Quantum feedback in a non-resonant cavity QED system
International Nuclear Information System (INIS)
Photon correlation measurements reveal the response of the conditional evolution of the cavity QED system to a novel quantum feedback protocol. A photodetection collapses the state of the system and triggers a feedback pulse with an adjustable delay and amplitude that alters the intensity driving the system. The conditional evolution of the system freezes into a new steady state where it resides until, after an amount of time determined by the experimenter, it re-equilibrates into the original steady state. We carry out a sensitivity analysis using a theoretical model with atomic detuning and make quantitative comparisons with measured results
Scheme for Quantum Entanglement Swapping on Cavity QED System
Institute of Scientific and Technical Information of China (English)
CHEN Chang-Yong; YU Yan
2006-01-01
We propose a scheme for realizing quantum entanglement swapping between the atoms in cavity QED.With only virtual excitation of the cavity during the interaction between the atoms and cavity, the scheme is insensitive to the cavity mode states and the cavity decay. The ideas can also be utilized for realizing entanglement swapping between the atomic levels in a single atom and the atomic levels in the Bell states and between the atomic levels in the Bell states and the atomic levels in the W states.
Quantum interference effects in a cavity QED system
International Nuclear Information System (INIS)
We consider the effect of quantum interference on population distribution and photon statistics of a cavity field interacting with dressed states of a strongly driven three-level atom. We analyse three coupling configurations of the cavity field to the driven atom, with the cavity frequency tuned to the outer Rabi sideband, the inner Rabi sideband and the central frequency of the 'singly dressed' three-level atom. The quantum doubly dressed states for each configuration are identified and the population distribution and photon statistics are interpreted in terms of transitions among these dressed states and their populations. We find that the population distribution depends strongly on quantum interference and the cavity damping. For the cavity field tuned to the outer or inner Rabi sidebands the cavity damping induces transitions between the dressed states which are forbidden for the ordinary spontaneous emission. Moreover, we find that in the case of the cavity field coupled to the inner Rabi sideband the population distribution is almost Poissonian with a large average number of photons that can be controlled by quantum interference. This system can be considered as a one-atom dressed-state laser with controlled intensity
Stimulated photon emission and two-photon Raman scattering in a coupled-cavity QED system
Li, C.; Song, Z.
2016-01-01
We study the scattering problem of photon and polariton in a one-dimensional coupled-cavity system. Analytical approximate analysis and numerical simulation show that a photon can stimulate the photon emission from a polariton through polariton-photon collisions. This observation opens the possibility of photon-stimulated transition from insulating to radiative phase in a coupled-cavity QED system. Inversely, we also find that a polariton can be generated by a two-photon Raman scattering process. This paves the way towards single photon storage by the aid of atom-cavity interaction. PMID:26877252
QND Measurements in a Resonant Cavity-QED System
Chen, Zilong; Bohnet, Justin G.; Dai; Thompson, James K.
2010-03-01
We demonstrate QND measurements on an ensemble of 10^6 ^87Rb atoms. Quantum state-dependent populations are determined at the projection noise level by measurements of the collective Vacuum Rabi Splitting for the resonantly coupled atom-cavity system. The splitting is measured by simultaneously scanning the frequency of two probes across the two transmission resonances and phase coherently detecting the full IQ response of the reflected electric fields. Measurement back-action imposes AC Stark shifts on the atoms, resulting in a reduction of the Ramsey fringe contrast due to inhomogeneity in the probe-atom coupling. We show that the spin-echo sequences that will be needed to achieve atomic spin-squeezing on the Rb clock transition also strongly suppress these AC stark shifts. The remaining probe-induced decoherence is close to the fundamental limit imposed by free space scattering of the probe photons.
Photonic ququart logic assisted by the cavity-QED system
Luo, Ming-Xing; Deng, Yun; Li, Hui-Ran; Ma, Song-Ya
2015-08-01
Universal quantum logic gates are important elements for a quantum computer. In contrast to previous constructions of qubit systems, we investigate the possibility of ququart systems (four-dimensional states) dependent on two DOFs of photon systems. We propose some useful one-parameter four-dimensional quantum transformations for the construction of universal ququart logic gates. The interface between the spin of a photon and an electron spin confined in a quantum dot embedded in a microcavity is applied to build universal ququart logic gates on the photon system with two freedoms. Our elementary controlled-ququart gates cost no more than 8 CNOT gates in a qubit system, which is far less than the 104 CNOT gates required for a general four-qubit logic gate. The ququart logic is also used to generate useful hyperentanglements and hyperentanglement-assisted quantum error-correcting code, which may be available in modern physical technology.
Quantum state tomography via mutually unbiased measurements in driven cavity QED systems
Yuan, Hao; Zhou, Zheng-Wei; Guo, Guang-Can
2016-04-01
We present a feasible proposal for quantum tomography of qubit and qutrit states via mutually unbiased measurements in dispersively coupled driven cavity QED systems. We first show that measurements in the mutually unbiased bases (MUBs) are practically implemented by projecting the detected states onto the computational basis after performing appropriate unitary transformations. The measurement outcomes can then be determined by detecting the steady-state transmission spectra (SSTS) of the driven cavity. It is found that all the measurement outcomes for each MUB (i.e., all the diagonal elements of the density matrix of each detected state) can be read out directly from only one kind of SSTS. In this way, we numerically demonstrate that the exemplified qubit and qutrit states can be reconstructed with the fidelities 0.952 and 0.961, respectively. Our proposal could be straightforwardly extended to other high-dimensional quantum systems provided that their MUBs exist.
Phase-selective reversible quantum decoherence in cavity QED experiment
Filip, Radim
2001-01-01
New feasible cavity QED experiment is proposed to analyse reversible quantum decoherence in consequence of quantum complementarity and entanglement. Utilizing the phase selective manipulations with enviroment, it is demonstrated how the complementarity particularly induces a preservation of visibility, whereas quantum decoherence is more progressive due to pronounced entanglement between system and enviroment. This effect can be directly observed using the proposed cavity QED measurements.
Feedback in a cavity QED system for control of quantum beats
Directory of Open Access Journals (Sweden)
Cimmarusti A.D.
2013-08-01
Full Text Available Conditional measurements on the undriven mode of a two-mode cavity QED system prepare a coherent superposition of ground states which generate quantum beats. The continuous system drive induces decoherence through the phase interruptions from Rayleigh scattering, which manifests as a decrease of the beat amplitude and an increase of the frequency of oscillation. We report recent experiments that implement a simple feedback mechanism to protect the quantum beat. We continuously drive the system until a photon is detected, heralding the presence of a coherent superposition. We then turn off the drive and let the superposition evolve in the dark, protecting it against decoherence. At a later time we reinstate the drive to measure the amplitude, phase, and frequency of the beats. The amplitude can increase by more than fifty percent, while the frequency is unchanged by the feedback.
Mass renormalization in cavity QED
International Nuclear Information System (INIS)
We show that the presence of a background medium and a boundary surface or surfaces in cavity QED produces no change in the energy shift of a free charged particle due to its coupling to the fluctuating electromagnetic field of the vacuum. This clarifies that the electromagnetic and the observed mass of the charged particle are not affected by the modification of the field of the vacuum. The calculations are nonrelativistic and restricted to the dipole approximation but are otherwise based on the general requirements of causality.
Cavity QED experiments with ion Coulomb crystals
DEFF Research Database (Denmark)
Herskind, Peter Fønss; Dantan, Aurélien; Marler, Joan; Albert, Magnus; Drewsen, Michael
Cavity QED experimental results demonstrating collective strong coupling between ensembles of atomic ions cooled into Coulomb crystals and optical cavity fields have been achieved. Collective Zeeman coherence times of milliseconds have furthermore been obtained.......Cavity QED experimental results demonstrating collective strong coupling between ensembles of atomic ions cooled into Coulomb crystals and optical cavity fields have been achieved. Collective Zeeman coherence times of milliseconds have furthermore been obtained....
Generation of hybrid four-qubit entangled decoherence-free states assisted by the cavity-QED system
Zhou, You-Sheng; Li, Xian; Deng, Yun; Li, Hui-Ran; Luo, Ming-Xing
2016-05-01
We propose three effective protocols to generate four-qubit entangled decoherence-free states assisted by the cavity-QED system. These schemes are based on optical selection rules realized with a single electron charged self-assembled GaAs/InAs quantum dot in a micropillar resonator. Compared with previous photonic protocols, the first scheme is to replace the entangled-state resources with much simpler single-photon resources and has a deterministic success probability. Moreover, the cavity-QED system may be used to generate four-spin entangled decoherence-free states and hybrid four-qubit of spin-photon entangled decoherence-free states. These states may be applied up to different requirements because of different superiorities of photons and spins. All schemes may be implemented with current physical technologies.
A Position-Dependent Two-Atom Entanglement in Real-Time Cavity QED System
Institute of Scientific and Technical Information of China (English)
GUO Yan-Qing; CAO Hai-Jing; SONG He-Shan
2007-01-01
We study a special two-atom entanglement case in assumed cavity QED experiment in which only one atom effectively exchanges a single photon with a cavity mode. We compute two-atom entanglement under position-dependent atomic resonant dipole-dipole interaction (RDDI) for large interatomic separation limit. We show that the RDDI, even that which is much smaller than the maximal atomic Rabi frequency, can induce distinct diatom entanglement. The peak entanglement reaches a maximum when RDDI strength can compare with the Rabi frequency of an atom.
Observing different quantum trajectories in cavity QED
Santos, Marcelo França
2011-01-01
The experimental observation of quantum jumps is an example of single open quantum systems that, when monitored, evolve in terms of stochastic trajectories conditioned on measurements results. Here we present a proposal that allows the experimental observation of a much larger class of quantum trajectories in cavity QED systems. In particular, our scheme allows for the monitoring of engineered thermal baths that are crucial for recent proposals for probing entanglement decay and also for entanglement protection. The scheme relies on the interaction of a three-level atom and a cavity mode that interchangeably play the roles of system and probe. If the atom is detected the evolution of the cavity fields follows quantum trajectories and vice-versa.
Simulating Topological Effects with Photons in Coupled QED Cavity Arrays
Noh, Changsuk; Angelakis, Dimitris G.
2014-01-01
We provide a pedagogical account of an early proposal realizing fractional quantum Hall effect (FQHE) using coupled quantum electrodynamics (QED) cavity arrays (CQCAs). We start with a brief introduction on the basics of quantum Hall effects and then review the early proposals in the simulation of spin-models and fractional quantum Hall (FQH) physics with photons in coupled atom-cavity arrays. We calculate the energy gap and the overlap between the ground state of the system and the corresponding Laughlin wavefunction to analyze the FQH physics arising in the system and discuss possibilities to reach the ground state using adiabatic methods used in Cavity QED.
Cavity QED with atom chips and micro-resonators
Lev, Benjamin; Barclay, Paul; Kerckhoff, Joseph; Painter, Oskar; Mabuchi, Hideo
2006-05-01
Cavity QED provides a rich experimental setting for quantum information processing, both in the implementation of quantum logic gates and in the development of quantum networks. Moreover, studies of cavity QED will help elucidate the dynamics of continuously observed open quantum systems with quantum- limited feedback. To achieve these goals in cavity QED, a neutral atom must be tightly confined inside a high-finesse cavity with small mode volume for long periods of time. Microfabricated wires on a substrate---known as an atom chip---can create sufficiently high-curvature magnetic potentials to trap atoms in the Lamb- Dicke regime. The integration of micro-resonators, such as microdisks and photonic bandgap cavities, with atom chips forms a robust and scalable system capable of probing the strong- coupling regime of cavity QED with magnetically trapped atoms. We have recently built an atom-cavity chip utilizing a fiber taper coupled microdisk resonator. This device combines laser cooling and trapping of neutral atoms with magnetic microtraps and waveguides to deliver cold atoms to the small mode volume of the high-Q cavity. We will relate our progress toward detecting single atoms with this device.
International Nuclear Information System (INIS)
We propose a method for implementing the Grover search algorithm directly in a database containing any number of items based on multi-level systems. Compared with the searching procedure in the database with qubits encoding, our modified algorithm needs fewer iteration steps to find the marked item and uses the carriers of the information more economically. Furthermore, we illustrate how to realize our idea in cavity QED using Zeeman's level structure of atoms. And the numerical simulation under the influence of the cavity and atom decays shows that the scheme could be achieved efficiently within current state-of-the-art technology. -- Highlights: ► A modified Grover algorithm is proposed for searching in an arbitrary dimensional Hilbert space. ► Our modified algorithm requires fewer iteration steps to find the marked item. ► The proposed method uses the carriers of the information more economically. ► A scheme for a six-item Grover search in cavity QED is proposed. ► Numerical simulation under decays shows that the scheme can be achieved with enough fidelity.
Quantum signalling in cavity QED
Jonsson, Robert H.; Martin-Martinez, Eduardo; Kempf, Achim
2013-01-01
We consider quantum signalling between two-level quantum systems in a cavity, in the pertubative regime of the earliest possible arrival times of the signal. We present two main results: First we find that, perhaps surprisingly, the analogue of amplitude modulated signalling (Alice using her energy eigenstates |g>, |e>, as in the Fermi problem) is generally sub-optimal for communication. Namely, e.g., phase modulated signalling (Alice using, e.g., |+>,|e>-states) overcomes the quantum noise a...
Scheme for Implementation of Quantum Game in Cavity QED
Institute of Scientific and Technical Information of China (English)
ZHANG Li-Chun; CAO Shu-Ai; WU Yue-Qin; FANG Mao-Fa; LI Huai-Fan; ZHENG Xiao-Juan; ZHAO Ren; WANG Xin-Wen; LI Ze-Hua
2008-01-01
We propose an experimentally feasible scheme to implement two-player quantum game in cavity quantum electrodynamics (QED). During the process, the cavity is only virtually excited, thus our scheme is insensitive to the cavity field states and cavity decay. The scheme can be realized in the range of current cavity QED techniques.
Scheme for Implementation of Quantum Game in Cavity QED
International Nuclear Information System (INIS)
We propose an experimentally feasible scheme to implement two-player quantum game in cavity quantum electrodynamics (QED). During the process, the cavity is only virtually excited, thus our scheme is insensitive to the cavity field states and cavity decay. The scheme can be realized in the range of current cavity QED techniques.
Generation of Cluster States in Cavity QED
Institute of Scientific and Technical Information of China (English)
ZHOU Yan-Li; YANG Li-Jia; DAI Hong-Yi
2007-01-01
We propose two schemes for the generation of cluster states in the context of cavity quantum electrodynamics (QED).In the first scheme,we prepare multi-cavity cluster states with information encoded in the coherent states.The second scheme is to generate multi-atom cluster states,where qubits are represented by the states of cascade Rydberg atoms.Both the schemes are based on the atom-cavity interaction and the atomic spontaneous radiation can be effciently reduced since the cavity frequency is largely detuned from the atomic transition frequency.
Single ion cavity QED experiments
International Nuclear Information System (INIS)
Full text: We have set up a spherical Paul trap for a storing a single Ca+ ion placed in the center of a high finesse near confocal resonator. We report on experiments demonstrating the coupling of the narrow S1/2-D5/2 transition to the cavity internal light field. Due to the coupling, the ion acts as sensitive probe for the cavity internal field. We are able to map the field distribution by measuring the excitation probability. Scanning the cavity over the resonance imprints a Doppler frequency shift on the cavity field which leads to a spectral shift and a asymmetric broadening of the S-D transition. (author)
Theoretical analysis of quantum game in cavity QED
International Nuclear Information System (INIS)
Recent years, several ways of implementing quantum games in different physical systems have been presented. In this paper, we perform a theoretical analysis of an experimentally feasible way to implement a two player quantum game in cavity quantum electrodynamic(QED). In the scheme, the atoms interact simultaneously with a highly detuned cavity mode with the assistance of a classical field. So the scheme is insensitive to the influence from the cavity decay and the thermal field, and it does not require the cavity to remain in the vacuum state throughout the procedure. (general)
Quantum-to-Classical Transition in Cavity Quantum Electrodynamics (QED)
Fink, J M; Studer, P; Bishop, Lev S; Baur, M; Bianchetti, R; Bozyigit, D; Lang, C; Filipp, S; Leek, P J; Wallraff, A
2010-01-01
The quantum properties of electromagnetic, mechanical or any other type of harmonic oscillator can be revealed by investigating its strong coherent coupling to a single quantum two level system in an approach known as cavity QED. At temperatures much lower than the characteristic energy level spacing the observation of vacuum Rabi oscillations or mode splittings with one or a few quanta asserts the quantum nature of the system. Here, we study how the classical response of a quantum cavity QED system emerges when its thermal occupation -- or effective temperature -- is raised gradually over 5 orders of magnitude. In this way we explore in detail the continuous cross-over from a quantum response to a classical response in the spirit of Bohr's correspondence principle. We also demonstrate how to extract effective cavity field temperatures from both spectroscopic and time-resolved vacuum Rabi measurements.
Sensitive Detection of Individual Neutral Atoms in a Strong Coupling Cavity QED System
Institute of Scientific and Technical Information of China (English)
ZHANG Peng-Fei; ZHANG Yu-Chi; LI Gang; DU Jin-Jin; ZHANG Yan-Feng; GUO Yan-Qiang; WANG Jun-Min; ZHANG Tian-Cai; LI Wei-Dong
2011-01-01
We experimentally demonstrate real-time detection of individual cesium atoms by using a high-finesse optical micro-cavity in a strong coupling regime.A cloud of cesium atoms is trapped in a magneto-optical trap positioned at 5 mm above the micro-cavity center.The atoms fall down freely in gravitation after shutting off the magnetooptical trap and pass through the cavity.The cavity transmission is strongly affected by the atoms in the cavity, which enables the micro-cavity to sense the atoms individually.We detect the single atom transits either in the resonance or various detunings.The single atom vacuum-Rabi splitting is directly measured to be Ω = 2π × 23.9 MHz.The average duration of atom-cavity coupling of about 110μs is obtained according to the probability distribution of the atom transits.%@@ We experimentally demonstrate real-time detection of individual cesium atoms by using a high-finesse optical micro-cavity in a strong coupling regime.A cloud of cesium atoms is trapped in a magneto-optical trap positioned at 5mm above the micro-cavity center.The atoms fall down freely in gravitation after shutting off the magnetooptical trap and pass through the cavity.The cavity transmission is strongly affected by the atoms in the cavity, which enables the micro-cavity to sense the atoms individually.We detect the single atom transits either in the resonance or various detunings.The single atom vacuum-Rabi splitting is directly measured to be Ω＝2π×23.9 MHz.The average duration of atom-cavity coupling of about 110μs is obtained according to the probability distribution of the atom transits.
Scheme for implementing quantum secret sharing via cavity QED
Institute of Scientific and Technical Information of China (English)
Chen Zhi-Hua; Lin Xiu-Min
2005-01-01
An experimentally feasible scheme for implementing quantum secret sharing via cavity quantum electrodynamics (QED) is proposed. The scheme requires the large detuning of the cavity field from the atomic transition, the cavity is only virtually excited, thus the requirement on the quality factor of the cavity is greatly loosened.
High-Q 3D coaxial resonators for cavity QED
Yoon, Taekwan; Owens, John C.; Naik, Ravi; Lachapelle, Aman; Ma, Ruichao; Simon, Jonathan; Schuster, David I.
Three-dimensional microwave resonators provide an alternative approach to transmission-line resonators used in most current circuit QED experiments. Their large mode volume greatly reduces the surface dielectric losses that limits the coherence of superconducting circuits, and the well-isolated and controlled cavity modes further suppress coupling to the environment. In this work, we focus on unibody 3D coaxial cavities which are only evanescently coupled and free from losses due to metal-metal interfaces, allowing us to reach extremely high quality-factors. We achieve quality-factor of up to 170 million using 4N6 Aluminum at superconducting temperatures, corresponding to an energy ringdown time of ~4ms. We extend our methods to other materials including Niobium, NbTi, and copper coated with Tin-Lead solder. These cavities can be further explored to study their properties under magnetic field or upon coupling to superconducting Josephson junction qubits, e.g. 3D transmon qubits. Such 3D cavity QED system can be used for quantum information applications, or quantum simulation in coupled cavity arrays.
Distillation of bi-partite entanglement from W state with cavity QED
Institute of Scientific and Technical Information of China (English)
Deng Li; Chen Ai-Xi; Chen De-Hai; Huang Ke-Lin
2008-01-01
Following the theoretical protocol described by Fortescue and Lo [Fortescue B and Lo H K 2007 Phys. Rev. Lett. 98 260501], we present a scheme in which one can distill maximally entangled bi-partite states from a tri-partite W state with cavity QED. Our scheme enables the concrete physical system to realize its protocol. In our scheme, the rate distillation also asymptotically approaches one. Based on the present cavity QED techniques, we discuss the experimental feasibility.
A Cavity QED Implementation of Deutsch-Jozsa Algorithm
Guerra, E. S.
2004-01-01
The Deutsch-Jozsa algorithm is a generalization of the Deutsch algorithm which was the first algorithm written. We present schemes to implement the Deutsch algorithm and the Deutsch-Jozsa algorithm via cavity QED.
Phase-factor-dependent symmetries and quantum phases in a three-level cavity QED system
Fan, Jingtao; Yu, Lixian; Chen, Gang; Jia, Suotang
2016-05-01
Unlike conventional two-level particles, three-level particles may support some unitary-invariant phase factors when they interact coherently with a single-mode quantized light field. To gain a better understanding of light-matter interaction, it is thus necessary to explore the phase-factor-dependent physics in such a system. In this report, we consider the collective interaction between degenerate V-type three-level particles and a single-mode quantized light field, whose different components are labeled by different phase factors. We mainly establish an important relation between the phase factors and the symmetry or symmetry-broken physics. Specifically, we find that the phase factors affect dramatically the system symmetry. When these symmetries are breaking separately, rich quantum phases emerge. Finally, we propose a possible scheme to experimentally probe the predicted physics of our model. Our work provides a way to explore phase-factor-induced nontrivial physics by introducing additional particle levels.
Phase-factor-dependent symmetries and quantum phases in a three-level cavity QED system
Fan, Jingtao; Yu, Lixian; Chen, Gang; Jia, Suotang
2016-01-01
Unlike conventional two-level particles, three-level particles may support some unitary-invariant phase factors when they interact coherently with a single-mode quantized light field. To gain a better understanding of light-matter interaction, it is thus necessary to explore the phase-factor-dependent physics in such a system. In this report, we consider the collective interaction between degenerate V-type three-level particles and a single-mode quantized light field, whose different components are labeled by different phase factors. We mainly establish an important relation between the phase factors and the symmetry or symmetry-broken physics. Specifically, we find that the phase factors affect dramatically the system symmetry. When these symmetries are breaking separately, rich quantum phases emerge. Finally, we propose a possible scheme to experimentally probe the predicted physics of our model. Our work provides a way to explore phase-factor-induced nontrivial physics by introducing additional particle levels. PMID:27139573
Single atoms on demand for cavity QED experiments
International Nuclear Information System (INIS)
Cavity quantum electrodynamics (cavity QED) describes electromagnetic fields in a confined space and the radiative properties of atoms in such fields. The simplest example of such system is a single atom interacting with one mode of a high-finesse resonator. Besides observation and exploration of fundamental quantum mechanical effects, this system bears a high potential for applications quantum information science such as, e.g., quantum logic gates, quantum communication and quantum teleportation. In this thesis I present an experiment on the deterministic coupling of a single neutral atom to the mode of a high-finesse optical resonator. In Chapter 1 I describe our basic techniques for trapping and observing single cesium atoms. As a source of single atoms we use a high-gradient magneto-optical trap, which captures the atoms from background gas in a vacuum chamber and cools them down to millikelvin temperatures. The atoms are then transferred without loss into a standing-wave dipole trap, which provides a conservative potential required for experiments on atomic coherence such as quantum information processing and metrology on trapped atoms. Moreover, shifting the standing-wave pattern allows us to deterministically transport the atoms (Chapter 2). In combination with nondestructive fluorescence imaging of individual trapped atoms, this enables us to control their position with submicrometer precision over several millimeters along the dipole trap. The cavity QED system can distinctly display quantum behaviour in the so-called strong coupling regime, i.e., when the coherent atom-cavity coupling rate dominates dissipation in the system. This sets the main requirements on the resonator's properties: small mode volume and high finesse. Chapter 3 is devoted to the manufacturing, assembling, and testing of an ultra-high finesse optical Fabry-Perot resonator, stabilized to the atomic transition. In Chapter 4 I present the transportation of single atoms into the cavity
Single atoms on demand for cavity QED experiments
Energy Technology Data Exchange (ETDEWEB)
Dotsenko, I.
2007-09-06
Cavity quantum electrodynamics (cavity QED) describes electromagnetic fields in a confined space and the radiative properties of atoms in such fields. The simplest example of such system is a single atom interacting with one mode of a high-finesse resonator. Besides observation and exploration of fundamental quantum mechanical effects, this system bears a high potential for applications quantum information science such as, e.g., quantum logic gates, quantum communication and quantum teleportation. In this thesis I present an experiment on the deterministic coupling of a single neutral atom to the mode of a high-finesse optical resonator. In Chapter 1 I describe our basic techniques for trapping and observing single cesium atoms. As a source of single atoms we use a high-gradient magneto-optical trap, which captures the atoms from background gas in a vacuum chamber and cools them down to millikelvin temperatures. The atoms are then transferred without loss into a standing-wave dipole trap, which provides a conservative potential required for experiments on atomic coherence such as quantum information processing and metrology on trapped atoms. Moreover, shifting the standing-wave pattern allows us to deterministically transport the atoms (Chapter 2). In combination with nondestructive fluorescence imaging of individual trapped atoms, this enables us to control their position with submicrometer precision over several millimeters along the dipole trap. The cavity QED system can distinctly display quantum behaviour in the so-called strong coupling regime, i.e., when the coherent atom-cavity coupling rate dominates dissipation in the system. This sets the main requirements on the resonator's properties: small mode volume and high finesse. Chapter 3 is devoted to the manufacturing, assembling, and testing of an ultra-high finesse optical Fabry-Perot resonator, stabilized to the atomic transition. In Chapter 4 I present the transportation of single atoms into the
Non-markovian effects in semiconductor cavity QED: Role of phonon-mediated processes
DEFF Research Database (Denmark)
Nielsen, Per Kær; Nielsen, Torben Roland; Lodahl, Peter;
We show theoretically that the non-Markovian nature of the carrier-phonon interaction influences the dynamical properties of a semiconductor cavity QED system considerably, leading to asymmetries with respect to detuning in carrier lifetimes. This pronounced phonon effect originates from the pola...... polaritonic quasi-particle nature of the carrier-photon system interacting with the phonon reservoir.......We show theoretically that the non-Markovian nature of the carrier-phonon interaction influences the dynamical properties of a semiconductor cavity QED system considerably, leading to asymmetries with respect to detuning in carrier lifetimes. This pronounced phonon effect originates from the...
Protocol for multi-party superdense coding by using multi-atom in cavity QED
Institute of Scientific and Technical Information of China (English)
Tan Jia; Fang Mao-Fa
2006-01-01
We present a protocol for multi-party superdense coding by using multi-atom in cavity quantum electrodynamics (QED). It is shown that, with a highly detuned cavity mode and a strong driving field, the protocol is insensitive to both cavity decay and thermal field. It is even certain to identify GHZ states via detecting the atomic states. Therefore we can realize the quantum dense coding in a simple way in the multiparty system.
Atomic teleportation via cavity QED and position measurements: Efficiency analysis
Tumminello, M.; Ciccarello, F.
2008-07-01
We have recently presented a novel protocol to teleport an unknown atomic state via cavity QED and position measurements. Here, after a brief review of our scheme, we provide a quantitative study of its efficiency. This is accomplished by an explicit description of the measurement process that allows us to derive the fidelity with respect to the atomic internal state to be teleported.
Scheme for Implementing Quantum Cloning Restoring Machine in Cavity QED
Institute of Scientific and Technical Information of China (English)
YU Long-Bao; ZHANG Wen-Hai; YE Liu
2007-01-01
We propose an experimentally feasible scheme for implementing quantum restoring machine of the optimal universal 1 → 2 quanturn cloning machine in the context of cavity QED.In our scheme,two atoms (the clones) simultaneously interact with a cavity field,and meanwhile they are driven by a classical field.Then an arbitrary unknown input state can be restored in the ancilla by applying appropriate unitary local operation.
Generation of four-photon W state via cavity QED
Institute of Scientific and Technical Information of China (English)
Zhong Zhi-Rong
2008-01-01
This paper proposes an alternative scheme for generating four-photon W state via cavity QED.The scheme bases on the resonant interaction of a A-type three level atom with two bimodal cavities.The detection of atom collapses the cavity to the desired state.Comparing with previous schemes,the advantage of this scheme is that the interaction time can be greatly shortened since it uses the resonant interaction between atom and cavities.Moreover,the proposed scheme is more experimentally feasible than the previous ones.
Strong-Driving-Assisted Probabilistic State Preparation in Cavity QED
Institute of Scientific and Technical Information of China (English)
YANG Zhen-Biao
2006-01-01
An alternative scheme is proposed for preparing the superpositions of coherent states with controllable weighting factors along a straight line for a cavity field. The scheme is based on the interaction of a single-mode cavity field with a resonant two-level atom driven by a strong classical field. It is in contrast to the previous methods used in cavity QED of injecting a coherent state into a cavity via a microwave source. In the scheme, the interaction between the cavity mode and atoms is fully resonant, thus the required interaction time is greatly shortened. Moreover, the present scheme requires smaller numbers of operations. In view of decoherence, a reduction of interaction time and numbers of operations for the state preparation is very important for experimental implementation of quantum state engineering.
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.
Cavity QED Detection of Interfering Matter Waves
Bourdel, T; Donner, T.; Ritter, S; Öttl, A.; Köhl, M.; Esslinger, T.
2005-01-01
We observe the build-up of a matter wave interference pattern from single atom detection events in a double-slit experiment. The interference arises from two overlapping atom laser beams extracted from a Rubidium Bose-Einstein condensate. Our detector is a high-finesse optical cavity which realizes the quantum measurement of the presence of an atom and thereby projects delocalized atoms into a state with zero or one atom in the resonator. The experiment reveals simultaneously the granular and...
Cavity QED on a nanofiber using a composite photonic crystal cavity
Yalla, Ramachandrarao; Nayak, Kali P; Hakuta, Kohzo
2014-01-01
We demonstrate cavity QED conditions in the Purcell regime for single quantum emitters on the surface of an optical nanofiber. The cavity is formed by combining an optical nanofiber and a nanofabricated grating to create a composite photonic crystal cavity. Using this technique, significant enhancement of the spontaneous emission rate into the nanofiber guided modes is observed for single quantum dots. Our results pave the way for enhanced on-fiber light-matter interfaces with clear applications to quantum networks.
Efficient atomic quantum memory for photonic qubits in cavity QED
Yamada, H; Yamada, Hiroyuki; Yamamoto, Katsuji
2007-01-01
We investigate a scheme of atomic quantum memory to store photonic qubits of polarization in cavity QED. It is observed that the quantum-state swapping between a single-photon pulse and a $ \\Lambda $-type atom can be made via scattering in an optical cavity [T. W. Chen, C. K. Law, P. T. Leung, Phys. Rev. A {\\bf 69} (2004) 063810]. This swapping operates limitedly in the strong coupling regime for $ \\Lambda $-type atoms with equal dipole couplings. We extend this scheme in cavity QED to present a more feasible and efficient method for quantum memory combined with projective measurement. This method works without requiring such a condition on the dipole couplings. The fidelity is significantly higher than that of the swapping, and even in the moderate coupling regime it reaches almost unity by narrowing sufficiently the photon-pulse spectrum. This high performance is rather unaffected by the atomic loss, cavity leakage or detunings, while a trade-off is paid in the success probability for projective measurement...
Transformation of bipartite non-maximally entangled states into a tripartiteWstate in cavity QED
Indian Academy of Sciences (India)
ZANG XUE-PING; YANG MING; DU CHAO-QUN; WANG MIN; FANG SHU-DONG; CAO ZHUO-LIANG
2016-05-01
We present two schemes for transforming bipartite non-maximally entangled states into a W state in cavity QED system, by using highly detuned interactions and the resonant interactions between two-level atoms and a single-mode cavity field. A tri-atom W state can be generated by adjusting the interaction times between atoms and the cavity mode. These schemes demonstrate that two bipartite non-maximally entangled states can be merged into a maximally entangled W state. So the scheme can, in some sense, be regarded as an entanglement concentration process. The experimental feasibility of the schemes is also discussed.
Quantum repeater based on cavity QED evolutions and coherent light
Gonţa, Denis; van Loock, Peter
2016-05-01
In the framework of cavity QED, we propose a quantum repeater scheme that uses coherent light and chains of atoms coupled to optical cavities. In contrast to conventional repeater schemes, in our scheme there is no need for an explicit use of two-qubit quantum logical gates by exploiting solely the cavity QED evolution. In our previous work (Gonta and van Loock in Phys Rev A 88:052308, 2013), we already proposed a quantum repeater in which the entanglement between two neighboring repeater nodes was distributed using controlled displacements of input coherent light, while the produced low-fidelity entangled pairs were purified using ancillary (four-partite) entangled states. In the present work, the entanglement distribution is realized using a sequence of controlled phase shifts and displacements of input coherent light. Compared to previous coherent-state-based distribution schemes for two-qubit entanglement, our scheme here relies only upon a simple discrimination of two coherent states with opposite signs, which can be performed in a quantum mechanically optimal fashion via a beam splitter and two on-off detectors. For the entanglement purification, we employ a method that avoids the use of extra entangled ancilla states. Our repeater scheme exhibits reasonable fidelities and repeater rates providing an attractive platform for long-distance quantum communication.
Observation of Cavity QED in thick dielectric films
Sarabi, Bahman; Ramanayaka, A. N.; Gladchenko, S.; Stoutimore, M. J. A.; Khalil, M. S.; Osborn, K. D.
2013-03-01
Cavity QED in amorphous dielectrics is investigated by measuring five linear superconducting resonators with thick dielectric films and capacitor volumes ranging from 80 μm3 to 5000 μm3. In the smallest volume dielectrics we observe additional resonances which may be explained by CQED, despite the dielectric volume which is many orders of magnitude larger than Josephson junction barrier volumes. In addition to the volume dependence of the CQED resonances, we will report on the stability of the resonances in time and the phase noise. This research allows new fundamental studies on TLS phenomena in meso-volume amorphous dielectrics.
Quantum Logic Network for Cloning a State Near a Given One Based on Cavity QED
Institute of Scientific and Technical Information of China (English)
ZHANG Da-Wei; SHAO Xiao-Qiang; ZHU Ai-Dong
2008-01-01
A quantum logic network is constructed to simulate a cloning machine which copies states near a given one. Meanwhile, a scheme for implementing this cloning network based on the technique of cavity quantum electrody-namics (QED) is presented. It is easy to implement this network of cloning machine in the framework of cavity QED and feasible in the experiment.
Quantum Logic Network for Cloning a State Near a Given One Based on Cavity QED
International Nuclear Information System (INIS)
A quantum logic network is constructed to simulate a cloning machine which copies states near a given one. Meanwhile, a scheme for implementing this cloning network based on the technique of cavity quantum electrodynamics (QED) is presented. It is easy to implement this network of cloning machine in the framework of cavity QED and feasible in the experiment. (general)
Cavity-QED models of switches for attojoule-scale nanophotonic logic
International Nuclear Information System (INIS)
Quantum optical input-output models are described for a class of optical switches based on cavity quantum electrodynamics (QED) with a single multilevel atom (or comparable bound system of charges) coupled simultaneously to several resonant field modes. A recent limit theorem for quantum stochastic differential equations is used to show that such models converge to a simple scattering matrix in a type of strong-coupling limit that seems natural for nanophotonic systems. Numerical integration is used to show that the behavior of the prelimit model approximates that of the simple scattering matrix in a realistic regime for the physical parameters and that it is possible in the proposed cavity-QED configuration for low-power optical signals to switch higher-power signals at attojoule energy scales.
International Nuclear Information System (INIS)
We investigate a two-level atom interacting with a quantized cavity field and a classical driving field in the presence of phase decoherence and find that a stationary quantum discord can arise in the interaction of the atom and cavity field as the time turns to infinity. We also find that the stationary quantum discord can be increased by applying a classical driving field. Furthermore, we explore the quantum discord dynamics of two identical non-interacting two-level atoms independently interacting with a quantized cavity field and a classical driving field in the presence of phase decoherence. Results show that the quantum discord between two atoms is more robust than entanglement under phase decoherence and the classical driving field can help to improve the amount of quantum discord of the two atoms. (general)
Transferring a cavity field entangled state in cavity QED
Energy Technology Data Exchange (ETDEWEB)
Ye Liu [Anhui Key Laboratory of Information Material and Devices, School of Physics and Material Science, Anhui University, Hefei 230039 (China); Guo Guangcan [Key Laboratory of Quantum Information, University of Science and Technology of China, Chinese Academy of Sciences, Hefei 230026 (China)
2005-08-01
We propose a scheme for transferring an entanglement of zero- and one-photon states from one cavity to another. The scheme, which has 100% success probability, is mainly based on a two-mode cavity dispersively interacting with a three-level atom in the {lambda} configuration and does not involve Bell-state measurement. This scheme can also be used to teleport an unknown atomic state.
Quantum-trajectory simulations of a two-level atom cascaded to a cavity QED laser
International Nuclear Information System (INIS)
We use the quantum theory of cascaded open systems to calculate the transmitted photon flux for a weak beam of photons from a cavity QED laser strongly focused onto a single, resonant two-state atom in the narrow-bandwidth limit. We study the dependence of the transmitted flux on the quantum statistics of the incident light. Both bunched and antibunched light generated by the microlaser are considered as input. Working within and outside the semiclassical perturbative regime, we explicitly demonstrate that the normalized transmitted photon flux may coincide with the second-order correlation function of the incident bunched light, but not for incident antibunched light both of which are generated by a cavity QED laser. Interestingly, the thresholdless cavity QED laser is ideal for investigating statistical saturation effects by virtue of its small system size and the large quantum fluctuations accompanying it. It has the advantage of characterizing to a certain extent the quantum noise responsible for the statistical saturation. One can also easily vary the degree of antibunching of the incident light by manipulating the pumping rate of the laser
Nonprobabilistic teleportation of field state via cavity QED
De Carvalho, Carlos Renato; Guerra, Emerson S.; Jalbert, Ginette; Garreau, Jean Claude
2007-01-01
International audience In this article we discuss a teleportation scheme of coherent states of cavity field. The experimental realization proposed makes use of cavity quatum electrodynamics involving the interaction of Rydberg atoms with micromaser and Ramsey cavities. In our scheme the Ramsey cavities and the atoms play the role of auxiliary systems used to teleport the state from a micromaser cavity to another. We show that, even if the correct atomic detection fails in the first trials,...
Quantum optics and cavity QED with quantum dots in photonic crystals
Vuckovic, Jelena
2014-01-01
This chapter will primarily focus on the studies of quantum optics with semiconductor, epitaxially grown quantum dots embedded in photonic crystal cavities. We will start by giving brief introductions into photonic crystals and quantum dots, then proceed with the introduction to cavity quantum electrodynamics (QED) effects, with a particular emphasis on the demonstration of these effects on the quantum dot-photonic crystal platform. Finally, we will focus on the applications of such cavity QED effects.
Nonprobabilistic teleportation of field state via cavity QED
De Carvalho, C R; Jalbert, G; Garreau, J C; Carvalho, Carlos Renato De; Guerra, Emerson S.; Jalbert, Ginette; Garreau, Jean Claude
2007-01-01
In this article we discuss a teleportation scheme of coherent states of cavity field. The experimental realization proposed makes use of cavity quatum electrodynamics involving the interaction of Rydberg atoms with micromaser and Ramsey cavities. In our scheme the Ramsey cavities and the atoms play the role of auxiliary systems used to teleport the state from a micromaser cavity to another. We show that, even if the correct atomic detection fails in the first trials, one can succeed in teleportating the cavity field state if the proper measurement occurs in a later atom.
Nonprobabilistic teleportation of a field state via cavity QED
Energy Technology Data Exchange (ETDEWEB)
Carvalho, C R [Instituto de Fisica, Universidade Federal do Rio de Janeiro, Cx. Postal 68528, 21941-972 Rio de Janeiro, RJ (Brazil); Guerra, E S [Departamento de Fisica, Universidade Federal Rural do Rio de Janeiro, Cx. Postal 23851, 23890-000 Seropedica, RJ (Brazil); Jalbert, Ginette [Instituto de Fisica, Universidade Federal do Rio de Janeiro, Cx. Postal 68528, 21941-972 Rio de Janeiro, RJ (Brazil); Garreau, J C [Laboratoire de Physique des Lasers, Atomes et Molecules, Universite des Sciences et Technologies de Lille, Bat. P5, F-59650 Villeneuve d' Ascq Cedex (France)
2007-03-28
In this paper, we discuss a teleportation scheme of coherent states of a cavity field. The experimental realization proposed makes use of cavity quantum electrodynamics, involving the interaction of Rydberg atoms with micromaser and Ramsey cavities. In our scheme the Ramsey cavities and the atoms play the role of auxiliary systems used to teleport the state from one micromaser cavity to another. We show that, even if the correct atomic detection fails in the first trials, one can succeed in teleportating the cavity field state if proper measurement occurs in a later atom.
Fabrication of Glass Micro-Cavities for Cavity QED Experiments
Roy, Arpan
2011-01-01
We report a process for fabricating high quality, defect-free spherical mirror templates suitable for developing high finesse optical Fabry-Perot resonators. The process utilizes the controlled reflow of borosilicate glass and differential pressure to produce mirrors with 0.3 nanometer surface roughness. The dimensions of the mirrors are in the 0.5-5mm range making them suitable candidates for integration with on-chip neutral atom and ion experiments where enhanced interaction between atoms and photons are required. Moreover the mirror curvature, dimension and placement is readily controlled and the process can easily provide an array of such mirrors. We show that cavities constructed with these mirror templates are well suited to quantum information applications such as single photon sources and atom-photon entanglement.
Dynamical Properties of Two Coupled Dissipative QED Cavities Driven by Coherent Fields
Institute of Scientific and Technical Information of China (English)
无
2007-01-01
When two identical QED cavities driven by the coherent fields are located in a uniform environment, in addition to dissipation, there appears an indirect coupling between the two cavities induced by the background fields. We investigate the effects of the coherent fields, the dissipation as well as the incoherent coupling on the following dynamical properties of the system: photon transfer, reversible decoherence, and quantum state transfer, etc. We find that the photons in the cavities do not leak completely into the environment due to the collective coupling between the cavities and the enviroment, and the photons are transferred irreversibly from the cavity with more photons to the cavity with less ones due to the incoherent coupling so that they are equally distributed among the two cavities. The coherent field pumping on the two cavities increases the mean photons, complements the revived magnitude of the reversible decoherence, but hinders the quantum state transfer between the two cavities. The above phenomena may find applications in quantum communication and other basic fields.
Scheme for implementing quantum dense coding with W-class state in cavity QED
Institute of Scientific and Technical Information of China (English)
He Juan; Ye Liu; Ni Zhi-Xiang
2008-01-01
An experimentally feasible protocol for realizing dense coding by using a class of W-state in cavity quantum electrodynamics (QED) is proposed in this paper.The prominent advantage of our scheme is that the succeasful probability of the dense coding with a W-class state can reach 1.In addition,the scheme can be implemented by the present cavity QED techniques.
Scheme to Implement Scheme 1 → M Economical Phase-Covariant Telecloning via Cavity QED
Institute of Scientific and Technical Information of China (English)
LIU Qi; ZHANG Wen-Hai; YE Liu
2008-01-01
We propose an experimentally feasible scheme to implement the economical 1 → M(M = 2k + 1) phase-covariant telecloning without ancilla based on cavity QED. The scheme requires cavity-assisted collision processes between atoms, which cross through the off-resonant cavity field in the vacuum states. During the telecloning process, the cavity is only virtually excited and it thus greatly prolongs the efficient decoherent time. Therefore, our scheme may be realized in experiment in future.
Local and non-local Schroedinger cat states in cavity QED
International Nuclear Information System (INIS)
Full text: I will review recent experiments performed on mesoscopic state superpositions of field states in cavity QED. Proposals to extend these studies to Schroedinger cat states delocalized in two cavities will be discussed. New versions of Bell's inequality tests will probe the non-local behavior of these cats and study their sensitivity to decoherence. (author)
A scheme for implementing quantum clock synchronization algorithm in cavity QED
Institute of Scientific and Technical Information of China (English)
Wu Qin-Qin; Kuang Le-Man
2006-01-01
In this paper, we propose a scheme for implementing the quantum clock synchronization (QCS) algorithm in cavity quantum electrodynamic (QED) formalism. Our method is based on three-level ladder-type atoms interacting with classical and quantized cavity fields. Atom-qubit realizations of three-qubit and four-qubit QCS algorithms are explicitly presented.
Extended Jaynes-Cummings Models In Cavity Qed
Larson, Jonas
2005-01-01
Due to the improvement within cavity quantum electrodynamics experiments during the last decades, what was former seen as 'toy models' are today realized in laboratories. A controlled isolated coherent evolution of one or a few atoms coupled to a single mode inside a cavity is achievable. Such systems are well suited for studying purely quantum mechanical effects, and also for performing quantum gates, necessary for quantum computing. The Jaynes-Cummings model has served as a theoretical desc...
