariantly. Models show that one must allow for 'truncation' in the tensor product of representations of a quantum symmetry. This means that the dimension of the tensor product of two representations of dimension σ 1 and σ 2 may be strictly smaller than σ 1 σ 2 . Consistency of the transformation law of field operators local braid relations leads us to expect, that (weak) quasi quantum groups are the most general symmetries in local quantum theory. The elements of the R-matrix which appears in these local braid relations turn out to be operators on H in general. It will be explained in detail how examples of field algebras with weak quasi quantum group symmetry can be obtained. Given a set of observable field with a finite number of superselection sectors, a quantum symmetry together with a complete set of covariant field operators which obey local braid relations are constructed. A covariant transformation law for adjoint fields is not automatic but will follow when the existence of an appropriate antipode is assumed. At the example of the chiral critical Ising model, non-uniqueness of the quantum symmetry will be demonstrated. Generalized quantum symmetries yield examples of gauge symmetries in non-commutative geometry. Quasi-quantum planes are introduced as the simplest examples of quasi-associative differential geometry. (Weak) quasi quantum groups can act on them by generalized derivations much as quantum groups do in non-commutative (differential-) geometry

Quantum information. Teleportation - cryptography - quantum computer

International Nuclear Information System (INIS)

Koenneker, Carsten

2012-01-01

The following topics are dealt with: Reality in the test facility, quantum teleportation, the reality of quanta, interaction-free quantum measurement, rules for quantum computers, quantum computers with ions, spintronics with diamond, the limits of the quantum computers, a view in the future of quantum optics. (HSI)

Quantumness-generating capability of quantum dynamics

Science.gov (United States)

Li, Nan; Luo, Shunlong; Mao, Yuanyuan

2018-04-01

We study quantumness-generating capability of quantum dynamics, where quantumness refers to the noncommutativity between the initial state and the evolving state. In terms of the commutator of the square roots of the initial state and the evolving state, we define a measure to quantify the quantumness-generating capability of quantum dynamics with respect to initial states. Quantumness-generating capability is absent in classical dynamics and hence is a fundamental characteristic of quantum dynamics. For qubit systems, we present an analytical form for this measure, by virtue of which we analyze several prototypical dynamics such as unitary dynamics, phase damping dynamics, amplitude damping dynamics, and random unitary dynamics (Pauli channels). Necessary and sufficient conditions for the monotonicity of quantumness-generating capability are also identified. Finally, we compare these conditions for the monotonicity of quantumness-generating capability with those for various Markovianities and illustrate that quantumness-generating capability and quantum Markovianity are closely related, although they capture different aspects of quantum dynamics.

Watch your step! A frustrated total internal reflection approach to forensic footwear imaging.

Science.gov (United States)

Needham, J A; Sharp, J S

2016-02-16

Forensic image retrieval and processing are vital tools in the fight against crime e.g. during fingerprint capture. However, despite recent advances in machine vision technology and image processing techniques (and contrary to the claims of popular fiction) forensic image retrieval is still widely being performed using outdated practices involving inkpads and paper. Ongoing changes in government policy, increasing crime rates and the reduction of forensic service budgets increasingly require that evidence be gathered and processed more rapidly and efficiently. A consequence of this is that new, low-cost imaging technologies are required to simultaneously increase the quality and throughput of the processing of evidence. This is particularly true in the burgeoning field of forensic footwear analysis, where images of shoe prints are being used to link individuals to crime scenes. Here we describe one such approach based upon frustrated total internal reflection imaging that can be used to acquire images of regions where shoes contact rigid surfaces.

Watch your step! A frustrated total internal reflection approach to forensic footwear imaging

Science.gov (United States)

Needham, J. A.; Sharp, J. S.

2016-02-01

Forensic image retrieval and processing are vital tools in the fight against crime e.g. during fingerprint capture. However, despite recent advances in machine vision technology and image processing techniques (and contrary to the claims of popular fiction) forensic image retrieval is still widely being performed using outdated practices involving inkpads and paper. Ongoing changes in government policy, increasing crime rates and the reduction of forensic service budgets increasingly require that evidence be gathered and processed more rapidly and efficiently. A consequence of this is that new, low-cost imaging technologies are required to simultaneously increase the quality and throughput of the processing of evidence. This is particularly true in the burgeoning field of forensic footwear analysis, where images of shoe prints are being used to link individuals to crime scenes. Here we describe one such approach based upon frustrated total internal reflection imaging that can be used to acquire images of regions where shoes contact rigid surfaces.