Quantum optics and cavity QED with quantum dots in photonic crystals
Vuckovic, Jelena
2014-01-01
This chapter will primarily focus on the studies of quantum optics with semiconductor, epitaxially grown quantum dots embedded in photonic crystal cavities. We will start by giving brief introductions into photonic crystals and quantum dots, then proceed with the introduction to cavity quantum electrodynamics (QED) effects, with a particular emphasis on the demonstration of these effects on the quantum dot-photonic crystal platform. Finally, we will focus on the applications of such cavity QE...
Teleportation of GHZ-States in QED-Cavities without the Explicit Bell-State Measurement
Cardoso, W. B.
2008-04-01
In this paper we show how to teleport N-entangled states of N-QED-cavities without Bell-state measurements. The method has potential application in teleportation schemes requiring multipartite entanglements. The success probability and fidelity of the teleportation are also considered.
Scheme for Implementing Teleporting an Arbitrary Tripartite Entangled State in Cavity QED
Wang, Xue-Wen; Peng, Zhao-Hui
2009-10-01
We propose to teleport an arbitrary tripartite entangled state in cavity QED. In this scheme, the five-qubit Brown state is chosen as the quantum channel. It has been shown that the teleportation protocol can be completed perfectly with two different measurement methods. In the future, our scheme might be realizable based on present experimental technology.
Geometric phase in cavity QED containing a nonlinear optical medium and a quantum well
Mohamed, A.-B. A.; Eleuch, H.
2015-11-01
The geometric phase (GP) in cavity QED filled with a nonlinear medium and containing a quantum well is analyzed. We observe collapses and revivals. The optical nonlinearity leads to high frequency oscillations of the GP. The GP is very sensitive not only to the dissipation rates but also to the amplitude of the laser pump.
Bloch-wave engineered submicron-diameter quantum-dot micropillars for cavity QED experiments
DEFF Research Database (Denmark)
Gregersen, Niels; Lermer, Matthias; Reitzenstein, Stephan;
2013-01-01
The semiconductor micropillar is attractive for cavity QED experiments. For strong coupling, the figure of merit is proportional to Q/√V, and a design combining a high Q and a low mode volume V is thus desired. However, for the standard submicron diameter design, poor mode matching between the...
Bloch-wave engineered submicron-diameter quantum-dot micropillars for cavity QED experiments
DEFF Research Database (Denmark)
Gregersen, Niels; Lermer, Matthias; Reitzenstein, Stephan;
2013-01-01
The semiconductor micropillar is attractive for cavity QED experiments. For strong coupling, the figure of merit is proportional to Q/√V, and a design combining a high Q and a low mode volume V is thus desired. However, for the standard submicron diameter design, poor mode matching between the ca...
Probabilistic cloning of a single-atom state via cavity QED
Zhang, Wen; Rui, Pinshu; Lu, Yan; Yang, Qun; Zhao, Yan
2015-06-01
We propose a scheme for probabilistically cloning a two-level state of an atom to a polarization photon via cavity QED system combined with linear optics elements. By choosing appropriate parameters, a controlled phase flip (CPF) gate between the atom and the probe photon is realized. Then we can judge that the cloning process should be continued (with the optimal probability) or interrupted by detecting the probe photon. If the cloning can be continued, the original atom state is deterministically cloned to the cloning photon by performing two more CPF gates and three single-qubit unitary operations. Otherwise, if the detection shows that the cloning should be interrupted, the cloning photon and the relevant operations are omitted.
Zhang, Shu-Qun; Chen, Zhi-De
2014-02-01
We present nonperturbative treatment of the vacuum field bath for two cases, a two-level emitter (TLE) in free space and a lossy TLE coupled to a cavity mode (CM), and the condition that guarantees the validity of the perturbative treatment in both cases is studied. It is shown that the perturbative treatment in the first case is always valid for a real system. In the second case, nevertheless, the perturbative treatment ignores a coupling term, which can bring effects similar to a phonon bath, e.g., coupling renormalization, off-resonance assisted feeding, and pure dephasing inside the resonance region. All of these effects are important for understanding the experimental observations, including the far-off-resonance cavity fluorescence and the additional CM line inside the resonance region in the strong coupling regime.
Multipartite entangled states in coupled quantum dots and cavity QED
International Nuclear Information System (INIS)
We investigate the generation of multipartite entangled state in a system of N quantum dots embedded in a microcavity and examine the emergence of genuine multipartite entanglement by three different characterizations of entanglement. At certain times of dynamical evolution one can generate multipartite entangled coherent exciton states or multiqubit W states by initially preparing the cavity field in a superposition of coherent states or the Fock state with one photon, respectively. Finally, we study environmental effects on multipartite entanglement generation and find that the decay rate for the entanglement is proportional to the number of excitons
Preparation of the W state via cavity QED
Institute of Scientific and Technical Information of China (English)
ZHANG Jin; YE Liu
2004-01-01
A scheme for preparation of the tripartite W state via cavity quantum electrodynamics is presented in this paper. And the scheme can be generalized to prepare the n-atom W states. The second part of this paper shows how to prepare n-cavity W states. All cavities involved are initially in the vacuum states, thus the requirement on the quality factor of the cavities is greatly loosened.
A simple scheme for generating multi-atom GHZ state via cavity QED
Institute of Scientific and Technical Information of China (English)
Wang Jun; Yu Long-Bao; Ye Liu
2007-01-01
This paper proposes a simple scheme for generating a three-atom GHZ state via cavity quantum electrodynamics (QED). The task can be achieved through the interaction between two EPR states, which can be prepared easily with current technology. In this scheme, the cavity field is only virtually excited during the interaction process, and no quantum information transfer between the atoms and the cavity is required. Thus it greatly prolongs the efficient decoherent time. Moreover, this scheme is also applicable for generating an .N-atom GHZ state.
Teleportation of a two-atom entangled state using a single EPR pair in cavity QED
Institute of Scientific and Technical Information of China (English)
Ji Xin; Li Ke; Zhang Shou
2006-01-01
We propose a scheme for teleporting a two-atom entangled state in cavity quantum electrodynamics(QED).In the scheme,we choose a single Einstein-Podolsky-Rosen (EPR) pair as the quantum channel which is shared by the sender and the receiver.By using the atom-cavity-field interaction and introducing an additional atom,we can teleport the two-atom entangled state successfully with a probability of 1.0.Moreover,we show that the scheme is insensitive to cavity decay and thermal field.
Unified single-photon and single-electron counting statistics: From cavity QED to electron transport
International Nuclear Information System (INIS)
A key ingredient of cavity QED is the coupling between the discrete energy levels of an atom and photons in a single-mode cavity. The addition of periodic ultrashort laser pulses allows one to use such a system as a source of single photons--a vital ingredient in quantum information and optical computing schemes. Here we analyze and time-adjust the photon-counting statistics of such a single-photon source and show that the photon statistics can be described by a simple transport-like nonequilibrium model. We then show that there is a one-to-one correspondence of this model to that of nonequilibrium transport of electrons through a double quantum dot nanostructure, unifying the fields of photon-counting statistics and electron-transport statistics. This correspondence empowers us to adapt several tools previously used for detecting quantum behavior in electron-transport systems (e.g., super-Poissonian shot noise and an extension of the Leggett-Garg inequality) to single-photon-source experiments.
Manipulating nanoscale atom-atom interactions with cavity QED
Pal, Arpita; Deb, Bimalendu
2016-01-01
We theoretically explore manipulation of interactions between excited and ground state atoms at nanoscale separations by cavity quantum electrodynamics (CQED). We develop an adiabatic molecular dressed state formalism and show that it is possible to generate Fano-Feshbach resonances between ground and long-lived excited-state atoms inside a cavity. The resonances are shown to arise due to non-adiabatic coupling near a pseudo-crossing between the dressed state potentials. We illustrate our results with a model study using fermionic $^{171}$Yb atoms in a two-modal cavity. Our study is important for manipulation of interatomic interactions at low energy by cavity field.
Photon Berry phases, Instantons and Schrodinger Cats with oscillating parities in cavity QED
Yi-Xiang, Yu; Liu, W M; Zhang, CunLin
2015-01-01
The four standard quantum optics model in cavity QED such as Rabi, Dicke, Jaynes-Cummings ( JC ) and Tavis-Cummings (TC) model were proposed many decades ago. Despite their relative simple forms and many previous theoretical works, their solutions at a finite $ N $ inside the superradiant regime remain unknown. In view of recent remarkable experimental advances in several experimental systems such as cold atoms inside a cavity or superconducting qubits inside a microcavity to realize these models, it becomes topical and important to understand what would be the new phenomena in these models at a finite $ N $, especially inside the superradaint regime. In this work, we resolved this outstanding problem. We use three independent methods such as $ 1/J $ expansion, the strong coupling expansion and exact diagonization (ED) to study $ U(1)/Z_2 $ Dicke model at a finite $ N $ and different anisotropy parameters $ 0 \\leq \\beta \\leq 1 $ as the atom-photon interaction strength increases. This model include the four st...
Novel High Cooperativity Photon-Magnon Cavity QED
Tobar, Michael; Bourhill, Jeremy; Kostylev, Nikita; G, Maxim; Creedon, Daniel
Novel microwave cavities are presented, which couple photons and magnons in YIG spheres in a super- and ultra-strong way at around 20 mK in temperature. Few/Single photon couplings (or normal mode splitting, 2g) of more than 6 GHz at microwave frequencies are obtained. Types of cavities include multiple post reentrant cavities, which co-couple photons at different frequencies with a coupling greater that the free spectral range, as well as spherical loaded dielectric cavity resonators. In such cavities we show that the bare dielectric properties can be obtained by polarizing all magnon modes to high energy using a 7 Tesla magnet. We also show that at zero-field, collective effects of the spins significantly perturb the photon modes. Other effects like time-reversal symmetry breaking are observed.
Perturbative approach to open circuit QED systems
Li, Andy C. Y.; Petruccione, Francesco; Koch, Jens
2014-03-01
Perturbation theory (PT) is a powerful and commonly used tool in the investigation of closed quantum systems. In the context of open quantum systems, PT based on the Markovian quantum master equation is much less developed. The investigation of open systems mostly relies on exact diagonalization of the Liouville superoperator or quantum trajectories. In this approach, the system size is rather limited by current computational capabilities. Analogous to closed-system PT, we develop a PT suitable for open quantum systems. The proposed method is useful in the analytical understanding of open systems as well as in the numerical calculation of system observables, which would otherwise be impractical. This enables us to investigate a variety of open circuit QED systems, including the open Jaynes-Cummings lattice model.
Probabilistic Teleportation of an Arbitrary Two-Atom State in Cavity QED
International Nuclear Information System (INIS)
We propose a scheme for the teleportation of an arbitrary two-atom state by using two pairs of two-atom nonmaximally entangled states as the quantum channel in cavity QED. It is shown that no matter whether the arbitrary two-atom pure state to be teleported is entangled or not, our teleportation scheme can always be probabilistically realized. The success probability of teleportation is determined by the smaller coefficients of the two initially entangled atom pairs.
Probabilistic Teleportation of an Arbitrary Two-Atom State in Cavity QED
Institute of Scientific and Technical Information of China (English)
LIU Jin-Ming
2007-01-01
We propose a scheme for the teleportation of an arbitrary two-atom state by using two pairs of two-atom nonmaximally entangled states as the quantum channel in cavity QED.It is shown that no matter whether the arbitrary two-atom pure state to be teleported is entangled or not,our teleportation scheme can always be probabilistically realized.The success probability of teleportation is determined by the smaller coefficients of the two initially entangled atom pairs.
Scheme for realizing assisted cloning of an unknown two-atom entangled state via cavity QED
Institute of Scientific and Technical Information of China (English)
Zhan You-Bang
2008-01-01
This paper proposes a scheme where one can realize quantum cloning of an unknown two-atom entangled state with assistance of a state preparer in cavity QED.The first stage of the scheme requires usual teleportation.In the second stage of the scheme,with the assistance of the preparer,the perfect copies of an unknown atomic entangled state can be produced.
Realization of atomic GHZ states via cavity QED
International Nuclear Information System (INIS)
In this work we propose a scheme in which it is possible to generate atomic GHZ states by letting three-level atoms in a lambda configuration to interact with a cavity field followed by a displacement of the cavity field and a selective measurements on two-level atoms which disentangle the atoms and field states. We also propose a GHZ test based on such states. (author)
High flux cold Rubidium atomic beam for strongly coupled Cavity QED
Roy, Basudev
2012-01-01
This paper presents a setup capable of producing a high-flux continuous beam of cold rubidium atoms for cavity QED experiments in the regime of strong coupling. A 2 $D^+$ MOT, loaded by rubidium getters in a dry film coated vapor cell, fed a secondary moving-molasses MOT (MM-MOT) at a rate of 1.5 x $10^{10}$ atoms/sec. The MM-MOT provided a continuous beam with tunable velocity. This beam was then directed through the waist of a 280 $\\mu$m cavity resulting in a Rabi splitting of more than +/- 10 MHz. The presence of sufficient number of atoms in the cavity mode also enabled splitting in the polarization perpendicular to the input. The cavity was in the strong coupling regime, with parameters (g, $\\kappa$, $\\gamma$)/2$\\pi$ equal to (7, 3, 6)/ 2$\\pi$ MHz.
Teleportation of atomic and photonic states in low-Q cavity QED
Peng, Zhao-Hui; Zou, Jian; Liu, Xiao-Juan; Kuang, Le-Man
2012-11-01
We propose two alternative teleportation protocols in low-Q cavity QED. Through the input-output process of photons, we can generate atom-photon entangled states as the quantum channel. Then we propose to teleport single-atom (two-atom entangled) state using coherent photonic states, and to teleport single photonic state with the assistance of three-level atom. The distinct feature of our protocols is that we can teleport both atomic and photonic states via the input-output process of photons in the low-Q cavity. Furthermore, as our protocols work in low-Q cavities and only involve virtual excitation of atoms, they are insensitive to both cavity decay and atomic spontaneous emission, and may be feasible with current technology.
Alternative Scheme for Teleportation of Two-Atom Entangled State in Cavity QED
Institute of Scientific and Technical Information of China (English)
YANG Zhen-Biao
2006-01-01
We have proposed an alternative scheme for teleportation of two-atom entangled state in cavity QED. It is based on the degenerate Raman interaction of a single-mode cavity field with a ∧-type three-level atom. The prominent feature of the scheme is that only one cavity is required, which is prior to the previous one. Moreover, the atoms need to be detected are reduced compared with the previous scheme. The experimental feasibility of the scheme is discussed.The scheme can easily be generalized for teleportation of N-atom GHZ entangled states. The number of the atoms needed to be detected does not increase as the number of the atoms in GHZ state increases.
Implementation of a many-qubit Grover search by cavity QED
Institute of Scientific and Technical Information of China (English)
Fan Hao-Quan; Yang Wan-Li; Huang Xue-Ren; Feng Mang
2009-01-01
We explore the possibility of an N-qubit (N>3) Grover search in cavity QED, based on a fast operation of an N-qubit controlled phase-flip with atoms in resonance with the cavity mode. We demonstrate both analytically and numerically that our scheme can be achieved efficiently to find a marked state with high fidelity and high success probability. As an example, a ten-qubit Grover search is simulated specifically under the discussion of experimental feasibility and challenge. We argue that our scheme is applicable to the case involving an arbitrary number of qubits. As cavity decay is involved in our quantum trajectory treatment, we can analytically understand the implementation of a Grover search subject to dissipation, which will be very helpful for relevant experiments.
From blockade to transparency: controllable photon transmission through a circuit QED system
Liu, Yu-xi; Xu, Xun-Wei; Miranowicz, Adam; Nori, Franco
2012-01-01
A strong photon-photon nonlinear interaction is a necessary condition for photon blockade. Moreover, this nonlinearity can also result a bistable behavior in the cavity field. We analyze the relation between detecting field and photon blockade in a superconducting circuit QED system, and show that photon blockade cannot occur when the detecting field is in the bistable regime. This photon blockade is the microwave-photonics analog of the Coulomb blockade. We further demonstrate that the photo...
Strategies for real-time position control of a single atom in cavity QED
International Nuclear Information System (INIS)
Recent realizations of single-atom trapping and tracking in cavity QED open the door for feedback schemes which actively stabilize the motion of a single atom in real time. We present feedback algorithms for cooling the radial component of motion for a single atom trapped by strong coupling to single-photon fields in an optical cavity. Performance of various algorithms is studied through simulations of single-atom trajectories, with full dynamical and measurement noise included. Closed loop feedback algorithms compare favourably to open loop 'switching' analogues, demonstrating the importance of applying actual position information in real time. The high optical information rate in current experiments enables real-time tracking that approaches the standard quantum limit for broadband position measurements, suggesting that realistic active feedback schemes may reach a regime where measurement backaction appreciably alters the motional dynamics
Realization of a bipolar atomic Solc filter in the cavity-QED microlaser
International Nuclear Information System (INIS)
We report experimental realization of a rudimentary atomic Solc filter, recently proposed by Hong et al. [Opt. Express 17, 15455 (2009)]. It is realized by employing a bipolar atom-cavity coupling constant in the cavity-QED microlaser operating with a TEM10 mode in a strong coupling regime. The polarity flip in the coupling constant dramatically changes the photoemission probability of a two-level atom relative to unipolar coupling, resulting in multiple narrow emission bands in the detuning curve of the microlaser mean photon number. The observed resonance curves are explained well by a two-step, three-dimensional, geodesic-like motion of the Bloch vector in the semiclassical limit.
Two-Frequency Jahn-Teller Systems in Circuit QED
Dereli, Tekin; Müstecaplıoğlu, Özgür E
2011-01-01
We investigate simulating two-frequency (two-mode) jahn-Teller systems in Circuit QED. Our system is composed of two superconducting transmission line resonators interacting with a common flux qubit in the ultrastrong coupling regime. We translate the quantum optical Circuit QED model of the system to an extended two-mode Jahn-Teller Hamiltonian. It is shown that the system can be tuned to an effective single mode Hamiltonian systematically from the two-mode model the varying the coupling strength between the resonators.
Role of the lightmatter coupling strength on nonMarkovian phonon effects in semiconductor cavity QED
DEFF Research Database (Denmark)
Nielsen, Per Kær; Nielsen, Torben Roland; Lodahl, Peter;
2011-01-01
Semiconductor cavity quantum electrodynamical (CQED) devices are believed to be important components for future quantum information technologies. Being composed of a single quantum dot (QD) embedded in a cavity, semiconductor CQED systems resemble atomic CQED systems. However, recent experiments [1...
Transferring of a Two-Mode Entangled State Between Two Cavities via Cavity QED
Institute of Scientific and Technical Information of China (English)
WU Tao; NI Zhi-Xiang; YE Liu
2007-01-01
We propose a scheme for transferring of a two-mode entanglement of zero- or one-photon entangled states between two cavities via atom-cavity field resonant interaction.In our proposal,in order to transfer the entangled state,we only need two identical two-level atoms and a two-mode cavity for receiving the teleported state.This scheme does not require Bell-state measurement and performing any transformations to reconstruct the initial state.And the transfer can occur with 100% success probability in a simple manner.And a network for transferring of a two-mode entangled state between cavities is suggested.This scheme can also be extended to transfer N-mode entangled state of cavity.
Institute of Scientific and Technical Information of China (English)
无
2009-01-01
A scheme is proposed to simulate the Ising model and preserve the maximum entangled states (Bell states) in cavity quantum electrodynamics (QED) driven by a classical field with large detuning. In the strong driving and large-detuning regime, the effective Hamiltonian of the system is the same as the standard Ising model, and the scheme can also make the initial four Bell states of two atoms at the maximum entanglement all the time. So it is a simple memory for the maximal entangled states. The system is insensitive to the cavity decay and the thermal field and more immune to decoherence. These advantages can warrant the experimental feasibility of the current scheme. Furthermore, the genuine four-atom entanglement may be acquired via two Bell states through one-step implementation on four two-level atoms in the strong-driven model, and when two Greenberger-Horne-Zeilinger (GHZ) states are prepared in our scheme, the entangled cluster state may be acquired easily. The success probability for the scheme is 1.
International Nuclear Information System (INIS)
A scheme is proposed for the controlled teleportation of an arbitrary two-atom state via special W-type entangled states and QED cavity. The scheme does not involve the direct joint Bell-state-measurement (BSM). We show that the quantum information is split into two parts, thus the original atomic state cannot be perfectly restored by the receiver without the other agent's collaboration and classical communication. In addition, the physical realization of this scheme is not difficult
Generation of Maximally Entangled States of Two Nonidentical Atoms in Cavity QED
Institute of Scientific and Technical Information of China (English)
LIYu-Liang; ZHOUZheng-Wei; PANGChao-Yang; GUOGuang-Can
2005-01-01
We have discussed the system which consists of two nonidentical two-level atoms trapped simultaneously in a large-detuned single-mode cavity field in this paper. The results show that it is possible to generate maximally entangled states for two nonidentical two-level atoms only if the cavity frequency and difference of two nonidentical atoms transition frequency are selected and the cavity-atom interacation time is controlled.
Photon collection from a trapped ion--cavity system
Sterk, J. D.; Luo, L.; Manning, T. A.; P. Maunz; Monroe, C.
2011-01-01
We present the design and implementation of a trapped ion cavity QED system. A single ytterbium ion is confined by a micron-scale ion trap inside a 2 mm optical cavity. The ion is coherently pumped by near resonant laser light while the cavity output is monitored as a function of pump intensity and cavity detuning. We observe a Purcell enhancement of scattered light into the solid angle subtended by the optical cavity, as well as a three-peak structure arising from strongly driving the atom. ...
Fusion of entangled coherent W and GHZ states in cavity QED
Zang, Xue-Ping; Yang, Ming; Song, Wei; Cao, Zhuo-Liang
2016-07-01
Efficient preparation of W and GHZ states encoded in various degrees of freedom of quantum particles is vital in quantum information science. So far, most of the studies have focused on polarization encoded photonic W and GHZ states. In this paper, we focus on W- and GHZ-class entangled coherent states, and propose schemes to fuse small W- and GHZ-entangled coherent states into larger ones. Based on successive detuned interactions between optical modes and an ancilla atom, an (N + M - 2)-mode entangled coherent W state can be probabilistically prepared from an N-mode and an M-mode entangled coherent W states. This fusion scheme applies to entangled coherent GHZ states too, and it can succeed in a deterministic way. The ancilla atom only interacts with a single optical mode, which avoids the problem of synchronizing many atoms in the previous cavity QED based fusion schemes. The detuning property of the interaction makes the current fusion scheme more feasible that the ones based on resonant atom-light interactions. In addition, the two levels of the ancilla atom for encoding quantum information are two degenerate ground states, and the excited state is adiabatically eliminated during the fusion process, so the atomic decay from excited states does not affect the quality of the fusion process.
BRAVO for many-server QED systems with finite buffers
Daley, DJ; Leeuwaarden, van, JSH Johan; Nazarathy, Y Yoni
2015-01-01
This paper demonstrates the occurrence of the feature called BRAVO (balancing reduces asymptotic variance of output) for the departure process of a finite-buffer Markovian many-server system in the QED (quality and efficiency-driven) heavy-traffic regime. The results are based on evaluating the limit of an equation for the asymptotic variance of death counts in finite birth-death processes.
Enhancements to cavity quantum electrodynamics system
Cimmarusti, A D; Norris, D G; Orozco, L A
2011-01-01
We show the planned upgrade of a cavity QED experimental apparatus. The system consists of an optical cavity and an ensemble of ultracold $^{85}$Rb atoms coupled to its mode. We propose enhancements to both. First, we document the building process for a new cavity, with a planned finesse of $\\sim$20000. We address problems of maintaining mirror integrity during mounting and improving vibration isolation. Second, we propose improvements to the cold atom source in order to achieve better optical pumping and control over the flux of atoms. We consider a 2-D optical molasses for atomic beam deflection, and show computer simulation results for evaluating the design. We also examine the possibility of all-optical atomic beam focusing, but find that it requires unreasonable experimental parameters.
Two-frequency Jahn-Teller systems in circuit QED
Dereli, Tekin; Gül, Yusuf; Müstecaplıoğlu, Özgür E.; Forn-Diaz, Pol
2012-01-01
PHYSICAL REVIEW A 85, 053841 (2012) Two-frequency Jahn-Teller systems in circuit QED Tekin Dereli,1 Yusuf Gu¨l,1 Pol Forn-D´ıaz,2 and O¨ zgu¨r E. Mu¨stecaplıog˘lu1,* 1Department of Physics, Koc¸ University, Sarıyer, Istanbul, 34450, Turkey 2Norman Bridge Laboratory of Physics, California Institute of Technology, Pasadena, CA 91125, USA (Received 6 September 2011; published 30 May 2012) We investigate the simulation of Jahn-Teller models with two nondegenerate vibrational mod...
QED of lossy cavities: Operator and quantum-state input-output relations
International Nuclear Information System (INIS)
Within the framework of exact quantization of the electromagnetic field in dispersing and absorbing media the input-output problem of a high-Q cavity is studied, with special emphasis on the absorption losses in the coupling mirror. As expected, the cavity modes are found to obey quantum Langevin equations, which could be also obtained from quantum noise theories, by appropriately coupling the cavity modes to dissipative systems, including the effect of the mirror-assisted absorption losses. On the contrary, the operator input-output relations obtained in this way would be incomplete in general, as the exact calculation shows. On the basis of the operator input-output relations the problem of extracting the quantum state of an initially excited cavity mode is studied and input-output relations for the s-parametrized phase-space function are derived, with special emphasis on the relation between the Wigner functions of the quantum states of the outgoing field and the cavity field
Broadband Waveguide QED System on a Chip
Quan, Qimin; Bulu, Irfan; Loncar, Marko
2009-01-01
We demonstrate that a slot waveguide provides a broadband loss-free platform suitable for applications in quantum optics. We find that strong coupling between light quanta and a single quantum emitter placed in the waveguide slot can be achieved with efficiency higher than 96% and Purcell factor (spontaneous emission factor) larger than 200. The proposed system is a promising platform for quantum information processing and can be used to realize an efficient single photon source and optically...
Generation of multipartite entangled states for chains of atoms in the framework of cavity-QED
International Nuclear Information System (INIS)
Cavity quantum electrodynamics is a research field that studies electromagnetic fields in confined spaces and the radiative properties of atoms in such fields. Experimentally, the simplest example of such system is a single atom interacting with modes of a high-finesse resonator. Theoretically, such system bears an excellent framework for quantum information processing in which atoms and light are interpreted as bits of quantum information and their mutual interaction provides a controllable entanglement mechanism. In this thesis, we present several practical schemes for generation of multipartite entangled states for chains of atoms which pass through one or more high-finesse resonators. In the first step, we propose two schemes for generation of one- and two-dimensional cluster states of arbitrary size. These schemes are based on the resonant interaction of a chain of Rydberg atoms with one or more microwave cavities. In the second step, we propose a scheme for generation of multipartite W states. This scheme is based on the off-resonant interaction of a chain of three-level atoms with an optical cavity and a laser beam. We describe in details all the individual steps which are required to realize the proposed schemes and, moreover, we discuss several techniques to reveal the non-classical correlations associated with generated small-sized entangled states. (orig.)
Generation of multipartite entangled states for chains of atoms in the framework of cavity-QED
Energy Technology Data Exchange (ETDEWEB)
Gonta, Denis
2010-07-07
Cavity quantum electrodynamics is a research field that studies electromagnetic fields in confined spaces and the radiative properties of atoms in such fields. Experimentally, the simplest example of such system is a single atom interacting with modes of a high-finesse resonator. Theoretically, such system bears an excellent framework for quantum information processing in which atoms and light are interpreted as bits of quantum information and their mutual interaction provides a controllable entanglement mechanism. In this thesis, we present several practical schemes for generation of multipartite entangled states for chains of atoms which pass through one or more high-finesse resonators. In the first step, we propose two schemes for generation of one- and two-dimensional cluster states of arbitrary size. These schemes are based on the resonant interaction of a chain of Rydberg atoms with one or more microwave cavities. In the second step, we propose a scheme for generation of multipartite W states. This scheme is based on the off-resonant interaction of a chain of three-level atoms with an optical cavity and a laser beam. We describe in details all the individual steps which are required to realize the proposed schemes and, moreover, we discuss several techniques to reveal the non-classical correlations associated with generated small-sized entangled states. (orig.)
On superradiant phase transitions and effective models in circuit QED
International Nuclear Information System (INIS)
Circuit QED systems of artificial atoms interacting with microwaves have been proved to behave in many respects analogously to their counterparts with real atoms in cavity QED. However, it has been predicted recently that the analogy fails if a large number of (artificial) atoms couple strongly to the electromagnetic radiation: Whereas for real atoms a no-go theorem rules out the possibility of a superradiant quantum phase transition as the coupling is increased, the standard description of circuit QED systems by an effective model based on macroscopic quantities does allow it. We investigate the possibility of a superradiant quantum phase transition in circuit QED systems from a microscopic point of view. Our analysis shows that also circuit QED systems are subject to the no-go theorem. It hence restores the analogy of circuit QED and cavity QED and challenges the applicability of the standard description of circuit QED systems in the regime under concern. In the light of this analysis, the no-go theorem is scrutinized and confirmed in a way more adequate for realistic physical systems.
Enhancing Quantum Discord in Cavity QED by Applying Classical Driving Field
Institute of Scientific and Technical Information of China (English)
QIAN Yi; XU Jing-Bo
2012-01-01
We investigate the quantum discord dynamics in a cavity quantum electrodynamics system, which consists of two noninteracting two-level atoms driven by independent optical Gelds and classical fields, and find that the quantum discord vanishes only asymptotically although entanglement disappears suddenly during the time evolution in the absence of classical fields. It is shown that the amount of quantum discord can be increased by adjusting the classical driving fields because the increasing degree of the amount of quantum mutual information is greater than classical correlation by applying the classical driving fields. Finally, the influence of the classical driving field on the fidelity of the system is also examined.%We investigate the quantum discord dynamics in a cavity quantum electrodynamics system,which consists of two noninteracting two-level atoms driven by independent optical fields and classical fields,and find that the quantum discord vanishes only asymptotically although entanglement disappears suddenly during the time evolution in the absence of classical fields.It is shown that the amount of quantum discord can be increased by adjusting the classical driving fields because the increasing degree of the amount of quantum mutual information is greater than classical correlation by applying the classical driving fields.Finally,the influence of the classical driving field on the fidelity of the system is also examined.
Quantum Dot Cavity-QED in the Presence of Strong Electron-Phonon Interactions
Wilson-Rae, I
2001-01-01
A quantum dot strongly coupled to a single high finesse optical microcavity mode constitutes a new fundamental system for quantum optics. Here, the effect of exciton-phonon interactions on reversible quantum-dot cavity coupling is analysed without making Born-Markov approximation. The analysis is based on techniques that have been used to study the ``spin boson'' Hamiltonian. Observability of vacuum-Rabi splitting depends on the strength and the frequency dependence of the spectral density function characterizing the interactions with phonons, both of which can be influenced by phonon confinement.
Photon-photon interaction in strong-coupling cavity-atom system
Energy Technology Data Exchange (ETDEWEB)
Yang, Jian; Kwiat, Paul G. [Department of Physics, University of Illinois at Urbana-Champaign (United States)
2014-12-04
We study photon-photon interactions mediated by a cavity-atom system in the strongcoupling regime of cavity quantum electrodynamics (QED). Different temporal shapes of the incident photons have been explored via numerical calculations. Especially, time-reversed photons can be in the cavity simultaneously and potentially acquire strong interaction with each other, advancing quantum information applications, e.g., quantum non-demolition (QND) measurement.
High-Q submicron-diameter quantum-dot microcavity pillars for cavity QED experiments
DEFF Research Database (Denmark)
Gregersen, Niels; Lermer, Matthias; Dunzer, Florian;
As/AlAs micropillar design where Bloch-wave engineering is employed to significally enhance the cavity mode confinement in the submicron diameter regime. We demonstrate a record-high vacuum Rabi splitting of 85 µeV of the strong coupling for pillars incorporating quantum dots with modest oscillator strength f ≈ 10....... It is well-known that light-matter interaction depends on the photonic environment, and thus proper engineering of the optical mode in microcavity systems is central to obtaining the desired functionality. In the strong coupling regime, the visibility of the Rabi splitting is described by the light...... coupling in micropillars relied on quantum dots with high oscillator strengths f > 50, our advanced design allows for the observation of strong coupling for submicron diameter quantum dot-pillars with standard f ≈ 10 oscillator strength. A quality factor of 13600 and a vacuum Rabi splitting of 85 µeV are...
Meissner-like effect for synthetic gauge field in multimode cavity QED
Ballantine, Kyle E; Keeling, Jonathan
2016-01-01
Previous realizations of synthetic gauge fields for ultracold atoms do not allow the spatial profile of the field to evolve freely. We propose a scheme which overcomes this restriction by using the light in a multimode cavity, in conjunction with Raman coupling, to realize an artificial magnetic field which acts on a Bose-Einstein condensate of neutral atoms. We describe the evolution of such a system, and present the results of numerical simulations which show dynamical coupling between the effective field and the matter on which it acts. Crucially, the freedom of the spatial profile of the field is sufficient to realize a close analogue of the Meissner effect, where the magnetic field is expelled from the superfluid. This back-action of the atoms on the synthetic field distinguishes the Meissner-like effect described here from the Hess-Fairbank suppression of rotation in a neutral superfluid observed elsewhere.
Atoms and Molecules in Cavities: From Weak to Strong Coupling in QED Chemistry
Flick, Johannes; Appel, Heiko; Rubio, Angel
2016-01-01
In this work, we provide an overview of how well-established concepts in the fields of quantum chemistry and material sciences have to be adapted when the quantum nature of light becomes important in correlated matter-photon problems. Therefore, we analyze model systems in optical cavities, where the matter-photon interaction is considered from the weak- to the strong coupling limit and for individual photon modes as well as for the multi-mode case. We identify fundamental changes in Born-Oppenheimer surfaces, spectroscopic quantities, conical intersections and efficiency for quantum control. We conclude by applying our novel recently developed quantum-electrodynamical density-functional theory to single-photon emission and show how a straightforward approximation accurately describes the correlated electron-photon dynamics. This paves the road to describe matter-photon interactions from first-principles and addresses the emergence of new states of matter in chemistry and material science.
Guerra, E S
2004-01-01
In this article we discuss two schemes of teleportation of atomic states. In the first scheme we consider atoms in a three-level cascade configuration and in the second scheme we consider atoms in a three-level lambda configuration. The experimental realization proposed makes use of cavity Quatum Electrodynamics involving the interaction of Rydberg atoms with a micromaser cavity prepared in a state $|\\psi >_{C}=(|0> +|1>)/\\sqrt{2}$
Institute of Scientific and Technical Information of China (English)
Wu Xi; Chen Zhi-Hua; Zhang Yong; Chen Yue-Hua; Ye Ming-Yong; Lin Xiu-Min
2011-01-01
Schemes are presented for realizing quantum controlled phase gate and preparing an N-qubit W-like state, which are based on the large-detuned interaction among three-state atoms, dual-mode cavity and a classical pulse. In particular, a class of W states that can be used for perfect teleportation and superdense coding is generated by only one step.Compared with the previous schemes, cavity decay is largely suppressed because the cavity is only virtually excited and always in the vacuum state and the atomic spontaneous emission is strongly restrained due to a large atom-field detuning.
Implementation of n-qubit Deutsch-Jozsa algorithm using resonant interaction in cavity QED
Institute of Scientific and Technical Information of China (English)
Wang Hong-Fu; Zhang Shou
2008-01-01
We propose a scheme to implement the n-qubit Deutsch-Jozsa algorithm based on resonant interaction between the atoms and a single-mode cavity. In the scheme, the resonant transitions between two ground states and one excited state of an atom are changed alternately by adjusting the cavity frequency appropriately, and the operations required to complete the algorithm can be significantly simplified following the increment of the number of qubits. The implementation of the scheme in experiment would show the full power of quantum algorithm and would be significative and important for more complicated quantum algorithm in cavity quantum electrodynamics.
Generation of four-particle GHZ states in bimodal cavity QED
Institute of Scientific and Technical Information of China (English)
Yang Zhen-Biao
2007-01-01
We propose a scheme for preparing four-particle Greenberger-Horne-Zeilinger states using two identical bimodal cavities, each supports two modes with different frequencies. This scheme is an alternative to another published work[Christopher C Gerry 1996 Phys. Rev. A 53 4591]. Comparisons between them are discussed. The fidelity and the probability of success influenced by cavity decay for the generated states are also considered.
Continuous Pump Assisted Conditional Synthesis of Nonclassical States in a Dispersive Cavity QED
Institute of Scientific and Technical Information of China (English)
GUOJian-Hong
2003-01-01
The interaction of N identical atoms with both a quantized cavity field and an external classical pumping field with the fields being degenerate in frequency, is studied in the regime where the atoms and fields are highly detuned. This dispersive interaction can be used to generate coherent states for the cavity field. By preparing the injected atoms in a superposition of the bare atomic states, various types of Schroedinger-cat-like states may be generated.
Continuous Pump Assisted Conditional Synthesis of Nonclassical States in a Dispersive Cavity QED
Institute of Scientific and Technical Information of China (English)
GUO Jian-Hong
2003-01-01
The interaction of N identical atoms with both a quantized cavity field and an external classical pumpingfield with the fields being degenerate in frequency, is studied in the regime where the atoms and fields are highly detuned.This dispersive interaction can be used to generate coherent states for the cavity field. By preparing the injected atomsin a superposition of the bare atomic states, various types of Schrodinger-cat-like states may be generated.
High-flux cold rubidium atomic beam for strongly-coupled cavity QED
International Nuclear Information System (INIS)
This paper presents a setup capable of producing a high-flux continuous beam of cold rubidium atoms for cavity quantum electrodynamics experiments in the region of strong coupling. A 2D+ magneto-optical trap (MOT), loaded with rubidium getters in a dry-film-coated vapor cell, fed a secondary moving-molasses MOT (MM-MOT) at a rate greater than 2 x 1010 atoms/s. The MM-MOT provided a continuous beam with a tunable velocity. This beam was then directed through the waist of a cavity with a length of 280 μm, resulting in a vacuum Rabi splitting of more than ±10 MHz. The presence of a sufficient number of atoms in the cavity mode also enabled splitting in the polarization perpendicular to the input. The cavity was in the strong coupling region, with an atom-photon dipole coupling coefficient g of 7 MHz, a cavity mode decay rate κ of 3 MHz, and a spontaneous emission decay rate γ of 6 MHz.
High-flux cold rubidium atomic beam for strongly-coupled cavity QED
Energy Technology Data Exchange (ETDEWEB)
Roy, Basudev [Indian Institute of Science Education and Research, Kolkata (India); University of Maryland, MD (United States); Scholten, Michael [University of Maryland, MD (United States)
2012-08-15
This paper presents a setup capable of producing a high-flux continuous beam of cold rubidium atoms for cavity quantum electrodynamics experiments in the region of strong coupling. A 2D{sup +} magneto-optical trap (MOT), loaded with rubidium getters in a dry-film-coated vapor cell, fed a secondary moving-molasses MOT (MM-MOT) at a rate greater than 2 x 10{sup 10} atoms/s. The MM-MOT provided a continuous beam with a tunable velocity. This beam was then directed through the waist of a cavity with a length of 280 μm, resulting in a vacuum Rabi splitting of more than ±10 MHz. The presence of a sufficient number of atoms in the cavity mode also enabled splitting in the polarization perpendicular to the input. The cavity was in the strong coupling region, with an atom-photon dipole coupling coefficient g of 7 MHz, a cavity mode decay rate κ of 3 MHz, and a spontaneous emission decay rate γ of 6 MHz.
Quantum state engineering and reconstruction in cavity QED. An analytical approach
Energy Technology Data Exchange (ETDEWEB)
Lougovski, P.
2004-09-25
The models of a strongly-driven micromaser and a one-atom laser are developed. Their analytical solutions are obtained by means of phase space techniques. It is shown how to exploit the model of a one-atom laser for simultaneous generation and monitoring of the decoherence of the atom-field ''Schroedinger cat'' states. The similar machinery applied to the problem of the generation of the maximally-entangled states of two atoms placed inside an optical cavity permits its analytical solution. The steady-state solution of the problem exhibits a structure in which the two-atom maximally-entangled state correlates with the vacuum state of the cavity. As a consequence, it is demonstrated that the atomic maximally-entangled state, depending on a coupling regime, can be produced via a single or a sequence of no-photon measurements. The question of the implementation of a quantum memory device using a dispersive interaction between the collective internal ground state of an atomic ensemble and two orthogonal modes of a cavity is addressed. The problem of quantum state reconstruction in the context of cavity quantum electrodynamics is considered. The optimal operational definition of the Wigner function of a cavity field is worked out. It is based on the Fresnel transform of the atomic inversion of a probe atom. The general integral transformation for the Wigner function reconstruction of a particle in an arbitrary symmetric potential is derived.
Cavity QED Experiments with Ion Coulomb Crystals. Towards quantum memories and photon counters
International Nuclear Information System (INIS)
Trapped and laser cooled atomic ions in the form of Coulomb crystals represent interesting objects for investigation of Cavity Quantum ElectroDynamics (CQED) and related phenomena. First of all, the number and density of atoms in such crystals as well as the shapes of the crystals can relatively easily be controlled. Second, the ion-ion Coulomb repulsion results in an essentially collision-free environment with the prospect of long coherence times. These properties were recently exploited in experiments focused on investigations of the collective coupling of cold ion ensembles to light modes of a Fabry-Perot cavity, as well as in demonstration of cavity Electromagnetically induced Transparency (EIT) and a photon blockade mechanism. The next step of these experiments will be to realize a light storage scheme, partly for demonstrating an efficient photon counting device and partly for eventually establishing a quantum memory for light with both high efficiency and fidelity. (author)
DEFF Research Database (Denmark)
Nielsen, Per Kær; Nielsen, Torben Roland; Lodahl, P.;
2012-01-01
dependencies are covered. We find that in general the electron-phonon interaction gives rise to a greatly increased bandwidth of the coupling between quantum dot and cavity. At low temperature, an asymmetry in the quantum dot decay rate is observed, leading to a faster decay when the quantum dot has a larger...
Influence of the Stark Shift on Entanglement Sudden Death and Birth in Cavity QED
Institute of Scientific and Technical Information of China (English)
ZHANG Jian-Song; CHEN Ai-Xi; WU Kun-Hua
2011-01-01
We investigate the entanglement dynamics of two two-level atoms interacting with two vacuum fields of two spatially separated cavities with the Stark effects by employing the concurrence. It is shown that the entanglement sudden death (ESD) and birth (ESB) could be controlled by adjusting the Stark-shift parameters. If the Stark-shift parameters are chosen appropriately, then ESD and ESB phenomena will appear. In addition, the appearance of ESD before or after ESB depends on the Stark-shift values.
Quantum state engineering and reconstruction in cavity QED: An analytical approach
Lougovski, Pavel
2004-01-01
The models of a strongly-driven micromaser and a one-atom laser are developed. Their analytical solutions are obtained by means of phase space techniques. It is shown how to exploit the model of a one-atom laser for simultaneous generation and monitoring of the decoherence of the atom-field "Schrödinger cat" states. The similar machinery applied to the problem of the generation of the maximally-entangled states of two atoms placed inside an optical cavity permits its analytical solution. The ...
Institute of Scientific and Technical Information of China (English)
GUO Jian-Hong
2004-01-01
The interaction of N two-level atoms with both a two-mode cavity field and an external classical pumping field, and with the fields being degenerate in frequency, is studied in the regime where the atoms and fields are highly detuned. This dispersive interaction can be used to generate a large number of important entangled coherent states conditional on the initial atomic states and state-selective measurements. A dynamical relation is established between the results for the case with continuous pumping and the case without external driving where the coherent field is put in as the initial condition.
Macroscopic Quantum Criticality in a Circuit QED
Wang, Y D; Nori, F; Quan, H T; Sun, C P; Liu, Yu-xi; Nori, Franco
2006-01-01
Cavity quantum electrodynamic (QED) is studied for two strongly-coupled charge qubits interacting with a single-mode quantized field, which is provided by a on-chip transmission line resonator. We analyze the dressed state structure of this superconducting circuit QED system and the selection rules of electromagnetic-induced transitions between any two of these dressed states. Its macroscopic quantum criticality, in the form of ground state level crossing, is also analyzed, resulting from competition between the Ising-type inter-qubit coupling and the controllable on-site potentials.
International Nuclear Information System (INIS)
We propose a way for generating n-qubit Greenberger-Horne-Zeilinger (GHZ) entangled states with a three-level qubit system and (n-1) four-level qubit systems in a cavity. This proposal does not require identical qubit-cavity coupling constants and thus is tolerant to qubit-system parameter nonuniformity and nonexact placement of qubits in a cavity. The proposal does not require adjustment of the qubit-system level spacings during the entire operation. Moreover, it is shown that entanglement can be deterministically generated using this method and the operation time is independent of the number of qubits. The present proposal is quite general, which can be applied to physical systems such as various types of superconducting devices coupled to a resonator or atoms trapped in a cavity.
From strong to ultrastrong coupling in circuit QED architectures
International Nuclear Information System (INIS)
The field of cavity quantum electrodynamics (cavity QED) studies the interaction between light and matter on a fundamental level: a single atom interacts with a single photon. If the atom-photon coupling is larger than any dissipative effects, the system enters the strong-coupling limit. A peculiarity of this regime is the possibility to form coherent superpositions of light and matter excitations - a kind of 'molecule' consisting of an atomic and a photonic contribution. The novel research field of circuit QED extends cavity QED concepts to solid-state based system. Here, a superconducting quantum bit is coupled to an on-chip superconducting one-dimensional waveguide resonator. Owing to the small mode-volume of the resonant cavity, the large dipole moment of the 'artificial atom' and the enormous engineering potential inherent to superconducting quantum circuits, remarkable atom-photon coupling strengths can be realized. This thesis describes the theoretical framework, the development of fabrication techniques and the implementation of experimental characterization techniques for superconducting quantum circuits for circuit QED applications. In particular, we study the interaction between superconducting flux quantum bits and high-quality coplanar waveguide resonators in the strong-coupling limit. Furthermore, we report on the first experimental realization of a circuit QED system operating in the ultrastrong-coupling regime, where the atom-photon coupling rate reaches a considerable fraction of the relevant system frequencies. In these experiments we could observe phenomena that can not be explained within the renowned Jaynes-Cummings model. (orig.)
General QED/QCD aspects of simple systems
International Nuclear Information System (INIS)
This paper discusses the following topics: renormalization theory; the Kinoshita-Lee-Nauenberg theorem; the Yennie-Frautschi-Suura relation; scale invariance at large momentum transfer; scaling and scaling violation at large momentum transfers; low-energy theorem in Compton scattering; does the perturbation series in QED converge; renormalization of the weak angle Θw; the Nambu-Bethe-Salpeter (NBS) equation; the decay rate of 3S, positronium; radiative corrections to QCD Born cross section; and progress on the relativistic 2-body equation
Coto, Raul; Orszag, Miguel
2014-05-01
Multipartite quantum correlation is one of the most relevant indicators of the quantumness of a system in many body systems. This remarkable feature is in general difficult to characterize and the known definitions are hard to measure. Besides the efforts dedicated to solve this problem, the question of which is the best approach remains open. In this paper, we study the global quantum discord (GQD) as a bipartite and multipartite measure. We also check the limits of this definition and present an experimental scheme to determine the maximum of the GQD via the measurements of the system’s excitations, during the time evolution of the present system.
Controlling entanglement sudden death in cavity QED by classical driving fields
Zhang, Jian-Song; Xu, Jing-Bo; Lin, Qiang
2008-01-01
We investigate the entanglement dynamics of a quantum system consisting of two-level atoms interacting with vacuum or thermal fields with classical driving fields. We find that the entanglement of the system can be improved by adjusting the classical driving field. The influence of the classical field and the purity of the initial state on the entanglement sudden death is also studied. It is shown that the time of entanglement sudden death can be controlled by the classical driving fields. Pa...
Quantum optics and cavity QED Quantum network with individual atoms and photons
Directory of Open Access Journals (Sweden)
Rempe G.
2013-08-01
Full Text Available Quantum physics allows a new approach to information processing. A grand challenge is the realization of a quantum network for long-distance quantum communication and large-scale quantum simulation. This paper highlights a first implementation of an elementary quantum network with two fibre-linked high-finesse optical resonators, each containing a single quasi-permanently trapped atom as a stationary quantum node. Reversible quantum state transfer between the two atoms and entanglement of the two atoms are achieved by the controlled exchange of a time-symmetric single photon. This approach to quantum networking is efficient and offers a clear perspective for scalability. It allows for arbitrary topologies and features controlled connectivity as well as, in principle, infinite-range interactions. Our system constitutes the largest man-made material quantum system to date and is an ideal test bed for fundamental investigations, e.g. quantum non-locality.
Pfaffian states in coupled atom-cavity systems
Hayward, Andrew L. C.; Martin, Andrew M.
2016-05-01
Coupled atom-cavity arrays, such as those described by the Jaynes-Cummings-Hubbard model, have the potential to emulate a wide range of condensed-matter phenomena. In particular, the strongly correlated states of the fractional quantum Hall effect can be realized. At some filling fractions, the fraction quantum Hall effect has been shown to possess ground states with non-Abelian excitations. The most well studied of these states is the Pfaffian state of Moore and Read G. Moore and N. Read, Nucl. Phys. B 360, 362 (1991), 10.1016/0550-3213(91)90407-O, which is the ground state of a Hall liquid with a three-body interaction. We show how an effective three-body interaction can be generated within the cavity QED framework, and that a Pfaffian-like ground state of these systems exists.
Photon transport in a one-dimensional nanophotonic waveguide QED system
Liao, Zeyang; Zeng, Xiaodong; Nha, Hyunchul; Zubairy, M. Suhail
2016-06-01
The waveguide quantum electrodynamics (QED) system may have important applications in quantum device and quantum information technology. In this article we review the methods being proposed to calculate photon transport in a one-dimensional (1D) waveguide coupled to quantum emitters. We first introduce the Bethe ansatz approach and the input–output formalism to calculate the stationary results of a single photon transport. Then we present a dynamical time-dependent theory to calculate the real-time evolution of the waveguide QED system. In the longtime limit, both the stationary theory and the dynamical calculation give the same results. Finally, we also briefly discuss the calculations of the multiphoton transport problems.
One-step multi-qubit GHZ state generation in a circuit QED system
Wang, Ying-Dan; Loss, Daniel; Bruder, Christoph
2009-01-01
We propose a one-step scheme to generate GHZ states for superconducting flux qubits or charge qubits in a circuit QED setup. The GHZ state can be produced within the coherence time of the multi-qubit system. Our scheme is independent of the initial state of the transmission line resonator and works in the presence of higher harmonic modes. Our analysis also shows that the scheme is robust to various operation errors and environmental noise.
Energy Technology Data Exchange (ETDEWEB)
Dong, Dong; Zhang, Yan-Lei; Zou, Chang-Ling, E-mail: clzou321@ustc.edu.cn; Zou, Xu-Bo, E-mail: xbz@ustc.edu.cn; Guo, Guang-Can
2015-10-09
We propose an experimental feasible scheme for implementing two-qubit quantum phase gate with atoms trapped in an optical cavity. The scheme is based on the dispersive interaction between the optical cavity mode and the three-level atoms in Λ configuration, which has been demonstrated in recent cavity-induced spin squeezing experiment (Leroux et al., 2010) [26]. We also discuss the influence of the cavity decay on the gate fidelity. It is shown that the fidelity of the phase gate is robust to the cavity decay and the high-fidelity quantum phase gate can be implemented with the current experimental technology. - Highlights: • A experimental feasible scheme for implementing two-qubit quantum phase gate. • Based on the dispersive interaction between the optical cavity mode and the symmetrically configurated three-level atoms. • Influence of the cavity decay on the gate fidelity is discussed.
From strong to ultrastrong coupling in circuit QED architectures
Energy Technology Data Exchange (ETDEWEB)
Niemczyk, Thomas
2011-08-10
The field of cavity quantum electrodynamics (cavity QED) studies the interaction between light and matter on a fundamental level: a single atom interacts with a single photon. If the atom-photon coupling is larger than any dissipative effects, the system enters the strong-coupling limit. A peculiarity of this regime is the possibility to form coherent superpositions of light and matter excitations - a kind of 'molecule' consisting of an atomic and a photonic contribution. The novel research field of circuit QED extends cavity QED concepts to solid-state based system. Here, a superconducting quantum bit is coupled to an on-chip superconducting one-dimensional waveguide resonator. Owing to the small mode-volume of the resonant cavity, the large dipole moment of the 'artificial atom' and the enormous engineering potential inherent to superconducting quantum circuits, remarkable atom-photon coupling strengths can be realized. This thesis describes the theoretical framework, the development of fabrication techniques and the implementation of experimental characterization techniques for superconducting quantum circuits for circuit QED applications. In particular, we study the interaction between superconducting flux quantum bits and high-quality coplanar waveguide resonators in the strong-coupling limit. Furthermore, we report on the first experimental realization of a circuit QED system operating in the ultrastrong-coupling regime, where the atom-photon coupling rate reaches a considerable fraction of the relevant system frequencies. In these experiments we could observe phenomena that can not be explained within the renowned Jaynes-Cummings model. (orig.)
High-Q AlAs/GaAs adiabatic micropillar cavities with submicron diameters for cQED experiments
DEFF Research Database (Denmark)
Lermer, M.; Gregersen, Niels; Dunzer, F.; Mørk, Jesper; Reitzenstein, S.; Höfling, S.; Kamp, M.; Forchel, A.
microcavity design [1, 2]. To overcome the trade-off between high Q and low Vmode, we designed and implemented a novel adiabatic AlAs/GaAs cavity design (MC1) with 3 taper segments (Fig. 1 (a)) as it was suggested by Zhang et al. for SiO2/TiO2 micropillar cavities [3]. Comparative measurements of the Q factor...
International Nuclear Information System (INIS)
We propose a scheme to realize the optimal economical 1->2 phase-covariant quantum cloning machine (QCM) in 2 dimension with superconducting quantum interference device (SQUID) qubits in a microwave cavity. In our scheme, two-SQUID qubits are fixed into a microwave cavity by adiabatic passage method for their manipulation. Using this method, we can realize the optimal phase-covariant QCM only by one step
RF cavity vacuum interlock system
Jordan, K.; Crawford, K.; Bundy, R.; Dylla, H. F.; Heckman, J.; Marshall, J.; Nichols, R.; Osullivan, S.; Preble, J.; Robb, J.
1992-03-01
The Continuous Electron Beam Accelerator Facility (CEBAF), a continuous wave (CW) 4 GeV Electron Accelerator is undergoing construction in Newport News, Virginia. When completed in 1994, the accelerator will be the largest installation of radio-frequency superconductivity. Production of cryomodules, the fundamental building block of the machine, has started. A cryomodule consists of four sets of pairs of 1497 MHz, 5 cell niobium cavities contained in separate helium vessels and mounted in a cryostat with appropriate end caps for helium supply and return. Beam vacuum of the cavities, the connecting beam piping, the waveguides, and the cryostat insulating vacuum are crucial to the performance of the machine. The design and initial experience of the vacuum systems for the first 2 1/4 cryomodules that makeup the 45 MEV injector are discussed.
PREFACE: Heavy-Ion Spectroscopy and QED Effects in Atomic Systems
Lindgren, Ingvar; Martinson, Indrek; Schuch, Reinhold
1993-01-01
Experimental studies of heavy and highly charged ions have made remarkable progress in recent years. Today it is possible to produce virtually any ion up to hydrogen-like uranium; to study collisions of those ions with atoms, electrons, and solid surfaces; to excite such an ion and accurately measure the radiation emitted. This progress is largely due to the development of new experimental methods, for instance, the high-energy ion accelerators, laser-produced plasmas, advanced ion sources and ion traps (such as EBIS, EBIT, ECR, etc.), high temperature magnetically confined plasmas and heavy-ion storage rings. The motivations for studies of collisions with highly charged ions and for the understanding of the structure of heavy atomic systems are multi-faceted. Besides of the basic scientific aspects which are mainly the subject of this symposium, much incentive is experienced by applications, e.g., the interpretation of spectra from space (solar corona, solar flares and hot stars), the modelling of stellar atmospheres, the diagnostics of fusion plasma impurities, and the development of X-ray lasers. Since quite some time highly charged ions play a key role for high-precision metrology of atomic structure. These studies have been benchmarks for tests of advanced theories, including many-body theories of interelectronic correlations, relativistic and quantum-electrodynamic (QED) effects, effects due to the finite size of the nucleus and to parity non-conservation (PNC). The interest in QED effects in heavy ions has increased drastically in the last few years. The remarkable experiment on Li-like uranium, recently reported from Berkeley, has stimulated several groups to perform very accurate Lamb-shift calculations on such systems, and reports from three groups were given about such work. The agreement between the calculations as well as with experiment was generally very good, which implies that the problem of evaluating the first-order Lamb shift for any element is
The QED engine system: Direct-electric fusion-powered rocket propulsion systems
International Nuclear Information System (INIS)
Practical ground-to-orbit and inter-orbital space flights both require propulsion systems of large flight-path-averaged specific impulse (Isp) and engine system thrust-to-mass-ratio (F/me=[F]) for useful payload and structure fractions in single-stage vehicles (Hunter 1966). Current rocket and air-breathing engine technologies lead to enormous vehicles and small payloads; a natural result of the limited specific energy available from chemical reactions. While nuclear energy far exceeds these specific energy limits (Bussard and DeLauer 1958), the inherent high-Isp advantages of fission propulsion concepts for space and air-breathing flight (Bussard and DeLauer 1965) are negated for manned systems by the massive radiation shielding required by their high radiation output (Bussard 1971). However, there are well-known radiation-free nuclear fusion reactions (Gross 1984) between isotopes of selected light elements (such as H+11B, D+3He) that yield only energetic charged particles, whose energy can be converted directly into electricity by confining electric fields (Moir and Barr 1973,1983). New confinement concepts using magnetic-electric-potentials (Bussard 1989a) or inertial-collisional-compression (ICC) (Bussard 1990) have been found that offer the prospect of clean, compact fusion systems with very high output and low mass. Their radiation-free d.c. electrical output can power unique new electron-beam-driven thrust systems of extremely high performance. Parametric design studies show that such charged-particle electric-discharge engines (''QED'' engines) might yield rocket propulsion systems with performance in the ranges of 2sp<5500 sec
International Nuclear Information System (INIS)
Full text: We perform the stochastic quantization of scalar as well as of fermionic QED based on a generalization of the stochastic gauge fixing scheme and its geometrical interpretation. It is shown that the stochastic quantization scheme agrees exactly with the usual path integral formulation. (author)
Von starker zu ultrastarker Kopplung in Schaltkreis QED Architekturen
Niemczyk, Thomas
2011-01-01
Das Forschungsgebiet der Hohlraum-Quantenelektrodynamik (cavity QED) untersucht die Wechselwirkung zwischen Licht und Materie auf fundamentaler Ebene: ein einzelnes Atom wechselwirkt mit einem einzelnen Photon. Falls die Atom-Photon Kopplung stärker ist als alle anderen dissipativen Effekte, befindet sich das System im sogenannten Regime starker Kopplung. Eine Besonderheit dieses Regimes besteht in der Möglichkeit der Formierung eines kohärenten Superpositionszustands aus Licht- und Materiean...
SPS RF System an Accelerating Cavity
1975-01-01
The picture shows one of the two initially installed cavities. The main RF-system of the SPS comprises four cavities: two of 20 m length and two of 16.5 m length. They are all installed in one long straight section (LSS 3). These cavities are of the travelling-wave type operating at a centre frequency of 200.2 MHz. They are wideband, filling time about 700 ns and untuned. The power amplifiers, using tetrodes are installed in a surface building 200 m from the cavities. Initially only two cavities were installed, a third cavity was installed in 1978 and a forth one in 1979. The number of power amplifiers was also gradually increased: by end 1980 there were 8 500 kW units combined in pairs to feed each of the 4 cavities with up to about 1 MW RF power, resulting in a total accelerating voltage of about 8 MV. See also 7412017X, 7411048X.
Spallation neutron source RF cavity bias system
International Nuclear Information System (INIS)
The Spallation Neutron Source r.f. cavity bias system is described under the topic headings: bias system, r.f. cavity, cables, d.c. bias power supply, transistor regulator and control system. Calculation of 4 core 300 mm solid aluminium cable inductance, coaxial shunt frequency response and transistor regulator computed frequency response, are discussed in appendices 1-3. (U.K.)
Testing quantum nonlocality for three coupled quantum dots within optical microcavity QED
Moradi, Shahpoor
2012-01-01
Bell's inequality in three coupled quantum dots (QDs) within cavity QED, including Forster and exciton-phonon interactions, is investigated theoretically. For an initially entangled state, Bell's inequality is valid for certain times and violated for some other times. It is shown that the system moves from a product state to a entangled state and back again during it's time evolution.
Theory of implementation of an impedance-matched Λ system in circuit QED
Koshino, Kazuki; Inomata, Kunihiro; Yamamoto, Tsuyoshi; Nakamura, Yasunobu
2014-03-01
In one-dimensional optical setups, light-matter interaction is drastically enhanced by the interference between the incident and scattered fields. Particularly, in an impedance-matched Λ-type three-level system, which has two identical radiative decay rates from the top level and interacts with a semi-infinite one-dimensional field in reflection geometry, a single photon deterministically induces the Raman transition and switches the electronic state of the system. Here we theoretically investigate a circuit QED system composed of a driven superconducting qubit and a resonator in the dispersive regime. We show that the dressed states of this system constitute an impedance-matched Λ system under a proper choice of the frequency and power of the qubit drive. When we apply a resonant probe field to this system, it is down-converted nearly perfectly after a single reflection as long as the probe power is sufficiently weak. This indicates a deterministic quantum dynamics induced by single photons, which is applicable, for example, to the detection of single microwave photons and the bidirectional quantum memory (swapping) between a microwave photon and a superconducting qubit. This work was partly supported by FIRST, MEXT KAKENHI (21102002 and 25400417), SCOPE (111507004) and NICT.
DEFF Research Database (Denmark)
Nielsen, Per Kær; Nielsen, Torben Roland; Lodahl, Peter;
2010-01-01
treatments. A pronounced consequence is the emergence of a phonon induced spectral asymmetry when detuning the cavity from the quantum-dot resonance. The asymmetry can only be explained when considering the polaritonic quasiparticle nature of the quantum-dot-cavity system. Furthermore, a temperature induced......We investigate the influence of electron-phonon interactions on the dynamical properties of a quantum-dot-cavity QED system. We show that non-Markovian effects in the phonon reservoir lead to strong changes in the dynamics, arising from photon-assisted dephasing processes, not present in Markovian...
Design of the ILC Crab Cavity System
Energy Technology Data Exchange (ETDEWEB)
Adolphsen, C.; Beard, C.; Bellantoni, L.; Burt, G.; Carter, R.; Chase, B.; Church, M.; Dexter, A.; Dykes, M.; Edwards, H.; Goudket, P; Jenkins, R.; Jones, R.M.; Kalinin,; Khabiboulline, T.; Ko, K.; Latina, A.; Li, Z.; Ma, L.; McIntosh, P.; Ng, C.; /SLAC /Daresbury /Fermilab /Cockcroft Inst. Accel. Sci. Tech. /CERN
2007-08-15
The International Linear Collider (ILC) has a 14 mrad crossing angle in order to aid extraction of spent bunches. As a result of the bunch shape at the interaction point, this crossing angle at the collision causes a large luminosity loss which can be recovered by rotating the bunches prior to collision using a crab cavity. The ILC baseline crab cavity is a 9-cell superconducting dipole cavity operating at a frequency of 3.9 GHz. In this paper the design of the ILC crab cavity and its phase control system, as selected for the RDR in February 2007 is described in fuller detail.
Design of the ILC Crab Cavity System
International Nuclear Information System (INIS)
The International Linear Collider (ILC) has a 14 mrad crossing angle in order to aid extraction of spent bunches. As a result of the bunch shape at the interaction point, this crossing angle at the collision causes a large luminosity loss which can be recovered by rotating the bunches prior to collision using a crab cavity. The ILC baseline crab cavity is a 9-cell superconducting dipole cavity operating at a frequency of 3.9 GHz. In this paper the design of the ILC crab cavity and its phase control system, as selected for the RDR in February 2007 is described in fuller detail
Giant photon gain in large-scale quantum dot circuit-QED systems
Agarwalla, Bijay Kumar; Mukamel, Shaul; Segal, Dvira
2016-01-01
Motivated by recent experiments on the generation of coherent light in engineered hybrid quantum systems, we investigate gain in a microwave photonic cavity coupled to quantum dot structures, and develop concrete directions for achieving a giant amplification in photon transmission. We propose two architectures for scaling up the electronic gain medium: (i) $N$ double quantum dot systems (N-DQD), (ii) $M$ quantum dots arranged in series akin to a quantum cascade laser setup. In both setups, the fermionic reservoirs are voltage biased, and the quantum dots are coupled to a single-mode cavity. Optical amplification is explained based on a sum rule for the transmission function, and it is determined by an intricate competition between two different processes: charge density response in the gain medium, and cavity losses to input and output ports. The same design principle is also responsible for the corresponding giant amplification in other photonic observables, mean photon number and emission spectrum, thereby...
Probing phases of interacting polaritons in circuit QED setups
International Nuclear Information System (INIS)
Circuit QED systems pose a new paradym for reaching the strong coupling regime of photonic and atomic degrees of freedom and are thus ideal candidates for quantum simulation and computation. We are investigating one-dimensional arrays of transmission-line cavities, where each cavity is coupled to a transmon-qubit. This system can be used as a quantum many-body simulator, lowering the experimental requirements for prescission control with respect to the use as a quantum computing device. We exploit the intermediate qubit-harmonic oscillator regime of the transmon to simulate Bose-Hubbard physics. As a suitable experimental setup we consider a system where the first cavity is driven by a classical microwave source and the output voltage is monitored, with respect to signatures of a quantum phase transition, at the last cavity.
Drummond, I T
2016-01-01
We study, as a model of Lorentz symmetry breaking, the quantisation and renormalisation of an extension of QED in a flat spacetime where the photons and electrons propagate differently and do not share the same lightcone. We will refer to this model as Bimetric QED (BIMQED). As a preliminary we discuss the formulation of electrodynamics in a pre-metric formalism showing nevertheless that there is, on the basis of a simple criteron, a preferred metric. Arising from this choice of metric is a Weyl-like tensor (WLT). The Petrov classification of the WLT gives rise to a corresponding classification of Lorentz symmetry breaking. We do not impose any constraint on the strength of the symmetry breaking and are able to obtain explicit dispersion relations for photon propagation in each of the Petrov classes. The associated birefringence appears in some cases as two distinct polarisation dependent lightcones and in other cases as a a more complicated structure that cannot be disentangled in a simple way. We show how i...
Calderón Losada, Omar
2010-01-01
Se estudia un método para generar enredamiento entre dos átomos que atraviesan secuencialmente una cavidad cuántica electrodinámica (cQED) mediante interacciones átomo-campo en las que se intercambian un fotón o dos fotones. Se analizan las condiciones bajo las cuales es válido el hamiltoniano para el caso de intercambio de dos fotones, que se construye empleando la teoría de perturbaciones independiente del tiempo. Se muestra que, cuando dos átomos que atraviesan secuencialmente el campo de ...
Shallow Cavities in Multiple-Planet Systems
Duffell, Paul C.; Dong, Ruobing
2014-01-01
Large cavities are often observed in protoplanetary disks, which might suggest the presence of planets opening gaps in the disk. Multiple planets are necessary to produce a wide cavity in the gas. However, multiple planets may also be a burden to the carving out of very deep gaps. When additional planets are added to the system, the time-dependent perturbations from these additional satellites can stir up gas in the gap, suppressing cavity opening. In this study, we perform two-dimensional nu...
Atom-field dressed states in slow-light waveguide QED
Calajó, Giuseppe; Ciccarello, Francesco; Chang, Darrick; Rabl, Peter
2016-03-01
We discuss the properties of atom-photon bound states in waveguide QED systems consisting of single or multiple atoms coupled strongly to a finite-bandwidth photonic channel. Such bound states are formed by an atom and a localized photonic excitation and represent the continuum analog of the familiar dressed states in single-mode cavity QED. Here we present a detailed analysis of the linear and nonlinear spectral features associated with single- and multiphoton dressed states and show how the formation of bound states affects the waveguide-mediated dipole-dipole interactions between separated atoms. Our results provide both a qualitative and quantitative description of the essential strong-coupling processes in waveguide QED systems, which are currently being developed in the optical and microwave regimes.
International Nuclear Information System (INIS)
Inertial confinement fusion (ICF) embodies the simultaneous firing of large-scale multiple high intensity mega-joule laser pulses at targets of pea-sized deuterium pellets. Fusion is initiated on the premise that temperatures over 100 million degrees and density 1000x normal solid density are produced in pellet implosion. Contrary to large scale ICF reactor designs, neutrons were recently found in Berlin with a significantly down-sized table-top system using a 815 nm laser depositing ∼ 35 femto-second pulses of 120 milli-joules to a spray of submicron droplets of heavy water. Ionization of the D2O is thought to leave the submicron droplets with charged D2O+ ions as the electrons rapidly escape at which time the droplets undergo Coulomb explosions. Neutrons are produced in the collisions of the D2O+ ions with those emitted from neighboring droplets. Although a convenient source of submicron D2O droplets, the spray lacks containment of the Coulomb explosion to produce the high pressures necessary to significantly increase neutron yield. A containment shell encapsulating the D2O is proposed here to briefly increase the pressure by confining the D2O+ ions in the Coulomb explosion. In pea-sized targets this is not possible because the shell would vaporize under the high temperatures necessary for implosion. But with submicron targets, the temperature does not increase during the absorption of the laser photons because of the quantum electrodynamics (QED) confinement of the electromagnetic (EM) radiation.. Specifically, IR radiation from absorbed photons is precluded having half-wavelengths larger than the target diameter, or equivalently any increase in target temperature that accompanies the IR radiation is forbidden. What this means is that in pea-sized targets large in relation to the half-IR wavelength, the deposition of laser energy is allowed to be conserved by an increase in temperature; whereas, in submicron targets far smaller than the respective half
Ion-cavity system for quantum networks
International Nuclear Information System (INIS)
Full text: A single atom interacting with a single mode of a cavity allows us to probe the quantum interaction between light and matter. In the context of quantum networks, such a system can provide an interface between stationary and flying qubits, making it possible for single photons to transport quantum information between the network nodes. We study a single 40Ca+ ion trapped inside a high-finesse optical resonator. First, we demonstrate and characterize a single-photon source, in which a vacuum-stimulated Raman process transfers atomic population between two Zeeman states of the ion, creating a single photon in the cavity. We evaluate the photon statistics by measuring the second-order correlation function. Moreover, we obtain the photon temporal profile and investigate the dynamics of the process. Secondly, we perform Raman spectroscopy using the cavity. Residual motion of the ion introduces motional sidebands in the Raman spectrum and thus offers prospects for cavity-assisted cooling. (author)
Cryogenic system for TRISTAN superconducting RF cavity
International Nuclear Information System (INIS)
Superconducting RF cavities will be installed in TRISTAN at KEK to upgrade the electron-positron beam energy to 33 GeV x 33 GeV. Two 5-cell cavities are coupled together, enclosed in a cryostat, and cooled by liquid helium pool boiling. The cryogenic system for the cavities is described and a system flow diagram constructed. Heat loads are estimated and component specifications are given. The capacity of the helium refrigerator is 4 kW at 4.4 K with liquid nitrogen precooling and two expansion turbines. The system is designed to be upgraded to 6.5 kW with added expansion turbines and compressors and the elimination of liquid nitrogen
Polariton states in circuit QED for electromagnetically induced transparency
Gu, Xiu; Huai, Sai-Nan; Nori, Franco; Liu, Yu-xi
2016-06-01
Electromagnetically induced transparency (EIT) has been extensively studied in various systems. However, it is not easy to observe in superconducting quantum circuits (SQCs) because the Rabi frequency of the strong-controlling field corresponding to EIT is limited by the decay rates of the SQCs. Here, we show that EIT can be achieved by engineering decay rates in a superconducting circuit QED system through a classical driving field on the qubit. Without such a driving field, the dressed states of the system, describing a superconducting qubit coupled to a cavity field, are approximately product states of the cavity and qubit states in the large-detuning regime. However, the driving field can strongly mix these dressed states. These doubly dressed states, here called polariton states, are formed by the driving field and dressed states, and are a mixture of light and matter. The weights of the qubit and cavity field in the polariton states can now be tuned by the driving field, and thus the decay rates of the polariton states can be changed. We choose the three lowest-energy polariton states with a Λ -type transition in such a driven circuit QED system, and demonstrate how EIT and Autler-Townes splitting can be realized in this compound system. We believe that this study will be helpful for EIT experiments using SQCs.
A microelectromechanically controlled cavity optomechanical sensing system
Miao, Houxun; Aksyuk, Vladimir
2012-01-01
Microelectromechanical systems (MEMS) have been applied to many measurement problems in physics, chemistry, biology and medicine. In parallel, cavity optomechanical systems have achieved quantum-limited displacement sensitivity and ground state cooling of nanoscale objects. By integrating a novel cavity optomechanical structure into an actuated MEMS sensing platform, we demonstrate a system with high quality-factor interferometric readout, electrical tuning of the optomechanical coupling by two orders of magnitude, and a mechanical transfer function adjustable via feedback. The platform separates optical and mechanical components, allowing flexible customization for specific scientific and commercial applications. We achieve displacement sensitivity of 4.6 fm/Hz^1/2 and force sensitivity of 53 aN/Hz^1/2 with only 250 nW optical power launched into the sensor. Cold-damping feedback is used to reduce the thermal mechanical vibration of the sensor by 3 orders of magnitude and to broaden the sensor bandwidth by a...
Optical cavity and transport system for FELI
International Nuclear Information System (INIS)
FELI (Free Electron Laser Research Institute, Inc.) is aiming at FIR-, IR-, VISIBLE-, and UV-FEL (spectral range from 0.3 to 22.7μm) generation using 30-, 75-, 120-, 165-MeV beams, respectively. The linear accelerator and four undulators are installed in the ground floor and five FEL users rooms are located in the third floor, so the longest FEL transport pass is about 80m long. We will adopt hole out coupling for FIR- and IR-FEL optical cavities. The output beam is collimated by an inverted telescope and transported to the users rooms via N2 purged pipes. Achieving optical beam stability and quality are primary concerns. For keeping optical beam stability and quality, a beam axis control unit and a position monitoring system are used. These optical cavities and FEL transport systems are under construction and will be used for FIR- and IR-FEL experiments in this summer. (author)
Quantum Dynamics of Nonlinear Cavity Systems
Nation, Paul D
2010-01-01
We investigate the quantum dynamics of three different configurations of nonlinear cavity systems. To begin, we carry out a quantum analysis of a dc superconducting quantum interference device (SQUID) mechanical displacement detector comprised of a SQUID with a mechanically compliant loop segment. The SQUID is approximated by a nonlinear current-dependent inductor, inducing a flux tunable nonlinear Duffing term in the cavity equation of motion. Expressions are derived for the detector signal and noise response where it is found that a soft-spring Duffing self-interaction enables a closer approach to the displacement detection standard quantum limit, as well as cooling closer to the ground state. Next, we make use of a superconducting transmission line formed from an array of dc-SQUIDs for investigating analogue Hawking radiation. Biasing the array with a space-time varying flux modifies the propagation velocity of the transmission line, leading to an effective metric with a horizon. This setup allows for quan...
Luo, Yongjiang; Li, Lijia; Peng, Jianming; Yin, Kun; Li, Peng; Gan, Xin; Zhao, Letao; Su, Wei
2015-12-01
The subterranean cavities are seriously threatened to construction and mining safety, and it's important to obtain the exact localization and dimensions of subterranean cavities for the planning of geotechnical and mining activities. Geophysical investigation is an alternative method for cavity detection, but it usually failed for the uncertainly solution of information and data obtained by Geophysical methods. Drilling is considered as the most accurate method for cavity detection. However, the conventional drilling methods can only be used for single cavity detection, and there is no effective solution for multilayer cavities detection have been reported. In this paper, a reverse circulation (RC) down-the-hole (DTH) air hammer system with a special structured drill bit is built and a cavity auto scanning laser system based on laser range finding technique was employed to confirm the localization and dimensions of the cavities. This RC-DTH air hammer system allows drilling through the upper cavities and putting the cavity auto scanning laser system into the cavity area through the central passage of the drill tools to protect the detection system from collapsing of borehole wall. The RC-DTH air hammer system was built, and field tests were conducted in Lanxian County Iron Ore District, which is located in Lv Liang city of Shan Xi province, the northwest of china. Field tests show that employing the RC-DTH air hammer system assisted by the cavity auto scanning laser system is an efficiency method to detect multilayer cavities.
International Nuclear Information System (INIS)
We present measurements and modelling of the susceptibility of a 2D microstrip cavity coupled to a driven transmon qubit. We are able to fit the response of the cavity to a weak probe signal with high accuracy in the strong coupling, low detuning, i.e., non-dispersive, limit over a wide bandwidth. The observed spectrum is rich in multi-photon processes for the doubly dressed transmon. These features are well explained by including the higher transmon levels in the driven Jaynes–Cummings model and solving the full master equation to calculate the susceptibility of the cavity. (paper)
Development of oral cavity inspecting system
Zhang, Hongxia; Wu, Di; Jia, Dagong; Zhang, Yimo
2009-11-01
An oral cavity inspecting system is designed and developed to inspect the detail of teeth. The inspecting system is composed of microscopic imaging part, illuminating part, image capture and processing, display part. The two groups of cemented lenses were optimized to minimize the optical aberration and the collimated beam light is gotten between the two lenses. A relay lens is adopted to allow the probe to access the oral cavity depth. The illumination optic fiber is used and the brightness and color temperature can be adjustable. The illumination fiber end surface is oblique cut and the optimum angle is 37°. The image of teeth is imaged on CMOS and captured into computer. The illumination intensity and uniformity were tested and the proper parameter is set. Foucault chart was observed and the system resolution is higher than 100lp/mm. The oral inspecting system is used to test standard tooth model and patho-teeth model. The tooth image is clear and the details can be observed. The experimental results show that the system could meet dental medical application requirements.
Ruesink, Freek; Doeleman, Hugo M; Hendrikx, Ruud; Koenderink, A Femius; Verhagen, Ewold
2015-11-13
The influence of a small perturbation on a cavity mode plays an important role in fields like optical sensing, cavity quantum electrodynamics, and cavity optomechanics. Typically, the resulting cavity frequency shift directly relates to the polarizability of the perturbation. Here, we demonstrate that particles perturbing a radiating cavity can induce strong frequency shifts that are opposite to, and even exceed, the effects based on the particles' polarizability. A full electrodynamic theory reveals that these anomalous results rely on a nontrivial phase relation between cavity and nanoparticle radiation, allowing backaction via the radiation continuum. In addition, an intuitive model based on coupled mode theory is presented that relates the phenomenon to retardation. Because of the ubiquity of dissipation, we expect these findings to benefit the understanding and engineering of a wide class of systems. PMID:26613442
Beam commissioning of KEKB crab cavity RF system
International Nuclear Information System (INIS)
KEKB started the first crab crossing operation in February 2007 with two superconducting crab cavities. After four months operation dedicated for machine tuning, physics run with high-current beams resumed in October with the crab crossing. The crab cavities have been working stably for one and a half years. The crab cavity RF system, commissioning process and performance of the crab cavities with high-current beams are presented. (author)
Precision Study of Positronium: Testing Bound State QED Theory
Karshenboim, Savely G.
2003-01-01
As an unstable light pure leptonic system, positronium is a very specific probe atom to test bound state QED. In contrast to ordinary QED for free leptons, the bound state QED theory is not so well understood and bound state approaches deserve highly accurate tests. We present a brief overview of precision studies of positronium paying special attention to uncertainties of theory as well as comparison of theory and experiment. We also consider in detail advantages and disadvantages of positro...
International Nuclear Information System (INIS)
We propose a simple scheme to realize 1→M economical phase-covariant quantum cloning machine (EPQCM) with superconducting quantum interference device (SQUID) qubits. In our scheme, multi-SQUIDs are fixed into a microwave cavity by adiabatic passage for their manipulation. Based on this model, we can realize the EPQCM with high fidelity via adiabatic quantum computation
... the bacteria produce acids that cause decay. Tooth pain occurs after decay reaches the inside of the tooth. Dentists can detect cavities by examining the teeth and taking x-rays periodically. Good oral hygiene and regular dental care plus a healthy diet can help prevent cavities. ...
Photon-photon interactions with inner coupled double-cavity
Institute of Scientific and Technical Information of China (English)
Lai Wen-Xi; Li Hong-Cai; Yang Rong-Can
2008-01-01
This paper describes the interaction between two spatial modes of the optical fields with a single atom trapped inner coupled double-cavity.Theoretical derivation and numerical simulation with the experimental available parameters show that photon-photon switching and π phase shift of single photons may be achieved with current experimental technology.As the probe and control fields are in different spatial modes,the system is superior for implementing cavity QED-based photonic quantum networks.
International Nuclear Information System (INIS)
In this paper we present a method to engineer the unitary charge conjugation operator, as given by quantum field theory, in the highly controlled context of quantum optics, thus allowing one to simulate the creation of charged particles with well-defined momenta simultaneously with their respective antiparticles. Our method relies on trapped ions driven by a laser field and interacting with a single mode of a light field in a high Q cavity. (paper)
Photon-assisted tunnelling with nonclassical microwaves in hybrid circuit QED systems
Souquet, Jean-René; Woolley, Matthew; Gabelli, Julien; Simon, Pascal; Clerk, Aashish
2015-03-01
Motivated by recent experiments where superconducting microwave circuits have been coupled to electrons in semiconductor nanostructures, we study theoretically the interplay of non-classical light produced in a cavity with electron transport through a tunnel junction. We demonstrate that this basic light-matter interaction is naturally characterized by non-positive definite quasi-probability distributions which are intimately connected to the Glauber-Sudarshan P-function. We further demonstrate that this negative quasiprobability has unequivocal signatures on the differential conductance that should be easily detectable in state of art experiments. This thus turns the tunnel junction into a non-trivial probe of the microwave state. We also discuss the non-trivial backaction of the junction current on the cavity.
International Nuclear Information System (INIS)
The lecture concerns quantum electrodynamics (QED), the relativistic quantum theory of electromagnetic interactions. Antiparticles, electrodynamics of spinless particles, the dirac equation and electrodynamics of spin 1/2 particles are discussed in detail. (U.K.)
Interacting Photons in Waveguide-QED and Applications in Quantum Information Processing
Zheng, Huaixiu
Strong coupling between light and matter has been demonstrated both in classical cavity quantum electrodynamics (QED) systems and in more recent circuit-QED experiments. This enables the generation of strong nonlinear photon-photon interactions at the single-photon level, which is of great interest for the observation of quantum nonlinear optical phenomena, the control of light quanta in quantum information protocols such as quantum networking, as well as the study of strongly correlated quantum many-body systems using light. Recently, strong coupling has also been realized in a variety of one-dimensional (1D) waveguide- QED experimental systems, which in turn makes them promising candidates for quantum information processing. Compared to cavity-QED systems, there are two new features in waveguide-QED: the existence of a continuum of states and the restricted 1D phase space, which together bring in new physical effects, such as the bound-state effects. This thesis consists of two parts: 1) understanding the fundamental interaction between local quantum objects, such as two-level systems and four-level systems, and photons confined in the waveguide; 2) exploring its implications in quantum information processing, in particular photonic quantum computation and quantum key distribution. First, we demonstrate that by coupling a two-level system (TLS) or three/four-level system to a 1D continuum, strongly-correlated photons can be generated inside the waveguide. Photon-photon bound states, which decay exponentially as a function of the relative coordinates of photons, appear in multiphoton scattering processes. As a result, photon bunching and antibunching can be observed in the photon-photon correlation function, and nonclassical light source can be generated on demand. In the case of an N-type four-level system, we show that the effective photon-photon interaction mediated by the four-level system, gives rise to a variety of nonlinear optical phenomena, including
Cavity parameters identification for TESLA control system development
International Nuclear Information System (INIS)
The control system modeling for the TESLA - TeV-Energy Superconducting Linear Accelerator project has been developed for the efficient stabilization of the pulsed, accelerating EM field of the resonator. The cavity parameters identification is an essential task for the comprehensive control algorithm. The TESLA cavity simulator has been successfully implemented by applying very high speed FPGA - Field Programmable Gate Array technology. The electromechanical model of the cavity resonator includes the basic features - Lorentz force detuning and beam loading. The parameters identification bases on the electrical model of the cavity. The model is represented by the state space equation for the envelope of the cavity voltage driven by the current generator and the beam loading. For a given model structure, the over-determined matrix equation is created covering the long enough measurement range with the solution according to the least squares method. A low degree polynomial approximation is applied to estimate the time-varying cavity detuning during the pulse. The measurement channel distortion is considered, leading to the external cavity model seen by the controller. The comprehensive algorithm of the cavity parameters identification has been implemented in the Matlab system with different modes of the operation. Some experimental results have been presented for different cavity operational conditions. The following considerations have lead to the synthesis of the efficient algorithm for the cavity control system predicted for the potential FPGA technology implementation. (orig.)
Renormalization of QED near Decoupling Temperature
Masood, Samina S
2014-01-01
We study the effective parameters of QED near decoupling temperatures and show that the QED perturbative series is convergent, at temperatures below the decoupling temperature. The renormalization constant of QED acquires different values if a system cools down from a hotter system to the electron mass temperature or heats up from a cooler system to the same temperature. At T = m, the first order contribution to the electron selfmass, {\\delta}m/m is 0.0076 for a heating system and 0.0115 for a cooling system and the difference between two values is equal to 1/3 of the low temperature value and 1/2 of the high temperature value around T~m. This difference is a measure of hot fermion background at high temperatures. With the increase in release of more fermions at hotter temperatures, the fermion background contribution dominates and weak interactions have to be incorporated to understand the background effects.
Cavity Ring-down Spectroscopic System And Method
Alquaity, Awad Bin Saud
2015-05-14
A system and method for cavity ring-down spectroscopy can include a pulsed quantum cascade laser, an optical ring-down cavity, a photodetector, and an oscilloscope. The system and method can produce pulse widths of less than 200 ns with bandwidths greater than 300 pm, as well as provide temporal resolution of greater than 10 .mu.s.
Reactor cavity cleanup system shielded filter installation
International Nuclear Information System (INIS)
The Seabrook Station reactor cavity cleanup system provides a flow path for refueling pool purification and drain down during plant refueling evolutions. The original system design included refueling pool surface skimmers and drains, a skimmer pump, an unshielded duplex basket type pump suction strainer and interconnecting stainless steel piping. The piping design utilized socket welded joints in small bore pipe with diaphragm values installed in the horizontal pipe runs downstream of the skimmer pump. The previously installed unshielded strainer in addition to the skimmer pump downstream piping components were determined to be inconsistent with Seabrook's proactive approach to dose reduction. To be consistent with ALARA (As Low As Reasonably Achievable) policy, a plant design change was authorized to install a lead shielded filter unit as a replacement for the existing duplex strainer. This filter unit, which utilizes multiple micron rating disposable basket type cartridges, has a threefold function of protecting the skimmer pump from large solids, providing bulk filtration of activated corrosion products from the refueling water in order to minimize CRUD buildup in downstream components, and enabling retrieval of foreign material drawn into the refueling pool drains
Entangled Schrodinger cats in circuit QED: Experimental Architecture
Wang, Chen; Gao, Yvonne Y.; Reinhold, Philip; Heeres, Reinier W.; Ofek, Nissim; Chou, Kevin; Axline, Christopher; Frunzio, Luigi; Devoret, Michel H.; Schoelkopf, Robert J.
The development of quantum information technology relies on creating and controling entanglement over an increasingly large Hilbert space. Superconducting cavities offer high-dimensional spaces for quantum states in a low-loss and hardware-efficient fashion, making it an ideal memory of quantum information and an important element towards fault-tolerant quantum computation. In this talk we present a cQED architecture that allows quantum control over the coherent state basis of two superconducting cavities with millisecond coherence. In particular, we show deterministic entanglement of coherent-state microwave fields in two superconducting cavities of the form: 1/√{ 2}" open="" separators="">βa" open="" separators="">βa +/- -" open="" separators="">βa -" open="" separators="">βa . We engineer the capability to measure the joint photon number parity to achieve complete state tomography of the two-cavity state. Following widespread efforts of realizing ``Schrodinger's cat''-like mesoscopic superposition in various physical systems, this experiment demonstrates mesoscopic entanglement between two ``Schrodinger's cats''.
Quantum memory with millisecond coherence in circuit QED
Reagor, Matthew; Pfaff, Wolfgang; Axline, Christopher; Heeres, Reinier W.; Ofek, Nissim; Sliwa, Katrina; Holland, Eric; Wang, Chen; Blumoff, Jacob; Chou, Kevin; Hatridge, Michael J.; Frunzio, Luigi; Devoret, Michel H.; Jiang, Liang; Schoelkopf, Robert J.
2016-07-01
Significant advances in coherence render superconducting quantum circuits a viable platform for fault-tolerant quantum computing. To further extend capabilities, highly coherent quantum systems could act as quantum memories for these circuits. A useful quantum memory must be rapidly addressable by Josephson-junction-based artificial atoms, while maintaining superior coherence. We demonstrate a superconducting microwave cavity architecture that is highly robust against major sources of loss that are encountered in the engineering of circuit QED systems. The architecture allows for storage of quantum superpositions in a resonator on the millisecond scale, while strong coupling between the resonator and a transmon qubit enables control, encoding, and readout at MHz rates. This extends the maximum available coherence time attainable in superconducting circuits by almost an order of magnitude compared to earlier hardware. Our design is an ideal platform for studying coherent quantum optics and marks an important step towards hardware-efficient quantum computing in Josephson-junction-based quantum circuits.