Circuit-extension handshakes for Tor achieving forward secrecy in a quantum world

Directory of Open Access Journals (Sweden)

Schanck John M.

2016-10-01

Full Text Available We propose a circuit extension handshake for Tor that is forward secure against adversaries who gain quantum computing capabilities after session negotiation. In doing so, we refine the notion of an authenticated and confidential channel establishment (ACCE protocol and define pre-quantum, transitional, and post-quantum ACCE security. These new definitions reflect the types of adversaries that a protocol might be designed to resist. We prove that, with some small modifications, the currently deployed Tor circuit extension handshake, ntor, provides pre-quantum ACCE security. We then prove that our new protocol, when instantiated with a post-quantum key encapsulation mechanism, achieves the stronger notion of transitional ACCE security. Finally, we instantiate our protocol with NTRU-Encrypt and provide a performance comparison between ntor, our proposal, and the recent design of Ghosh and Kate.

Negative probabilities and counter-factual reasoning in quantum cognition

International Nuclear Information System (INIS)

J Acacio de Barros; G Oas

2014-01-01

In this paper we discuss quantum-like decision-making experiments using negative probabilities. We do so by showing how the two-slit experiment, in the simplified version of the Mach–Zehnder interferometer, can be described by this formalism. We show that negative probabilities impose constraints to what types of counter-factual reasoning we can make with respect to (quantum) internal representations of the decision maker. (paper)

From transistor to trapped-ion computers for quantum chemistry.

Science.gov (United States)

Yung, M-H; Casanova, J; Mezzacapo, A; McClean, J; Lamata, L; Aspuru-Guzik, A; Solano, E

2014-01-07

Over the last few decades, quantum chemistry has progressed through the development of computational methods based on modern digital computers. However, these methods can hardly fulfill the exponentially-growing resource requirements when applied to large quantum systems. As pointed out by Feynman, this restriction is intrinsic to all computational models based on classical physics. Recently, the rapid advancement of trapped-ion technologies has opened new possibilities for quantum control and quantum simulations. Here, we present an efficient toolkit that exploits both the internal and motional degrees of freedom of trapped ions for solving problems in quantum chemistry, including molecular electronic structure, molecular dynamics, and vibronic coupling. We focus on applications that go beyond the capacity of classical computers, but may be realizable on state-of-the-art trapped-ion systems. These results allow us to envision a new paradigm of quantum chemistry that shifts from the current transistor to a near-future trapped-ion-based technology.

Photon-Mediated Quantum Gate between Two Neutral Atoms in an Optical Cavity

Science.gov (United States)

Welte, Stephan; Hacker, Bastian; Daiss, Severin; Ritter, Stephan; Rempe, Gerhard

2018-02-01

Quantum logic gates are fundamental building blocks of quantum computers. Their integration into quantum networks requires strong qubit coupling to network channels, as can be realized with neutral atoms and optical photons in cavity quantum electrodynamics. Here we demonstrate that the long-range interaction mediated by a flying photon performs a gate between two stationary atoms inside an optical cavity from which the photon is reflected. This single step executes the gate in 2 μ s . We show an entangling operation between the two atoms by generating a Bell state with 76(2)% fidelity. The gate also operates as a cnot. We demonstrate 74.1(1.6)% overlap between the observed and the ideal gate output, limited by the state preparation fidelity of 80.2(0.8)%. As the atoms are efficiently connected to a photonic channel, our gate paves the way towards quantum networking with multiqubit nodes and the distribution of entanglement in repeater-based long-distance quantum networks.