Cavity cooling and normal-mode spectroscopy of a bound atom-cavity system
International Nuclear Information System (INIS)
Full text: Single atoms strongly coupled to the field of an optical cavity form an attractive system for the realization of an atom-light interface useful for quantum information protocols. An experimental implementation of these schemes requires atoms which are trapped, cooled and localized in the cavity mode at a region of strong coupling. In the experiment presented here, single atoms are trapped and stored in a far-detuned intracavity dipole trap. We demonstrate cavity cooling by illuminating the system with a weak, slightly blue-detuned light beam. This extends the storage time of an atom, which is limited by parametric heating from fluctuations of the intracavity dipole trap, by more than a factor of two. The observed cooling force is of Sisyphus-type and was predicted. A special feature of this force is that it does not rely on the spontaneous emission of a photon by the atom, and therefore the cooling force is at least five times larger than the force achievable for free-space cooling methods with comparable excitation of a two-level atom. Preparing single atoms strongly-coupled to the mode of a high-finesse cavity in this way, we observe two well-resolved normal-mode peaks both in transmission of the cavity as well as in the trap lifetime. The experimental data agree well with a Monte Carlo simulation, demonstrating the localization of the atom to within a tenth of a wavelength at a cavity antinode. The ability to individually excite the normal modes of a bound atom-cavity system shows that we have reached good control over this fundamental quantum system. (author)
Petrov, E Yu
2016-01-01
The problem of longitudinal oscillations of an electric field and a charge polarization density in QED vacuum is considered. Within the framework of semiclassical analysis, we calculate time-periodic solutions of bosonized 1+1 dimensional QED (massive Schwinger model). Applying the Bohr--Sommerfeld quantization condition, we determine the mass spectrum of charge-zero bound states (plasmons) which correspond in quantum theory to the found classical solutions. We show that the existence of such plasmons does not contradict any fundamental physical laws and study qualitatively their excitation in 3+1 dimensional real world.
The Test of LLRF control system on superconducting cavity
Zhu, Zhenglong; Wen, Lianghua; Chang, Wei; Zhang, Ruifeng; Gao, Zheng; Chen, Qi
2014-01-01
The first generation Low-Level radio frequency(LLRF) control system independently developed by IMPCAS, the operating frequency is 162.5MHz for China ADS, which consists of superconducting cavity amplitude stability control, phase stability control and the cavity resonance frequency control. The LLRF control system is based on four samples IQ quadrature demodulation technique consisting an all-digital closed-loop feedback control. This paper completed the first generation of ADS LLRF control system in the low-temperature superconducting cavities LLRF stability and performance online tests. Through testing, to verify the performance of LLRF control system, to analysis on emerging issues, and in accordance with the experimental data, to summarize LLRF control system performance to accumulate experience for the future control of superconducting cavities.
Generation of nonclassical states in a large detuning cavity
Institute of Scientific and Technical Information of China (English)
Zhang Ying-Jie; Ren Ting-Qi; Xia Yun-Jie
2008-01-01
By using the theory of cavity QED, we study the system in which a two-level atom interacts with a cavity in the case of large detuning. Through the selective detecting of atomic state, SchrSdinger cat states and entangled coherent states are easily generated. When the atom is driven by a weak classical field and the cavity field is in the Schr(o)dinger cat state, we study the conditions of generating the Fock states and the maximal success probability. The maximal success probability in our scheme is larger than the previous one.
Environment-Assisted Speed-up of the Field Evolution in Cavity Quantum Electrodynamics
International Nuclear Information System (INIS)
We measure the quantum speed of the state evolution of the field in a weakly-driven optical cavity QED system. To this end, the mode of the electromagnetic field is considered as a quantum system of interest with a preferential coupling to a tunable environment: the atoms. By controlling the environment, i.e., changing the number of atoms coupled to the optical cavity mode, an environment assisted speed-up is realized: the quantum speed of the state re-population in the optical cavity increases with the coupling strength between the optical cavity mode and this non-Markovian environment (the number of atoms)
Dynamical mass generation in QED3
International Nuclear Information System (INIS)
We study chiral symmetry breaking for QED[3] with N fermion flavours, just above the critical threshold. By analysis of a consistently truncated Schwinger-Dyson system for the fermion propagator and the fermion-boson vertex, we argue that the critical coupling must be strictly positive. (author). 19 refs.; 5 figs.; 3 tabs
Proposal for a loophole-free Bell test based on spin-photon interactions in cavities
Brunner, Nicolas; Young, Andrew B.; Hu, Chengyong; Rarity, John G.
2013-01-01
We present a scheme to demonstrate loophole-free Bell inequality violation where the entanglement between photon pairs is transferred to solid state (spin) qubits mediated by cavity QED interactions. As this transfer can be achieved in a heralded way, our scheme is basically insensitive to losses on the channel, and works also in the weak coupling regime. We consider potential experimental realizations using single atom, colour centre and quantum dot cavity systems. Finally our scheme appears...
Indirect Coupling between Two Cavity Photon Systems via Ferromagnetic Resonance
Hyde, Paul; Harder, Michael; Match, Christophe; Hu, Can-Ming
2016-01-01
We experimentally realize indirect coupling between two cavity modes via strong coupling with the ferromagnetic resonance in Yttrium Iron Garnet (YIG). We find that some indirectly coupled modes of our system can have a higher microwave transmission than the individual uncoupled modes. Using a coupled harmonic oscillator model, the influence of the oscillation phase difference between the two cavity modes on the nature of the indirect coupling is revealed. These indirectly coupled microwave modes can be controlled using an external magnetic field or by tuning the cavity height. This work has potential for use in controllable optical devices and information processing technologies.
Triple optomechanical induced transparency in a two-cavity system
Shi-Chao, Wu; Li-Guo, Qin; Jun, Jing; Guo-Hong, Yang; Zhong-Yang, Wang
2016-05-01
We theoretically investigate the optomechanical induced transparency (OMIT) phenomenon in a two-cavity system which is composed of two optomechanical cavities. Both of the cavities consist of a fixed mirror and a high-Q mechanical resonator, and they couple to each other via a common waveguide. We show that in the presence of a strong pump field applied to one cavity and a weak probe field applied to the other, a triple-OMIT can be observed in the output field at the probe frequency. The two mechanical resonators in the two cavities are identical, but they lead to different quantum interference pathways. The transparency windows are induced by the coupling of the two cavities and the optical pressure radiated to the mechanical resonators, which can be controlled via the power of the pump field and the coupling strength of the two cavities. Project supported by the Strategic Priority Research Program, China (Grant No. XDB01010200), the Hundred Talents Program of the Chinese Academy of Sciences (Grant No. Y321311401), and the National Natural Sciences Foundation of China (Grant Nos. 11347147 and 1547035).
Directory of Open Access Journals (Sweden)
Jasmin C. Blanchette
2016-01-01
Full Text Available This paper surveys the emerging methods to automate reasoning over large libraries developed with formal proof assistants. We call these methods hammers. They give the authors of formal proofs a strong "one-stroke" tool for discharging difficult lemmas without the need for careful and detailed manual programming of proof search.The main ingredients underlying this approach are efficient automatic theorem provers that can cope with hundreds of axioms, suitable translations of richer logics to their formalisms, heuristic and learning methods that select relevant facts from large libraries, and methods that reconstruct the automatically found proofs inside the proof assistants.We outline the history of these methods, explain the main issues and techniques, and show their strength on several large benchmarks. We also discuss the relation of this technology to the QED Manifesto and consider its implications for QED-style efforts.
Generation of entanglement in cavity QED
Montenegro, V.; Orszag, M.
2011-01-01
Presentamos un modelo para generar entrelazamiento con atomos localizados en cavidades distantes. Consiste en dos cavidades conectadas ́ ́ por una fibra optica, donde cada cavidad interactua con un solo atomo de dos niveles. Para ciertos valores de los par ́ metros de acoplamiento a ́ ́ atomo–cavidad y cavidad–fibra, encontramos un plateau amplio en el tiempo para la concurrencia entre los atomos. El aumento del ́ desentonamiento atomo-cavidad da lugar a un aumento l ́neal en el ancho de...
Integrated optics for coupled-cavity QED
Energy Technology Data Exchange (ETDEWEB)
Lepert, G.; Hinds, E. A. [Centre for Cold Matter, Imperial College London (United Kingdom)
2014-12-04
We present an array of Fabry-Pérot free space microcavities, intended to contain atoms or other quantum emitters, coupled to each other by waveguides resonators on a chip. The concept is highly scalable and offers a unique degree of control, making it a promising platform for quantum simulations. We demonstrate experimentally the basic units of the device.
Quantum Mechanical Description of Raman Scattering from Molecules in Plasmonic Cavities.
Schmidt, Mikolaj K; Esteban, Ruben; González-Tudela, Alejandro; Giedke, Geza; Aizpurua, Javier
2016-06-28
Plasmon-enhanced Raman scattering can push single-molecule vibrational spectroscopy beyond a regime addressable by classical electrodynamics. We employ a quantum electrodynamics (QED) description of the coherent interaction of plasmons and molecular vibrations that reveal the emergence of nonlinearities in the inelastic response of the system. For realistic situations, we predict the onset of phonon-stimulated Raman scattering and a counterintuitive dependence of the anti-Stokes emission on the frequency of excitation. We further show that this QED framework opens a venue to analyze the correlations of photons emitted from a plasmonic cavity. PMID:27203727
Fermilab linac upgrade side coupled cavity temperature control system
International Nuclear Information System (INIS)
Each cavity section has a temperature control system which maintains the resonant frequency by exploiting the 17.8 ppm/degree C frequency sensitivity of the copper cavities. Each accelerating cell has a cooling tube brazed azimuthally to the outside surface. Alternate supply and return connection to the water manifolds reduce temperature gradients and maintain physical alignment of the cavity string. Special tubing with spiral inner fins and large flow rate are used to reduce the film coefficient. Temperature is controlled by mixing chilled water with the water circulating between the cavity and the cooling skid located outside the radiation enclosure. Chilled water flow is regulated with a valve controlled by a local microcomputer. The temperature loop set point will be obtained from a slower loop which corrects the phase error between the cavity section and the rf drive during normal beam loaded conditions. Time constants associated with thermal gradients induced in the cavity with the rf power require programming it to the nominal 7.1 MW level over a 1 minute interval to limit the reverse power. 4 refs., 4 figs
Fermilab linac upgrade side coupled cavity temperature control system
International Nuclear Information System (INIS)
Each cavity section has a temperature control system which maintains the resonant frequency by exploiting the 17.8 ppm/C frequency sensitivity of the copper cavities. Each accelerating cell has a cooling tube brazed azimuthally to the outside surface. Alternate supply and return connection to the water manifolds reduce temperature gradients and maintain physical alignment of the cavity string. Special tubing with a spiral inner fins and a large flow rate are used to reduce the film coefficient. Temperature is controlled by mixing chilled water with the water circulating between the cavity and the cooling skid located outside the radiation enclosure. Chilled water flow is regulated with a valve controlled by a local micro computer. The temperature loop set point will be obtained from a slower loop which corrects the phase error between the cavity section and the rf drive during normal beam loaded conditions. Time constants associated with thermal gradients induced in the cavity with the rf power require programming it to the nominal 7.1 MW level over a 1 minute interval to limit the reverse power
A geometric approach to identify cavities in particle systems
Voyiatzis, Evangelos; Böhm, Michael C.; Müller-Plathe, Florian
2015-11-01
The implementation of a geometric algorithm to identify cavities in particle systems in an open-source python program is presented. The algorithm makes use of the Delaunay space tessellation. The present python software is based on platform-independent tools, leading to a portable program. Its successful execution provides information concerning the accessible volume fraction of the system, the size and shape of the cavities and the group of atoms forming each of them. The program can be easily incorporated into the LAMMPS software. An advantage of the present algorithm is that no a priori assumption on the cavity shape has to be made. As an example, the cavity size and shape distributions in a polyethylene melt system are presented for three spherical probe particles. This paper serves also as an introductory manual to the script. It summarizes the algorithm, its implementation, the required user-defined parameters as well as the format of the input and output files. Additionally, we demonstrate possible applications of our approach and compare its capability with the ones of well documented cavity size estimators.
QED Reloaded: Towards a Pluralistic Formal Library of Mathematical Knowledge
Michael Kohlhase; Florian Rabe
2016-01-01
Proposed in 1994, the ``QED project'' was one of the seminally influential initiatives in automated reasoning: It envisioned the formalization of ``all of mathematics'' and the assembly of these formalizations in a single coherent database. Even though it never led to the concrete system, communal resource, or even joint research envisioned in the QED manifesto, the idea lives on and shapes the research agendas of a significant part of the communityThis paper surveys a decade of work on repre...
A coupled microwave-cavity system in the Rydberg-atom cavity detector for dark matter axions
Tada, M; Shibata, M; Kominato, K; Ogawa, I; Funahashi, H; Yamamoto, K; Matsuki, S
2001-01-01
A coupled microwave-cavity system of cylindrical TM$_{010}$ single-mode has been developed to search for dark matter axions around 10 $\\mu {\\rm eV}$(2.4 GHz) with the Rydberg-atom cavity detector at 10 mK range temperature. One component of the coupled cavity (conversion cavity) made of oxygen-free high-conductivity copper is used to convert an axion into a single photon with the Primakoff process in the strong magnetic field, while the other component (detection cavity) made of Nb is utilized to detect the converted photons with Rydberg atoms passed through it without magnetic field. Top of the detection cavity is attached to the bottom flange of the mixing chamber of a dilution refrigerator, thus the whole cavity is cooled down to 10 mK range to reduce the background thermal blackbody-photons in the cavity. The cavity resonant frequency is tunable over $\\sim$ 15% by moving dielectric rods inserted independently into each part of the cavities along the cylindrical axis. In order to reduce the heat load from ...
Strong atom-field coupling for Bose-Einstein condensates in an optical cavity on a chip
Colombe, Yves; Steinmetz, Tilo; Dubois, Guilhem; Linke, Felix; Hunger, David; REICHEL, Jakob
2007-01-01
An optical cavity enhances the interaction between atoms and light, and the rate of coherent atom-photon coupling can be made larger than all decoherence rates of the system. For single atoms, this strong coupling regime of cavity quantum electrodynamics (cQED) has been the subject of spectacular experimental advances, and great efforts have been made to control the coupling rate by trapping and cooling the atom towards the motional ground state, which has been achieved in one dimension so fa...
Chester, Shai M
2016-01-01
We initiate the conformal bootstrap study of Quantum Electrodynamics in $2+1$ space-time dimensions (QED$_{3}$) with $N$ flavors of charged fermions by focusing on the 4-point function of four monopole operators with the lowest unit of topological charge. We obtain upper bounds on the scaling dimension of the doubly-charged monopole operator, with and without assuming other gaps in the operator spectrum. Intriguingly, we find a (gap-dependent) kink in these bounds that comes reasonably close to the large $N$ extrapolation of the scaling dimensions of the singly-charged and doubly-charged monopole operators down to $N=4$ and $N=6$.
Autonomous quantum thermal machines in atom-cavity systems
Mitchison, Mark T; Prior, Javier; Woods, Mischa P; Plenio, Martin B
2016-01-01
An autonomous quantum thermal machine comprising a trapped atom or ion placed inside an optical cavity is proposed and analysed. Such a machine can operate as a heat engine whose working medium is the quantised atomic motion, or as an absorption refrigerator which cools without any work input. Focusing on the refrigerator mode, we predict that it is possible with state-of-the-art technology to cool a trapped ion almost to its motional ground state using a thermal light source such as sunlight. We nonetheless find that a laser or similar reference system is necessary to stabilise the cavity frequencies. Furthermore, we establish a direct and heretofore unacknowledged connection between the abstract theory of quantum absorption refrigerators and practical sideband cooling techniques. We also highlight and clarify some assumptions underlying several recent theoretical studies on self-contained quantum engines and refrigerators. Our work indicates that cavity quantum electrodynamics is a promising and versatile e...
Observation of Non-Markovian Dynamics of a Single Quantum Dot in a Micropillar Cavity
DEFF Research Database (Denmark)
Madsen, Kristian Høeg; Ates, Serkan; Lund-Hansen, Toke; Löffler, A.; Reitzenstein, S.; Forchel, A.; Lodahl, Peter
2011-01-01
We measure the detuning-dependent dynamics of a quasiresonantly excited single quantum dot coupled to a micropillar cavity. The system is modeled with the dissipative Jaynes-Cummings model where all experimental parameters are determined by explicit measurements. We observe non-Markovian dynamics...... when the quantum dot is tuned into resonance with the cavity leading to a nonexponential decay in time. Excellent agreement between experiment and theory is observed with no free parameters providing the first quantitative description of an all-solid-state cavity QED system based on quantum dot...
Solid state high power RF system for superconducting cavities
International Nuclear Information System (INIS)
Solid State High Power RF System is proposed for XFEL and ILC. It includes individual RF power supply for each SC cavity and common control system. Each RF power supply includes Solid State Generator, circulator and Q-tuner. Triggering, synchronization, output power and phase of each Solid State Generator are controlled from the common control system through fiber-optic lines. Main parameters of Solid State Generator are: frequency 1.3 GHz, peak power 128 kW, pulse length 1.4 msec, repetition rate 10 Hz, average power 1.8 kW, CW power 2.5 kW. Advantages of Solid State High Power RF System are: simple triggering, synchronization, output power and phase adjustment for all cavities separately, operation both in pulse and in CW modes, unlimited lifetime, no high voltage, no oil-tank, compactness.
Hwang, Myung-Joong; Kim, M S; Choi, Mahn-Soo
2016-04-15
We explore the photon population dynamics in two coupled circuit QED systems. For a sufficiently weak intercavity photon hopping, as the photon-cavity coupling increases, the dynamics undergoes double transitions first from a delocalized to a localized phase and then from the localized to another delocalized phase. The latter delocalized phase is distinguished from the former one; instead of oscillating between the two cavities, the photons rapidly quasiequilibrate over the two cavities. These intriguing features are attributed to an interplay between two qualitatively distinctive nonlinear behaviors of the circuit QED systems in the utrastrong coupling regime, whose distinction has been widely overlooked. PMID:27127967
Physical Angular Momentum Separation for QED
Sun, Weimin
2016-01-01
We study the non-uniqueness problem of the gauge-invariant angular momentum separation for the case of QED, which stems from the recent controversy concerning the proper definitions of the orbital angular momentum and spin operator of the individual parts of a gauge field system. For the free quantum electrodynamics without matter, we show that the basic requirement of Euclidean symmetry selects a unique physical angular momentum separation scheme from the multitude of the possible angular momentum separation schemes constructed using the various Gauge Invariant Extentions. Based on these results, we propose a set of natural angular momentum separation schemes for the case of interacting QED by invoking the formalism of asymptotic fields. Some perspectives on such a problem for the case of QCD are briefly discussed.
Design of a high power three-cavity gyroklystron system
International Nuclear Information System (INIS)
The University of Maryland is designing a 30 MW gyroklystron amplifier to demonstrate the feasibility of this type of device as a driver for future 1-TeV linear colliders. The authors' system uses a beam produced by a magnetron injection gun. The system is designed to yield a 500 kV, 200 A, 1 μs beam with α = 1.5 and low velocity spread. Linear collider systems require a large number of microwave sources operating in a phase-locked mode, and thus large input powers will not be available. The authors' modeling has shown that to achieve the necessary gain they must use a system with three or more cavities. The experimental effort has focused on characterizing the beam with air core transformers, 90 degrees-sector capacitive probes, diamagnetic loops and a B probe. The authors have also built and have tested a TE011 two-cavity device. This has allowed to study the start oscillation current and test the design codes on a relatively simple system before attempting the more complex three-cavity system
Cooling and control of a cavity opto-electromechanical system
Lee, Kwan H; Harris, Glen I; Knittel, Joachim; Bowen, Warwick P
2009-01-01
Mechanical oscillators provide a quintessential example of the profound difference between quantum and classical behaviour. However, the quantum regime is yet to be observed. Rapid progress is underway in cavity optomechanical systems (COMS) and nanoelectromechanical systems (NEMS). COMS have superior mechanical transduction sensitivity, able to resolve mechanical zero-point fluctuations. However, the electrical actuation of NEMS provides far greater scope for quantum control. By combining electrical gradient forces from NEMS with the ultrasensitive transduction from COMS, we implement a cavity optoelectromechanical system (COEMS), demonstrating both control and feedback cooling capabilities. Out-of-loop mechanical transduction provides, for the first time, independent temperature verification even when opto-mechanical correlations exist due to strong interactions such as measurement backaction. This technology has significance in fundamental science, improving our capacity to engineer mechanical quantum syst...
International Nuclear Information System (INIS)
The thermodynamics of gauge theories such as QED and QCD are slightly more complicated than that of theories such as scalar field theory or free fremion field theory. We shall consider QED in some detail in this lecture, and shall generalize the results we find to more complicated gauge theories such as QCD. The results of this analysis are easily generalized to non-abelian gauge theories with scalar fields and spontaneous symmetry breaking such as GUTS
Cavity Beam Position Monitor System for ATF2
Energy Technology Data Exchange (ETDEWEB)
Boogert, Stewart; /Oxford U., JAI; Boorman, Gary; /Oxford U., JAI; Swinson, Christina; /Oxford U., JAI; Ainsworth, Robert; /Royal Holloway, U. of London; Molloy, Stephen; /Royal Holloway, U. of London; Aryshev, Alexander; /KEK, Tsukuba; Honda, Yosuke; /KEK, Tsukuba; Tauchi, Toshiaki; /KEK, Tsukuba; Terunuma, Nobuhiro; /KEK, Tsukuba; Urakawa, Junji; /KEK, Tsukuba; Frisch, Josef; /SLAC; May, Justin; /SLAC; McCormick, Douglas; /SLAC; Nelson, Janice; /SLAC; Smith, Tonee; /SLAC; White, Glen; /SLAC; Woodley, Mark; /SLAC; Heo, Ae-young; /Kyungpook Natl. U.; Kim, Eun-San; /Kyungpook Natl. U.; Kim, Hyoung-Suk; /Kyungpook Natl. U.; Kim, Youngim; /Kyungpook Natl. U. /University Coll. London /Kyungpook Natl. U. /Fermilab /Pohang Accelerator Lab.
2012-07-09
The Accelerator Test Facility 2 (ATF2) in KEK, Japan, is a prototype scaled demonstrator system for the final focus required for a future high energy lepton linear collider. The ATF2 beam-line is instrumented with a total of 38 C and S band resonant cavity beam position monitors (CBPM) with associated mixer electronics and digitizers. The current status of the BPM system is described, with a focus on operational techniques and performance. The ATF2 C-band system is performing well, with individual CBPM resolution approaching or at the design resolution of 50 nm. The changes in the CBPM calibration observed over three weeks can probably be attributed to thermal effects on the mixer electronics systems. The CW calibration tone power will be upgraded to monitor changes in the electronics gain and phase. The four S-band CBPMs are still to be investigated, the main problem associated with these cavities is a large cross coupling between the x and y ports. This combined with the large design dispersion in that degion makes the digital signal processing difficult, although various techniques exist to determine the cavity parameters and use these coupled signals for beam position determination.
Energy Technology Data Exchange (ETDEWEB)
Lange, B.
2006-12-20
Combining an optical resonator with an ion trap provides the possibility for QED experiments with single or few particles interacting with a single mode of the electro-magnetic field (Cavity-QED). In the present setup, fluctuations in the count rate on a time scale below 30 seconds were purely determined by the photon statistics due to finite emission and detection efficiency, whereas a marginal drift of the system was noticeable above 200 seconds. To find methods to increase the efficiency of the photon source, investigations were conducted and experimental improvements of the setup implemented in the frame of this thesis. Damping of the resonator field and coupling of ion and field were considered as the most important factors. To reduce the damping of the resonator field, a resonator with a smaller transmissivity of the output mirror was set up. The linear trap used in the experiment allows for the interaction of multiple ions with the resonator field, so that more than one photon may be emitted per pump pulse. This was investigated in this thesis with two ions coupled to the resonator. The cross correlation of the emitted photons was measured with the Hanbury Brown-Twiss method. (orig.)
Axisymmetric Predictions of Fluid Flow inside a Rotating Cavity System
Directory of Open Access Journals (Sweden)
Mujeebuddin Memon
2013-07-01
Full Text Available Accurate prediction of fluid flow in the rotating cavity system is of practical interest as it is most commonly used in the gas turbine engines and compressors. This paper presents the numerical predictions of a rotating cavity flow system for Reynolds numbers of the range 1x105 < Re? < 4x105 and two different mass flow rates Cw=1092 and 2184. A finite-difference technique is employed for a Steady-state solution in the axisymmetric cylindrical polar coordinate frame of reference. The two low Reynolds number turbulence models, the low Reynolds number k-? model and the low Reynolds number second moment closure have been used to compute the basic characteristics of the flow inside the rotating cavity flow system. Different flow regions have been identified by computing flow structures and dimensions of those regions have also been studied under different flow rates. A comparison of the computed variation of moment coefficient of both the turbulence models are presented for the above mentioned parameters and the parametric effects on the moment coefficients have been discussed
International Nuclear Information System (INIS)
The generation and control of quantum states of spatially-separated qubits distributed in different cavities constitute fundamental tasks in cavity quantum electrodynamics (QED). An interesting question in this context is how to prepare entanglement and realize quantum information transfer between qubits located at different cavities, which are important in large-scale quantum information processing. In this paper, we consider a physical system consisting of two cavities and three qubits. Two of the qubits are placed in two different cavities while the remaining one acts as a coupler, which is used to connect the two cavities. We propose an approach for generating quantum entanglement and implementing quantum information transfer between the two spatially-separated inter-cavity qubits. The quantum operations involved in this proposal are performed by a virtual photon process; thus the cavity decay is greatly suppressed during operations. In addition, to complete these tasks, only one coupler qubit and one operation step are needed. Moreover, there is no need to apply classical pulses, so that the engineering complexity is much reduced and the operation procedure is greatly simplified. Finally, our numerical results illustrate that high-fidelity implementation of this proposal using superconducting phase qubits and one-dimensional transmission line resonators is feasible for current circuit QED implementations. This proposal can also be applied to other types of superconducting qubits, including flux and charge qubits. (paper)
Yang, Chui-Ping; Su, Qi-Ping; Nori, Franco
2013-11-01
The generation and control of quantum states of spatially-separated qubits distributed in different cavities constitute fundamental tasks in cavity quantum electrodynamics (QED). An interesting question in this context is how to prepare entanglement and realize quantum information transfer between qubits located at different cavities, which are important in large-scale quantum information processing. In this paper, we consider a physical system consisting of two cavities and three qubits. Two of the qubits are placed in two different cavities while the remaining one acts as a coupler, which is used to connect the two cavities. We propose an approach for generating quantum entanglement and implementing quantum information transfer between the two spatially-separated inter-cavity qubits. The quantum operations involved in this proposal are performed by a virtual photon process; thus the cavity decay is greatly suppressed during operations. In addition, to complete these tasks, only one coupler qubit and one operation step are needed. Moreover, there is no need to apply classical pulses, so that the engineering complexity is much reduced and the operation procedure is greatly simplified. Finally, our numerical results illustrate that high-fidelity implementation of this proposal using superconducting phase qubits and one-dimensional transmission line resonators is feasible for current circuit QED implementations. This proposal can also be applied to other types of superconducting qubits, including flux and charge qubits.
Entangling atoms in bad cavities
Sorensen, Anders S.; Molmer, Klaus
2002-01-01
We propose a method to produce entangled spin squeezed states of a large number of atoms inside an optical cavity. By illuminating the atoms with bichromatic light, the coupling to the cavity induces pairwise exchange of excitations which entangles the atoms. Unlike most proposals for entangling atoms by cavity QED, our proposal does not require the strong coupling regime g^2/\\kappa\\Gamma>> 1, where g is the atom cavity coupling strength, \\kappa is the cavity decay rate, and \\Gamma is the dec...
International Nuclear Information System (INIS)
Existence of a strong coupling phase in QED has been suggested in solutions of the Schwinger-Dyson equation and in Monte Carlo simulation of lattice QED. In this article we recapitulate the previous arguments, and formulate the problem in the modern framework of the renormalization theory, Wilsonian renormalization. This scheme of renormalization gives the best understanding of the basic structure of a field theory especially when it has a multi-phase structure. We resolve some misleading arguments in the previous literature. Then we set up a strategy to attack the strong phase, if any. We describe a trial; a coupled Schwinger-Dyson equation. Possible picture of the strong coupling phase QED is presented. (author)
Squeezing enhancement by damping in a driven atom-cavity system
Nha, H; Kim, S W; An, K; Nha, Hyunchul; Chough, Young-Tak; Kim, Sang Wook; An, Kyungwon
2001-01-01
In a driven atom-cavity coupled system in which the two-level atom is driven by a classical field, the cavity mode which should be in a coherent state in the absence of its reservoir, can be squeezed by coupling to its reservoir. The squeezing effect is enhanced as the damping rate of the cavity is increased to some extent.
QED Reloaded: Towards a Pluralistic Formal Library of Mathematical Knowledge
Directory of Open Access Journals (Sweden)
Michael Kohlhase
2016-01-01
Full Text Available Proposed in 1994, the ``QED project'' was one of the seminally influential initiatives in automated reasoning: It envisioned the formalization of ``all of mathematics'' and the assembly of these formalizations in a single coherent database. Even though it never led to the concrete system, communal resource, or even joint research envisioned in the QED manifesto, the idea lives on and shapes the research agendas of a significant part of the communityThis paper surveys a decade of work on representation languages and knowledge management tools for mathematical knowledge conducted in the KWARC research group at Jacobs University Bremen.It assembles the various research strands into a coherent agenda for realizing the QED dream with modern insights and technologies.
Universal quantum gates for photon-atom hybrid systems assisted by bad cavities
Wang, Guan-yu; Liu, Qian; Wei, Hai-Rui; Ai, Qing; Deng, Fu-Guo
2015-01-01
We present two deterministic schemes for constructing a CNOT gate and a Toffoli gate on photon-atom and photon-atom-atom hybrid quantum systems assisted by bad cavities, respectively. They are achieved by cavity-assisted photon scattering and work in the intermediate coupling region with bad cavities, which relaxes the difficulty of their implementation in experiment. Also, bad cavities are feasible for fast quantum operations and reading out information. Compared with previous works, our sch...
Universal quantum gates for photon-atom hybrid systems assisted by bad cavities
Guan-Yu Wang; Qian Liu; Hai-Rui Wei; Tao Li; Qing Ai; Fu-Guo Deng
2016-01-01
We present two deterministic schemes for constructing a CNOT gate and a Toffoli gate on photon-atom and photon-atom-atom hybrid quantum systems assisted by bad cavities, respectively. They are achieved by cavity-assisted photon scattering and work in the intermediate coupling region with bad cavities, which relaxes the difficulty of their implementation in experiment. Also, bad cavities are feasible for fast quantum operations and reading out information. Compared with previous works, our sch...
Leading quantum gravitational corrections to QED
Butt, M. S.
2006-01-01
We consider the leading post-Newtonian and quantum corrections to the non-relativistic scattering amplitude of charged spin-1/2 fermions in the combined theory of general relativity and QED. The coupled Dirac-Einstein system is treated as an effective field theory. This allows for a consistent quantization of the gravitational field. The appropriate vertex rules are extracted from the action, and the non-analytic contributions to the 1-loop scattering matrix are calculated in the non-relativi...
CFD modeling of the HTR reactor cavity cooling system
International Nuclear Information System (INIS)
This report describes the heat transport under accident conditions from the reactor vessel wall of the INCOGEN installation to the environment. For this purpose, the heat transfer mechanisms as well as the flow patterns inside the cavity and the Reactor Cavity Cooling System (RCCS) have been calculated by the CFD (Computational Fluid Dynamics) code called CFDS-FLOW3D. The main purpose of the calculations is to determine the vessel wall temperature at which the power produced in the vessel is removed. An important assumption of the calculations is that a total of 1 MW of decay power and fission power has to be removed by the RCCS under accident conditions. In the reference calculation, about 80% of the heat is transported by radiation to the RCCS, while the remaining 20% is transported by convection of the gas in the cavity. The maximum calculated temperature on the outside of the vessel in 634 K. The reference calculation is assessed by a number of sensitivity calculations. In these calculations, the influence of the following parameters on the reactor vessel wall temperature has been determined: The turbulence model, the properties of the inlet and the outlet structures, the heat loss from the reactor vessel wall, the emissivity of structures, and the interaction between gas and radiation. Most of the parameters investigated have a small influence on the reactor vessel wall temperature. The following changes result in an increase of the reactor vessel wall temperature by 25 K or more: An increase of the heat loss from 1 MW to 2 MW, an increase of the inlet temperature from 300 K to 350 K, a decrease of the emissivity of the reactor vessel wall from 0.8 to 0.6, or very high concentrations of scattering aerosol particles. (orig.)
TESLA cavity modeling and digital implementation in FPGA technology for control system development
Energy Technology Data Exchange (ETDEWEB)
Czarski, T.; Pozniak, K.T.; Romaniuk, R.S. [Warsaw Univ. of Technology (Poland); Simrock, S. [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany)
2006-07-01
The electromechanical model of the TESLA cavity has been implemented in FPGA technology for real-time testing of the control system. The model includes Lorentz force detuning and beam loading effects. Step operation and vector stimulus operation modes are applied for the evaluation of a FPGA cavity simulator operated by a digital controller. The performance of the cavity hardware model is verified by comparing with a software model of the cavity implemented in the MATLAB system. The numerical aspects are considered for an optimal DSP calculation. Some experimental results are presented for different cavity operational conditions. (orig.)
TESLA cavity modeling and digital implementation in FPGA technology for control system development
International Nuclear Information System (INIS)
The electromechanical model of the TESLA cavity has been implemented in FPGA technology for real-time testing of the control system. The model includes Lorentz force detuning and beam loading effects. Step operation and vector stimulus operation modes are applied for the evaluation of a FPGA cavity simulator operated by a digital controller. The performance of the cavity hardware model is verified by comparing with a software model of the cavity implemented in the MATLAB system. The numerical aspects are considered for an optimal DSP calculation. Some experimental results are presented for different cavity operational conditions. (orig.)
QED corrections to atomic wavefunctions in highly charged ions
International Nuclear Information System (INIS)
Bound electron states in highly charged ions are strongly influenced by the effects of relativity and quantum electrodynamics (QED). These effects induce shifts of the binding energies as well as corrections to observables related to atomic processes. In this work a numerical procedure is described and implemented in which the QED effects are treated as corrections to relativistic bound-state wavefunctions. This approach, which is based on the recently developed covariant evolution-operator formalism, allows for a merging of QED with the standard methods of many-body perturbation theory. In particular, it enables an evaluation of the combined effect of QED and electron correlation in few-electron systems. Numerical results for this effect are presented for the ground state energy of helium-like ions. A detailed analysis of the contribution from the electron self-energy is carried out in both the Feynman and Coulomb gauge. It is found that the Feynman gauge suffers from large numerical cancellations and acquires significant contributions from terms involving multiple interactions with the nuclear potential (the so-called many-potential terms), while the Coulomb gauge is well suited for an approximate treatment based on terms involving only freely propagating electrons (the zero-potential terms). With the help of QED-corrected wavefunctions it is also possible to compute corrections to observables in basic atomic processes. In this work some of the one-loop QED corrections (those derivable from perturbed wavefunctions and energies) to the differential cross section and distribution of polarization in radiative recombination of initially bare uranium nuclei are evaluated, as well as the corresponding corrections to the ratio τE1/τM2 of the electric dipole and magnetic quadrupole transition amplitudes in the 2p3/2→1s radiative decay of hydrogenlike uranium. The results from these calculations are all of the expected magnitude, namely on the order of the fine
QED corrections to atomic wavefunctions in highly charged ions
Energy Technology Data Exchange (ETDEWEB)
Holmberg, Johan
2015-11-18
Bound electron states in highly charged ions are strongly influenced by the effects of relativity and quantum electrodynamics (QED). These effects induce shifts of the binding energies as well as corrections to observables related to atomic processes. In this work a numerical procedure is described and implemented in which the QED effects are treated as corrections to relativistic bound-state wavefunctions. This approach, which is based on the recently developed covariant evolution-operator formalism, allows for a merging of QED with the standard methods of many-body perturbation theory. In particular, it enables an evaluation of the combined effect of QED and electron correlation in few-electron systems. Numerical results for this effect are presented for the ground state energy of helium-like ions. A detailed analysis of the contribution from the electron self-energy is carried out in both the Feynman and Coulomb gauge. It is found that the Feynman gauge suffers from large numerical cancellations and acquires significant contributions from terms involving multiple interactions with the nuclear potential (the so-called many-potential terms), while the Coulomb gauge is well suited for an approximate treatment based on terms involving only freely propagating electrons (the zero-potential terms). With the help of QED-corrected wavefunctions it is also possible to compute corrections to observables in basic atomic processes. In this work some of the one-loop QED corrections (those derivable from perturbed wavefunctions and energies) to the differential cross section and distribution of polarization in radiative recombination of initially bare uranium nuclei are evaluated, as well as the corresponding corrections to the ratio τ{sub E1}/τ{sub M2} of the electric dipole and magnetic quadrupole transition amplitudes in the 2p{sub 3/2}→1s radiative decay of hydrogenlike uranium. The results from these calculations are all of the expected magnitude, namely on the order
Dissipated power measurements in the A0 SRF cavity system
International Nuclear Information System (INIS)
Fermilab operates a single TESLA 9-cell superconducting RF cavity in support of a photoelectron R and D beam line. Power going into the 1.8K cryogenic system via static heat leak and RF dissipation is measured from the rate of rise of the pressure in the helium bath. This paper describes the techniques used to determine the cryostat heat load and the RF performance of the cavity. A photo-injector has been constructed at Fermilab to produce a low-energy (14--18 MeV) electron beam with high charge per bunch (8 nC), short bunch length (1 mm RMS), and small transverse emittance (<20 mm mrad). The facility was used to commission a photo-cathode RF gun for the TESLA Test Facility (TTF) Linac at DESY. At present, the Fermilab machine is being used for R and D in bunch length compression and fast beam diagnostics; experiments in plasma wake field acceleration and channeling acceleration are in preparation
Ooi, K. J. A.; Bai, P.; Gu, M. X.; Ang, L. K.
2012-07-01
A plasmonic coupled-cavity system, which consists of a quarter-wave coupler cavity, a resonant Fabry-Pérot detector nanocavity, and an off-resonant reflector cavity, is used to enhance the localization of surface plasmons in a plasmonic detector. The coupler cavity is designed based on transmission line theory and wavelength scaling rules in the optical regime, while the reflector cavity is derived from off-resonant resonator structures to attenuate transmission of plasmonic waves. We observed strong coupling of the cavities in simulation results, with an 86% improvement of surface plasmon localization achieved. The plasmonic coupled-cavity system may find useful applications in areas of nanoscale photodetectors, sensors, and an assortment of plasmonic-circuit devices.
The Phase Servo Tuner Control system of the ALS 500 MHz cavity
International Nuclear Information System (INIS)
Three 500 MHz cavities are used in the Booster and Storage Ring of the Advanced Light Source (ALS). Due to different varying parameters, a control system is required to keep the cavities in tune during operation. The tuning of the 500 MHz cavity is achieved by detecting the phase error between the drive signal and the cavity probe signal. The error signal is amplified and used to drive a stepping motor which in turn moves a metallic cylinder in or out of the cavity to achieve tuning
Note: auto-relock system for a bow-tie cavity for second harmonic generation.
Haze, Shinsuke; Hata, Sousuke; Fujinaga, Munekazu; Mukaiyama, Takashi
2013-02-01
This Note reports on the implementation of an automatic relocking system for a bow-tie cavity for second harmonic generation to produce an ultra-violet laser source. The system is based on a sample-and-hold technique for controlling the cavity length using simple servo electronics. Long-term stabilization of the cavity output power is successfully achieved, which makes this system suitable for designing stable atomic physics experiments. PMID:23464273
Cavity BPM System Tests for the ILC Spectrometer
Energy Technology Data Exchange (ETDEWEB)
Slater, M.
2007-12-21
The main physics program of the International Linear Collider (ILC) requires a measurement of the beam energy at the interaction point with an accuracy of 10{sup -4} or better. To achieve this goal a magnetic spectrometer using high resolution beam position monitors (BPMs) has been proposed. This paper reports on the cavity BPM system that was deployed to test this proposal. We demonstrate sub-micron resolution and micron level stability over 20 hours for a 1 m long BPM triplet. We find micron-level stability over 1 hour for 3 BPM stations distributed over a 30 m long baseline. The understanding of the behavior and response of the BPMs gained from this work has allowed full spectrometer tests to be carried out.
RF and Data Acquisition Systems for Fermilab's ILC SRF Cavity Vertical Test Stand
International Nuclear Information System (INIS)
Fermilab is developing a facility for vertical testing of SRF cavities as part of a program to improve cavity performance reproducibility for the ILC. The RF system for this facility, using the classic combination of oscillator, phase detector/mixer, and loop amplifier to detect the resonant cavity frequency and lock onto the cavity, is based on the proven production cavity test systems used at Jefferson Lab for CEBAF and SNS cavity testing. The design approach is modular in nature, using commercial-off-the-shelf (COTS) components. This yields a system that can be easily debugged and modified, and with ready availability of spares. Data acquisition and control is provided by a PXI-based hardware platform in conjunction with software developed in the LabView programming environment. This software provides for amplitude and phase adjustment of incident RF power, and measures all relevant cavity power levels, cavity thermal environment parameters, as well as field emission-produced radiation. It also calculates the various cavity performance parameters and their associated errors. Performance during system commissioning and initial cavity tests will be presented
Updating of Optical Inspection System for 6 GHz Superconducting Cavities
Institute of Scientific and Technical Information of China (English)
YU; Guo-long
2013-01-01
As a validation tool for the material properties and the surface treatment process,6 GHz superconducting cavity needs complex surface treatment process during its manufacture.It is verynecessary to record and monitor the statues of the internal surface of the cavity after each surface treatment,such as ultrasonic washing,mechanical polishing,electronic polishing(EP),buffered chemical
Phonon routing in integrated optomechanical cavity-waveguide systems
Fang, Kejie; Luan, Xingsheng; Painter, Oskar
2015-01-01
The mechanical properties of light have found widespread use in the manipulation of gas-phase atoms and ions, helping create new states of matter and realize complex quantum interactions. The field of cavity-optomechanics strives to scale this interaction to much larger, even human-sized mechanical objects. Going beyond the canonical Fabry-Perot cavity with a movable mirror, here we explore a new paradigm in which multiple cavity-optomechanical elements are wired together to form optomechanical circuits. Using a pair of optomechanical cavities coupled together via a phonon waveguide we demonstrate a tunable delay and filter for microwave-over-optical signal processing. In addition, we realize a tight-binding form of mechanical coupling between distant optomechanical cavities, leading to direct phonon exchange without dissipation in the waveguide. These measurements indicate the feasibility of phonon-routing based information processing in optomechanical crystal circuitry, and further, to the possibility of re...
Institute of Scientific and Technical Information of China (English)
Lin Xiu; Li Hong-Cai; Yang Rong-Can; Huang Zhi-Ping
2007-01-01
This paper proposes a scheme for realizing entanglement swapping in cavity QED. The scheme is based on the resonant interaction of a two-mode cavity field with a A-type three-level atom. In contrast with the previously proposed schemes, the present scheme is ascendant, since the fidelity is 1.0 and the joint measurement isn't needed. And the scheme is experimentally feasible based on the current cavity QED technique.
International Nuclear Information System (INIS)
Physicists believe that the world is described in terms of gauge theories. A popular technique for investigating these theories is to discretize them onto a lattice and simulate numerically by a computer, yielding so-called lattice gauge theory. Such computations require at least 1014 floating-point operations, necessitating the use of advanced architecture supercomputers such as the Connection Machine. Currently the most important gauge theory to be solved is that describing the sub-nuclear world of high energy physics: quantum chromo-dynamics (QCD). The simplest example of a gauge theory is Quantum electro-dynamics (QED), the theory which describes the interaction of electrons and photons. Simulation of QCD requires computer software very similar to that for the simpler QED problem. The authors' current QED code achieves a computational rate of 1.6 million lattice site updates per second for a Monte Carlo algorithm, and 7.4 million site updates per second for a microcanonical algorithm. The estimate performance for a Monte Carlo QCD code is 200,000 site updates per second (or 5.6 Gflops/sec)
International Nuclear Information System (INIS)
The relevance of Quantum Electrodynamics (Qed) in contemporary atomic structure theory is reviewed. Recent experimental advances allow both the production of heavy ions of high charge as well as the measurement of atomic properties with a precision never achieved before. The description of heavy atoms with few electrons via the successive incorporation of one, two, etcetera photons in a rigorous manner and within the bound state Furry representation of Qed is technically feasible. For many-electron atoms the many-body (correlation) effects are very important and it is practically impossible to evaluate all the relevant Feynman diagrams to the required accuracy. Thus, it is necessary to develop a theoretical scheme in which the radiative and nonradiative effects are taken into account in an effective way making emphasis in electronic correlation. Preserving gauge invariance, and avoiding both continuum dissolution and variational collapse are basic problems that must be solved when using effective potential methods and finite-basis representations of them. In this context, we shall discuss advances and problems in the description of atoms as Qed bound states. (Author)
Two-resonator circuit QED: A superconducting quantum switch
International Nuclear Information System (INIS)
Coupling different kind of superconducting (sc) qubits to on-chip microwave resonators has strongly advanced the field of circuit QED. Regarding the application of circuit QED systems in quantum information processing it would be highly desirable to switch on and off the interaction between two resonators. We introduce a formalism for two-resonator circuit QED where two on-chip microwave resonators are simultaneously coupled to one sc qubit. In this three-circuit network, the qubit mediates a geometric and a dynamic second-order interaction between the two resonators. These two coupling strengths can be tuned to be equal by varying the qubit operation point, thus permitting to switch on and off the interaction between the resonators. We discuss the effect of the qubit on the dynamic second-order coupling and how it can be deliberately manipulated to realize a sc quantum switch. Finally, we present a realistic design for implementing a two-resonator circuit QED setup based on a flux qubit and show preliminary experimental results.
Institute of Scientific and Technical Information of China (English)
Zhong Zhi-Rong
2008-01-01
An alternative scheme to approximately conditionally teleport entangled two-mode cavity state without Bell state measurement in cavity QED is proposed.The scheme is based on the resonant interaction of a ladder-type three-level atom with two bimodal cavities.The entangled cavity state is reconstructed with only one atom interacting with the two cavities successively.
Zhong, Zhi-Rong
2008-05-01
An alternative scheme to approximately conditionally teleport entangled two-mode cavity state without Bell state measurement in cavity QED is proposed. The scheme is based on the resonant interaction of a ladder-type three-level atom with two bimodal cavities. The entangled cavity state is reconstructed with only one atom interacting with the two cavities successively.
Experimental Studies of NGNP Reactor Cavity Cooling System With Water
Energy Technology Data Exchange (ETDEWEB)
Corradini, Michael; Anderson, Mark; Hassan, Yassin; Tokuhiro, Akira
2013-01-16
This project will investigate the flow behavior that can occur in the reactor cavity cooling system (RCCS) with water coolant under the passive cooling-mode of operation. The team will conduct separate-effects tests and develop associated scaling analyses, and provide system-level phenomenological and computational models that describe key flow phenomena during RCCS operation, from forced to natural circulation, single-phase flow and two-phase flow and flashing. The project consists of the following tasks: Task 1. Conduct separate-effects, single-phase flow experiments and develop scaling analyses for comparison to system-level computational modeling for the RCCS standpipe design. A transition from forced to natural convection cooling occurs in the standpipe under accident conditions. These tests will measure global flow behavior and local flow velocities, as well as develop instrumentation for use in larger scale tests, thereby providing proper flow distribution among standpipes for decay heat removal. Task 2. Conduct separate-effects experiments for the RCCS standpipe design as two-phase flashing occurs and flow develops. As natural circulation cooling continues without an ultimate heat sink, water within the system will heat to temperatures approaching saturation , at which point two-phase flashing and flow will begin. The focus is to develop a phenomenological model from these tests that will describe the flashing and flow stability phenomena. In addition, one could determine the efficiency of phase separation in the RCCS storage tank as the two-phase flashing phenomena ensues and the storage tank vents the steam produced. Task 3. Develop a system-level computational model that will describe the overall RCCS behavior as it transitions from forced flow to natural circulation and eventual two-phase flow in the passive cooling-mode of operation. This modeling can then be used to test the phenomenological models developed as a function of scale.
Jazayeri, Amir M
2016-01-01
Optomechanics of nanoparticles purports to reach the quantum regime, but experimental evidence suggests otherwise. We believe that the discrepancy is due to the omission of the deleterious effects of the EM field levitating the particle. This letter focuses on quantum fluctuations in the levitating field. In a cavity-assisted system, they lead to fluctuations in the gradient force, and encourage escape of the particle. In a feedback system, they lead to the detector shot noise besides fluctuations in the gradient force and radiation pressure, and render the system very vulnerable to the thermal noise of the feedback circuit.
Structure an dynamics in cavity quantum electrodynamics
International Nuclear Information System (INIS)
Much of the theoretical background related to the radiative processes for atoms in the presence of boundaries comes from two often disjoint areas, namely cavity quantum electrodynamics and optical bistability with two-state atoms. While the former of these areas has been associated to a large degree with studies in a perturbative domain of altered associated to a large degree with studies in a perturbative domain of altered emission processes in the presence of boundaries other than those of free space, the latter is often viewed from the perspective of hysteresis cycles and device applications. With the exception of the laser, however, perhaps the most extensive investigations of quantum statistical processes in quantum optics are to be found in the literature on bistability with two-state atoms and on cavity QED. Unfortunately, the degree of overlap of these two areas has not always been fully appreciated. This circumstance is perhaps due in part to the fact that the investigation of dynamical processes in cavity QED has had as its cornerstone the Jaynes-Cummings problem, with extensions to include, for example, small amounts of dissipation. On the other hand, a principle aspect of the bistability literature has been the study of quantum fluctuations in open systems for which dissipation plays a central role, but for which the coherent quantum dynamics of the Haynes-Cummings model are to a large measure lost due to the usual assumption of large system size and weak coupling (as in the standard theory of the laser). 132 refs., 26 figs., 1 tab
Dynamically controlling the emission of single excitons in photonic crystal cavities
Pagliano, Francesco; Xia, Tian; van Otten, Frank; Johne, Robert; Fiore, Andrea
2014-01-01
Single excitons in semiconductor microcavities represent a solid-state and scalable platform for cavity quantum electrodynamics (c-QED), potentially enabling an interface between flying (photon) and static (exciton) quantum bits in future quantum networks. While both single-photon emission and the strong coupling regime have been demonstrated, further progress has been hampered by the inability to control the coherent evolution of the c-QED system in real time, as needed to produce and harness charge-photon entanglement. Here, using the ultrafast electrical tuning of the exciton energy in a photonic crystal (PhC) diode, we demonstrate the dynamic control of the coupling of a single exciton to a PhC cavity mode on a sub-ns timescale, faster than the natural lifetime of the exciton, for the first time. This opens the way to the control of single-photon waveforms, as needed for quantum interfaces, and to the real-time control of solid-state c-QED systems.
Bistability and Entanglement of a Two-Mode Cavity Optomechanical System
Yousif, Taha; Zhou, Wenjun; Zhou, Ling
2016-02-01
We investigate the bistable properties and the entanglement in a two-mode cavity optomechanical system. Our results show that the bistable regime in terms of pumping amplitude can be adjusted by tuning the detunning. Although the two modes of the cavity interact with the same mechanical mode, there is no entanglement between them, while the two modes entangle with the mechanical mode seperately.
A temperature-mapping system for multi-cell SRF accelerating cavities
Ge, M; Furuta, F; Smith, E; Liepe, M; Posen, S; Padamsee, H; Hartill, D; Mi, X
2015-01-01
A Temperature mapping (T-map) system for Superconducting Radio Frequency (SRF) cavities consists of a thermometer array positioned precisely on an exterior cavity wall, capable of detecting small increases in temperature; therefore it is a powerful tool for research on the quality factor (Q0) of SRF cavities. A new multi-cell T-mapping system is has been developed at Cornell University. The system has nearly two thousand thermometers to cover 7-cell SRF cavities for Cornell ERL project. A new multiplexing scheme was adopted to reduce number of wires. A 1mK resolution of the temperature increase Delta T is achieved. A 9-cell cavity of TESLA geometry was tested with the T-map system. By converting Delta T to power loss and quality factor, it has been found that for this cavity, most surface losses were generated by the first cell when the accelerating gradient is increased above 15MV/m. The comparison of Q-value between with and without hotspots shows the heating on cavity wall degraded cavity Q0 about 1.65 tim...
QED vacuum loops and inflation
Energy Technology Data Exchange (ETDEWEB)
Fried, H.M. [Brown University, Department of Physics, Providence, RI (United States); Gabellini, Y. [UMR 6618 CNRS, Institut Non Lineaire de Nice, Valbonne (France)
2015-03-01
A QED-based model of a new version of vacuum energy has recently been suggested, which leads to a simple, finite, one parameter representation of dark energy. An elementary, obvious, but perhaps radical generalization is then able to describe both dark energy and inflation in the same framework of vacuum energy. One further, obvious generalization then leads to a relation between inflation and the big bang, to the automatic inclusion of dark matter, and to a possible understanding of the birth (and death) of a universe. (orig.)
Leading quantum gravitational corrections to QED
Butt, M S
2006-01-01
We consider the leading post-Newtonian and quantum corrections to the non-relativistic scattering amplitude of charged spin-1/2 fermions in the combined theory of general relativity and QED. The coupled Dirac-Einstein system is treated as an effective field theory. This allows for a consistent quantization of the gravitational field. The appropriate vertex rules are extracted from the action, and the non-analytic contributions to the 1-loop scattering matrix are calculated in the non-relativistic limit. The non-analytical parts of the scattering amplitude are known to give the long range, low energy, leading quantum corrections, are used to construct the leading post-Newtonian and quantum corrections to the two-particle non-relativistic scattering matrix potential for two massive fermions with electric charge.
Emergent SUSY Theories: QED, SM & GUT
Chkareuli, J L
2014-01-01
It might be expected that only global symmetries are fundamental symmetries of Nature, whereas local symmetries and associated massless gauge fields could solely emerge due to spontaneous breaking of underlying spacetime symmetries involved, such as relativistic invariance and supersymmetry. This breaking, taken in the form of the nonlinear -model type pattern for vector fields or superfields, puts essential restrictions on geometrical degrees of freedom of a physical field system that makes it to adjust itself in such a way that its global internal symmetry G turns into the local symmetry G_{loc}. Remarkably, this emergence process may naturally be triggered by spontaneously broken supersymmetry, as is illustrated in detail by an example of a general supersymmetric QED model which is then extended to electroweak models and grand unified theories. Among others, the U(1)xSU(2) symmetrical Standard Model and flipped SU(5) GUT appear preferable to emerge at high energies.
Single quantum dot controls a plasmonic cavity's scattering and anisotropy.
Hartsfield, Thomas; Chang, Wei-Shun; Yang, Seung-Cheol; Ma, Tzuhsuan; Shi, Jinwei; Sun, Liuyang; Shvets, Gennady; Link, Stephan; Li, Xiaoqin
2015-10-01
Plasmonic cavities represent a promising platform for controlling light-matter interaction due to their exceptionally small mode volume and high density of photonic states. Using plasmonic cavities for enhancing light's coupling to individual two-level systems, such as single semiconductor quantum dots (QD), is particularly desirable for exploring cavity quantum electrodynamic (QED) effects and using them in quantum information applications. The lack of experimental progress in this area is in part due to the difficulty of precisely placing a QD within nanometers of the plasmonic cavity. Here, we study the simplest plasmonic cavity in the form of a spherical metallic nanoparticle (MNP). By controllably positioning a semiconductor QD in the close proximity of the MNP cavity via atomic force microscope (AFM) manipulation, the scattering spectrum of the MNP is dramatically modified due to Fano interference between the classical plasmonic resonance of the MNP and the quantized exciton resonance in the QD. Moreover, our experiment demonstrates that a single two-level system can render a spherical MNP strongly anisotropic. These findings represent an important step toward realizing quantum plasmonic devices. PMID:26372957
Czarski, Tomasz; Romaniuk, Ryszard S.; Pozniak, Krzysztof T.; Simrock, Stefan
2004-07-01
The cavity control system for the TESLA -- TeV-Energy Superconducting Linear Accelerator project is initially introduced. The elementary analysis of the cavity resonator on RF (radio frequency) level and low level frequency with signal and power considerations is presented. For the field vector detection the digital signal processing is proposed. The electromechanical model concerning Lorentz force detuning is applied for analyzing the basic features of the system performance. For multiple cavities driven by one klystron the field vector sum control is considered. Simulink model implementation is developed to explore the feedback and feed-forward system operation and some experimental results for signals and power considerations are presented.
Levy, M C; Ratan, N; Sadler, J; Ridgers, C P; Kasim, M; Ceurvorst, L; Holloway, J; Baring, M G; Bell, A R; Glenzer, S H; Gregori, G; Ilderton, A; Marklund, M; Tabak, M; Wilks, S C; Norreys, P A
2016-01-01
Absorption covers the physical processes which convert intense photon flux into energetic particles when a high-power laser illuminates optically-thick matter. It underpins important petawatt-scale applications today, e.g., medical-quality proton beam production. However, development of ultra-high-field applications has been hindered since no study so far has described absorption throughout the entire transition from the classical to the quantum electrodynamical (QED) regime of plasma physics. Here we present a model of absorption that holds over an unprecedented six orders-of-magnitude in optical intensity and lays the groundwork for QED applications of laser-driven particle beams. We demonstrate 58% efficient \\gamma-ray production at $1.8\\times 10^{25}~\\mathrm{W~ cm^{-2}}$ and the creation of an anti-matter source achieving $4\\times 10^{24}\\ \\mathrm{positrons}\\ \\mathrm{cm^{-3}}$, $10^{6}~\\times$ denser than of any known photonic scheme. These results will find applications in scaled laboratory probes of bla...
Entangling movable mirrors in a double cavity system
DEFF Research Database (Denmark)
Pinard, Michel; Dantan, Aurelien Romain; Vitali, David;
2005-01-01
We propose a double-cavity set-up capable of generating a stationary entangled state of two movable mirrors at cryogenic temperatures. The scheme is based on the optimal transfer of squeezing of input optical fields to mechanical vibrational modes of the mirrors, realized by the radiation pressur...
Design study on side-coupled cavity linac in accelerator-driven energy system
International Nuclear Information System (INIS)
In the normal conductive project of high beam in density proton linac in accelerator-driven energy system, the high energy section uses side-coupled cavity linac(CCL)structure, its frequency is 700 MHz, and operates on π/2 mode. CCL section accelerates the 30 mA, 80 MeV proton beam from the coupled-cavity drift tube linac(CCDTL) to 1 GeV. The total length of CCL is 1064 m, the focusing lattice is FODO, the focusing period is 8βλ. Bore radii of the cavities are 2.00, 2.25 and 2.50 cm, respectively. The cavities are optimized with SUPERFISH code. The calculation results of the cavities and energy gain are presented
International Nuclear Information System (INIS)
The detection efficiency using the gravimetry method is significantly low; therefore, it requires large surveying time. The magnetometry method detects the cavities by the magnitude of the magnetic field. However, the magnetometry method is problematical in urban areas due to pipes and electrical installations. GPR is the method that uses high frequency electromagnetic wave. This method is widely used for the inspection; however, the detection accuracy of sinkholes can be low in specific soil types. In this study, to verify the feasibility of the neutron source-based inspection system to detect the cavity detection, the Monte Carlo simulation was performed using neutron source. The analysis shows that the detection of the cavity with the given condition is possible when the diameter of cavity is over 100 cm. However, the detection efficiency can be enough increased if some optimization strategies for the inspection are developed. Also, it is expected that the proposed inspection method can detect the expected locations of the cavities
Energy Technology Data Exchange (ETDEWEB)
Yim, Che Wook; Kim, Song Hyun; Kim, Do Hyun; Shin, Chang Ho [Hanyang University, Seoul (Korea, Republic of)
2015-05-15
The detection efficiency using the gravimetry method is significantly low; therefore, it requires large surveying time. The magnetometry method detects the cavities by the magnitude of the magnetic field. However, the magnetometry method is problematical in urban areas due to pipes and electrical installations. GPR is the method that uses high frequency electromagnetic wave. This method is widely used for the inspection; however, the detection accuracy of sinkholes can be low in specific soil types. In this study, to verify the feasibility of the neutron source-based inspection system to detect the cavity detection, the Monte Carlo simulation was performed using neutron source. The analysis shows that the detection of the cavity with the given condition is possible when the diameter of cavity is over 100 cm. However, the detection efficiency can be enough increased if some optimization strategies for the inspection are developed. Also, it is expected that the proposed inspection method can detect the expected locations of the cavities.
Large payload quantum steganography based on cavity quantum electrodynamics
International Nuclear Information System (INIS)
A large payload quantum steganography protocol based on cavity quantum electrodynamics (QED) is presented in this paper, which effectively uses the evolutionary law of atoms in cavity QED. The protocol builds up a hidden channel to transmit secret messages using entanglement swapping between one GHZ state and one Bell state in cavity QED together with the Hadamard operation. The quantum steganography protocol is insensitive to cavity decay and the thermal field. The capacity, imperceptibility and security against eavesdropping are analyzed in detail in the protocol. It turns out that the protocol not only has good imperceptibility but also possesses good security against eavesdropping. In addition, its capacity for a hidden channel achieves five bits, larger than most of the previous quantum steganography protocols. (general)
Large payload quantum steganography based on cavity quantum electrodynamics
Institute of Scientific and Technical Information of China (English)
Ye Tian-Yu; Jiang Li-Zhen
2013-01-01
A large payload quantum steganography protocol based on cavity quantum electrodynamics (QED) is presented in this paper,which effectively uses the evolutionary law of atoms in cavity QED.The protocol builds up a hidden channel to transmit secret messages using entanglement swapping between one GHZ state and one Bell state in cavity QED together with the Hadamard operation.The quantum steganography protocol is insensitive to cavity decay and the thermal field.The capacity,imperceptibility and security against eavesdropping are analyzed in detail in the protocol.It turns out that the protocol not only has good imperceptibility but also possesses good security against eavesdropping.In addition,its capacity for a hidden channel achieves five bits,larger than most of the previous quantum steganography protocols.
Relativistic QED Plasma at Extremely High Temperature
Masood, Samina S
2016-01-01
Renormalization scheme of QED (Quantum Electrodynamics) at high temperatures is used to calculate the effective parameters of relativistic plasma in the early universe. Renormalization constants of QED play role of effective parameters of the theory and can be used to determine the collective behavior of the medium. We explicitly show that the dielectric constant, magnetic reluctivity, Debye length and the plasma frequency depend on temperature in the early universe. Propagation speed, refractive index, plasma frequency and Debye shielding length of a QED plasma are computed at extremely high temperatures in the early universe. We also found the favorable conditions for the relativistic plasma from this calculations.
Transport Spectroscopy of a Spin-Coherent Dot-Cavity System.
Rössler, C; Oehri, D; Zilberberg, O; Blatter, G; Karalic, M; Pijnenburg, J; Hofmann, A; Ihn, T; Ensslin, K; Reichl, C; Wegscheider, W
2015-10-16
Quantum engineering requires controllable artificial systems with quantum coherence exceeding the device size and operation time. This can be achieved with geometrically confined low-dimensional electronic structures embedded within ultraclean materials, with prominent examples being artificial atoms (quantum dots) and quantum corrals (electronic cavities). Combining the two structures, we implement a mesoscopic coupled dot-cavity system in a high-mobility two-dimensional electron gas, and obtain an extended spin-singlet state in the regime of strong dot-cavity coupling. Engineering such extended quantum states presents a viable route for nonlocal spin coupling that is applicable for quantum information processing. PMID:26550890
Design of a 4 Rod Crab Cavity Cryomodule System for HL-LHC
Burt, G; Wright, L; Peterson, T J; Jones, T; McIntosh, P A; Templeton, N; Pattalwar, S; Wheelhouse, A E
2013-01-01
The LHC requires compact SRF crab cavities for the HL-LHC and 3 potential solutions are under consideration. One option is to develop a 4 rod cavity utilising for quarter wave rods to maintain a dipole field. The cavity design has been developed including power and LOM/HOM couplers have been developed, as well as a conceptual design of a complete cryomodule system including ancillaries and this is presented. The cryomodule is designed to allow easy access during testing and uses a novel support system and contains the opposing beamline section to fit inside the LHC envelope.
Digital Measurement System for the HIE-Isolde Superconducting Accelerating Cavities
Elias, Michal
Extensive R&D efforts are being invested at CERN into the fundamental science of the RF superconductivity, cavity design, niobium sputtering, coating and RF properties of superconducting cavities. Fast and precise characterization and measurements of RF parameters of the newly produced cavities is essential for advances with the cavity production. The currently deployed analogue measurement system based on an analogue phase discriminators and tracking RF generators is not optimal for efficient work at the SM18 superconducting cavity test stand. If exact properties of the cavity under test are not known a traditional feedback loop will not be able to find resonant frequency in a reasonable time or even at all. This is mainly due to a very high Q factor. The resonance peak is very narrow (fraction of a Hz at 100 MHz). If the resonant frequency is off by several bandwidths, small changes of the cavity field during the tuning will not be measureable. Also cavity field will react only very slowly to any change...
Cavity beam position monitor system for the Accelerator Test Facility 2
Kim, Y I; Aryshev, A; Boogert, S T; Boorman, G; Frisch, J; Heo, A; Honda, Y; Hwang, W H; Huang, J Y; Kim, E -S; Kim, S H; Lyapin, A; Naito, T; May, J; McCormick, D; Mellor, R E; Molloy, S; Nelson, J; Park, S J; Park, Y J; Ross, M; Shin, S; Swinson, C; Smith, T; Terunuma, N; Tauchi, T; Urakawa, J; White, G R
2013-01-01
The Accelerator Test Facility 2 (ATF2) is a scaled demonstrator system for final focus beam lines of linear high energy colliders. This paper describes the high resolution cavity beam position monitor (BPM) system, which is a part of the ATF2 diagnostics. Two types of cavity BPMs are used, C-band operating at 6.423 GHz, and S-band at 2.888 GHz with an increased beam aperture. The cavities, electronics, and digital processing are described. The resolution of the C-band system with attenuators was determined to be approximately 250 nm and 1 m for the S-band system. Without attenuation the best recorded C-band cavity resolution was 27 nm.
Cryogenic sub-system for the 56 MHz SRF storage cavity for RHIC
International Nuclear Information System (INIS)
A 56 MHz Superconducting RF Storage Cavity is being constructed for the RHIC collider. This cavity is a quarter wave resonator that will be operated in a liquid helium bath at 4.4 K. The cavity requires an extremely quiet environment to maintain its operating frequency. The cavity, besides being engineered for a mechanically quiet system, also requires a quiet cryogenic system. The helium is taken from RHIC's main helium supply header at 3.5 atm, 5.3K at a phase separator tank. The boil-off is sent back to the RHIC refrigeration system to recover the cooling. To acoustically separate the RHIC helium supply and return lines, a condenser/boiler heat exchanger condenses the helium vapor generated in the RF cavity bath. A system description and operating parameters are given about the cryogen delivery system. The 56 MHz superconducting storage RF cavity project is making progress. The cryogenic system design is in its final stage. The helium supply lines have been tapped into the RHIC helium distribution lines. The plate-and-fin heat exchanger design is near completion and specification will be sent out for bid soon. The cold helium vapor heating system design will start soon as well. A booster compressor specification is underway. The first phase separator and transfer line design work is near completion and will be sent out for bid soon.
Teleportation of atomic entangled states with a thermal cavity
Institute of Scientific and Technical Information of China (English)
Zheng Xiao-Juan; Fang Mao-Fa; Cai Jian-Wu; Liao Xiang-Ping
2006-01-01
We propose a most simple and experimentally feasible scheme for teleporting unknown atomic entangled states in driven cavity quantum electrodynamics (QED). In our scheme, the joint Bell-state measurement (BSM) is not required,and the successful probability can reach 1.0. Furthermore, the scheme is insensitive to the cavity decay and the thermal field.
Performance of a High Resolution Cavity Beam Position Monitor System
Energy Technology Data Exchange (ETDEWEB)
Walston, S; Boogert, S; Chung, C; Fitsos, P; Frisch, J; Gronberg, J; Hayano, H; Honda, Y; Kolomensky, Y; Lyapin, A; Malton, S; May, J; McCormick, D; Meller, R; Miller, D; Orimoto, T; Ross, M; Slater, M; Smith, S; Smith, T; Terunuma, N; Thomson, M; Urakawa, J; Vogel, V; Ward, D; White, G
2006-12-18
It has been estimated that an RF cavity Beam Position Monitor (BPM) could provide a position measurement resolution of less than one nanometer. We have developed a high resolution cavity BPM and associated electronics. A triplet comprised of these BPMs was installed in the extraction line of the Accelerator Test Facility (ATF) at the High Energy Accelerator Research Organization (KEK) for testing with its ultra-low emittance beam. The three BPMs were each rigidly mounted inside an alignment frame on six variable-length struts which could be used to move the BPMs in position and angle. We have developed novel methods for extracting the position and tilt information from the BPM signals including a robust calibration algorithm which is immune to beam jitter. To date, we have demonstrated a position resolution of 15.6 nm and a tilt resolution of 2.1 {micro}rad over a dynamic range of approximately {+-} 20 {micro}m.
Performance of a High Resolution Cavity Beam Position Monitor System
Energy Technology Data Exchange (ETDEWEB)
Walston, Sean; Boogert, Stewart; Chung, Carl; Fitsos, Joe; Frisch, Joe; Gronberg, Jeff; Hayano, Hitoshi; Honda, Yosuke; Kolomensky, Yury; Lyapin, Alexey; Malton, Stephen; May, Justin; McCormick, Douglas; Meller, Robert; Miller, David John; Orimoto, Toyoko; Ross, Marc; Slater, Mark; Smith, Steve; Smith, Tonee; Terunuma, Nobuhiro; /Fermilab /UC,
2007-06-08
It has been estimated that an RF cavity Beam Position Monitor (BPM) could provide a position measurement resolution of less than one nanometer. We have developed a high resolution cavity BPM and associated electronics. A triplet comprised of these BPMs was installed in the extraction line of the Accelerator Test Facility (ATF) at the High Energy Accelerator Research Organization (KEK) for testing with its ultra-low emittance beam. The three BPMs were each rigidly mounted inside an alignment frame on six variable-length struts which could be used to move the BPMs in position and angle. We have developed novel methods for extracting the position and tilt information from the BPM signals including a robust calibration algorithm which is immune to beam jitter. To date, we have demonstrated a position resolution of 15.6 nm and a tilt resolution of 2.1 {mu}rad over a dynamic range of approximately {+-} 20 {mu}m.
Institute of Scientific and Technical Information of China (English)
LI Sheng-Chang; YANG Wen-Xing; DUAN Wen-Shan
2008-01-01
An alternative scheme is proposed for the generation of n-qubit W states of superconducting quantum interference devices (SQUID) in cavity QED. In this scheme, Raman coupling of two lower flux states of SQUID system is achieved via a microwave pulse and the cavity mode. Conditioned on no photon leakage from the cavity, the n-qubit W state can be generated whether the effective coupling parameters of the SQUID to cavity mode and classical microwave fields are the same or different. Our strictly numerical simulations of the time evolution of the system including decay show that the success probability of our scheme is almost unity and the interaction time is on the order of 10-9 s. The scheme can also be used to generate the Schrfdinger cat states of multi-SQUID.
Fiber Optic Based Thermometry System for Superconducting RF Cavities
Energy Technology Data Exchange (ETDEWEB)
Kochergin, Vladimir [Microxact Inc.
2013-05-06
Thermometry is recognized as the best technique to identify and characterize losses in SRF cavities. The most widely used and reliable apparatus for temperature mapping at cryogenic temperatures is based on carbon resistors (RTDs). The use of this technology on multi-cell cavities is inconvenient due to the very large number of sensors required to obtain sufficient spatial resolution. Recent developments make feasible the use of multiplexible fiber optic sensors for highly distributed temperature measurements. However, sensitivity of multiplexible cryogenic temperature sensors was found extending only to 12K at best and thus was not sufficient for SRF cavity thermometry. During the course of the project the team of MicroXact, JLab and Virginia Tech developed and demonstrated the multiplexible fiber optic sensor with adequate response below 20K. The demonstrated temperature resolution is by at least a factor of 60 better than that of the best multiplexible fiber optic temperature sensors reported to date. The clear path toward at least 10times better temperature resolution is shown. The first to date temperature distribution measurements with ~2.5mm spatial resolution was done with fiber optic sensors at 2K to4K temperatures. The repeatability and accuracy of the sensors were verified only at 183K, but at this temperature both parameters significantly exceeded the state of the art. The results of this work are expected to find a wide range of applications, since the results are enabling the whole new testing capabilities, not accessible before.
Development and operation of 65 KW capacity precision cooling system for the Indus-2 RF cavities
International Nuclear Information System (INIS)
The Indus-2 electron synchrotron accelerator RF cavity body requires a dedicated De-ionised (DI) precision water-cooling system. The performance of cavity is of critical importance at accelerator machine. Any change in temperature causes corresponding change in cavity body size, indirectly changing its frequency and harmonics. The proper operation of the accelerator machine requires precise synchronization of the cavity frequency with particle revolution. Two cooling loops are being operated by Low Conductivity Water (LCW) System to fulfil these requirements. The RF Cavity HOM coupler and bracket assembly are being cooled by the central LCW plant with temperature stability of ±1.0 ℃. The RF Cavity body is provided with a precision cooling system with temperature stability of ±0.1℃ at any set temperature from 25 ℃ to 80 ℃. The plate heat exchanger and three-way control valve mechanism provides the precision chilling loop and maintains the process water tank temperature. The controlled heating system refines the pipeline thermal losses. The fast-response direct-immersion RTD temperature sensor provides feedback signal to Proportional-Integral-Derivative (PID) controller. Downtime of the precision cooling system for any reason can result in downtime of entire accelerator, hence improvement has been carried out. In this paper, the development of precision cooling chillers system, instrumentation, hydraulic manifold and improvement in operational reliability is elaborated. (author)
Anomaly-Induced Dynamical Refringence in Strong-Field QED.
Mueller, N; Hebenstreit, F; Berges, J
2016-08-01
We investigate the impact of the Adler-Bell-Jackiw anomaly on the nonequilibrium evolution of strong-field quantum electrodynamics (QED) using real-time lattice gauge theory techniques. For field strengths exceeding the Schwinger limit for pair production, we encounter a highly absorptive medium with anomaly induced dynamical refractive properties. In contrast to earlier expectations based on equilibrium properties, where net anomalous effects vanish because of the trivial vacuum structure, we find that out-of-equilibrium conditions can have dramatic consequences for the presence of quantum currents with distinctive macroscopic signatures. We observe an intriguing tracking behavior, where the system spends longest times near collinear field configurations with maximum anomalous current. Apart from the potential relevance of our findings for future laser experiments, similar phenomena related to the chiral magnetic effect are expected to play an important role for strong QED fields during initial stages of heavy-ion collision experiments. PMID:27541456
Anomaly-induced dynamical refringence in strong-field QED
Mueller, Niklas; Berges, Jürgen
2016-01-01
We investigate the impact of the Adler-Bell-Jackiw anomaly on the nonequilibrium evolution of strong-field quantum electrodynamics (QED) using real-time lattice gauge theory techniques. For field strengths exceeding the Schwinger limit for pair production, we encounter a highly absorptive medium with anomaly-induced dynamical refractive properties. In contrast to earlier expectations based on equilibrium properties, where net anomalous effects vanish because of the trivial vacuum structure, we find that out-of-equilibrium conditions can have dramatic consequences for the presence of quantum currents with distinctive macroscopic signatures. We observe an intriguing tracking behavior, where the system spends longest times near collinear field configurations with maximum anomalous current. Apart from the potential relevance of our findings for future laser experiments, similar phenomena related to the chiral magnetic effect are expected to play an important role for strong QED fields during initial stages of hea...
Anomaly-Induced Dynamical Refringence in Strong-Field QED
Mueller, N.; Hebenstreit, F.; Berges, J.
2016-08-01
We investigate the impact of the Adler-Bell-Jackiw anomaly on the nonequilibrium evolution of strong-field quantum electrodynamics (QED) using real-time lattice gauge theory techniques. For field strengths exceeding the Schwinger limit for pair production, we encounter a highly absorptive medium with anomaly induced dynamical refractive properties. In contrast to earlier expectations based on equilibrium properties, where net anomalous effects vanish because of the trivial vacuum structure, we find that out-of-equilibrium conditions can have dramatic consequences for the presence of quantum currents with distinctive macroscopic signatures. We observe an intriguing tracking behavior, where the system spends longest times near collinear field configurations with maximum anomalous current. Apart from the potential relevance of our findings for future laser experiments, similar phenomena related to the chiral magnetic effect are expected to play an important role for strong QED fields during initial stages of heavy-ion collision experiments.
Hughes, S
2011-01-01
The input/output characteristics of coherent photon transport through a semiconductor cavity system containing a single quantum dot is presented. The nonlinear quantum optics formalism uses a master equation approach and focuses on a waveguide-cavity system containing a semiconductor quantum dot; our general technique also applies to studying coherent reflection from a micropillar cavity. We investigate the effects of light propagation and show the need for quantized multiphoton effects for various dot-cavity systems, including weakly-coupled, intermediately-coupled, and strongly-coupled regimes. We demonstrate that for mean photon numbers much less than 0.1, the commonly adopted weak excitation (single quantum) approximation breaks down---even in the weak coupling regime. As a measure of the photon correlations, we compute the Fano factor and the error associated with making a semiclassical approximation. We also investigate the role of electron--acoustic-phonon scattering and show that phonon-mediated scatt...
All-optical signal amplifier and distributor using cavity-atom coupling systems
Duan, Yafan; Lin, Gongwei; Niu, Yueping; Gong, Shangqing
2016-05-01
We report an all-optical signal amplifier and a signal distributor using cavity-atom coupling systems. In this system we couple atoms with an optical cavity and realize the great enhancement of a control laser by the cavity with the help of two high coupling lasers. By this effect, we can use one weak control field to control another strong target field and the intensity changes are linear with our experimental conditions. This can be used as an all-optical signal amplifier, also known as a ‘transphasor’. In our experiment, the gain of the weak field to strong field can be as high as 60. Furthermore, we can realize the distribution of optical signals, if we coordinate multiple cavity-atom coupling systems.
Exploring the QED vacuum with laser interferometers
Boer, Daniel; van Holten, Jan-Willem
2002-01-01
It is demonstrated that the nonlinear, and as yet unobserved, QED effect of slowing down light by application of a strong magnetic field may be observable with large laser interferometers like for instance LIGO or GEO600.
Parton distributions incorporating QED contributions
Energy Technology Data Exchange (ETDEWEB)
Martin, A.D.; Stirling, W.J. [University of Durham, Institute for Particle Physics Phenomenology (United Kingdom); Roberts, R.G. [Rutherford Appleton Laboratory, Chilton, Didcot, Oxon (United Kingdom); Thorne, R.S. [University of Cambridge, Cavendish Laboratory, Cambridge (United Kingdom)
2005-02-01
We perform a global parton analysis of deep inelastic and related hard-scattering data, including O({alpha}{sub QED}) corrections to the parton evolution. Although the quality of the fit is essentially unchanged, there are two important physical consequences. First, the different DGLAP evolution of uand dtype quarks introduces isospin violation, i.e. u{sup p}{ne}d{sup n}, which is found to be unambiguously in the direction to reduce the NuTeV sin {sup 2}{theta}{sub W} anomaly. A second consequence is the appearance of photon parton distributions {gamma}(x,Q{sup 2}) of the proton and the neutron. In principle these can be measured at HERA via the deep inelastic scattering processes eN{yields}e{gamma}X; our predictions are in agreement with the present data. (orig.)
Gauge anomalies in Lorentz-violating QED
Santos, Tiago R S
2016-01-01
In this work we study the issue of gauge anomalies in Lorentz-violating QED. To do so, we opt to use the BRST formalism within of the algebraic renormalization approach, reducing our study to a cohomology problem. Since that this approach is independent of the renormalization scheme, the results here obtained are expected to be general. We find that the Lorentz-violating QED is free of gauge anomalies to all orders in perturbation theory.
Asymptotic completeness in QED. Pt. 1
International Nuclear Information System (INIS)
Projection operators onto the asymptotic scattering states are defined in the space of quasilocal states of QED in a Gupta-Bleuler formulation. They are obtained as weak limits for t → ±∞ of expressions formed with interacting fields, in close analogy to the LSZ expressions known from field theories without infrared problems. It is shown that these limits exist in perturbative QED and are equal to the identity. (orig.)
Entanglement evolution of three-qubit mixed states in multipartite cavity-reservoir systems
Institute of Scientific and Technical Information of China (English)
Xu Jing-Zhou; Guo Jin-Bao; Wen Wei; Bai Yan-Kui; Yan Feng-Li
2012-01-01
We analyze the multipartite entanglement evolution of three-qubit mixed states composed of a GHZ state and a W state.For a composite system consisting of three cavities interacting with independent reservoirs,it is shown that the entanglement evolution is restricted by a set of monogamy relations.Furthermore,as quantified by the negativity,the entanglement dynamical property of the mixed entangled state of cavity photons is investigated.It is found that the three cavity photons can exhibit the phenomenon of entanglement sudden death (ESD).However,compared with the evolution of a generalized three-qubit GHZ state which has the equal initial entanglement,the ESD time of mixed states is later than that of the pure state.Finally,we discuss the entanglement distribution in the multipartite system,and point out the intrinsic relation between the ESD of cavity photons and the entanglement sudden birth of reservoirs.
Autonomous quantum thermal machines in atom-cavity systems
Mitchison, Mark T.; Huber, Marcus; Prior, Javier; Woods, Mischa P.; Plenio, Martin B.
2016-01-01
An autonomous quantum thermal machine comprising a trapped atom or ion placed inside an optical cavity is proposed and analysed. Such a machine can operate as a heat engine whose working medium is the quantised atomic motion, or as an absorption refrigerator which cools without any work input. Focusing on the refrigerator mode, we predict that it is possible with state-of-the-art technology to cool a trapped ion almost to its motional ground state using a thermal light source such as sunlight...
Discussion of mechanical design for pressured cavity-air-receiver in solar power tower system
Energy Technology Data Exchange (ETDEWEB)
Fan, Zhilin; Zhang, Yaoming; Liu, Deyou; Wang, Jun; Liu, Wei [Hohai Univ., Nanjing (China). New Materials and Energy Sources Research and Exploitation Inst.
2008-07-01
In 2005, Hohai university and Nanjing Chunhui science and technology Ltd. of China, cooperating with Weizmann Institute of Science and EDIG Ltd. of Israel, built up a 70kWe solar power tower test plant in Nanjing, Jiangsu province, China, which was regarded as the first demonstration project to demonstrate the feasibility of solar power tower system in China. The system consists of heliostats field providing concentrated sunlight, a solar tower with a height of 33 meter, a pressured cavity-air-receiver transforming solar energy to thermal energy, a modified gas turbine adapting to solar power system, natural gas subsystem for solar-hybrid generation, cooling water subsystem for receiver and CPC, controlling subsystem for whole plant, et al. In this system, air acts as actuating medium and the system works in Brayton cycle. Testing results show that solar power tower system is feasible in China. To promote the development of solar powered gas turbine system and the pressured cavity-air-receiver technology in China, it is necessary to study the mechanical design for pressured Cavity-air-receiver. Mechanical design of pressured cavity-air-receiver is underway and some tentative principles for pressured cavity-air-receiver design, involving in power matching, thermal efficiency, material choosing, and equipment security and machining ability, are presented. At the same time, simplified method and process adapted to engineering application for the mechanical design of pressured cavity-air-receiver are discussed too. Furthermore, some design parameters and appearance of a test sample of pressured cavity-air-receiver designed in this way is shown. It is appealed that, in China, the research in this field should be intensified and independent knowledge patents for pivotal technological equipments such as receiver in solar power tower system should be formed. (orig.)
McCloud, Peter L.
2010-01-01
Thermal Protection System (TPS) Cavity Heating is predicted using Computational Fluid Dynamics (CFD) on unstructured grids for both simplified cavities and actual cavity geometries. Validation was performed using comparisons to wind tunnel experimental results and CFD predictions using structured grids. Full-scale predictions were made for simplified and actual geometry configurations on the Space Shuttle Orbiter in a mission support timeframe.
Auto-tuning systems for J-PARC LINAC RF cavities
International Nuclear Information System (INIS)
The 400-MeV proton linear accelerator (LINAC) at the Japan Proton Accelerator Research Complex (J-PARC) consists of 324-MHz low-β and 972-MHz high-β accelerator sections. From October 2006 to May 2013, only the 324-MHz low-β accelerator section was in operation. From the summer of 2013 the J-PARC LINAC was upgraded by installing the 972-MHz high-β accelerator section, and the proton beam was successfully accelerated to 400 MeV in January 2014. Auto-tuning systems for the J-PARC LINAC RF cavities have been successfully developed. A first generation design, an auto-tuning system using a mechanical tuner controller, was developed and operated for the first 3 years. Then the second-generation auto-tuning system was developed using a new approach to the RF cavity warm-up process, and this was applied to the accelerator operation for the subsequent 4 years. During the RF cavity warm-up process in this system, the mechanical tuner is constantly fixed and the input RF frequency is automatically tuned to the cavity resonance frequency using the FPGA (Field-Programmable Gate Array) of the digital feedback RF control system. After the input power level reaches the required value, input RF frequency tuning is stopped and it is switched to the operation frequency. Then, the mechanical tuner control begins operation. This second-generation auto-tuning system was extremely effective for the 324-MHz cavity operation. However, if we apply this approach to the 972-MHz RF cavities, an interlock due to the RF cavity reflection amplitude occasionally occurs at the end of the warm-up process. In order to solve this problem a third generation novel auto-tuning system was successfully developed in December 2013 and applied to the operation of the J-PARC LINAC, including the 972-MHz ACS RF cavities. During the warm-up process both the mechanical tuner controller and the input RF frequency tuning are in operation, and good matching between the input RF frequency and the RF cavity is
International Nuclear Information System (INIS)
Cavity beam position monitor (BPM) is widely used in a precise electron beam position measurement. Based on high performance oscilloscope-embedded EPICS input/output controller, we developed an on-line cavity BPM signal processing system for fast data acquisition solution when designing a cavity BPM. Also, methods for extracting the position information from cavity pickup signals and calibration algorithm are included in this solution. (authors)
X-Band Crab Cavities for the CLIC Beam Delivery System
International Nuclear Information System (INIS)
The CLIC machine incorporates a 20 mrad crossing angle at the IP to aid the extraction of spent beams. In order to recover the luminosity lost through the crossing angle a crab cavity is proposed to rotate the bunches prior to collision. The crab cavity is chosen to have the same frequency as the main linac (11.9942 GHz) as a compromise between size, phase stability requirements and beam loading. It is proposed to use a HE11 mode travelling wave structure as the CLIC crab cavity in order to minimise beam loading and mode separation. The position of the crab cavity close to the final focus enhances the effect of transverse wake-fields so effective wake-field damping is required. A damped detuned structure is proposed to suppress and de-cohere the wake-field hence reducing their effect. Design considerations for the CLIC crab cavity will be discussed as well as the proposed high power testing of these structures at SLAC. Design of a crab cavity for CLIC is underway at the Cockcroft Institute in collaboration with SLAC. This effort draws on a large degree of synergy with the ILC crab cavity developed at the Cockcroft Institute and other deflecting structure development at SLAC. A study of phase and amplitude variations in the cavity suggests that the tolerances are very tight and require a 'beyond state of the art' LLRF control system. A study of cavity geometry and its effect on the cavity fields has been performed using Microwave studio. This study has suggested that for our cavity an iris radius between 4-5 mm is optimum with an iris thickness of 2-3 mm based on group velocity and peak fields. A study of the cavity wakefields show that the single bunch wakes are unlikely to be a problem but the short bunch spacing may cause the multi-bunch wakefields to be an issue. This will require some of the modes to be damped strongly so that the wake is damped significantly before any following bunch arrives. Various methods of damping have been investigated and suggest that
X-Band Crab Cavities for the CLIC Beam Delivery System
Energy Technology Data Exchange (ETDEWEB)
Burt, G.; Ambattu, P.K.; Dexter, A.C.; Abram, T.; /Cockcroft Inst. Accel. Sci. Tech. /Lancaster U.; Dolgashev, V.; Tantawi, S.; /SLAC; Jones, R.M.; /Cockcroft Inst. Accel. Sci. Tech. /Manchester U.
2011-11-22
The CLIC machine incorporates a 20 mrad crossing angle at the IP to aid the extraction of spent beams. In order to recover the luminosity lost through the crossing angle a crab cavity is proposed to rotate the bunches prior to collision. The crab cavity is chosen to have the same frequency as the main linac (11.9942 GHz) as a compromise between size, phase stability requirements and beam loading. It is proposed to use a HE11 mode travelling wave structure as the CLIC crab cavity in order to minimise beam loading and mode separation. The position of the crab cavity close to the final focus enhances the effect of transverse wake-fields so effective wake-field damping is required. A damped detuned structure is proposed to suppress and de-cohere the wake-field hence reducing their effect. Design considerations for the CLIC crab cavity will be discussed as well as the proposed high power testing of these structures at SLAC. Design of a crab cavity for CLIC is underway at the Cockcroft Institute in collaboration with SLAC. This effort draws on a large degree of synergy with the ILC crab cavity developed at the Cockcroft Institute and other deflecting structure development at SLAC. A study of phase and amplitude variations in the cavity suggests that the tolerances are very tight and require a 'beyond state of the art' LLRF control system. A study of cavity geometry and its effect on the cavity fields has been performed using Microwave studio. This study has suggested that for our cavity an iris radius between 4-5 mm is optimum with an iris thickness of 2-3 mm based on group velocity and peak fields. A study of the cavity wakefields show that the single bunch wakes are unlikely to be a problem but the short bunch spacing may cause the multi-bunch wakefields to be an issue. This will require some of the modes to be damped strongly so that the wake is damped significantly before any following bunch arrives. Various methods of damping have been investigated and
Nonlinear Temporal Dynamics of Strongly Coupled Quantum Dot-Cavity System
Majumdar, Arka; Bajcsy, Michal; Vuckovic, Jelena
2011-01-01
We theoretically analyze and simulate the temporal dynamics of strongly coupled quantum dot-cavity system driven by a resonant laser pulse. We observe the signature of Rabi oscillation in the time resolved response of the system (i.e., in the numerically calculated cavity output), derive simplified linear and non-linear semi-classical models that approximate well the system's behavior in the limits of high and low power drive pulse, and describe the role of quantum coherence in the exact dynamics of the system. Finally, we also present experimental data showing the signature of the Rabi oscillation in time domain.