Photon-Mediated Quantum Gate between Two Neutral Atoms in an Optical Cavity

Directory of Open Access Journals (Sweden)

Stephan Welte

2018-02-01

Full Text Available Quantum logic gates are fundamental building blocks of quantum computers. Their integration into quantum networks requires strong qubit coupling to network channels, as can be realized with neutral atoms and optical photons in cavity quantum electrodynamics. Here we demonstrate that the long-range interaction mediated by a flying photon performs a gate between two stationary atoms inside an optical cavity from which the photon is reflected. This single step executes the gate in 2  μs. We show an entangling operation between the two atoms by generating a Bell state with 76(2% fidelity. The gate also operates as a cnot. We demonstrate 74.1(1.6% overlap between the observed and the ideal gate output, limited by the state preparation fidelity of 80.2(0.8%. As the atoms are efficiently connected to a photonic channel, our gate paves the way towards quantum networking with multiqubit nodes and the distribution of entanglement in repeater-based long-distance quantum networks.

Quantum entanglement and quantum teleportation

International Nuclear Information System (INIS)

Shih, Y.H.

2001-01-01

One of the most surprising consequences of quantum mechanics is the entanglement of two or more distance particles. The ''ghost'' interference and the ''ghost'' image experiments demonstrated the astonishing nonlocal behavior of an entangled photon pair. Even though we still have questions in regard to fundamental issues of the entangled quantum systems, quantum entanglement has started to play important roles in quantum information and quantum computation. Quantum teleportation is one of the hot topics. We have demonstrated a quantum teleportation experiment recently. The experimental results proved the working principle of irreversibly teleporting an unknown arbitrary quantum state from one system to another distant system by disassembling into and then later reconstructing from purely classical information and nonclassical EPR correlations. The distinct feature of this experiment is that the complete set of Bell states can be distinguished in the Bell state measurement. Teleportation of a quantum state can thus occur with certainty in principle. (orig.)

Quantum ensembles of quantum classifiers.

Science.gov (United States)

Schuld, Maria; Petruccione, Francesco

2018-02-09

Quantum machine learning witnesses an increasing amount of quantum algorithms for data-driven decision making, a problem with potential applications ranging from automated image recognition to medical diagnosis. Many of those algorithms are implementations of quantum classifiers, or models for the classification of data inputs with a quantum computer. Following the success of collective decision making with ensembles in classical machine learning, this paper introduces the concept of quantum ensembles of quantum classifiers. Creating the ensemble corresponds to a state preparation routine, after which the quantum classifiers are evaluated in parallel and their combined decision is accessed by a single-qubit measurement. This framework naturally allows for exponentially large ensembles in which - similar to Bayesian learning - the individual classifiers do not have to be trained. As an example, we analyse an exponentially large quantum ensemble in which each classifier is weighed according to its performance in classifying the training data, leading to new results for quantum as well as classical machine learning.

Quantum computer games: quantum minesweeper

Science.gov (United States)

Gordon, Michal; Gordon, Goren

2010-07-01

The computer game of quantum minesweeper is introduced as a quantum extension of the well-known classical minesweeper. Its main objective is to teach the unique concepts of quantum mechanics in a fun way. Quantum minesweeper demonstrates the effects of superposition, entanglement and their non-local characteristics. While in the classical minesweeper the goal of the game is to discover all the mines laid out on a board without triggering them, in the quantum version there are several classical boards in superposition. The goal is to know the exact quantum state, i.e. the precise layout of all the mines in all the superposed classical boards. The player can perform three types of measurement: a classical measurement that probabilistically collapses the superposition; a quantum interaction-free measurement that can detect a mine without triggering it; and an entanglement measurement that provides non-local information. The application of the concepts taught by quantum minesweeper to one-way quantum computing are also presented.

PREFACE: Loops 11: Non-Perturbative / Background Independent Quantum Gravity

Science.gov (United States)

Mena Marugán, Guillermo A.; Barbero G, J. Fernando; Garay, Luis J.; Villaseñor, Eduardo J. S.; Olmedo, Javier