Hybrid Quantum System:Coupling Color Centers to Superconducting Cavities
International Nuclear Information System (INIS)
Full text: Reversible transfer of quantum information between long-lived memories and quantum processors is a favorable building block of scalable quantum information devices. We present recent experimental results of strong coupling between an ensemble of nitrogen-vacancy center electron spins in diamond and a superconducting microwave coplanar waveguide resonator. Although the coupling between a single spin and the electromagnetic field is typically rather weak, collective enhancement allows entering the strong coupling regime. With our experimental set-up we are able to directly observe this characteristic scaling of the collective coupling strength with the square root of the number of emitters. Additionally, we measure hyperfine coupling to 13C nuclear spins, which is a first step towards a nuclear ensemble quantum memory. Using the dispersive shift of the cavity resonance frequency, we measure the relaxation time T1 of the NV center at milli kelvin temperatures in a nondestructive way. (author)
International Nuclear Information System (INIS)
RRCAT is developing a Vertical Test Stand (VTS) to test and qualify 1.3 GHz/650 MHz, SCRF Cavities in collaboration with Fermi National Accelerator Laboratory (FNAL) under Indian Institutions' Fermilab Collaboration. The technical details for VTS is being provided by FNAL, USA. The RF System of VTS needs to provide stable RF power to SCRF cavity with control of amplitude, relative phase and frequency. The incident, reflected, transmitted power and field decay time constant of the cavity are measured to evaluate cavity performance parameters (E, Qo). RF Power is supplied via 500 W Solid State amplifier, 1270-1310 MHz being developed by PHPMS, RRCAT. VTS system is controlled by PXI Platform and National Instruments LabVIEW software. Low Level RF (LLRF) system is used to track the cavity frequency using Phase Locked Loop (PLL). The system is comprised of several integrated functional modules which would be assembled, optimized, and tested separately. Required components and instruments have been identified and procurement for the same is underway. Inhouse development for the Solid State RF amplifier and instrument interfacing is in progress. This paper describes the progress on the development of the RF system for VTS. (author)
Ultrahigh quality factor in a metal-embedded semiconductor microdisk cavity.
Kurosawa, Hiroyuki; Kumano, Hidekazu; Suemune, Ikuo
2015-12-15
We numerically and theoretically investigate electrodynamics of a metal-embedded semiconductor microdisk cavity. The electrodynamics of a cavity mode is discussed from the viewpoint of quantum mechanics, which clarifies the condition for high Q factor. Using numerical calculations, we optimize the cavity structure and show that the Q factor can be increased up to 1,700,000. Our study suggests that the metal-embedded cavity is a promising candidate for cavity quantum electrodynamics (QED) devices. PMID:26670507
Efficient generation of Bell-cat states in remote cavities
Institute of Scientific and Technical Information of China (English)
LI Xing; ZHANG Ying-Jie; XIA Yun-Jie
2008-01-01
In the context of cavity quantum electrodynamics (QED), a potential scheme is proposed to generate entangled coherentstates. The scheme includes twice interactions of two-level atoms with cavities. In the first interaction, two atoms are sentinto a microwave cavity with the large detuning respectively. And then the second interaction is that the two atoms enteranother microwave cavity and are driven by a resonant classical field meantime. When we choose the proper interactiontime and make measurement on the two atoms, the two microwave cavity mode fields are determinatively entangled. Inaddition, it is easy to generalize the scheme to multi-cavity and multi-atom.
Controllable optical bistability in a cavity optomechanical system with a Bose–Einstein condensate
Hamideh Kazemi, Seyedeh; Ghanbari, Saeed; Mahmoudi, Mohammad
2016-05-01
The optical bistability (OB) in a two-mode optomechanical system with a Bose–Einstein condensate (BEC) is studied. By investigating the behavior of steady state solutions, we show that how OB develops in the system for a certain range of cavity-pump detunings and pump amplitudes. We then investigate the effects of the decay rate of the cavity photons and coupling strength between the cavity and the BEC as well as the pump-atom detuning on the optical behaviour of the system. We find that one can control the OB threshold and width of the bistability curve via adjusting properly the coupling strength and the detuning. By applying Routh–Hurwitz criterion, we then derive stability conditions for different branches of the OB curve. Moreover, by introducing an effective potential for the system, a simple physical interpretation is obtained.
Quantum superdense coding via cavity-assisted interactions
International Nuclear Information System (INIS)
Quantum superdense coding (QSC) is an example of how entanglement can be used to minimize the number of carriers of classical information. This paper proposes two schemes for implementing QSC by means of cavity assisted interactions with single-photon pulses. The schemes are insensitive to the cavity decay and the thermal field, thus it might be realizable based on the current cavity QED techniques
Scalable photonic quantum computation through cavity-assisted interaction
Duan, L M
2003-01-01
We propose a scheme for scalable photonic quantum computation based on cavity assisted interaction between single-photon pulses. The prototypical quantum controlled phase-flip gate between the single-photon pulses is achieved by successively reflecting them from an optical cavity with a single-trapped atom. Our proposed protocol is shown to be robust to practical nose and experimental imperfections in current cavity-QED setups.
Universal quantum gates for photon-atom hybrid systems assisted by bad cavities
Wang, Guan-Yu; Liu, Qian; Wei, Hai-Rui; Li, Tao; Ai, Qing; Deng, Fu-Guo
2016-01-01
We present two deterministic schemes for constructing a CNOT gate and a Toffoli gate on photon-atom and photon-atom-atom hybrid quantum systems assisted by bad cavities, respectively. They are achieved by cavity-assisted photon scattering and work in the intermediate coupling region with bad cavities, which relaxes the difficulty of their implementation in experiment. Also, bad cavities are feasible for fast quantum operations and reading out information. Compared with previous works, our schemes do not need any auxiliary qubits and measurements. Moreover, the schematic setups for these gates are simple, especially that for our Toffoli gate as only a quarter wave packet is used to interact the photon with each of the atoms every time. These atom-cavity systems can be used as the quantum nodes in long-distance quantum communication as their relatively long coherence time is suitable for multi-time operations between the photon and the system. Our calculations show that the average fidelities and efficiencies of our two universal hybrid quantum gates are high with current experimental technology. PMID:27067992
Universal quantum gates for photon-atom hybrid systems assisted by bad cavities
Wang, Guan-Yu; Liu, Qian; Wei, Hai-Rui; Li, Tao; Ai, Qing; Deng, Fu-Guo
2016-04-01
We present two deterministic schemes for constructing a CNOT gate and a Toffoli gate on photon-atom and photon-atom-atom hybrid quantum systems assisted by bad cavities, respectively. They are achieved by cavity-assisted photon scattering and work in the intermediate coupling region with bad cavities, which relaxes the difficulty of their implementation in experiment. Also, bad cavities are feasible for fast quantum operations and reading out information. Compared with previous works, our schemes do not need any auxiliary qubits and measurements. Moreover, the schematic setups for these gates are simple, especially that for our Toffoli gate as only a quarter wave packet is used to interact the photon with each of the atoms every time. These atom-cavity systems can be used as the quantum nodes in long-distance quantum communication as their relatively long coherence time is suitable for multi-time operations between the photon and the system. Our calculations show that the average fidelities and efficiencies of our two universal hybrid quantum gates are high with current experimental technology.
Universal quantum gates for photon-atom hybrid systems assisted by bad cavities.
Wang, Guan-Yu; Liu, Qian; Wei, Hai-Rui; Li, Tao; Ai, Qing; Deng, Fu-Guo
2016-01-01
We present two deterministic schemes for constructing a CNOT gate and a Toffoli gate on photon-atom and photon-atom-atom hybrid quantum systems assisted by bad cavities, respectively. They are achieved by cavity-assisted photon scattering and work in the intermediate coupling region with bad cavities, which relaxes the difficulty of their implementation in experiment. Also, bad cavities are feasible for fast quantum operations and reading out information. Compared with previous works, our schemes do not need any auxiliary qubits and measurements. Moreover, the schematic setups for these gates are simple, especially that for our Toffoli gate as only a quarter wave packet is used to interact the photon with each of the atoms every time. These atom-cavity systems can be used as the quantum nodes in long-distance quantum communication as their relatively long coherence time is suitable for multi-time operations between the photon and the system. Our calculations show that the average fidelities and efficiencies of our two universal hybrid quantum gates are high with current experimental technology. PMID:27067992
Institute of Scientific and Technical Information of China (English)
郑仕标
2001-01-01
A scheme is proposed for generating the superpositions of several coherent states in a cavity field with dispersive cavity quantum electrodynamics (QED). In the scheme, a sequence of atoms interacts dispersively with the cavity field, connected with a microwave source, and is manipulated by classical fields, followed by state-selective measurements. In this way, the cavity field is collapsed onto a superposition of several coherent states along a straight line with controllable coefficients. This scheme provides the possibility for quantum state engineering via coherent-state superpositions along a straight line in cavity QED for the first time.
Parton distribution functions with QED corrections
Carrazza, Stefano
2015-01-01
We present the first unbiased determination of parton distribution functions (PDFs) with electroweak corrections. The aim of this thesis is to provide an exhaustive description of the theoretical framework and the technical implementation which leads to the determination of a set of PDFs which includes the photon PDF and quantum electrodynamics (QED) contributions to parton evolution. First, we introduce and motivate the need of including electroweak corrections to PDFs, providing phenomenological examples and presenting an overview of the current state of the art in PDF fits. The theoretical implications of such corrections are then described through the implementation of the combined QCD+QED evolution in APFEL, a public code for the solution of the PDF evolution developed particularly for this thesis. We proceed by presenting the new structure of the Neural-Network PDF (NNPDF) methodology used for the extraction of this set of PDFs with QED corrections. We then provide a first determination of the full set ...
Indian Academy of Sciences (India)
Pier A Mello
2001-02-01
Universal statistical aspects of wave scattering by a variety of physical systems ranging from atomic nuclei to mesoscopic systems and microwave cavities are described. A statistical model for the scattering matrix is employed to address the problem of quantum chaotic scattering. The model, introduced in the past in the context of nuclear physics, discusses the problem in terms of a prompt and an equilibrated component: it incorporates the average value of the scattering matrix to account for the prompt processes and satisﬁes the requirements of ﬂux conservation, causality and ergodicity. The main application of the model is the analysis of electronic transport through ballistic mesoscopic cavities: it describes well the results from the numerical solutions of the Schrödinger equation for two-dimensional cavities.
International Nuclear Information System (INIS)
The RF system of superconducting cyclotron operates between 9-27 MHz. The RF cavities are consisting of three numbers of half wave (λ/2) coaxial sections. RF power from the tuned RF amplifier is capacitively coupled to the dee (accelerating electrode) of the main resonant cavity through Coupler (Coupling capacitor). The coupler is used to match the high shunt impedance of the main resonant cavity to the 50 Ohm output impedance of final RF power amplifier. Owing to RF thermal instability the volume inside the cavity changes as results there is a shift in frequency of resonance, consequently sharp fall in Dee voltages. Hydraulic drive based Trimmer capacitor operates in closed loop for the adjustment of a small variation in tuned frequency due to thermal effect and beam loading of the cavity. The impedance matching during the close loop operation is maintained by trimmer movement system. The precise movement of trimmer is necessary to compensate the change in volume of the cavity due to thermal expansion and maintain impedance matching between RF amplifier and RF cavity. Phase detector is used to detect the cavity de-tuning angle by comparing the phase difference between the cavity pickup (Dee pick-up) signal and cavity driven signal. This signal is fed to the PLC based digital P.I. controller to control the movement of trimmer capacitor. The control system has been modelled, analyzed, optimized and is operating round-the-clock with the K-500 SC Cyclotron system successfully. (author)
Theory and simulation of cavity quantum electro-dynamics in multi-partite quantum complex systems
International Nuclear Information System (INIS)
The cavity quantum electrodynamics of various complex systems is here analyzed using a general versatile code developed in this research. Such quantum multi-partite systems normally consist of an arbitrary number of quantum dots in interaction with an arbitrary number of cavity modes. As an example, a nine-partition system is simulated under different coupling regimes, consisting of eight emitters interacting with one cavity mode. Two-level emitters (e.g. quantum dots) are assumed to have an arrangement in the form of a linear chain, defining the mutual dipole-dipole interactions. It was observed that plotting the system trajectory in the phase space reveals a chaotic behavior in the so-called ultrastrong-coupling regime. This result is mathematically confirmed by detailed calculation of the Kolmogorov entropy, as a measure of chaotic behavior. In order to study the computational complexity of our code, various multi-partite systems consisting of one to eight quantum dots in interaction with one cavity mode were solved individually. Computation run times and the allocated memory for each system were measured. (orig.)
Theory and simulation of cavity quantum electro-dynamics in multi-partite quantum complex systems
Energy Technology Data Exchange (ETDEWEB)
Alidoosty Shahraki, Moslem; Khorasani, Sina; Aram, Mohammad Hasan [Sharif University of Technology, School of Electrical Engineering, Tehran (Iran, Islamic Republic of)
2014-05-15
The cavity quantum electrodynamics of various complex systems is here analyzed using a general versatile code developed in this research. Such quantum multi-partite systems normally consist of an arbitrary number of quantum dots in interaction with an arbitrary number of cavity modes. As an example, a nine-partition system is simulated under different coupling regimes, consisting of eight emitters interacting with one cavity mode. Two-level emitters (e.g. quantum dots) are assumed to have an arrangement in the form of a linear chain, defining the mutual dipole-dipole interactions. It was observed that plotting the system trajectory in the phase space reveals a chaotic behavior in the so-called ultrastrong-coupling regime. This result is mathematically confirmed by detailed calculation of the Kolmogorov entropy, as a measure of chaotic behavior. In order to study the computational complexity of our code, various multi-partite systems consisting of one to eight quantum dots in interaction with one cavity mode were solved individually. Computation run times and the allocated memory for each system were measured. (orig.)
Lorentz violation in simple QED processes
de Brito, G P; Kroff, D; Malta, P C; Marques, C
2016-01-01
We determine the effect of a CPT-even and Lorentz violating non-minimal coupling on the differential cross sections for some of the most important tree-level processes in QED, namely, Compton and Bhabha scatterings, as well as electron-positron annihilation. Experimental limits constraining the allowed deviation of the differential cross sections relative to pure QED allow us to place upper bounds on the Lorentz violating parameters. A constraint based on the decay rate of para-positronium is also obtained.
Superposition of Fock states via adiabatic passage in a coupled four-level atom-cavity system
Institute of Scientific and Technical Information of China (English)
Gong Shang-Qing; Jin Shi-Qi; Li Ru-Xin; Zheng Zhen-Xun; Xu Zhi-Zhan
2004-01-01
We have investigated the behaviour of an atom-cavity system via a stimulated Raman adiabatic passage technique in a four-level system, in which two dark states are present. We find, because of the coherent control field, that a superposition of Fock states can be prepared, even when the cavity is initially not in its vacuum state. This method provides a way to generate arbitrary quantum states of a cavity field.
Proposal for a Cavity Phase Observation System in the PS Machine
Angoletta, Maria Elena; Pedersen, F; Schokker, M; Vallet, J L; CERN. Geneva. AB Department
2006-01-01
In multi-cavity synchrotrons it is essential to be able to measure the phase difference between RF cavities. Errors in relative phase can have a particularly deleterious effect on the beam during RF gymnastics. Currently, two methods are available to measure the relative phase in the CERN Proton Synchrotron (PS), but neither attains the desired resolution nor covers the full arsenal of cavities. This note describes a system that will measure the relative phase between cavities with high resolution. The system makes use of the digital hardware deployed in the LEIR beam control and of the corresponding DSP and FPGA signal processing. The focus is on beams controlled by the Multi Harmonic Source (MHS) clock. The system described here is also a step towards the deployment of a new generation of digital beam control systems for the PS Complex machines, within the framework of the LHC injector consolidation and following the successful commissioning of the LEIR digital beam control system. Some expected benefits ar...
Multi-target-qubit unconventional geometric phase gate in a multi-cavity system.
Liu, Tong; Cao, Xiao-Zhi; Su, Qi-Ping; Xiong, Shao-Jie; Yang, Chui-Ping
2016-01-01
Cavity-based large scale quantum information processing (QIP) may involve multiple cavities and require performing various quantum logic operations on qubits distributed in different cavities. Geometric-phase-based quantum computing has drawn much attention recently, which offers advantages against inaccuracies and local fluctuations. In addition, multiqubit gates are particularly appealing and play important roles in QIP. We here present a simple and efficient scheme for realizing a multi-target-qubit unconventional geometric phase gate in a multi-cavity system. This multiqubit phase gate has a common control qubit but different target qubits distributed in different cavities, which can be achieved using a single-step operation. The gate operation time is independent of the number of qubits and only two levels for each qubit are needed. This multiqubit gate is generic, e.g., by performing single-qubit operations, it can be converted into two types of significant multi-target-qubit phase gates useful in QIP. The proposal is quite general, which can be used to accomplish the same task for a general type of qubits such as atoms, NV centers, quantum dots, and superconducting qubits. PMID:26898176
Integrated system modeling analysis of a cryogenic multi-cell deflecting-mode cavity resonator
International Nuclear Information System (INIS)
A deflecting mode cavity is the integral element for six-dimensional phase-space beam control in bunch compressors and emittance transformers at high energy beam test facilities. RF performance of a high-Q device is, however, highly sensitive to operational conditions, in particular in a cryo-cooling environment. Using analytic calculations and RF simulations, we examined cavity parameters and deflecting characteristics of TM110,π mode of a 5 cell resonator in a liquid nitrogen cryostat, which has long been used at the Fermilab A0 Photoinjector (A0PI). The sensitivity analysis indicated that the cavity could lose 30%–40% of deflecting force due to defective input power coupling accompanying non-uniform field distribution across the cells with 40 ∼ 50 MeV electron beam and 70–80 kW klystron power. Vacuum-cryomodules of the 5 cell cavity are planned to be installed at the Fermilab Advanced Superconducting Test Accelerator facility. Comprehensive modeling analysis integrated with multi-physics simulation tools showed that RF loading of 1 ms can cause a ∼5 K maximum temperature increase, corresponding to a ∼4.3 μm/ms deformation and a 1.32 MHz/K maximum frequency shift. The integrated system modeling analysis will improve design process of a high-Q cavity with more accurate prediction of cryogenic RF performance under a high power pulse operation
Flow Tones in a Pipeline-Cavity System: Effect of Pipe Asymmetry
Energy Technology Data Exchange (ETDEWEB)
D. Erdem; D. rockwell; P. Oshkai; M. Pollack
2002-05-29
Flow tones in a pipeline-cavity system are characterized in terms of unsteady pressure within the cavity and along the pipe. The reference case corresponds to equal lengths of pipe connected to the inlet and outlet ends of the cavity. Varying degrees of asymmetry of this pipe arrangement are investigated. The asymmetry is achieved by an extension of variable length, which is added to the pipe at the cavity outlet. An extension length as small as a few percent of the acoustic wavelength of the resonant mode can yield a substantial reduction in the pressure amplitude of the flow tone. This amplitude decrease occurs in a similar fashion within both the cavity and the pipe resonator, which indicates that it is a global phenomenon. Furthermore, the decrease of pressure amplitude is closely correlated with a decrease of the Q (quality)-factor of the predominant spectral component of pressure. At a sufficiently large value of extension length, however, the overall form of the pressure spectrum recovers to the form that exists at zero length of the extension. Further insight is provided by variation of the inflow velocity at selected values of extension length. Irrespective of its value, both the magnitude and frequency of the peak pressure exhibit a sequence of resonant-like states. Moreover, the maximum attainable magnitude of the peak pressure decreases with increasing extension length.
Flow Tones in a Pipeline-Cavity System: Effect of Pipe Asymmetry
Energy Technology Data Exchange (ETDEWEB)
D. Erdem; D. Rockwell; P.L. Oshkai; M. Pollack
2001-02-28
Flow tones in a pipeline-cavity system are characterized in terms of unsteady pressure within the cavity and along the pipe. The reference case corresponds to equal lengths of pipe connected to the inlet and outlet ends of the cavity. Varying degrees of asymmetry of this pipe arrangement are investigated. The asymmetry is achieved by an extension of variable length, which is added to the pipe at the cavity outlet. An extension length as small as a few percent of the acoustic wavelength of the resonant mode can yield a substantial reduction in the pressure amplitude of the flow tone. This amplitude decrease occurs in a similar fashion within both the cavity and the pipe resonator, which indicates that it is a global phenomenon. Furthermore, the decrease of pressure amplitude is closely correlated with a decrease of the Q (quality)-factor of the predominant spectral component of pressure. At a sufficiently large value of extension length, however, the overall form of the pressure spectrum recovers to the form that exists at zero length of the extension. Further insight is provided by variation of the inflow velocity at selected values of extension length. Irrespective of its value, both the magnitude and frequency of the peak pressure exhibit a sequence of resonant-like states. moreover, the maximum attainable magnitude of the peak pressure decreases with increasing extension length.
Tuner control system of spoke012 SRF cavity for C-ADS injector I at IHEP
Liu, Na; Wang, Guang-Wei; Mi, Zheng-Hui; Lin, Hai-Ying; Wang, Qun-Yao; Liu, Rong; Ma, Xin-Peng
2016-01-01
A new tuner control system of spoke superconducting radio frequency (SRF) cavity has been developed and applied to cryomodule I (CM1) of C-ADS injector I at IHEP. We have successfully implemented the tuner controller based on Programmable Logic Controller (PLC) for the first time and achieved a cavity tuning phase error of 0.7degrees (about 4 Hz peak to peak) in the presence of electromechanical coupled resonance. This paper will present the preliminary experimental results based on PLC tuner controller under proton beam commissioning.
Tunable two-photon correlation in a double-cavity optomechanical system
Directory of Open Access Journals (Sweden)
Zhi-Bo Feng
2015-12-01
Full Text Available Correlated photons are essential sources for quantum information processing. We propose a practical scheme to generate pairs of correlated photons in a controllable fashion from a double-cavity optomechanical system, where the variable optomechanical coupling strength makes it possible to tune the photon correlation at our will. The key operation is based on the repulsive or attractive interaction between the two photons intermediated by the mechanical resonator. The present protocol could provide a potential approach to coherent control of the photon correlation using the optomechanical cavity.
Tunable two-photon correlation in a double-cavity optomechanical system
Energy Technology Data Exchange (ETDEWEB)
Feng, Zhi-Bo, E-mail: zbfeng010@163.com [School of Electric and Information Engineering, Xuchang University, Xuchang 461000 (China); State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics, Wuhan Institute of Physics and Mathematics, Chinese Academy of Sciences, Wuhan 430071 (China); Zhang, Jian-Qi [State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics, Wuhan Institute of Physics and Mathematics, Chinese Academy of Sciences, Wuhan 430071 (China)
2015-12-15
Correlated photons are essential sources for quantum information processing. We propose a practical scheme to generate pairs of correlated photons in a controllable fashion from a double-cavity optomechanical system, where the variable optomechanical coupling strength makes it possible to tune the photon correlation at our will. The key operation is based on the repulsive or attractive interaction between the two photons intermediated by the mechanical resonator. The present protocol could provide a potential approach to coherent control of the photon correlation using the optomechanical cavity.
Tunable two-photon correlation in a double-cavity optomechanical system
International Nuclear Information System (INIS)
Correlated photons are essential sources for quantum information processing. We propose a practical scheme to generate pairs of correlated photons in a controllable fashion from a double-cavity optomechanical system, where the variable optomechanical coupling strength makes it possible to tune the photon correlation at our will. The key operation is based on the repulsive or attractive interaction between the two photons intermediated by the mechanical resonator. The present protocol could provide a potential approach to coherent control of the photon correlation using the optomechanical cavity
A photonic transistor device based on photons and phonons in a cavity electromechanical system
International Nuclear Information System (INIS)
We present a scheme for photonic transistors based on photons and phonons in a cavity electromechanical system, which is composed of a superconducting microwave cavity coupled to a nanomechanical resonator. Control of the propagation of photons is achieved through the interaction of microwave field (photons) and nanomechanical vibrations (phonons). By calculating the transmission spectrum of the signal field, we show that the signal field can be efficiently attenuated or amplified, depending on the power of a second ‘gating’ (pump) field. This scheme may be a promising candidate for single-photon transistors and pave the way for numerous applications in telecommunication and quantum information technologies.
Cavity-Controlled Chemistry in Molecular Ensembles
Herrera, Felipe; Spano, Frank C.
2016-06-01
The demonstration of strong and ultrastrong coupling regimes of cavity QED with polyatomic molecules has opened new routes to control chemical dynamics at the nanoscale. We show that strong resonant coupling of a cavity field with an electronic transition can effectively decouple collective electronic and nuclear degrees of freedom in a disordered molecular ensemble, even for molecules with high-frequency quantum vibrational modes having strong electron-vibration interactions. This type of polaron decoupling can be used to control chemical reactions. We show that the rate of electron transfer reactions in a cavity can be orders of magnitude larger than in free space for a wide class of organic molecular species.
Cavity-controlled chemistry in molecular ensembles
Herrera, Felipe
2015-01-01
The demonstration of strong and ultrastrong coupling regimes of cavity QED with polyatomic molecules has opened new routes to control chemical dynamics at the nanoscale. We show that strong resonant coupling of a cavity field with an electronic transition can effectively decouple collective electronic and nuclear degrees of freedom in a disordered molecular ensemble, even for molecules with high-frequency quantum vibrational modes having strong electron-vibration interactions. This type of polaron decoupling can be used to control chemical reactions. We show that the rate of electron transfer reactions in a cavity can be orders of magnitude larger than in free space, for a wide class of organic molecular species.
Dynamical Change of Quantum Fisher Information of Cavity-Reservoir Systems
Huang, Jiang; Xie, Qin
2016-04-01
We study the quantum Fisher information (QFI) dynamics of the phase parameter in the enlarged cavity-reservoir systems at zero temperature under two situations of large N limit and non-Markovian environment, respectively. We find an important relation that the total quantities of QFI of the cavity and reservoir are equal to unit during the dynamical evolution. The lost QFI of the cavity transfers to its corresponding reservoir with the same quantities simultaneously. Moreover, we also find that the detuning parameter and non-Markovian effect are two significant factors to affect the preservation of QFI. Supported by the National Natural Science Foundation of China under Grant No. 11374096 and the Natural Science Foundation of Guangdong Province under Grant No. 2015A030310354 and the Projection of Enhancing School with Innovation of Guangdong Ocean University under Grant Nos. GDOU2014050251 and GDOU2014050252
Multiparty Quantum Secret Sharing of Classical Message using Cavity Quantum Electrodynamic System
Institute of Scientific and Technical Information of China (English)
HAN Lian-Fang; LIU Yi-Min; ZHANG Zhan-Jun
2006-01-01
@@ An experimental feasible scheme of multiparty secret sharing of classical messages is proposed, based on a cavity quantum electrodynamic system. The secret messages are imposed on atomic Bell states initially in the sender's possession by local unitary operations. By swapping quantum entanglement of atomic Bell states, the secret messages are split into several parts and each part is distributed to a separate party. In this case, any subset of the entire party group can not read out the secret message but the entirety via mutual cooperations. In this scheme, to discriminate atomic Bell states, additional classical fields are employed besides the same highly-detuned single-mode cavities used to prepare atomic Bell states. This scheme is insensitive to the cavity decay and the thermal field, and usual joint Bell-state measurements are unnecessary.
Yousif, Taha; Zhou, Wenjun; Zhou, Ling
2014-08-01
We investigate coupled two-cavity optomechanical systems to show their potential usages by revealing the physical processes. Under two conditions, we deduce the correspondingly effective Hamiltonian with beam splitter type and nondegenerate parametric-down conversion type, respectively. Including the whole interactions, we show that the state transfer and the stationary entanglement between the two mechanical resonators can be achieved.
Are there background fields that can induce QED phase transitions at weak coupling?
International Nuclear Information System (INIS)
The existence of a new, non-perturbative phase of QED as indicated by studies of Schwinger-Dyson equations and lattice calculations. The crucial question is whether the phase transition point can be driven down to α ∼ 1/137 presumably by appropriate background fields. It appears that magnetic fields potentially can induce such a phase transition. Our investigation is related to our original conjecture that the anomalous e+e- events at GSI are due to the decay of a new positronium system formed in the new QED phase which is induced by the electromagnetic fields of the heavy-ions. 25 refs
Fully quantum treatment of the Landau-Pomeranchuk-Migdal effect in QED and QCD
International Nuclear Information System (INIS)
For the first time a rigorous quantum treatment of the Landau-Pomeranchuk-Migdal effect in QED and QCD is given. The rate of photon (gluon) radiation by an electron (quark) in medium is expressed through the Green's function of a two-dimensional Schroedinger equation with an imaginary potential. In QED this potential is proportional to the dipole cross section for scattering of e+e- pair off an atom, in QCD it is proportional to the cross section of interaction with color centre of the color singlet quark-antiquark-gluon system. 7 refs
Observing the nonequilibrium dynamics of the quantum transverse-field Ising chain in circuit QED.
Viehmann, Oliver; von Delft, Jan; Marquardt, Florian
2013-01-18
We show how a quantum Ising spin chain in a time-dependent transverse magnetic field can be simulated and experimentally probed in the framework of circuit QED with current technology. The proposed setup provides a new platform for observing the nonequilibrium dynamics of interacting many-body systems. We calculate its spectrum to offer a guideline for its initial experimental characterization. We demonstrate that quench dynamics and the propagation of localized excitations can be observed with the proposed setup and discuss further possible applications and modifications of this circuit QED quantum simulator. PMID:23373908
Many-body-QED perturbation theory: Connection to the Bethe-Salpeter equation
Lindgren, Ingvar
2005-01-01
The connection between many-body theory (MBPT)--in perturbative and non-perturbative form--and quantum-electrodynamics (QED) is reviewed for systems of two fermions in an external field. The treatment is mainly based upon the recently developed covariant-evolution-operator method for QED calculations [Lindgren et al. Phys. Rep. 389, 161 (2004)], which has a structure quite akin to that of many-body perturbation theory. At the same time this procedure is closely connected to the S-matrix and t...
Two-photon entanglement in multiqubit bidirectional-waveguide QED
Mirza, Imran M.; Schotland, John C.
2016-07-01
We study entanglement generation and control in bidirectional-waveguide QED driven by a two-photon Gaussian wave packet. In particular, we focus on how increasing the number of qubits affects the overall average pairwise entanglement in the system. We also investigate how the presence of a second photon can introduce nonlinearities, thereby manipulating the generated entanglement. In addition, we show that, through the introduction of chirality and small decay rates, entanglement can be stored and enhanced up to factors of 2 and 3, respectively. Finally, we analyze the influence of finite detunings and time-delays on the generated entanglement.
Li, Jiahua; Yu, Rong; Liu, Jiuyang; Ding, Chunling; Wu, Ying
2016-05-01
We study the probe-field transmission in cavity quantum electrodynamics (cavity-QED) systems with a partially transmitting element (PTE), where the PTE is used to control and tune the amplitude of the weak probe field propagating along a single waveguide channel in the structure. We derive analytic formulas utilized to determine the transmission coefficient of the probe field within the framework of quantum optics. Using experimentally accessible parameters, it is clearly shown that the asymmetric Fano-resonance line shape can be formed and manipulated by means of the added PTE. Furthermore, we reveal that there exists superluminal light with large intensity transmission in the transport spectrum of the waveguide-coupled cavity-QED system. This superluminal-light propagation effect, which exhibits the anomalous phase shift and is characterized by the negative group delay, can be enhanced by properly choosing the system parameters. The obtained results may be used for designing switching, modulation, and sensing for nanophotonic applications and ultrafast on-chip signal processing in telecom applications.
Circulation system for flowing uranium hexafluoride cavity reactor experiments
Jaminet, J. F.; Kendall, J. S.
1976-01-01
Research related to determining the feasibility of producing continuous power from fissile fuel in the gaseous state is presented. The development of three laboratory-scale flow systems for handling gaseous UF6 at temperatures up to 500 K, pressure up to approximately 40 atm, and continuous flow rates up to approximately 50g/s is presented. A UF6 handling system fabricated for static critical tests currently being conducted is described. The system was designed to supply UF6 to a double-walled aluminum core canister assembly at temperatures between 300 K and 400 K and pressure up to 4 atm. A second UF6 handling system designed to provide a circulating flow of up to 50g/s of gaseous UF6 in a closed-loop through a double-walled aluminum core canister with controlled temperature and pressure is described. Data from flow tests using UF6 and UF6/He mixtures with this system at flow rates up to approximately 12g/s and pressure up to 4 atm are presented. A third UF6 handling system fabricated to provide a continuous flow of UF6 at flow rates up to 5g/s and at pressures up to 40 atm for use in rf-heated, uranium plasma confinement experiments is described.
Behaviour of ohmic systems in cavities--a non-perturbative approach
International Nuclear Information System (INIS)
We consider a system consisting of a particle in the approximation of a harmonic oscillator, coupled to an ohmic environment inside a spherical reflecting cavity of radius R. Starting from the solution of the confined problem, we study the behaviour of the system in free space understood as the limit of an arbitrarily large radius in the quantities describing the confined solution. From a mathematical point of view we show that this method to approach the problem is not equivalent to consider the system a priori embedded in unbounded space. In particular, the matrix elements of the transformation turning the system to principal axis do not tend to distributions in the limit of an arbitrarily large cavity as it should be the case if the two procedures were mathematically equivalent. By introducing dressed coordinates we define dressed states which allow a non-perturbative unified description of the time evolution process for the system, in both cases of a small or an arbitrarily large cavity, for weak and strong coupling regimes. In particular we perform a study of the time energy distribution in a small cavity, with the initial condition that the particle is in the first excited state. We conclude for the quasi-stability of the excited particle in the weak coupling regime, which is a well-known experimental fact. Also our study of a superposition of dressed states in a large cavity concludes that it obeys a statistical distribution for very large times, in other words, we find a kind of 'spontaneous' decoherence in free space
Predictions of buoyancy-induced flow in asymmetrical heated rotating cavity system
International Nuclear Information System (INIS)
This paper presents the finite difference solutions for buoyancy-induced flow in the asymmetrical heated rotating cavity system for the range of rotational Reynolds numbers Re =6.13x10/sup 5/< Re/sub theta/=4.4*10/sup 6/ and the mass flow rates C/sub w/ <28000< C/sub w/ <3000. All the simulations have been carried out through the CFD (computational Fluid Dynamics) commercial code, ANSYS Fluent 12.0, by adopting axisymmetric, steady-state and elliptic technique. Two well know models namely k-epsilon and the Reynolds stress models have been employed. The simulated results illustrate the important aspects of the heated rotating cavity flow system. The noteworthy influence of buoyancy-induced flow have been observed on the predicted stream line, static temperature contours and the local Nusselt numbers for the rotating cavity flow system. The noteworthy influence of buoyancy-induced flow have been observed on the predicted stream lines, static temperature contours and the local Nusselt numbers for the rotating cavity space. A comparison of the predicted local nusselt numbers for the hot and cold discs showed a good level of agreement with the measurement. (author)
Uncoupled achromatic condition of a dog-leg system with the presence of RF cavities
Geng, Huiping
2013-01-01
To merge the beam from either of the two injectors to the main linac, a dog-leg system will be employed in the second Medium Energy Beam Transport (MEBT2) line of the China ADS driving accelerator. The achromatic condition has to be guaranteed to avoid beam center excursion against energy jitter. RF cavities were found indispensable to control the bunch length growth in the dog-leg system of MEBT2. The full uncoupling between transverse and longitudinal plane is desired to minimize the growth of projected rms emittances. The uncoupled achromatic condition of this dogleg system with the presence of RF bunching cavities will be deduced using the method of transfer matrixes. It is found that to fulfil the uncoupling condition, the distance between the bunching cavities is uniquely determined by the maximum energy gain of the RF cavities. The theoretical analysis is verified by the simulation code TraceWin. The space charge effect on the uncoupled achromatic condition and the beam emittance growth will also be di...
Compact lattice QED with Wilson fermions
International Nuclear Information System (INIS)
We study the phase structure and the chiral limit of 4d compact lattice QED with Wilson fermions (both dynamical and quenched). We use the standard Wilson gauge action and also a modified one suppressing lattice artifacts. Different techniques and observables to locate the chiral limit are discussed. (orig.)
A semi perturbative method for QED
Jora, Renata
2014-01-01
We compute the QED beta function using a new method of functional integration. It turns out that in this procedure the beta function contains only the first two orders coefficients and thus corresponds to a new renormalization scheme, long time supposed to exist.
Nonperturbative infrared dynamics in three dimensional QED
International Nuclear Information System (INIS)
A non-linear Schwinger-Dyson (SD) equation for the gauge boson propagator of massless QED in 2 + 1 dimensions is studied. It is shown that the nonperturbative solution leads to a non-trivial renormalization-group infrared fixed point quantitatively close to the one found in the leading order of the 1/N expansion, with N the number of fermion flavors
On QED radiative corrections at HERA
International Nuclear Information System (INIS)
For the QED radiative corrections to the inclusive deep inelastic scattering process ep→eX at HERA energies complete analytic expressions are obtained and numerically presented. Photon- and Z-boson exchange are included as well as soft photon exponentiation. 7 refs.; 1 fig
Probing QED Vacuum with Heavy Ions
Rafelski, Johann; Müller, Berndt; Reinhardt, Joachim; Greiner, Walter
2016-01-01
We recall how nearly half a century ago the proposal was made to explore the structure of the quantum vacuum using slow heavy-ion collisions. Pursuing this topic we review the foundational concept of spontaneous vacuum decay accompanied by observable positron emission in heavy-ion collisions and describe the related theoretical developments in strong fields QED.
Quantising general relativity using QED theory
Bell, Sarah B. M.; Diaz, Bernard M.
2002-01-01
We apply QED theory to quantum gravity and find it leads to general relativity in the classical limit. We discuss the implications of the result for the quantum-classical divide. This enables us to relate our result to M-theory.
CEBAF [Continuous Electron Beam Accelerator Facility] superconducting cavity rf drive system
International Nuclear Information System (INIS)
The CEBAF rf system consists of 418 individual rf amplifier chains. Each superconducting cavity is phase locked to the master drive reference line to within 1 degree, and the cavity field gradient is regulated to within 1 part in 104 by a state-of-the-art rf control module. Precision, continuously adjustable, modulo 3600 phase shifters are used to generate the individual phase references, and a compensated rf detector is used for level feedback. The close coupled digital system enhances system accuracy, provides self-calibration, and continuously checks the system for malfunction. Calibration curves, the operating program, and system history are stored in an on board EEPROM. The rf power is generated by a 5kW, water cooled, permanent magnet focused klystron. The klystrons are clustered in groups of 8 and powered from a common supply. rf power is transmitted to the accelerator sections by semiflexible waveguide
The mucosal immune system in the oral cavity-an orchestra of T cell diversity
Institute of Scientific and Technical Information of China (English)
Rui-Qing Wu; Dun-Fang Zhang; Eric Tu; Qian-Ming Chen; WanJun Chen
2014-01-01
The mucosal immune system defends against a vast array of pathogens, yet it exhibits limited responses to commensal microorganisms under healthy conditions. The oral-pharyngeal cavity, the gateway for both the gastrointestinal and respiratory tracts, is composed of complex anatomical structures and is constantly challenged by antigens from air and food. The mucosal immune system of the oral-pharyngeal cavity must prevent pathogen entry while maintaining immune homeostasis, which is achieved via a range of mechanisms that are similar or different to those utilized by the gastrointestinal immune system. In this review, we summarize the features of the mucosal immune system, focusing on T cell subsets and their functions. We also discuss our current understanding of the oral-pharyngeal mucosal immune system.
International Nuclear Information System (INIS)
This article describes the configuration and heat loads of the large-scale helium refrigeration system for the superconducting cavities utilized for the TRISTAN and KEKB Factory accelerators. The control system of the refrigeration system is also introduced. The fatal failures of the refrigeration system during the past long-term operation are summarized to entice discussions on future stable operation of the refrigeration system, since the refrigeration system will also be used for the SuperKEKB superconducting cavities. (author)
Calaga, R; Burt, G; Ratti, A
2015-01-01
The HL-LHC upgrade will use deflecting (or crab) cavities to compensate for geometric luminosity loss at low β* and non-zero crossing angle. A local scheme with crab cavity pairs across the IPs is used employing compact crab cavities at 400 MHz. Design of the cavities, the cryomodules and the RF system is well advanced. The LHC crab cavities will be validated initially with proton beam in the SPS.
Quantum backaction and noise interference in asymmetric two-cavity optomechanical systems
Yanay, Yariv; Sankey, Jack C.; Clerk, Aashish A.
2016-06-01
We study the effect of cavity damping asymmetries on backaction in a "membrane-in-the-middle" optomechanical system, where a mechanical mode modulates the coupling between two photonic modes. We show that when the energy difference between the optical modes dominates (i.e., in the adiabatic limit) this system generically realizes a dissipative optomechanical coupling, with an effective position-dependent photonic damping rate. The resulting quantum noise interference can be used to ground-state cool a mechanical resonator in the unresolved sideband regime. We explicitly demonstrate how quantum noise interference controls linear backaction effects and show that this interference persists even outside the adiabatic limit. For a one-port cavity in the extreme bad cavity limit, the interference allows one to cancel all linear backaction effects. This allows continuous measurements of position-squared, with no stringent constraints on the single-photon optomechanical coupling strength. In contrast, such a complete cancellation is not possible in the good cavity limit. This places strict bounds on the optomechanical coupling required for quantum nondemolition measurements of mechanical energy, even in a one-port device.
Czarski, Tomasz; Romaniuk, Ryszard S.; Pozniak, Krzysztof T.; Simrock, Stefan
2004-07-01
The cavity control system for the TESLA -- TeV-Energy Superconducting Linear Accelerator project is initially introduced in this paper. The FPGA -- Field Programmable Gate Array technology has been implemented for digital controller stabilizing cavity field gradient. The cavity SIMULINK model has been applied to test the hardware controller. The step operation method has been developed for testing the FPGA device coupled to the SIMULINK model of the analog real plant. The FPGA signal processing has been verified according to the required algorithm of the reference MATLAB controller. Some experimental results have been presented for different cavity operational conditions.
Quantum State Transfer between Charge and Flux Qubits in Circuit-QED
Institute of Scientific and Technical Information of China (English)
WU Qin-Qin; LIAO Jie-Qiao; KUANG Le-Man
2008-01-01
@@ We propose a scheme to implement quantum state transfer in a hybrid circuit quantum electrodynamics (QED)system which consists of a superconducting charge qubit, a flux qubit, and a transmission line resonator (TLR).It is shown that quantum state transfer between the charge qubit and the flux qubit can be realized by using the TLR as the data bus.
Huang, Yin; Veronis, Georgios; Min, Changjun
2015-11-16
We design a non-parity-time-symmetric plasmonic waveguide-cavity system, consisting of two metal-dielectric-metal stub resonators side coupled to a metal-dielectric-metal waveguide, to form an exceptional point, and realize unidirectional reflectionless propagation at the optical communication wavelength. The contrast ratio between the forward and backward reflection almost reaches unity. We show that the presence of material loss in the metal is critical for the realization of the unidirectional reflectionlessness in this plasmonic system. We investigate the realized exceptional point, as well as the associated physical effects of level repulsion, crossing and phase transition. We also show that, by periodically cascading the unidirectional reflectionless plasmonic waveguide-cavity system, we can design a wavelength-scale unidirectional plasmonic waveguide perfect absorber. Our results could be potentially important for developing a new generation of highly compact unidirectional integrated nanoplasmonic devices. PMID:26698471
Beam Pipe HOM Absorber for 750 MHz RF Cavity Systems
Energy Technology Data Exchange (ETDEWEB)
Johnson, Rolland; Neubauer, Michael
2014-10-29
This joint project of Muons, Inc., Cornell University and SLAC was supported by a Phase I and Phase II grant monitored by the SBIR Office of Science of the DOE. Beam line HOM absorbers are a critical part of future linear colliders. The use of lossy materials at cryogenic temperatures has been incorporated in several systems. The design in beam pipes requires cylinders of lossy material mechanically confined in such a way as to absorb the microwave energy from the higher-order modes and remove the heat generated in the lossy material. Furthermore, the potential for charge build-up on the surface of the lossy material requires the conductivity of the material to remain consistent from room temperature to cryogenic temperatures. In this program a mechanical design was developed that solved several design constraints: a) fitting into the existing Cornell load vacuum component, b) allowing the use of different material compositions, c) a thermal design that relied upon the compression of the lossy ceramic material without adding stress. Coating experiments were performed that indicated the design constraints needed to fully implement this approach for solving the charge build-up problem inherent in using lossy ceramics. In addition, the ACE3P program, used to calculate the performance of lossy cylinders in beam pipes in general, was supported by this project. Code development and documentation to allow for the more wide spread use of the program was a direct result of this project was well.
Beam self-excited rf cavity driver for a deflector or focusing system
Energy Technology Data Exchange (ETDEWEB)
Wadlinger, E.A.