2012-05-01

Loops 11 The international conference LOOPS'11 took place in Madrid from the 23-28 May 2011. It was hosted by the Instituto de Estructura de la Materia (IEM), which belongs to the Consejo Superior de Investigaciones Cientĺficas (CSIC). Like previous editions of the LOOPS meetings, it dealt with a wealth of state-of-the-art topics on Quantum Gravity, with special emphasis on non-perturbative background-independent approaches to spacetime quantization. The main topics addressed at the conference ranged from the foundations of Quantum Gravity to its phenomenological aspects. They encompassed different approaches to Loop Quantum Gravity and Cosmology, Polymer Quantization, Quantum Field Theory, Black Holes, and discrete approaches such as Dynamical Triangulations, amongst others. In addition, this edition celebrated the 25th anniversary of the introduction of the now well-known Ashtekar variables and the Wednesday morning session was devoted to this silver jubilee. The structure of the conference was designed to reflect the current state and future prospects of research on the different topics mentioned above. Plenary lectures that provided general background and the 'big picture' took place during the mornings, and the more specialised talks were distributed in parallel sessions during the evenings. To be more specific, Monday evening was devoted to Shape Dynamics and Phenomenology Derived from Quantum Gravity in Parallel Session A, and to Covariant Loop Quantum Gravity and Spin foams in Parallel Session B. Tuesday's three Parallel Sessions dealt with Black Hole Physics and Dynamical Triangulations (Session A), the continuation of Monday's session on Covariant Loop Quantum Gravity and Spin foams (Session B) and Foundations of Quantum Gravity (Session C). Finally, Thursday and Friday evenings were devoted to Loop Quantum Cosmology (Session A) and to Hamiltonian Loop Quantum Gravity (Session B). The result of the conference was very satisfactory and enlightening. Not

Quantum control limited by quantum decoherence

International Nuclear Information System (INIS)

Xue, Fei; Sun, C. P.; Yu, S. X.

2006-01-01

We describe quantum controllability under the influences of the quantum decoherence induced by the quantum control itself. It is shown that, when the controller is considered as a quantum system, it will entangle with its controlled system and then cause quantum decoherence in the controlled system. In competition with this induced decoherence, the controllability will be limited by some uncertainty relation in a well-armed quantum control process. In association with the phase uncertainty and the standard quantum limit, a general model is studied to demonstrate the possibility of realizing a decoherence-free quantum control with a finite energy within a finite time. It is also shown that if the operations of quantum control are to be determined by the initial state of the controller, then due to the decoherence which results from the quantum control itself, there exists a low bound for quantum controllability

Proceedings of the international conference on selected topics in quantum field theory and mathematical physics

Energy Technology Data Exchange (ETDEWEB)

Niederle, J; Bednar, M; Bicak, J

1987-01-01

The conference, the fourth in the series of conferences on this subject, was held at the Bechyne castle (Czechoslovakia) on June 23-27, 1986, and was attended by about 100 theoreticians from 15 countries. The conference was organized by the Institute of Physics of the Czechoslovak Academy of Sciences in Prague together with the Faculties of Mathematics and Physics of the Charles University, Prague, and of the Comenius University, Bratislava, the Faculty of Nuclear Science and Physical Engineering of the Czech Techical University, Prague, with the Institute of Physics of the Electro-Physical Research Centre of the Slovak Academy of Sciences, Bratislava, and the Institute of Nuclear Physics of the Czechoslovak Academy of Sciences in Rez. It was sponsored by the International Union for Pure and Applied Physics, the International Association of Mathematical Physics and the Physical Scientific Section of the Union of Czechoslovak Mathematicians and Physicists. The main subjects discussed at the conference were: supersymmetries, supergravity and superstring theories; quantum field theory and in particular gauge theories, theories on lattices, renormalization; selected topics in non-linear equations, scattering theory and quantization. Details are given in the attached program. The proceedings include invited talks and contributions presented respectively at the morning and afternoon sessions of the conference. The main part of the proceedings will be published in the Czechoslovak Journal of Physics v. 37(1987), nos. 3,4 and 9.

Proceedings of the international conference on selected topics in quantum field theory and mathematical physics

International Nuclear Information System (INIS)

Niederle, J.; Bednar, M.; Bicak, J.

1987-01-01

The conference, the fourth in the series of conferences on this subject, was held at the Bechyne castle (Czechoslovakia) on June 23-27, 1986, and was attended by about 100 theoreticians from 15 countries. The conference was organized by the Institute of Physics of the Czechoslovak Academy of Sciences in Prague together with the Faculties of Mathematics and Physics of the Charles University, Prague, and of the Comenius University, Bratislava, the Faculty of Nuclear Science and Physical Engineering of the Czech Techical University, Prague, with the Institute of Physics of the Electro-Physical Research Centre of the Slovak Academy of Sciences, Bratislava, and the Institute of Nuclear Physics of the Czechoslovak Academy of Sciences in Rez. It was sponsored by the International Union for Pure and Applied Physics, the International Association of Mathematical Physics and the Physical Scientific Section of the Union of Czechoslovak Mathematicians and Physicists. The main subjects discussed at the conference were: supersymmetries, supergravity and superstring theories; quantum field theory and in particular gauge theories, theories on lattices, renormalization; selected topics in non-linear equations, scattering theory and quantization. Details are given in the attached program. The proceedings include invited talks and contributions presented respectively at the morning and afternoon sessions of the conference. The main part of the proceedings will be published in the Czechoslovak Journal of Physics v. 37(1987), nos. 3,4 and 9. (author)

A Quantum of Solace: Guzman on the Classical Mechanics of International Law - Book Review: Andrew Guzman, How International Law Works. A Rational Choice Theory (2008

Directory of Open Access Journals (Sweden)

Matthias Goldmann

2009-02-01

class="ArticleText">Compared to the discipline of international law, scholars of physics are blessed. While the principles of classical mechanics were theorized several centuries ago, quantum theory and the theory of relativity offer supplementary ways for describing how material objects and energy interact where classical mechanics does not provide an explanation. Thus, even in the absence of an all-comprising “world theory”, physicists have a wide array of workable theories at their service. By contrast, the “classical mechanics” of international law, i.e. the explanation of the most basic causal relationships between international legal norms and the behaviour of states as the main subjects of international law, are still subject to deep theoretical controversies. International legal doctrine presupposes that international law does have an impact and does not aim at questioning or further explaining this assumption. Traditional legal theories that see the essence of legal normativity in the possibility to trigger mechanisms of physical constraint often come to the conclusion that international law, in the absence of central enforcement mechanisms, is at best a primitive form of law. More recent enquiries into international legal theory from very different theoretical angles come to even less uplifting conclusions. Some argue that international legal norms are either entirely devoid of content because of their inherent indeterminacy and therefore prone to be captured by special interests. Others consider international law to be merely epiphenomenal because rational states would only consent to legal norms if, and as long as, they describe a behaviour they would choose anyway because it promises higher payoffs. In particular the latter critique put forward so forcefully by Jack Goldsmith and Eric Posner sent considerable shock waves through the invisible college of international lawyers. This is the background that needs to be kept

From quantum coherence to quantum correlations

Science.gov (United States)

Sun, Yuan; Mao, Yuanyuan; Luo, Shunlong

2017-06-01

In quantum mechanics, quantum coherence of a state relative to a quantum measurement can be identified with the quantumness that has to be destroyed by the measurement. In particular, quantum coherence of a bipartite state relative to a local quantum measurement encodes quantum correlations in the state. If one takes minimization with respect to the local measurements, then one is led to quantifiers which capture quantum correlations from the perspective of coherence. In this vein, quantum discord, which quantifies the minimal correlations that have to be destroyed by quantum measurements, can be identified as the minimal coherence, with the coherence measured by the relative entropy of coherence. To advocate and formulate this idea in a general context, we first review coherence relative to Lüders measurements which extends the notion of coherence relative to von Neumann measurements (or equivalently, orthonomal bases), and highlight the observation that quantum discord arises as minimal coherence through two prototypical examples. Then, we introduce some novel measures of quantum correlations in terms of coherence, illustrate them through examples, investigate their fundamental properties and implications, and indicate their applications to quantum metrology.

Scaling of the Coulomb Energy Due to Quantum Fluctuations in the Charge on a Quantum Dot

DEFF Research Database (Denmark)

Molenkamp, L. W; Flensberg, Karsten; Kemerink, M.

1995-01-01

The charging energy of a quantum dot is measured through the effect of its potential on the conductance of a second dot. This technique allows a measurement of the scaling of the dot's charging energy with the conductance of the tunnel barriers leading to the dot. We find that the charging energy...... scales quadratically with the reflection probability of the barriers. The observed power law agrees with a recent theory....

Quantum Instantons and Quantum Chaos

OpenAIRE

Jirari, H.; Kröger, H.; Luo, X. Q.; Moriarty, K. J. M.; Rubin, S. G.