1996-09-01
A bunched beam from and accelerator can excite and power an rf cavity which then drives either a deflecting or focusing (including nonlinear focusing) rf cavity with and amplitude related to beam current. Rf power, generated when a bunched beam loses energy to an rf field when traversing an electric field that opposes the particle`s motion, is used to drive a separate (or the same) cavity to either focus or deflect the beam. The deflected beam can be stopped by an apertures or directed to a different area of a target depending on beam current. The beam-generated rf power can drive a radio-frequency quadrupole (RFQ) that can change the focusing properties of a beam channel as a function of beam current (space- charge force compensation or modifying the beam distribution on a target). An rf deflector can offset a beam to a downstream sextupole, effectively producing a position-dependent quadrupole field. The combination of rf deflector plus sextupole will produce a beam current dependent quadropole-focusing force. A static quadrupole magnet plus another rf deflector can place the beam back on the optic axis. This paper describes the concept, derives the appropriate equations for system analysis, and fives examples. A variation on this theme is to use the wake field generated in an rf cavity to cause growth in the beam emittance. The beam current would then be apertured by emittance defining slits.
Feasibility of fiber optic displacement sensor scanning system for imaging of dental cavity
Rahman, Husna Abdul; Che Ani, Adi Izhar; Harun, Sulaiman Wadi; Yasin, Moh.; Apsari, Retna; Ahmad, Harith
2012-07-01
The purpose of this study is to investigate the potential of intensity modulated fiber optic displacement sensor scanning system for the imaging of dental cavity. Here, we discuss our preliminary results in the imaging of cavities on various teeth surfaces, as well as measurement of the diameter of the cavities which are represented by drilled holes on the teeth surfaces. Based on the analysis of displacement measurement, the sensitivities and linear range for the molar, canine, hybrid composite resin, and acrylic surfaces are obtained at 0.09667 mV/mm and 0.45 mm 0.775 mV/mm and 0.4 mm 0.5109 mV/mm and 0.5 mm and 0.25 mV/mm and 0.5 mm, respectively, with a good linearity of more than 99%. The results also show a clear distinction between the cavity and surrounding tooth region. The stability, simplicity of design, and low cost of fabrication make it suitable for restorative dentistry.
Cool-down by compact refrigerators system for srf cavities in JAERI FEL
International Nuclear Information System (INIS)
We have developed a built-in cryogenic system using compact refrigerators for the JAERI FEL superconducting accelerator modules. The cryogenic system consists of a refrigerator operated at 4.2 K to keep liquid helium level and a Gifford-McMahon cycle refrigerator to cool duplex heat shields. By applying the compact refrigerators, the cryogenic system can be operated successfully without an operator of the cryogenic system. A Cool-down of the JAERI superconducting accelerating cavities by the compact refrigerators system was carried out without liquid N2 or cold helium gas. The cool-down will be reported and discussed in detail. (author)
Preparation of multi-photon Fock states and quantum entanglement properties in circuit QED
International Nuclear Information System (INIS)
We demonstrate the controllable generation of multi-photon Fock states in circuit quantum electrodynamics (circuit QED). The external bias flux regulated by a counter can effectively adjust the bias time on each superconducting flux qubit so that each flux qubit can pass in turn through the circuit cavity and thereby avoid the effect of decoherence. We further investigate the quantum correlation dynamics of coupling superconducting qubits in a Fock state. The results reveal that the lower the photon number of the light field in the number state, the stronger the interaction between qubits is, then the more beneficial to maintaining entanglement between qubits it will be. (general)
Institute of Scientific and Technical Information of China (English)
无
2008-01-01
Two vertical-cavity surface-emitting lasers(VCSELs) are mutually coupled through a partially transparent mirror (PTM) placed in the pathway. The PTM plays the role of external mirror,which controls the feedback strength and coupling strength.We numerically simulate this system by establishing a visible SIMULINK model.The results demonstrate that the anticipation synchronization is achieved and it can tolerate some extent frequency detuning.Moreover,the system shows similar chaos-pass filtering effect on unidirectionally coupled system even both VCSELs are modulated.This system allows simultaneously bidirectional secure message transmission on public channels.
Renormalization of QED at low temperature and high density
International Nuclear Information System (INIS)
The results of the calculation of charge renormalization constant in QED at low temperature and high value of the chemical potential is presented. It completes the discussion of renormalization of QED in different limits of temperature and chemical potential. As a simple illustration of this procedure the scalar Higgs decay (H→e+e-) rate is corrected for this limit showing that the KLN theorem of QED is correct for this region of temperatures and chemical potential also. (author). 12 refs, 2 figs
The Research and Development on Simulation of Oral Cavity Food Chewing System
Xiaoming Zhang; Min Hui
2015-01-01
This paper aimed to dig the destruction effect of change rules of oral cavity chewing system for food and the significance of relationship between chewing movement and chewing effect for the understanding of food quality and structure features. The process and effect of chewing movement for crushing food was stimulated and analyzed by reverse engineering technology combined with modern dental theory. The experiment results of uniform motion model and variable motion model showed that in grind...
Energy Technology Data Exchange (ETDEWEB)
Paranin, V D; Matyunin, S A; Tukmakov, K N [S.P. Korolev Samara State Aerospace University, Samara (Russian Federation)
2013-10-31
The spectrum of a semiconductor laser with a birefringent external Gires – Tournois cavity is studied. The generation of two main laser modes corresponding to the ordinary and extraordinary wave resonances is found. It is shown that the radiation spectrum is controlled with a high energy efficiency without losses for spectral filtration. The possibility of using two-mode lasing in optical communication systems with wavelength division multiplexing is shown. (control of laser radiation parameters)
Exact quantum Bayesian rule for qubit measurements in circuit QED
Feng, Wei; Liang, Pengfei; Qin, Lupei; Li, Xin-Qi
2016-02-01
Developing efficient framework for quantum measurements is of essential importance to quantum science and technology. In this work, for the important superconducting circuit-QED setup, we present a rigorous and analytic solution for the effective quantum trajectory equation (QTE) after polaron transformation and converted to the form of Stratonovich calculus. We find that the solution is a generalization of the elegant quantum Bayesian approach developed in arXiv:1111.4016 by Korotokov and currently applied to circuit-QED measurements. The new result improves both the diagonal and off-diagonal elements of the qubit density matrix, via amending the distribution probabilities of the output currents and several important phase factors. Compared to numerical integration of the QTE, the resultant quantum Bayesian rule promises higher efficiency to update the measured state, and allows more efficient and analytical studies for some interesting problems such as quantum weak values, past quantum state, and quantum state smoothing. The method of this work opens also a new way to obtain quantum Bayesian formulas for other systems and in more complicated cases.
Modeling vibroacoustic systems involving cascade open cavities and micro-perforated panels.
Yu, Xiang; Cheng, Li; Guyader, Jean-Louis
2014-08-01
While the structural-acoustic coupling between flexible structures and closed acoustic cavities has been extensively studied in the literature, the modeling of structures coupled through open cavities, especially connected in cascade, is still a challenging task for most of the existing methods. The possible presence of micro-perforated panels (MPPs) in such systems adds additional difficulties in terms of both modeling and physical understanding. In this study, a sub-structuring methodology based on the Patch Transfer Function (PTF) approach with a Compound Interface treatment technique, referred to as CI-PTF method, is proposed, for dealing with complex systems involving cascade open/closed acoustic cavities and MPPs. The co-existence of apertures and solid/flexible/micro-perforated panels over a mixed separation interface is characterized using a compound panel subsystem, which enhances the systematic coupling feature of the PTF framework. Using several typical configurations, the versatility and efficiency of the proposed method is illustrated. Numerical studies highlight the physical understanding on the behavior of MPP inside a complex vibroacoustic environment, thus providing guidance for the practical design of such systems. PMID:25096101
Noncommutative QED and anomalous dipole moments
International Nuclear Information System (INIS)
We study QED on noncommutative spaces, NCQED. In particular we present the detailed calculation for the noncommutative electron-photon vertex and show that the Ward identity is satisfied. We discuss that in the noncommutative case moving electron will show electric dipole effects. In addition, we work out the electric and magnetic dipole moments up to one loop level. For the magnetic moment we show that noncommutative electron has an intrinsic (spin independent) magnetic moment. (author)
Leading quantum gravitational corrections to scalar QED
Bjerrum-Bohr, N. E. J.
2002-01-01
We consider the leading post-Newtonian and quantum corrections to the non-relativistic scattering amplitude of charged scalars in the combined theory of general relativity and scalar QED. The combined theory is treated as an effective field theory. This allows for a consistent quantization of the gravitational field. The appropriate vertex rules are extracted from the action, and the non-analytic contributions to the 1-loop scattering matrix are calculated in the non-relativistic limit. The n...
The Gribov problem in Noncommutative QED
Canfora, Fabrizio; Rosa, Luigi; Vitale, Patrizia
2016-01-01
It is shown that in the noncommutative version of QED {(NCQED)} Gribov copies induced by the noncommutativity of space-time do appear in the Landau gauge. This is a genuine effect of noncommutative geometry which disappears when the noncommutative parameter vanishes. On the basis of existing applications of the Gribov-Zwanziger propagator in NCQED to deal with the UV/IR mixing problem, we argue that the two problems may have a common origin and possibly a common solution.
Nonlinear QED Effects in Heavy Ion Collisions
Klein, Spencer R.
2000-01-01
Peripheral collisions of relativistic heavy ions uniquely probe many aspects of QED. Examples include $e^+e^-$ pair production and nuclear excitation in strong fields. After discussing these reactions, I will draw parallels between $\\gamma\\to e^+e^-$ and $\\gamma\\to q\\bar q$ and consider partly hadronic reactions. The scattered $q\\bar q$ pairs are a prolific source of vector mesons, which demonstrate many quantum effects. The two ions are a two-source interferometer, demonstrating interference...
Asymptotic completeness in QED. Pt. 2
International Nuclear Information System (INIS)
Physical states and fields in QED are defined as limits in the sense of Wightman functions of states and composite fields of the Gupta-Bleuler formalism. A formulation of asymptotic completeness proposed in an earlier publication for the Gupta-Bleuler case is transferred to the physical state space and shown to be valid in perturbation theory. An application to the calculation of inclusive cross sections is discussed. (orig.)
Interfering QCD/QED vacuum polarization
International Nuclear Information System (INIS)
Vacuum polarization mediated by quark loops is susceptible to external electromagnetic fields as well as to the QCD vacuum structure. Employing the stochastic vacuum model, we calculate the modification of the one-loop Euler-Heisenberg effective action due to stochastic color fields with the Fock-Schwinger techniques. Our results indicate nonperturbative light quark contributions of the same order of magnitude as the usual QED terms. Various theoretical and experimental implications are discussed in this progress report. (author)
International Nuclear Information System (INIS)
In Indus-2 storage ling, coupled bunch instabilities (CBI) may get generated due to irregularities in vacuum chambers and bellows, modes of septum chamber and RF cavities etc. Longitudinal multi bunch feedback system (LMBFS) will be installed, which will damp the longitudinal instabilities by sensing the oscillations generated due to instabilities and applying a corrective RF kick, The broadband kicker RF cavity will be a part of this feedback system. The operating frequency range of the kicker RF cavity has been chosen as 1264 MHz to 1517 MHz with a central frequency 1391 MHz and bandwidth of 253 MHz. Cavity design is based on the pillbox type with nose cone geometry for higher shunt impedance. Large bandwidth has been obtained by strongly loading a pillbox cavity with special ridged waveguides followed by broadband transitions to 7/8 inch coaxial lines, which are placed symmetrically with respect to the fundamental mode field distribution. Half of the coaxial feedthroughs are used as input power while the remaining as matched terminations. Simulated values of central frequency and bandwidth of the cavity are 1391 MHz and 253 MHz respectively, with loaded quality factor 5.5. S-parameters have been also calculated for entire bandwidth for cavity with eight feedthroughs. Simulations have been carried out with the help of computer code SUPERFISH and 3D-CST Studio Suite and important RF parameters of the cavity were worked out. A prototype aluminum cavity has been fabricated in two half shells. Some dimensional allowances has been kept for final tuning of the cavity. Eight feedthroughs are also designed, fabricated and mounted to test the cavity. Preliminary RF characterization has been carried out on the fabricated kicker cavity using two 4-port splitters and two set of three 2-ports splitters. The measured central frequency of the cavity is 1406 MHz with bandwidth of ∼ 250 MHz and loaded quality factor 5.8. S-parameters of the cavity were also measured. This paper
Magneto-optical cavity quantum electrodynamics effects in quantum dot - micropillar systems
International Nuclear Information System (INIS)
We report on magneto-optical studies of strongly coupled quantum dot - micropillar cavity systems. Large In0.3Ga0.7As quantum dots (QDs) in the active layer of the micropillar facilitate the observation of strong coupling. In addition, they exhibit a particular large diamagnetic response which is exploited to demonstrate magneto-optical resonance tuning in the strong coupling regime. The magnetic field employed in Faraday configuration induces a transition from strong coupling towards the critical coupling regime which is explained in terms of a magnetic field dependent oscillator strength of the In0.3Ga0.7As QDs. We further study the coherent interaction between spin resolved states of the QDs and microcavity photon modes. A detailed oscillator model is used to extract the associated coupling parameters of the individual spin and cavity modes and reveals an effective coupling between photon modes that is mediated by the exciton spin states.
A waveguide overloaded cavity kicker for the HLS II longitudinal feedback system
Li, Wubin; Sun, Baogen; Wu, Fangfang; Xu, Wei; Lu, Ping; Yang, Yongliang
2013-01-01
In the upgrade project of Hefei Light Source (HLS II), a new digital longitudinal bunch-by-bunch feedback system will be developed to suppress the coupled bunch instabilities in the storage ring effectively. We design a new waveguide overloaded cavity longitudinal feedback kicker as the feedback actuator. The beam pipe of the kicker is racetrack shape so as to avoid a transition part to the octagonal vacuum chamber. The central frequency and the bandwidth of the kicker have been simulated and optimized to achieve design goals by the HFSS code. The higher shunt impedance can be obtained by using a nose cone to reduce the feedback power requirement. Before the kicker cavity was installed in the storage ring, a variety of measurements were carried out to check its performance. All these results of simulation and measurement are presented.
Sub-Poissonian photon emission in coupled double quantum dots-cavity system
Ye, Han; Peng, Yi-Wei; Yu, Zhong-Yuan; Zhang, Wen; Liu, Yu-Min
2015-11-01
In this work, we theoretically analyze the few-photon emissions generated in a coupled double quantum dots (CDQDs)-single mode microcavity system, under continuous wave and pulse excitation. Compared with the uncoupled case, strong sub-Poissonian character is achieved in a CDQDs-cavity system at a certain laser frequency. Based on the proposed scheme, single photon generation can be obtained separately under QD-cavity resonant condition and off-resonant condition. For different cavity decay rates, we reveal that laser frequency detunings of minimum second-order autocorrelation function are discrete and can be divided into three regions. Moreover, the non-ideal situation where two QDs are not identical is discussed, indicating the robustness of the proposed scheme, which possesses sub-Poissonian character in a large QD difference variation range. Project supported by the National Natural Science Foundation of China (Grant Nos. 61372037 and 61401035), the Beijing Excellent Ph.D. Thesis Guidance Foundation, China (Grant No. 20131001301), and the Fund of State Key Laboratory of Information Photonics and Optical Communications (Beijing University of Posts and Telecommunications), China (Grant No. IPOC2015ZC05).
Development of deflector cavity and RF amplifier for bunch length detector system
Pandey, H. K.; Bhattacharya, T. K.; Chakrabarti, A.
2016-02-01
A minimally-interceptive bunch length detector system is being developed for measurement of longitudinal dimension of the bunch beam from RFQ of the radioactive ion beam (RIB) facility at VECC. This detector system is based on secondary electrons emission produced by the primary ion beam hitting a thin tungsten wire placed in the beam path. In this paper we report the design, development and off line testing results of deflector cavity together with its RF sysytem. The deflector cavity is a capacitive loaded helical type λ/2 resonator driven by RF source of 500 W at 37.8 MHz solid state amplifier, realized by combining two amplifier modules of 300 W each. The measured RF characteristics of the resonator, such as frequency, Q value and shunt impedance have been found to be reasonably good and close to the analytical estimation and results of simulation. The design philosophy and test results of individual components of the amplifier are discussed. The test result upto full power shows a good harmonic separation at the individual module level and this is found to improve further when modules are combined together.The results of high power performance test of the deflector cavity together with amplifier are also reported.
Predictions of Buoyancy-induced Flow in Asymmetrical Heated Rotating Cavity System
Directory of Open Access Journals (Sweden)
Abdul Fatah Abbassi
2013-04-01
Full Text Available This paper presents the finite difference solutions for buoyancy-induced flow in the asymmetrical heated rotating cavity system for the range of rotational Reynolds numbers Reθ =6.13x10^5
Heat Transfer Distribution for Reactor Cavity Cooling System Riser Considering Thermal Conduction
International Nuclear Information System (INIS)
The reactor cavity cooling system (RCCS) is the safety grade system for a very high temperature reactor (VHTR). The main role of the RCCS is the heat removal from the reactor vessel. The verification of the performance of the passive RCCS is a key objective for the construction of demonstration plant. Korea Atomic Energy Research Institute (KAERI) is considering the air-cooled RCCS under natural convection operation for a PMR200. Bae et al. studied scaling of PMR200 RCCS prior to the experimental verification of the RCCS. The cavity radiation number and temperature ratio number were selected as controlling non-dimensional group. The heat transfer in the riser is one of the key phenomena to predict the performance of the prototype RCCS. The riser absorbs heat from the reactor vessel, through radiative heat transfer, and from the reactor cavity, through convective heat transfer. The absorbed heat is removed by convective heat transfer in the riser. CFD results showed that thermal conduction through the RCCS riser was not negligible. Because the material of the riser duct was carbon steel, the thermal conduction effect was comparable even with a small duct thickness to the convective heat transfer by air flow. It is strongly recommended that the heat transfer in RCCS should go with consideration on the thermal conduction of the RCCS riser duct
International Nuclear Information System (INIS)
A coupled plasmonic waveguide resonator system which can produce sharp and asymmetric Fano resonances was proposed and analyzed. Two Fano resonances are induced by the interactions between the narrow discrete whispering gallery modes in a plasmonic square cavity resonator and the broad spectrum of the metal–insulator–metal stub resonator. The relative peak amplitudes between the 1st and 2nd order Fano resonances can be adjusted by changing the structure parameters, such as the square cavity size, the stub size and the center-to-center distance between the square cavity and the stub resonators. And the 1st order Fano resonant peak, which is a standing-wave mode, will split into two resonant peaks (one standing-wave mode and one traveling-wave mode) when it couples with the 2nd Fano resonance. Also, the potential of the proposed Fano system as an integrated slow-light device and refractive index sensor was investigated. The results show that a maximum group index of about 100 can be realized, and a linear refractive index sensitivity of 938 nm/RIU with a figure of merit of about 1.35 × 104 can be obtained. (paper)
Development of PLC based control system for frequency tuning loop of 31.6 MHz RF cavity
International Nuclear Information System (INIS)
Two storage rings, Indus-1 and Indus-2 are operational at RRCAT. Both the storage rings share a common injector system consisting of a Microtron and a Booster Synchrotron. The electrons are generated and accelerated to 20 MeV in Microtron and injected through a transfer line into the Booster Synchrotron where its energy is increased to 450 MeV/550 MeV. In Booster Synchrotron, a MHz RF system is installed. This RF System includes 1 kW RF amplifier, re-entrant type RF cavity and its tuning system. The RF system works in ramp mode. In RF cavities, resonant frequency changes due to beam loading and temperature effect. Our aim is to keep the RF Cavity at fixed resonance. Frequency Tuning Loop (FTL) will keep the cavities tuned by compensating for both beam loading and temperature effects. This is realized by means of a mechanism, driven by a stepper motor, which changes the volume of RF cavity by moving the plunger in/out and therefore its frequency. A Programmable Logic Controller (PLC) based Control system was developed to replace existing control system for FTL of RF Cavity installed in Booster Synchrotron. The main components of the control system are the phase detector, PLC with analog module, optical isolation card and touch screen interface. Control logic was developed in Step-7 MicroWin. The complete control logic, advantages over the earlier control system and scope for adaptability has been thoroughly discussed in this paper
A digital frequency stabilization system of external cavity diode laser based on LabVIEW FPGA
Liu, Zhuohuan; Hu, Zhaohui; Qi, Lu; Wang, Tao
2015-10-01
Frequency stabilization for external cavity diode laser has played an important role in physics research. Many laser frequency locking solutions have been proposed by researchers. Traditionally, the locking process was accomplished by analog system, which has fast feedback control response speed. However, analog system is susceptible to the effects of environment. In order to improve the automation level and reliability of the frequency stabilization system, we take a grating-feedback external cavity diode laser as the laser source and set up a digital frequency stabilization system based on National Instrument's FPGA (NI FPGA). The system consists of a saturated absorption frequency stabilization of beam path, a differential photoelectric detector, a NI FPGA board and a host computer. Many functions, such as piezoelectric transducer (PZT) sweeping, atomic saturation absorption signal acquisition, signal peak identification, error signal obtaining and laser PZT voltage feedback controlling, are totally completed by LabVIEW FPGA program. Compared with the analog system, the system built by the logic gate circuits, performs stable and reliable. User interface programmed by LabVIEW is friendly. Besides, benefited from the characteristics of reconfiguration, the LabVIEW program is good at transplanting in other NI FPGA boards. Most of all, the system periodically checks the error signal. Once the abnormal error signal is detected, FPGA will restart frequency stabilization process without manual control. Through detecting the fluctuation of error signal of the atomic saturation absorption spectrum line in the frequency locking state, we can infer that the laser frequency stability can reach 1MHz.
Cavity atom optics and the `free atom laser'
Heurich, J.; Moore, M. G.; Meystre, P.
1999-01-01
The trap environment in which Bose-Einstein condensates are generated and/or stored strongly influences the way they interact with light. The situation is analogous to cavity QED in quantum optics, except that in the present case, one tailors the matter-wave mode density rather than the density of modes of the optical field. Just as in QED, for short times, the atoms do not sense the trap and propagate as in free space. After times long enough that recoiling atoms can probe the trap environme...
Quantum Interference Induced Photon Blockade in a Coupled Single Quantum Dot-Cavity System
Tang, Jing; Xu, Xiulai
2015-01-01
We propose an experimental scheme to implement a strong photon blockade with a single quantum dot coupled to a nanocavity. The photon blockade effect can be tremendously enhanced by driving the cavity and the quantum dot simultaneously with two classical laser fields. This enhancement of photon blockade is ascribed to the quantum interference effect to avoid two-photon excitation of the cavity field. Comparing with Jaynes-Cummings model, the second-order correlation function at zero time delay $g^{(2)}(0)$ in our scheme can be reduced by two orders of magnitude and the system sustains a large intracavity photon number. A red (blue) cavity-light detuning asymmetry for photon quantum statistics with bunching or antibunching characteristics is also observed. The photon blockade effect has a controllable flexibility by tuning the relative phase between the two pumping laser fields and the Rabi coupling strength between the quantum dot and the pumping field. Moreover, the photon blockade scheme based on quantum in...
International Nuclear Information System (INIS)
We report on magneto-optical studies of strongly coupled quantum dot - micropillar cavity systems. Laterally extended In0.3Ga0.7As quantum dots (QDs) in the active layer of a micropillar cavity facilitate the observation of strong coupling. These QDs are characterized by large oscillator strength and they exhibit a large diamagnetic response, which is exploited to demonstrate magneto-optical resonance tuning. In addition, the coherent interaction between spin resolved states of the QDs and microcavity photon modes is studied. We access the spin degree of freedom by applying a non-zero magnetic field in Faraday configuration, so that the spin degeneracy of the QD exciton is lifted, while the resonance tuning of the Zeeman split exciton lines is achieved by temperature variation. A detailed oscillator model is used to extract coupling parameters of the individual spin and cavity modes. Our results demonstrate an effective coupling between photon modes that is mediated by the exciton spin states. We further show simulations of the photon-photon coupling in dependence of the coupling parameters.
Optimizing RF gun cavity geometry within an automated injector design system
Energy Technology Data Exchange (ETDEWEB)
Alicia Hofler ,Pavel Evtushenko
2011-03-28
RF guns play an integral role in the success of several light sources around the world, and properly designed and optimized cw superconducting RF (SRF) guns can provide a path to higher average brightness. As the need for these guns grows, it is important to have automated optimization software tools that vary the geometry of the gun cavity as part of the injector design process. This will allow designers to improve existing designs for present installations, extend the utility of these guns to other applications, and develop new designs. An evolutionary algorithm (EA) based system can provide this capability because EAs can search in parallel a large parameter space (often non-linear) and in a relatively short time identify promising regions of the space for more careful consideration. The injector designer can then evaluate more cavity design parameters during the injector optimization process against the beam performance requirements of the injector. This paper will describe an extension to the APISA software that allows the cavity geometry to be modified as part of the injector optimization and provide examples of its application to existing RF and SRF gun designs.
Energy Technology Data Exchange (ETDEWEB)
Osman, K.I., E-mail: kie_osman@hotmail.com [Department of Mathematics, Al-Azhar University, Faculty of Science (Women' s Section), P.O. Box 11754, Nasr City, Cairo (Egypt); Joshi, A., E-mail: ajoshi@eiu.edu [Department of Physics, Eastern Illinois University, Charleston, IL 61920 (United States)
2012-07-30
A composite system consisting of a K-type atomic medium and a double optical cavity configuration is considered to study the phenomenon of atomic optical bistability (AOB) in the mean field approximation. The controllability of this phenomenon achieved by additional electromagnetic fields not circulating in the cavities is studied. Also, the effect of spontaneously generated coherence due to the quantum interference in decaying nearby levels on the multi-branched AOB is discussed. The system displays a new class of bifurcations. -- Highlights: ► Optical bistability (OB) in a K-type atomic medium inside a double optical cavity. ► Controllability of OB via electromagnetic fields not circulating in the cavities. ► Controllability of OB via spontaneously generated coherence due to decaying levels. ► The system displays a new class of bifurcations.
A Soluble Theory of Massless Scalar QED_2
Brandt, F. T.; Das, Ashok; Frenkel, J
1998-01-01
In this brief report, we analyze a generalized theory of massless scalar QED_2 and show that, unlike the conventional scalar QED_2, it is free from infrared divergence problems. The model is exactly soluble and may describe, in an 1+1 dimensional space-time, noninteracting spin-one tachyons.
Directory of Open Access Journals (Sweden)
Sharma Vivek
2009-01-01
Full Text Available Aim: This study was conducted to determine the effect of three cavity disinfectants (chlorhexidine gluconate based-Consepsis; benzalkonium chloride-based Tubulicid Red, iodine-potassium iodide/copper-sulphate based Ora-5 on the microleakage of a dentin bonding system, Clearfil SE Bond. Materials and Methods: Class V cavities were prepared on 45 extracted molars. The respective experimentalgroups were treated with cavity disinfectants and Clearfil SE Bond. Preparations without cavity disinfectants served as negative control and those with neither disinfectant nor dentin bonding resin application served as positive controls. After the cavity preparations were restored with resin composite (Clearfil APX, the specimens were subjected to dye penetration. Statistical analysis was performed using ANOVA (Kruskal-Wallis test. Results: Unlike Conspesis and Tubulicid Red, Ora-5 exhibited significantly higher microleakage and adversely affected the sealing ability of Clearfil SE bond. Only Consepsis and Tubulicid Red could be used as cavity disinfectants with Clearfil SE bond, without its sealing abilities being adversely affected. Conclusions: 1 Consepsis and Tubulicid Red can be used as cavity disinfectants with Clearfil SE Bond, without the sealing ability of Clearfil SE bond being affected. 2 Ora-5 is not an appropriate disinfectant to be used with this dentin bonding system, because it alters its sealing ability.
Euler-Heisenberg-Weiss action for QCD +QED
Ozaki, Sho; Arai, Takashi; Hattori, Koichi; Itakura, Kazunori
2015-07-01
We derive an analytic expression for one-loop effective action of QCD +QED at zero and finite temperatures by using the Schwinger proper time method. The result is a nonlinear effective action not only for electromagnetic and chromo-electromagnetic fields but also for the Polyakov loop, and thus reproduces the Euler-Heisenberg action in QED, QCD, and QED +QCD , and also the Weiss potential for the Polyakov loop at finite temperature. As applications of this "Euler-Heisenberg-Weiss" action in QCD +QED , we investigate quark pair productions induced by QCD +QED fields at zero temperature and the Polyakov loop in the presence of strong electromagnetic fields. Quark one-loop contribution to the effective potential of the Polyakov loop explicitly breaks the center symmetry, and is found to be enhanced by the magnetic field, which is consistent with the inverse magnetic catalysis observed in lattice QCD simulation.
Euler-Heisenberg-Weiss action for QCD+QED
Ozaki, Sho; Hattori, Koichi; Itakura, Kazunori
2015-01-01
We derive an analytic expression for one-loop effective action of QCD+QED at zero and finite temperatures by using the Schwinger's proper time method. The result is a nonlinear effective action not only for electromagnetic and chromo-electromagnetic fields but also the Polyakov loop, and thus reproduces the Euler-Heisenberg action in QED, QCD, and QED+QCD, and also the Weiss potential for the Polyakov loop at finite temperature. As applications of this "Euler-Heisenberg-Weiss" action in QCD+QED, we investigate quark pair productions induced by QCD+QED fields at zero temperature and the Polyakov loop in the presence of strong electromagnetic fields. Quark one-loop contribution to the effective potential of the Polyakov loop explicitly breaks the center symmetry, and is found to be enhanced by the magnetic field, which is consistent with the inverse magnetic catalysis observed in lattice QCD simulation.
International Nuclear Information System (INIS)
Multiple controllable spiking patterns are achieved in a 1310 nm Vertical-Cavity Surface Emitting Laser (VCSEL) in response to induced perturbations and for two different cases of polarized optical injection, namely, parallel and orthogonal. Furthermore, reproducible spiking responses are demonstrated experimentally at sub-nanosecond speed resolution and with a controlled number of spikes fired. This work opens therefore exciting research avenues for the use of VCSELs in ultrafast neuromorphic photonic systems for non-traditional computing applications, such as all-optical binary-to-spiking format conversion and spiking information encoding
Energy Technology Data Exchange (ETDEWEB)
Hurtado, Antonio, E-mail: antonio.hurtado@strath.ac.uk [Institute of Photonics, SUPA Department of Physics, University of Strathclyde, TIC Centre, 99 George Street, Glasgow G1 1RD (United Kingdom); Javaloyes, Julien [Departament de Fisica, Universitat de les Illes Balears, c/Valldemossa km 7.5, 07122 Mallorca (Spain)
2015-12-14
Multiple controllable spiking patterns are achieved in a 1310 nm Vertical-Cavity Surface Emitting Laser (VCSEL) in response to induced perturbations and for two different cases of polarized optical injection, namely, parallel and orthogonal. Furthermore, reproducible spiking responses are demonstrated experimentally at sub-nanosecond speed resolution and with a controlled number of spikes fired. This work opens therefore exciting research avenues for the use of VCSELs in ultrafast neuromorphic photonic systems for non-traditional computing applications, such as all-optical binary-to-spiking format conversion and spiking information encoding.
High order QED corrections in Z physics
International Nuclear Information System (INIS)
In this thesis a number of calculations of higher order QED corrections are presented, all applying to the standard LEP/SLC processes e+e-→ f-bar f, where f stands for any fermion. In cases where f≠ e-, νe, the above process is only possible via annihilation of the incoming electron positron pair. At LEP/SLC this mainly occurs via the production and the subsequent decay of a Z boson, i.e. the cross section is heavily dominated by the Z resonance. These processes and the corrections to them, treated in a semi-analytical way, are discussed (ch. 2). In the case f = e- (Bhabha scattering) the process can also occur via the exchange of a virtual photon in the t-channel. Since the latter contribution is dominant at small scattering angles one has to exclude these angles if one is interested in Z physics. Having excluded that region one has to recalculate all QED corrections (ch. 3). The techniques introduced there enables for the calculation the difference between forward and backward scattering, the forward backward symmetry, for the cases f ≠ e-, νe (ch. 4). At small scattering angles, where Bhabha scattering is dominated by photon exchange in the t-channel, this process is used in experiments to determine the luminosity of the e+e- accelerator. hence an accurate theoretical description of this process at small angles is of vital interest to the overall normalization of all measurements at LEP/SLC. Ch. 5 gives such a description in a semi-analytical way. The last two chapters discuss Monte Carlo techniques that are used for the cases f≠ e-, νe. Ch. 6 describes the simulation of two photon bremsstrahlung, which is a second order QED correction effect. The results are compared with results of the semi-analytical treatment in ch. 2. Finally ch. 7 reviews several techniques that have been used to simulate higher order QED corrections for the cases f≠ e-, νe. (author). 132 refs.; 10 figs.; 16 tabs
Non-Riemannian geometrical optics in QED
Garcia de Andrade, L C
2003-01-01
A non-minimal photon-torsion axial coupling in the quantum electrodynamics (QED) framework is considered. The geometrical optics in Riemannian-Cartan spacetime is considering and a plane wave expansion of the electromagnetic vector potential is considered leading to a set of the equations for the ray congruence. Since we are interested mainly on the torsion effects in this first report we just consider the Riemann-flat case composed of the Minkowskian spacetime with torsion. It is also shown that in torsionic de Sitter background the vacuum polarisation does alter the propagation of individual photons, an effect which is absent in Riemannian spaces.
Bound states -- from QED to QCD
Hoyer, Paul
2014-01-01
These lectures are divided into two parts. In Part 1 I discuss bound state topics at the level of a basic course in field theory: The derivation of the Schr\\"odinger and Dirac equations from the QED Lagrangian, by summing Feynman diagrams and in a Hamiltonian framework. Less well known topics include the equal-time wave function of Positronium in motion and the properties of the Dirac wave function for a linear potential. The presentation emphasizes physical aspects and provides the framework...
QED and relativistic corrections in superheavy elements
Indelicato, P J; Desclaux, J P; Santos, J P; Indelicato, Paul
2007-01-01
In this paper we review the different relativistic and QED contributions to energies, ionic radii, transition probabilities and Land\\'{e} $g$-factors in super-heavy elements, with the help of the MultiConfiguration Dirac-Fock method (MCDF). The effects of taking into account the Breit interaction to all orders by including it in the self-consistent field process are demonstrated. State of the art radiative corrections are included in the calculation and discussed. We also study the non-relativistic limit of MCDF calculation and find that the non-relativistic offset can be unexpectedly large.
On the construction of QED using ERG
Sonoda, Hidenori
2007-01-01
It has been known for some time that a smooth momentum cutoff is compatible with local gauge symmetries. In this paper we show concretely how to construct QED using the exact renormalization group (ERG). First, we give a new derivation of the Ward identity for the Wilson action using the technique of composite operators. Second, parameterizing the theory by its asymptotic behavior for a large cutoff, we show how to fine-tune the parameters to satisfy the identity. Third, we recast the identit...
Oblique photon expansion of QED structure functions
International Nuclear Information System (INIS)
In the oblique photon expansion, the collinear part of photon emission is summed up to all orders in perturbation theory. The number of oblique or non-collinear photons is the expansion order. Unlike in perturbation theory, every term of the expansion is both infrared finite and gauge invariant. The zero oblique photon contribution to the electromagnetic structure tensor in QED is computed in detail. The behaviors of the structure functions F1 and F2 are discussed in the soft and ultra-soft limits
Energy Technology Data Exchange (ETDEWEB)
Hassan, Yassin [Univ. of Wisconsin, Madison, WI (United Texas A & M Univ., College Station, TX (United States); Corradini, Michael; Tokuhiro, Akira; Wei, Thomas Y.C.
2014-07-14
The Reactor Cavity Cooling Systems (RCCS) is a passive safety system that will be incorporated in the VTHR design. The system was designed to remove the heat from the reactor cavity and maintain the temperature of structures and concrete walls under desired limits during normal operation (steady-state) and accident scenarios. A small scale (1:23) water-cooled experimental facility was scaled, designed, and constructed in order to study the complex thermohydraulic phenomena taking place in the RCCS during steady-state and transient conditions. The facility represents a portion of the reactor vessel with nine stainless steel coolant risers and utilizes water as coolant. The facility was equipped with instrumentation to measure temperatures and flow rates and a general verification was completed during the shakedown. A model of the experimental facility was prepared using RELAP5-3D and simulations were performed to validate the scaling procedure. The experimental data produced during the steady-state run were compared with the simulation results obtained using RELAP5-3D. The overall behavior of the facility met the expectations. The facility capabilities were confirmed to be very promising in performing additional experimental tests, including flow visualization, and produce data for code validation.
Testing Bell inequalities with circuit QEDs by joint spectral measurements
Yuan, Hao; Huang, J S; Wang, X H; Vedral, Vlatko
2011-01-01
We propose a feasible approach to test Bell's inequality with the experimentally-demonstrated circuit QED system, consisting of two well-separated superconducting charge qubits (SCQs) dispersively coupled to a common one-dimensional transmission line resonator (TLR). Our proposal is based on the joint spectral measurements of the two SCQs, i.e., their quantum states in the computational basis $\\{|kl>,\\,k,l=0,1\\}$ can be measured by detecting the transmission spectra of the driven TLR: each peak marks one of the computational basis and its relative height corresponds to the probability superposed. With these joint spectral measurements, the generated Bell states of the two SCQs can be robustly confirmed without the standard tomographic technique. Furthermore, the statistical nonlocal-correlations between these two distant qubits can be directly read out by the joint spectral measurements, and consequently the Bell's inequality can be tested by sequentially measuring the relevant correlations related to the sui...
Quantum trajectories for dispersive readout in superconducting circuit QED
International Nuclear Information System (INIS)
We present applications for the method of quantum trajectory simulations for the realistic simulation of single-shot readout experiments in superconducting circuit QED. Quantum trajectories generated by stochastic master equations allow to obtain a realistic measurement signal while one simultaneously gains access to the internal quantum dynamics of the system in question taking the measurement back-action into account correctly. Thus, useful insights beyond the ensemble average description of a conventional master equation can be obtained. To illustrate the power of the method, we present two important examples: (i) How to detect single itinerant microwave photons non-destructively (ii) How to generate massively entangled N-qubit states like W- and GHZ-states by measurement. We point out the presented examples can be realized using currently available experimental setups.
Belomestnykh, S A; Medjidzade, V; Padamsee, H; Veshcherevich, V G
2004-01-01
Development of a 150 kW CW RF power delivery system for 1300 MHz superconducting cavities is under way at Cornell University in collaboration with MEPhI. The system is based on a twin-coupler consisting of two identical coaxial antenna-type couplers derived from the TTF-3 input coupler design. Because the average power is much higher than in the TTF-3 coupler, the required coupling is stronger and we wanted to avoid multipacting phenomena, major changes were made to the prototype design. Presented coupler has completely redesigned cold part and significantly improved cooling of warm bellows. The results of thermal and mechanical stress calculations are reported. The magnitudes and phases of RF fields applied to each side of the twin-coupler must be very close to each other. This imposes very strict requirements upon a power dividing system. These requirements and proposed layout of a system satisfying them are discussed.
Quantum Fisher information for a qubit system placed inside a dissipative cavity
International Nuclear Information System (INIS)
We study the time evolution of the quantum Fisher information of a system whose the dynamics is described by the phase-damped model. We discuss the correlation between the Fisher information and entanglement dynamics of a qubit and single-mode quantized field in a coherent state inside phase-damped cavity. Analytic results under certain parametric conditions are obtained, by means of which we analyze the influence of dissipation on the negativity and quantum Fisher information for different values of the estimator parameter. An interesting monotonic relation between the Fisher information and nonlocal correlation behavior is observed during the time evolution. -- Highlights: ► Relation between the Fisher information and nonlocal correlation dynamics. ► Definition of quantum Fisher information for the atomic density operator. ► Investigation of Fisher information and negativity for the phase-damped model. ► Analytic solution of the master equation for the atom-field system in cavity field. ► Quantum Fisher information may be helpful in quantum information tasks.
Gamp, A
2011-01-01
We begin by giving a description of the rf generator-cavity-beam coupled system in terms of basic quantities. Taking beam loading and cavity detuning into account, expressions for the cavity impedance as seen by the generator and as seen by the beam are derived. Subsequently methods of beam-loading compensation by cavity detuning, rf feedback, and feed-forward are described. Examples of digital rf phase and amplitude control for the special case of superconducting cavities are also given. Finally, a dedicated phase loop for damping synchrotron oscillations is discussed.
Lorentz-invariant non-commutative QED
International Nuclear Information System (INIS)
Lorentz-invariant non-commutative QED (NCQED) is constructed so as to be a part of the Lorentz-invariant non-commutative Standard Model (NCSM), a subject to be treated in later publications. Our NCSM is based on Connes' observation that the total fermion field in the Standard Model can be regarded as a bi-module over a flavor-color algebra. In this paper, it is shown that there exist two massless gauge fields in NCQED that are interchanged by the C' transformation. Since C' is reduced to the conventional charge conjugation C in the commutative limit, in the same limit, the two gauge fields become identical to the photon field which couples to only four spinors, with charges ±2, ±1. Following Carlson, Carone and Zobin, our NCQED respects Lorentz invariance, employing the Doplicher-Fredenhagen-Roberts algebra instead of the usual algebra with constant θμν. In the new version, θμν becomes an integration variable. We show, using a simple NC scalar model, that the θ integration yields an invariant damping factor instead of the oscillating one in the nonplanar self-energy diagram in the one-loop approximation. The Seiberg-Witten map shows that the θ expansion of NCQED generates exotic but well-motivated derivative interactions beyond QED, with allowed charges being only 0, ±1, ±2. (author)
QED effects in the pseudoscalar meson sector
Horsley, R.; Nakamura, Y.; Perlt, H.; Pleiter, D.; Rakow, P. E. L.; Schierholz, G.; Schiller, A.; Stokes, R.; Stüben, H.; Young, R. D.; Zanotti, J. M.
2016-04-01
In this paper we present results on the pseudoscalar meson masses from a fully dynamical simulation of QCD+QED, concentrating particularly on violations of isospin symmetry. We calculate the π +- π 0 splitting and also look at other isospin violating mass differences. We have presented results for these isospin splittings in [1]. In this paper we give more details of the techniques employed, discussing in particular the question of how much of the symmetry violation is due to QCD, arising from the different masses of the u and d quarks, and how much is due to QED, arising from the different charges of the quarks. This decomposition is not unique, it depends on the renormalisation scheme and scale. We suggest a renormalisation scheme in which Dashen's theorem for neutral mesons holds, so that the electromagnetic self-energies of the neutral mesons are zero, and discuss how the self-energies change when we transform to a scheme such as overline{M S} , in which Dashen's theorem for neutral mesons is violated.
QED effects in the pseudoscalar meson sector
International Nuclear Information System (INIS)
We present results on the pseudoscalar meson masses from a fully dynamical simulation of QCD+QED. We concentrate particularly on violations of isospin symmetry. We calculate the π+-π0 splitting and also look at other isospin violating mass differences. We have presented results for these isospin splittings in arXiv:1508.06401 [hep-lat]. In this paper we give more details of the techniques employed, discussing in particular the question of how much of the symmetry violation is due to QCD, arising from the different masses of the u and d quarks, and how much is due to QED, arising from the different charges of the quarks. This decomposition is not unique, it depends on the renormalisation scheme and scale. We suggest a renormalisation scheme in which Dashen's theorem for neutral mesons holds, so that the electromagnetic self-energies of the neutral mesons are zero, and discuss how the self-energies change when we transform to a scheme such as MS, in which Dashen's theorem for neutral mesons is violated.
Bound states -- from QED to QCD
Hoyer, Paul
2014-01-01
These lectures are divided into two parts. In Part 1 I discuss bound state topics at the level of a basic course in field theory: The derivation of the Schr\\"odinger and Dirac equations from the QED Lagrangian, by summing Feynman diagrams and in a Hamiltonian framework. Less well known topics include the equal-time wave function of Positronium in motion and the properties of the Dirac wave function for a linear potential. The presentation emphasizes physical aspects and provides the framework for Part 2, which discusses the derivation of relativistic bound states at Born level in QED and QCD. A central aspect is the maintenance of Poincar\\'e invariance. The transformation of the wave function under boosts is studied in detail in D=1+1 dimensions, and its generalization to D=3+1 is indicated. Solving Gauss' law for $A^0$ with a non-vanishing boundary condition leads to a linear potential for QCD mesons, and an analogous confining potential for baryons.
A Perspective on External Field QED
Deckert, D -A
2015-01-01
In light of the conference Quantum Mathematical Physics held in Regensburg in 2014, we give our perspective on the external field problem in quantum electrodynamics (QED), i.e., QED without photons in which the sole interaction stems from an external, time-dependent, four-vector potential. Among others, this model was considered by Dirac, Schwinger, Feynman, and Dyson as a model to describe the phenomenon of electron-positron pair creation in regimes in which the interaction between electrons can be neglected and a mean field description of the photon degrees of freedom is valid (e.g., static field of heavy nuclei or lasers fields). Although it may appear as second easiest model to study, it already bares a severe divergence in its equations of motion preventing any straight-forward construction of the corresponding evolution operator. In informal computations of the vacuum polarization current this divergence leads to the need of the so-called charge renormalization. In an attempt to provide a bridge between...