1999-01-01

Based on a closed form expression for the path integral of quantum transition amplitudes, we suggest rigorous definitions of both, quantum instantons and quantum chaos. As an example we compute the quantum instanton of the double well potential.

Duality Quantum Information and Duality Quantum Communication

International Nuclear Information System (INIS)

Li, C. Y.; Wang, W. Y.; Wang, C.; Song, S. Y.; Long, G. L.

2011-01-01

Quantum mechanical systems exhibit particle wave duality property. This duality property has been exploited for information processing. A duality quantum computer is a quantum computer on the move and passing through a multi-slits. It offers quantum wave divider and quantum wave combiner operations in addition to those allowed in an ordinary quantum computer. It has been shown that all linear bounded operators can be realized in a duality quantum computer, and a duality quantum computer with n qubits and d-slits can be realized in an ordinary quantum computer with n qubits and a qudit in the so-called duality quantum computing mode. The quantum particle-wave duality can be used in providing secure communication. In this paper, we will review duality quantum computing and duality quantum key distribution.

Quantum computers and quantum computations

International Nuclear Information System (INIS)

Valiev, Kamil' A

2005-01-01

This review outlines the principles of operation of quantum computers and their elements. The theory of ideal computers that do not interact with the environment and are immune to quantum decohering processes is presented. Decohering processes in quantum computers are investigated. The review considers methods for correcting quantum computing errors arising from the decoherence of the state of the quantum computer, as well as possible methods for the suppression of the decohering processes. A brief enumeration of proposed quantum computer realizations concludes the review. (reviews of topical problems)

Undergraduate Research in Quantum Information Science

Science.gov (United States)

Lyons, David W.

2017-01-01

Quantum Information Science (QIS) is an interdisciplinary field involving mathematics, computer science, and physics. Appealing aspects include an abundance of accessible open problems, active interest and support from government and industry, and an energetic, open, and collaborative international research culture. We describe our student-faculty…

Advances in quantum mechanics contemporary trends and open problems

CERN Document Server

Dell'Antonio, Gianfausto

2017-01-01

This volume collects recent contributions on the contemporary trends in the mathematics of quantum mechanics, and more specifically in mathematical problems arising in quantum many-body dynamics, quantum graph theory, cold atoms, unitary gases, with particular emphasis on the developments of the specific mathematical tools needed, including: linear and non-linear Schrödinger equations, topological invariants, non-commutative geometry, resonances and operator extension theory, among others. Most of contributors are international leading experts or respected young researchers in mathematical physics, PDE, and operator theory. All their material is the fruit of recent studies that have already become a reference in the community. Offering a unified perspective of the mathematics of quantum mechanics, it is a valuable resource for researchers in the field.

Quantum Computation and Quantum Spin Dynamics

NARCIS (Netherlands)

Raedt, Hans De; Michielsen, Kristel; Hams, Anthony; Miyashita, Seiji; Saito, Keiji

2001-01-01

We analyze the stability of quantum computations on physically realizable quantum computers by simulating quantum spin models representing quantum computer hardware. Examples of logically identical implementations of the controlled-NOT operation are used to demonstrate that the results of a quantum

Logical reformulation of quantum mechanics. I. Foundations

International Nuclear Information System (INIS)

Omnes, R.

1988-01-01

The basic rules of quantum mechanics are reformulated. They deal primarily with individual systems and do not assume that every ket may represent a physical state. The customary kinematic and dynamic rules then allow to construct consistent Boolean logics describing the history of a system, following essentially Griffiths' proposal. Logical implication is defined within these logics, the multiplicity of which reflects the complementary principle. Only one interpretive rule of quantum mechanics is necessary in such a framework. It states that these logics provide bona fide foundations for the description of a quantum system and for reasoning about it. One attempts to build up classical physics, including classical logic, on these quantum foundations. The resulting theory of measurement needs not to state a priori that the eigenvalues of an observable have to be the results of individual measurements nor to assume wave packet reduction. Both these properties can be obtained as consequences of the basic rules. One also needs not to postulate that every observable is measurable, even in principle. A proposition calculus is obtained, allowing in principle the replacement of the discussion of problems concerned with the practical interpretation of experiments by due calculations

Sutherland models for complex reflection groups

International Nuclear Information System (INIS)