QED effects in the pseudoscalar meson sector
Energy Technology Data Exchange (ETDEWEB)
Horsley, R. [Edinburgh Univ. (United Kingdom). School of Physics and Astronomy; Nakamura, Y. [RIKEN Advanced Institute for Computational Science, Kobe (Japan); Perlt, H. [Leipzig Univ. (Germany). Inst. fuer Theoretische Physik; Collaboration: QCDSF-UKQCD Collaboration; and others
2015-09-15
We present results on the pseudoscalar meson masses from a fully dynamical simulation of QCD+QED. We concentrate particularly on violations of isospin symmetry. We calculate the π{sup +}-π{sup 0} splitting and also look at other isospin violating mass differences. We have presented results for these isospin splittings in arXiv:1508.06401 [hep-lat]. In this paper we give more details of the techniques employed, discussing in particular the question of how much of the symmetry violation is due to QCD, arising from the different masses of the u and d quarks, and how much is due to QED, arising from the different charges of the quarks. This decomposition is not unique, it depends on the renormalisation scheme and scale. We suggest a renormalisation scheme in which Dashen's theorem for neutral mesons holds, so that the electromagnetic self-energies of the neutral mesons are zero, and discuss how the self-energies change when we transform to a scheme such as MS, in which Dashen's theorem for neutral mesons is violated.
A broadband reflective filter for applying dc biases to high-Q superconducting microwave cavities
Hao, Yu; Rouxinol, Francisco; Lahaye, Matt
2015-03-01
The integration of dc-bias circuitry into low-loss microwave cavities is an important technical issue for topics in many fields that include research with qubit- and cavity-coupled mechanical system, circuit QED and quantum dynamics of nonlinear systems. The applied potentials or currents serve a variety of functions such as maintaining the operating state of device or establishing tunable electrostatic interactions between devices (for example, in order to couple a nanomechanical resonator to a superconducting qubit to generate and detect quantum states of a mechanical resonator). Here we report a bias-circuit design that utilizes a broadband reflective filter to connect to a high-Q superconducting coplanar waveguide (CPW) cavity. Our design allows us to apply dc-voltages to the center trace of CPW, with negligible changes in loaded quality factors of the fundamental mode. Simulations and measurements of the filter demonstrate insertion loss greater than 20 dB in the range of 3 to 10 GHz. Transmission measurements of the voltage-biased CPW show that loaded quality factors exceeding 105 can be achieved for dc-voltages as high as V = +/- 20V for the cavity operated in the single photon regime. National Science Foundation under Grant No. DMR-1056423 and Grant No. DMR-1312421.
International Nuclear Information System (INIS)
Highlights: • A specific SCRAP technique is proposed to realize quantum gates in the circuit QED. • These quantum gates are insensitive to the durations of the applied pluses. • The implemented quantum gates are robustness against the operational imperfections. - Abstract: We show that a set of universal quantum gates could be implemented robustly in a circuit QED system by using Stark-chirped rapid adiabatic passage (SCRAP) technique. Under the adiabatic limit we find that the population transfers could be deterministically passaged from one selected quantum states to the others, and thus the desired quantum gates can be implemented. The proposed SCRAP-based gates are insensitive to the details of the operations and thus relax the designs of the applied pulses, operational imperfections, and the decoherence of the system
Energy Technology Data Exchange (ETDEWEB)
Chen, Jingwei [State Key Laboratory of Optoelectronic Materials and Technologies, School of Physics and Engineering, Sun Yat-sen University, Guangzhou 510275 (China); Wei, L.F., E-mail: weilianfu@gmail.com [State Key Laboratory of Optoelectronic Materials and Technologies, School of Physics and Engineering, Sun Yat-sen University, Guangzhou 510275 (China); Quantum Optoelectronics Laboratory, School of Physics and Technology, Southwest Jiaotong University, Chengdu 610031 (China)
2015-10-23
Highlights: • A specific SCRAP technique is proposed to realize quantum gates in the circuit QED. • These quantum gates are insensitive to the durations of the applied pluses. • The implemented quantum gates are robustness against the operational imperfections. - Abstract: We show that a set of universal quantum gates could be implemented robustly in a circuit QED system by using Stark-chirped rapid adiabatic passage (SCRAP) technique. Under the adiabatic limit we find that the population transfers could be deterministically passaged from one selected quantum states to the others, and thus the desired quantum gates can be implemented. The proposed SCRAP-based gates are insensitive to the details of the operations and thus relax the designs of the applied pulses, operational imperfections, and the decoherence of the system.
Phase Transition and Absence Of Ghosts in Rigid QED
Awada, Moustafa; Zoller, David
1994-01-01
Ordinary QED formulated in the Feynman's space-time picture is equivalent to a one dimensional field theory. In the large N limit there is no phase transition in such a theory. In this letter, we show a phase transition does exist in a generalization of QED characterized by the addition of the curvature of the world line (rigidity) to the Feynman's space-time action. The large distance scale of the disordered phase essentially coincides with ordinary QED, while the ordered phase is strongly c...
Development of Nb{sub 3}Sn Cavity Vapor Diffusion Deposition System
Energy Technology Data Exchange (ETDEWEB)
Eremeev, Grigory V.; Macha, Kurt M.; Clemens, William A.; Park, HyeKyoung; Williams, R. Scott
2014-02-01
Nb{sub 3}Sn is a BCS superconductors with the superconducting critical temperature higher than that of niobium, so theoretically it surpasses the limitations of niobium in RF fields. The feasibility of technology has been demonstrated at 1.5 GHz with Nb{sub 3}Sn vapor deposition technique at Wuppertal University. The benefit at these frequencies is more pronounced at 4.2 K, where Nb{sub 3}Sn coated cavities show RF resistances an order of magnitude lower than that of niobium. At Jefferson Lab we started the development of Nb{sub 3}Sn vapor diffusion deposition system within an R\\&D development program towards compact light sources. Here we present the current progress of the system development.
Observing the Nonequilibrium Dynamics of the Quantum Transverse-Field Ising Chain in Circuit QED
Viehmann, Oliver; von Delft, Jan; Marquardt, Florian
2012-01-01
We show how a quantum Ising spin chain in a time-dependent transverse magnetic field can be simulated and experimentally probed in the framework of circuit QED with current technology. The proposed setup provides a new platform for observing the nonequilibrium dynamics of interacting many-body systems. We calculate its spectrum to offer a guideline for its initial experimental characterization. We demonstrate that quench dynamics and the propagation of localized excitations can be observed wi...
Directory of Open Access Journals (Sweden)
Hansen Anne
2007-08-01
Full Text Available Abstract Background The nasal cavity of all vertebrates houses multiple chemosensors, either innervated by the Ist (olfactory or the Vth (trigeminal cranial nerve. Various types of receptor cells are present, either segregated in different compartments (e.g. in rodents or mingled in one epithelium (e.g. fish. In addition, solitary chemosensory cells have been reported for several species. Alligators which seek their prey both above and under water have only one nasal compartment. Information about their olfactory epithelium is limited. Since alligators seem to detect both volatile and water-soluble odour cues, I tested whether different sensory cell types are present in the olfactory epithelium. Results Electron microscopy and immunocytochemistry were used to examine the sensory epithelium of the nasal cavity of the American alligator. Almost the entire nasal cavity is lined with olfactory (sensory epithelium. Two types of olfactory sensory neurons are present. Both types bear cilia as well as microvilli at their apical endings and express the typical markers for olfactory neurons. The density of these olfactory neurons varies along the nasal cavity. In addition, solitary chemosensory cells innervated by trigeminal nerve fibres, are intermingled with olfactory sensory neurons. Solitary chemosensory cells express components of the PLC-transduction cascade found in solitary chemosensory cells in rodents. Conclusion The nasal cavity of the American alligator contains two different chemosensory systems incorporated in the same sensory epithelium: the olfactory system proper and solitary chemosensory cells. The olfactory system contains two morphological distinct types of ciliated olfactory receptor neurons.
Massless Fermions and the Instanton Dipole Liquid in Compact QED_3
Fosco, C D
2006-01-01
We study the consequences of including parity preserving matter for the effective dual theory corresponding to compact QED_3; in particular we focus on the effect of that contribution on the confinement-deconfinement properties of the system. To that end, we compare two recent proposals when massless fermions are included, both based on an effective anomalous dual model, but having global and local Z_2 symmetries, respectively. We present a detailed analysis to show that while for large mass fermions the global Z_2 symmetry is preferred, in the massless fermion case the local Z_2 scenario turns out to be the proper one. We present a detailed discussion about how the inclusion of massless fermions in compact QED_3 leads to deconfinement, and discuss the stability of the deconfined phase by introducing a description based on an instanton dipole liquid picture.
Enhanced vacuum Rabi splitting and double dark states in a composite atom-cavity system
Institute of Scientific and Technical Information of China (English)
Tao LI; Hai-tao ZHOU; Zhong-hua LI; Yun-fei BAI; Yuan LI; Jiang-rui GAO; Jun-xiang ZHANG
2009-01-01
The transmission spectrum of four-level atoms in a cavity is calculated. It is shown that the four separate peaks associated with normal mode splitting and intra-cavity double dark states can be observed simultaneously. The position and intensity of the four peaks can be controlled by the intensity of the third interacting light. Therefore, the enhancement of normal mode splitting by a third coupling light of the intra-cavity four-level atoms is developed.
The present status of non-compact lattice QED
International Nuclear Information System (INIS)
We give a 1993 update of non-compact lattice QED, in particular the chiral condensate, finite size effects and meson mass ratios. We compare descriptions of the phase transition. Our previous conclusions remain valid. (orig.)
Miao, Xinyu; Yin, Longfei; Zhuang, Wei; Luo, Bin; Dang, Anhong; Chen, Jingbiao; Guo, Hong
2011-08-01
We demonstrate an external-cavity laser system using an anti-reflection coated laser diode as gain medium with about 60 nm fluorescence spectrum, and a Rb Faraday anomalous dispersion optical filter (FADOF) as frequency-selecting element with a transmission bandwidth of 1.3 GHz. With 6.4% optical feedback, a single stable longitudinal mode is obtained with a linewidth of 69 kHz. The wavelength of this laser is operating within the center of the highest transmission peak of FADOF over a diode current range from 55 mA to 142 mA and a diode temperature range from 15 °C to 35 °C, thus it is immune to the fluctuations of current and temperature. PMID:21895284
The Research and Development on Simulation of Oral Cavity Food Chewing System
Directory of Open Access Journals (Sweden)
Xiaoming Zhang
2015-03-01
Full Text Available This paper aimed to dig the destruction effect of change rules of oral cavity chewing system for food and the significance of relationship between chewing movement and chewing effect for the understanding of food quality and structure features. The process and effect of chewing movement for crushing food was stimulated and analyzed by reverse engineering technology combined with modern dental theory. The experiment results of uniform motion model and variable motion model showed that in grinding mode, a higher chewing rate had good effect on the destruction of the food and influence of acceleration change on chewing effect was relatively weak, in which uniform acceleration and deceleration motion was more suitable for grinding the elasticity and toughness of food.
Leading quantum gravitational corrections to scalar QED
International Nuclear Information System (INIS)
We consider the leading post-Newtonian and quantum corrections to the non-relativistic scattering amplitude of charged scalars in the combined theory of general relativity and scalar QED. The combined theory is treated as an effective field theory. This allows for a consistent quantization of the gravitational field. The appropriate vertex rules are extracted from the action, and the non-analytic contributions to the 1-loop scattering matrix are calculated in the non-relativistic limit. The non-analytical parts of the scattering amplitude, which are known to give the long range, low energy, leading quantum corrections, are used to construct the leading post-Newtonian and quantum corrections to the two-particle non-relativistic scattering matrix potential for two charged scalars. The result is discussed in relation to experimental verifications
Leading quantum gravitational corrections to scalar QED
Bjerrum-Bohr, N E J
2002-01-01
We consider the leading post-Newtonian and quantum corrections to the non-relativistic scattering amplitude of charged scalars in the combined theory of general relativity and scalar QED. The combined theory is treated as an effective field theory. This allows for a consistent quantization of the gravitational field. The appropriate vertex rules are extracted from the action, and the non-analytic contributions to the 1-loop scattering matrix are calculated in the non-relativistic limit. The non-analytical parts of the scattering amplitude, which are known to give the long range, low energy, leading quantum corrections, are used to construct the leading post-Newtonian and quantum corrections to the two-particle non-relativistic scattering matrix potential for two charged scalars. The result is discussed in relation to experimental verifications.
Spin decomposition of the electron in QED
Ji, Xiangdong; Schäfer, Andreas; Yuan, Feng; Zhang, Jian-Hui; Zhao, Yong
2016-03-01
We perform a systematic study on the spin decomposition of an electron in QED at one-loop order. It is found that the electron orbital angular momentum defined in Jaffe-Manohar and Ji spin sum rules agree with each other, and the so-called potential angular momentum vanishes at this order. The calculations are performed in both dimensional regularization and Pauli-Villars regularization for the ultraviolet divergences, and they lead to consistent results. We further investigate the calculations in terms of light-front wave functions and find a missing contribution from the instantaneous interaction in light-front quantization. This clarifies the confusing issues raised recently in the literature on the spin decomposition of an electron and will help consolidate the spin physics program for nucleons in QCD.
Detector and spectrometer development for QED tests
International Nuclear Information System (INIS)
Full text: The curved crystal spectrometer will be implemented, calibrated and analyzed for further work to be carried out upon it at NIST in Washington for accurate precision tests of QED in highly charged ions. At the moment using the fluorescent source we are able to resolve characteristic x-ray lines for inner shell transitions Ka1, Ka2, and Kβ1,3 for differing elements. The curved crystal spectrometer has a Germanium crystal operating along the principle of Bragg's law. Using this spectrometer a second stage will be combining the backgammon detector with the curved crystal spectrometer and therefore experimental and theoretical work on curved crystal dynamical diffraction for the state of the art spectrometer will also be achieved
Renormalization of the vector current in QED
International Nuclear Information System (INIS)
It is commonly asserted that the electromagnetic current is conserved and therefore is not renormalized. Within QED we show (a) that this statement is false (b) how to obtain the renormalization of the current to all orders of perturbation theory, and (c) how to correctly define an electron number operator. The current mixes with the four-divergence of the electromagnetic field-strength tensor. The true electron number operator is the integral of the time component of the electron number density, but only when the current differs from the MS-renormalized current by a definite finite renormalization. This happens in such a way that Gauss's law holds: the charge operator is the surface integral of the electric field at infinity. The theorem extends naturally to any gauge theory
Entanglement Transfer Between Cavity Fields and Excitons in a Driven Quantum Dot System
Institute of Scientific and Technical Information of China (English)
无
2007-01-01
We investigate entanglement transfer from two separate cavities to the excitons in two quantum dots separately placed in the two cavities. The cavity fields and the excitons are treated as two continuous-variable (CV) subsystems. The time-dependent characteristic functions in the Wigner representation for the two subsystems are analytically obtained. Under the conditions that one of the two CV subsystems is initially prepared in a two-mode squeezed vacuum state and the other in its lowest energy state, we show that the entanglement reciprocation between the cavity Reids and the excitons is realizable.
On the Bhabha scattering for $z=2$ Lifshitz QED
Bufalo, R
2015-01-01
In this paper we compute and discuss the differential cross section of the Bhabha scattering in the framework of the $z=2$ Lifshitz QED. We start by constructing the classical solutions for the fermionic fields, in particular the completeness relations, and also deriving the theory's propagators. Afterwards, we compute the photon exchange and pair annihilation contributions for the Bhabha's process, and upon the results we establish the magnitude of the theory's free parameter by looking for small deviations of the QED tree results.
International Nuclear Information System (INIS)
We extend an optimal entanglement distillation of the triplet Greenberger—Horne—Zeilinger (GHZ) state via entanglement concentrating in the three-partite partially electron-spin-entangled systems. Two entanglement concentration protocols are similarly designed in detail with the post-selection in quantum-dot (QD) and micro-cavity coupled systems. The proposed protocol can be repeated several rounds to achieve an optimal success probability with an assistance of the ancillary QD, where only the single photon needs to pass through the micro-cavity for each round. It increases the total success probability of the distillation even if the implemented cavity is imperfect in practice during the whole process. (general)
Commissioning results of Nb_{3}Sn cavity vapor diffusion deposition system at JLab
Energy Technology Data Exchange (ETDEWEB)
Eremeev, Grigory [Jefferson Lab., Newport News, VA (United States); Clemens, William A. [Jefferson Lab., Newport News, VA (United States); Macha, Kurt M. [Jefferson Lab., Newport News, VA (United States); Park, HyeKyoung [Jefferson Lab., Newport News, VA (United States); Williams, R. [Jefferson Lab., Newport News, VA (United States)
2015-09-01
Nb_{3}Sn as a BCS superconductor with a superconducting critical temperature higher than that of niobium offers potential benefit for SRF cavities via a lower-than-niobium surface resistance at the same temperature and frequency. A Nb_{3}Sn vapor diffusion deposition system designed for coating of 1.5 and 1.3 GHz single-cell cavities was built and commissioned at JLab. As the part of the commissioning, RF performance at 2.0 K of a single-cell 1.5 GHz CEBAF-shaped cavity was measured before and after coating in the system. Before Nb_{3}Sn coating the cavity had a Q_{0} of about 10^{10} and was limited by the high field Q-slope at E_{acc} ≅ 27 MV/m. Coated cavity exhibited the superconducting transition at about 17.9 K. The low-field quality factor was about 5∙10^{9} at 4.3 K and 7∙10^{9} at 2.0 K decreasing with field to about 1∙10^{9} at E_{acc} ≅ 8 MV/m at both temperatures. The highest field was limited by the available RF power.
The application of system identification techniques to an R.F. Cavity tuning loop
International Nuclear Information System (INIS)
System identification is the terminology used for the process of characterising a given control system. A mathematical representation of the frequency response characteristic is obtained to utilise all the known design techniques to arrange the feed-back loop to meet required control performance criterion. This is known as parametric system identification. The intention of this paper is to speed up the process of identifying the R.F. Cavity tuning system of the 800 MeV accelerator, ISIS. While achieving this goal the computer must not disturb noticeably the normal function set out by the system. This task of automatic characterisation is necessary so that a self-adapting feed-back loop can be arranged to adjust itself without human interference and meet severe R.F. tuning requirements on ISIS. In any case the results of parametric identifications are useful in designing a robust feed-back loop with appropriate gain and phase margins. The approach using a Pseudo Random Signal is currently practised in Process Industries. (author)
International Nuclear Information System (INIS)
The mechanism of a ferrite-loaded rf cavity is explained from the point of view of its operation. Then, an analysis of the automatic cavity-tuning system is presented using the transfer function; and a systematic analysis of a beam-feedback system using transfer functions is also presented. (author)
The two-photon self-energy and other QED radiative corrections
International Nuclear Information System (INIS)
One of the main issues in current nuclear physics is the precise measurement of the Lamb shift of strongly bound electrons in quantum electrodynamic (QED) tests in strong fields in highly charged ions. The currently performed high-precision measurements require extreme accuracy in the theoretical calculation of Lamb shift. This requires consideration of all α and α2 order QED corrections as well as of precisely all orders in Zα. In the past years most of these QED corrections have been calculated both in 1st order and in 2nd order interference theory. As yet however, it has not been possible to assess the contribution of the two-photon self-energy, which has therefore been the greatest uncertainty factor in predicting Lamb shift in hydrogen-like systems. This study examines the contribution of these processes to Lamb shift. It also provides the first ever derivation of renormalized terms of two-photon vacuum polarisation and self-energy vacuum polarisation. Until now it has only been possible to evaluate these contributions by way of an Uehling approximation
Many-body-QED perturbation theory: Connection to the two-electron Bethe-Salpeter equation
Lindgren, I.; Salomonson, S.; Hedendahl, D.
2005-03-01
The connection between many-body perturbation theory (MBPT) and quantum electrodynamics (QED) is reviewed for systems of two fermions in an external field. The treatment is mainly based on the recently developed covariant-evolution-operator method for QED calculations (I. Lindgren, S. Salomonson, and B. Asen. Phys. Rep. 389, 161 (2004)), which is quite similar in structure to MBPT. At the same time, this procedure is closely related to the S-matrix and Green's-function formalisms and can therefore serve as a bridge connecting various approaches. It is demonstrated that the MBPT-QED scheme, when carried to all orders, leads to a Schrodinger-like equation, equivalent to the Bethe-Salpeter (BS) equation. A Bloch equation in commutator form that can be used for an "extended" or quasi-degenerate model space is derived. This is a multi-state equation that has the same relation to the single-state BS equation as the standard Bloch equation has to the ordinary Schrodinger equation. It can be used to generate a perturbation expansion compatible with the BS equation even in the case of a quasi-degenerate model space.
Directory of Open Access Journals (Sweden)
Stephano Zerlottini Isaac
2013-09-01
Full Text Available OBJECTIVE: The aim of this in vitro study was to evaluate the microtensile bond strength (µTBS to dentin of two different restorative systems: silorane-based (P90, and methacrylate-based (P60, using two cavity models. MATERIAL AND METHODS: Occlusal enamel of 40 human third molars was removed to expose flat dentin surface. Class I cavities with 4 mm mesial-distal width, 3 mm buccal-lingual width and 3 mm depth (C-factor=4.5 were prepared in 20 teeth, which were divided into two groups (n=10 restored with P60 and P90, bulk-filled after dentin treatment according to manufacturer's instructions. Flat buccal dentin surfaces were prepared in the 20 remaining teeth (C-factor=0.2 and restored with resin blocks measuring 4x3x3 mm using the two restorative systems (n=10. The teeth were sectioned into samples with area between 0.85 and 1.25 mm2 that were submitted to µTBS testing, using a universal testing machine (EMIC at speed of 0.5 mm/min. Fractured specimens were analyzed under stereomicroscope and categorized according to fracture pattern. Data were analyzed using ANOVA and Tukey Kramer tests. RESULTS: For flat surfaces, P60 obtained higher bond strength values compared with P90. However, for Class I cavities, P60 showed significant reduction in bond strength (p0.05, or between Class I Cavity and Flat Surface group, considering P90 restorative system (p>0.05. Regarding fracture pattern, there was no statistical difference among groups (p=0.0713 and 56.3% of the fractures were adhesive. CONCLUSION: It was concluded that methacrylate-based composite µTBS was influenced by cavity models, and the use of silorane-based composite led to similar bond strength values compared to the methacrylate-based composite in cavities with high C-factor.
Stephano Zerlottini Isaac; Ana Claudia Pietrobom Bergamin; Cecilia Pedroso Turssi; Flavia Lucisano Botelho do Amaral; Roberta Tarkany Basting; Fabiana Mantovani Gomes Franca
2013-01-01
OBJECTIVE: The aim of this in vitro study was to evaluate the microtensile bond strength (µTBS) to dentin of two different restorative systems: silorane-based (P90), and methacrylate-based (P60), using two cavity models. MATERIAL AND METHODS: Occlusal enamel of 40 human third molars was removed to expose flat dentin surface. Class I cavities with 4 mm mesial-distal width, 3 mm buccal-lingual width and 3 mm depth (C-factor=4.5) were prepared in 20 teeth, which were divided into two groups (n...
In-plane electrical transport across cavity-quantum well system in Bose-Einstein condensate phase
Xie, Ming; MacDonald, Allan
Cavity polaritons are coupled states of quantum well excitons and vertical cavity photons which can undergo Bose-Einstein condensation under appropriate circumstances. The macroscopic condensate state can be described by two coupled order parameters - the coherent exciton field and the coherent photon field. When the dominant process for electron transfer between conduction and valence bands is by scattering off the photon condensate, electrical bias voltages can be used to control the condensate. We study the in-plane transport properties of electrical current through the cavity-quantum well system, and show how the coherent photon fields respond to the current flow. The possibility of tailoring light via electrical current and vice versa simultaneously might lead to interesting new applications.
International Nuclear Information System (INIS)
The basic properties of superconducting cavities for electron accelerators are discussed with special emphasis on the following topics: technical motivation for the use of superconducting cavities; surface impedance; the critical field of superconductors; anomalous losses; materials other than niobium; technological achievements for accelerating cavities. (author)
Electromagnetic SCRF Cavity Tuner
Energy Technology Data Exchange (ETDEWEB)
Kashikhin, V.; Borissov, E.; Foster, G.W.; Makulski, A.; Pischalnikov, Y.; Khabiboulline, T.; /Fermilab
2009-05-01
A novel prototype of SCRF cavity tuner is being designed and tested at Fermilab. This is a superconducting C-type iron dominated magnet having a 10 mm gap, axial symmetry, and a 1 Tesla field. Inside the gap is mounted a superconducting coil capable of moving {+-} 1 mm and producing a longitudinal force up to {+-} 1.5 kN. The static force applied to the RF cavity flanges provides a long-term cavity geometry tuning to a nominal frequency. The same coil powered by fast AC current pulse delivers mechanical perturbation for fast cavity tuning. This fast mechanical perturbation could be used to compensate a dynamic RF cavity detuning caused by cavity Lorentz forces and microphonics. A special configuration of magnet system was designed and tested.
Two-qubit parity meters in 3D and 2D circuit QED
Dicarlo, Leonardo
2014-03-01
Non-demolition measurements of multi-qubit observables and feedback control conditioned on their outcomes are essential for quantum error correction. We present two implementations of two-qubit parity meters in circuit QED. In 3D, we match the dispersive coupling of two qubits to a common cavity to encode parity in the transmission of an applied microwave pulse. In 2D, we first encode the parity of two data qubits in the computational state of an ancillary qubit using resonant interactions, and subsequently project the ancilla using a dedicated, dispersively-coupled resonator. A key advantage of this second scheme is the protection of data qubits from dephasing by measurement photons. First applications of these parity meters include probabilistic entanglement by measurement, and deterministic entanglement using digital feedback control. Current efforts target the implementation of measurement-based bit-flip error correction. Research funded by NWO, FOM, and the European projects SOLID and SCALEQIT.
Controllable high-fidelity quantum state transfer and entanglement generation in circuit QED.
Xu, Peng; Yang, Xu-Chen; Mei, Feng; Xue, Zheng-Yuan
2016-01-01
We propose a scheme to realize controllable quantum state transfer and entanglement generation among transmon qubits in the typical circuit QED setup based on adiabatic passage. Through designing the time-dependent driven pulses applied on the transmon qubits, we find that fast quantum sate transfer can be achieved between arbitrary two qubits and quantum entanglement among the qubits also can also be engineered. Furthermore, we numerically analyzed the influence of the decoherence on our scheme with the current experimental accessible systematical parameters. The result shows that our scheme is very robust against both the cavity decay and qubit relaxation, the fidelities of the state transfer and entanglement preparation process could be very high. In addition, our scheme is also shown to be insensitive to the inhomogeneous of qubit-resonator coupling strengths. PMID:26804326
X-band crab cavities for the CLIC beam delivery system
Burt, Graeme; Ambattu, Praveen; Dexter, Amos; Abram, Thomas; Dolgashev, V.; Tantawi, S.; Jones, R. M.
2008-01-01
The CLIC machine incorporates a 20 mrad crossing angle at the IP to aid the extraction of spent beams. In order to recover the luminosity lost through the crossing angle a crab cavity is proposed to rotate the bunches prior to collision. The crab cavity is chosen to have the same frequency as the main linac (11.9942 GHz) as a compromise between size, phase stability requirements and beam loading. It is proposed to use a HE11 mode travelling wave structure as the CLIC crab cavity in order to m...
Phase transitions due to interaction between photons and atoms in a cavity system
Shirai, Tatsuhiko; Miyashita, Seiji
2012-01-01
We survey phenomena of a cavity system in which many atoms coherently interact with a single quantized photon mode driven by the AC external field in a dissipative environment. It has been known that a strongly external field causes the so-called optical bistability which is a non-equilibrium phase transition for the balance of excitation and dissipation. On the other hand, a strong interaction causes the Dicke transition, which is a phase transition with a spontaneous appearance of excitations of atoms and photons in the equilibrium system as a consequence of the cooperative phenomena. We study the phenomena in full range of the strength of the interaction and the external field, and present a phase diagram of the stationary state. For the strong interaction region, in order to realize the ground state, appropriate form of the dissipative mechanism in the master equation is necessary instead of the conventional Lindblad form. We provide such an extended master equation. Moreover, the rotating wave approximat...
Development of non-contact 3D measurement system for parts of accelerator cavities
International Nuclear Information System (INIS)
We strive to develop a 3D coordinate measuring machine, which can measure the shape of parts of accelerator cavity with without contact and rapidly. Currently, the ILC (International Linear Collider) project is progressing through international collaboration. The major goal of ILC is to produce and investigate Higgs bosons. ILC consists of two linear accelerators facing each other, and will hurl some 10 billion electrons and positrons toward each other at nearly the speed of light. The cavity is an important component to accelerate particles to near light speed. A cavity's inner 3D shape influences the accelerating performance. Therefore, it is important to measure the shape of the parts of a cavity. We are developing a highly accurate and non-contact shape measuring machine using triangulation method. (author)
A scheme for transferring an unknown atomic entangled state via cavity quantum electrodynamics
Institute of Scientific and Technical Information of China (English)
Wu Tao; Ye Liu; Ni Zhi-Xiang
2006-01-01
In this paper, we propose a scheme for transferring an unknown atomic entangled state via cavity quantum electrodynamics (QED). This scheme, which has a successful probability of 100 percent, does not require Bell-state measurement and performing any operations to reconstruct an initial state. Meanwhile, the scheme only involves atomfield interaction with a large detuning and does not require the transfer of quantum information between the atoms and cavity. Thus the scheme is insensitive to the cavity field states and cavity decay. This scheme can also be extended to transfer ring an entangled state of n-atom.
Critical number of flavors in QED
International Nuclear Information System (INIS)
We demonstrate that in unquenched quantum electrodynamics (QED), chiral symmetry breaking ceases to exist above a critical number of fermion flavors Nf. This is a necessary and sufficient consequence of the fact that there exists a critical value of electromagnetic coupling α beyond which dynamical mass generation gets triggered. We employ a multiplicatively renormalizable photon propagator involving leading logarithms to all orders in α to illustrate this. We study the flavor and coupling dependence of the dynamically generated mass analytically as well as numerically. We also derive the scaling laws for the dynamical mass as a function of α and Nf. Up to a multiplicative constant, these scaling laws are related through (α,αc)↔(1/Nf,1/Nfc). Calculation of the mass anomalous dimension γm shows that it is always greater than its value in the quenched case. We also evaluate the β function. The criticality plane is drawn in the (α,Nf) phase space which clearly depicts how larger Nf is required to restore chiral symmetry for an increasing interaction strength.
Critical Number of Flavours in QED
Bashir, A; Gutiérrez-Guerrero, L X; Tejeda-Yeomans, M E
2011-01-01
We demonstrate that in unquenched quantum electrodynamics (QED), chiral symmetry breaking ceases to exist above a critical number of fermion flavours $N_f$. This is a necessary and sufficient consequence of the fact that there exists a critical value of electromagnetic coupling $\\alpha$ beyond which dynamical mass generation gets triggered. We employ a multiplicatively renormalizable photon propagator involving leading logarithms to all orders in $\\alpha$ to illustrate this. We study the flavour and coupling dependence of the dynamically generated mass analytically as well as numerically. We also derive the scaling laws for the dynamical mass as a function of $\\alpha$ and $N_f$. Up to a multiplicative constant, these scaling laws are related through $(\\alpha, \\alpha_c) \\leftrightarrow (1/N_f, 1/N_f^c)$. Calculation of the mass anomalous dimension $\\gamma_m$ shows that it is always greater than its value in the quenched case. We also evaluate the $\\beta$-function. The criticality plane is drawn in the $(\\alpha...
International Nuclear Information System (INIS)
This paper analyzed the shortage of M310 type reactor's reactor cavity and spent fuel pit cooling and treatment system by using the example of a domestic nuclear power plant and the necessity to improve it for Ningde nuclear power plant. This paper also introduced the design improvement project, analyzed the system operation advantages and disadvantages after improvement, and gave some advice for further improvement. (authors)
Thermal modeling of a greenhouse integrated to an aquifer coupled cavity flow heat exchanger system
Energy Technology Data Exchange (ETDEWEB)
Sethi, V.P. [Department of Mechanical Engineering, Punjab Agricultural University, Ludhiana 141 008, Punjab (India); Sharma, S.K. [Energy Research Centre, Panjab University, Chandigarh 160 017, Punjab (India)
2007-06-15
A thermal model is developed for heating and cooling of an agricultural greenhouse integrated with an aquifer coupled cavity flow heat exchanger system (ACCFHES). The ACCFHES works on the principal of utilizing deep aquifer water available at the ground surface through an irrigation tube well already installed in every agricultural field at constant year-round temperature of 24 C. The analysis is based on the energy balance equations for different components of the greenhouse. Using the derived analytical expressions, a computer program is developed in C{sup ++} for computing the hourly greenhouse plant and room air temperature for various design and climatic parameters. Experimental validation of the developed model is carried out using the measured plant and room air temperature data of the greenhouse (in which capsicum is grown) for the winter and summer conditions of the year 2004-2005 at Chandigarh (31 N and 78 E), Punjab, India. It is observed that the predicted and measured values are in close agreement. Greenhouse room air and plant temperature is maintained 6-7 K and 5-6 K below ambient, respectively for an extreme summer day and 7-8 K and 5-6 K above ambient, respectively for an extreme winter night. Finally, parametric studies are conducted to observe the effect of various operating parameters such as mass of the plant, area of the plant, mass flow rate of the circulating air and area of the ACCFHES on the greenhouse room air and plant temperature. (author)
New reactor cavity cooling system using novel shape for HTGRs and VHTRs
International Nuclear Information System (INIS)
A new, highly efficient reactor cavity cooling system (RCCS) with passive safety features without a requirement for electricity and mechanical drive is proposed for high temperature gas cooled reactors (HTGRs) and very high temperature reactors (VHTRs). The RCCS design consists of continuous closed regions; one is an ex-reactor pressure vessel (RPV) region and another is a cooling region having heat transfer area to ambient air assumed at 40 (°C). The RCCS uses a novel shape to efficiently remove the heat released from the RPV with radiation and natural convection. Employing the air as the working fluid and the ambient air as the ultimate heat sink, the new RCCS design strongly reduces the possibility of losing the heat sink for decay heat removal. Therefore, HTGRs and VHTRs adopting the new RCCS design can avoid core melting due to overheating the fuels. The simulation results from a commercial CFD code, STAR-CCM+, show that the temperature distribution of the RCCS is within the temperature limits of the structures, and the heat released from the RPV could be removed safely, even during a loss of coolant accident (LOCA). Therefore, the capacity of the new RCCS design would be sufficient for decay heat removal. (author)
Theory and practice of dressed coherent states in circuit QED
Wilhelm, Frank; Govia, Luke C. G.
In the dispersive regime of qubit-cavity coupling, classical cavity drive populates the cavity, but leaves the qubit state unaffected. However, the dispersive Hamiltonian is derived after both a frame transformation and an approximation. Therefore, to connect to external experimental devices, the inverse frame transformation from the dispersive frame back to the lab frame is necessary. We show that in the lab frame the system is best described by an entangled state known as the dressed coherent state, and thus even in the dispersive regime, entanglement is generated between the qubit and the cavity. Also, we show that further qubit evolution depends on both the amplitude and phase of the dressed coherent state. This provides a limitation to readout in the dispersive regime. We show that only in the limit of infinite measurement time is this protocol QND, as the formation of a dressed coherent state in the qubit-cavity system applies an effective rotation to the qubit state. We show how this rotation can be corrected by a unitary operation, leading to improved qubit initialization by measurement and unitary feedback.] L.C.G. Govia and F.K. Wllhelm Phys. Rev. Applied 4, 054001 (2015) LC.G. Govia and F.K. Wilhelm, arXiv:1506.04997 Supported by the ARO under contract W911NF-14-1-0080 and the European Union through ScaleQIT. LCGG acknowledges support from NSERC through an NSERC PGS-D.
International Nuclear Information System (INIS)
To develop cavity repair techniques is important for quality control of the superconducting rf cavity to get more better yield for high accelerating gradient. A high-quality optical inspection system with a high-resolution camera was developed as a tool of inspection of the cavities in 2008. It enables 2-D surface analysis on a defect of cavity inner surface by using striped illumination and image processing. For more detailed surface analysis, a replica technique was applied to cavity surface. By connecting defect information with quench location information, the cause of the performance limitation can be categorized by a geometrical defect or by issue of surface treatment and assembly work. By applying optical inspection at each step of the treatment, we can also obtain an information of defect appearance and its development. The cavities that quenched at low field by one or few geometrical defects can be improved by removing the defects at quench location. A local polishing system with a small grinding machine was developed for this purpose. This repair method was applied on the 9-cell cavities, and we succeeded to improve the cavity performance by the combination of local polishing and light electro-polish (EP). The method and results of the cavity inspection including the replica techniques and local polishing are presented in this paper. (author)
Viehmann, Oliver; von Delft, Jan; Marquardt, Florian
2013-01-01
We study several dynamical properties of a recently proposed implementation of the quantum transverse-field Ising chain in the framework of circuit QED. Particular emphasis is placed on the effects of disorder on the nonequilibrium behavior of the system. We show that small amounts of fabrication-induced disorder in the system parameters do not jeopardize the observation of previously-predicted phenomena. Based on a numerical extraction of the mean free path of the system, we also provide a s...
Teleportation with Tripartite Entangled State via Thermal Cavity
International Nuclear Information System (INIS)
Teleportation schemes with a tripartite entangled state in cavity QED are investigated. The schemes do not need Bell state measurements and the successful probabilities reach optimality. In addition, the schemes are insensitive to both the cavity decay and the thermal field. We first consider two teleportation schemes via a tripartite GHZ state. The first one is a controlled one for an unknown single-qubit state. The second scheme is teleportation of unknown two-atom entangled state. Then we consider teleporting of single-qubit arbitrary state via a tripartite W state.
Teleportation with Tripartite Entangled State via Thermal Cavity
Institute of Scientific and Technical Information of China (English)
XUE Zheng-Yuan; YI You-Min; CAO Zhuo-Liang
2006-01-01
Teleportation schemes with a tripartite entangled state in cavity QED are investigated. The schemes do not need Bell state measurements and the successful probabilities reach optimality. In addition, the schemes are insensitive to both the cavity decay and the thermal field. We first consider two teleportation schemes via a tripartite GHZ state.The first one is a controlled one for an unknown single-qubit state. The second scheme is teleportation of unknown two-atom entangled state. Then we consider teleporting of single-qubit arbitrary state via a tripartite W state.
Simplicity in the structure of QED and gravity amplitudes
International Nuclear Information System (INIS)
We investigate generic properties of one-loop amplitudes in unordered gauge theories in four dimensions. For such theories the organisation of amplitudes in manifestly crossing symmetric expressions poses restrictions on their structure and results in remarkable cancellations. We show that one-loop multi-photon amplitudes in QED with at least eight external photons are given only by scalar box integral functions. This QED 'no-triangle' property is true for all helicity configurations and has similarities to the 'notriangle' property found in the case of maximal N=8 supergravity. Results are derived both via a world-line formalism as well as using on-shell unitarity methods. We show that the simple structure of the loop amplitude originates from the extremely good BCFW scaling behaviour of the QED tree-amplitude. (orig.)
Simplicity in the structure of QED and gravity amplitudes
Badger, Simon; Bjerrum-Bohr, N. E. J.; Vanhove, Pierre
2009-02-01
We investigate generic properties of one-loop amplitudes in unordered gauge theories in four dimensions. For such theories the organisation of amplitudes in manifestly crossing symmetric expressions poses restrictions on their structure and results in remarkable cancellations. We show that one-loop multi-photon amplitudes in QED with at least eight external photons are given only by scalar box integral functions. This QED `no-triangle' property is true for all helicity configurations and has similarities to the `no-triangle' property found in the case of maximal Script N = 8 supergravity. Results are derived both via a world-line formalism as well as using on-shell unitarity methods. We show that the simple structure of the loop amplitude originates from the extremely good BCFW scaling behaviour of the QED tree-amplitude.
Laser absorption via QED cascades in counter propagating laser pulses
Grismayer, Thomas; Martins, Joana L; Fonseca, Ricardo A; Silva, Luis O
2015-01-01
A model for laser light absorption in electron-positron plasmas self-consistently created via QED cascades is described. The laser energy is mainly absorbed due to hard photon emission via nonlinear Compton scattering. The degree of absorption depends on the laser intensity and the pulse duration. The QED cascades are studied with multi-dimensional particle-in-cell simulations complemented by a QED module and a macro-particle merging algorithm that allows to handle the exponential growth of the number of particles. Results range from moderate-intensity regimes ($\\sim$ 10 PW) where the laser absorption is negligible, to extreme intensities (> 100 PW) where the degree of absorption reaches 80%. Our study demonstrates good agreement between the analytical model and simulations. The expected properties of the hard photon emission and the generated pair-plasma are investigated, and the experimental signatures for near-future laser facilities are discussed.
Chiral symmetry breaking in lattice QED model with fermion brane
Shintani, E
2012-01-01
We propose a novel approach of spontaneous chiral symmetry breaking at near zero temperature in 4 dimensional QED model with 3+1 dimensional fermion brane using Hybrid Monte Carlo simulation. We consider an anisotropic QED coupling in non-compact QED action with the manifest gauge invariant interaction and fermi-velocity which is less than speed of light. This model allows for the scaling study at low temperature and strong coupling region with reduced computational cost. We compute the chiral condensate and its susceptibility with different coupling constant, velocity parameter and flavor number, and therefore obtain a compatible behavior with gap equation in broken phase. We also discuss about the comparison of Graphene model.
A simple UV completion of QED in 5 dimensions
International Nuclear Information System (INIS)
We construct a Lifshitz-like version of five-dimensional (5D) QED which is UV completed and reduces at low energies to ordinary 5D QED. The UV quantum behavior of this theory is very smooth. In particular, the gauge coupling constant is finite at all energy scales and at all orders in perturbation theory. We study the IR properties of this theory, when compactified on a circle, and compare the one-loop energy dependence of the coupling in the Lifshitz theory with that coming from the standard 5D QED effective field theory. The range of validity of the 5D effective field theory is found to agree with the more conservative version of naive dimensional analysis.
Simplicity in the Structure of QED and Gravity Amplitudes
Badger, Simon; Vanhove, Pierre
2009-01-01
We investigate generic properties of one-loop amplitudes in unordered gauge theories in four dimensions. For such theories the organisation of amplitudes in manifestly crossing symmetric expressions poses restrictions on their structure and results in remarkable cancellations. We show that one-loop multi-photon amplitudes in QED with at least eight external photons are given only by scalar box integral functions. This QED `no-triangle' property is true for all helicity configurations and has similarities to the `no-triangle' property found in the case of maximal N = 8 supergravity. Results are derived both via a world-line formalism as well as using on-shell unitarity methods. We show that the simple structure of the loop amplitude originates from the extremely good BCFW scaling behaviour of the QED tree-amplitude.
X-band crab cavities for the CLIC beam delivery system
Burt, G; Dexter, A C; Abram, T; Dolgashev, V; Tantawi, S; Jones, R M
2009-01-01
The CLIC machine incorporates a 20 mrad crossing angle at the IP to aid the extraction of spent beams. In order to recover the luminosity lost through the crossing angle a crab cavity is proposed to rotate the bunches prior to collision. The crab cavity is chosen to have the same frequency as the main linac (11.9942 GHz) as a compromise between size, phase stability requirements and beam loading. It is proposed to use a HE11 mode travelling wave structure as the CLIC crab cavity in order to minimise beam loading and mode separation. The position of the crab cavity close to the final focus enhances the effect of transverse wake-fields so effective wake-field damping is required. A damped detuned structure is proposed to suppress and de-cohere the wake-field hence reducing their effect. Design considerations for the CLIC crab cavity will be discussed as well as the proposed high power testing of these structures at SLAC.
The QED engine spectrum - Fusion-electric propulsion for air-breathing to interstellar flight
Bussard, Robert W.; Jameson, Lorin W.
1993-01-01
A new inertial-electrostatic-fusion direct electric power source can be used to drive a relativistic e-beam to heat propellant. The resulting system is shown to yield specific impulse and thrust/mass ratio 2-3 orders of magnitude larger than from other advanced propulsion concepts. This QED system can be applied to aerospace vehicles from air-breathing to near-interstellar flight. Examples are given for Earth/Mars flight missions, that show transit times of 40 d with 20 percent payload in single-stage vehicles.
The QED engine - Fusion-electric propulsion for Cis-Oort/Quasi-Interstellar (QIS) flight
Bussard, Robert W.; Jameson, Lorin W.; Froning, H. D., Jr.
1993-01-01
A summary is presented of QED fusion-direct-electric engine systems, their features, and performance ranges. The principles and characteristics of inertial-electrostatic-fusion (IEF) power source systems are then reviewed, and their application to the diluted-fusion-product (DFP) engine concept for QIS missions is discussed. Particular attention is given to vehicle performance over a range of very high specific impulses and to specifications of a typical candidate DFP/IEF engine and a single-stage vehicle for rapid flight to 550 AU.
Liu, Yu-Long; Zhang, Jing; Özdemir, Şahin Kaya; Yang, Lan; Nori, Franco; Liu, Yu-xi
2016-01-01
We theoretically study a strongly-driven optomechanical system which consists of a passive optical cavity and an active mechanical resonator. When the optomechanical coupling strength is varied, phase transitions, which are similar those observed in $\\mathcal{PT}$-symmetric systems, are observed. We show that the optical transmission can be controlled by changing the gain of the mechanical resonator and loss of the optical cavity mode. Especially, we find that: (i) for balanced gain and loss, optical amplification and absorption can be tuned by changing the optomechanical coupling strength through a control field; (ii) for unbalanced gain and loss, even with a tiny mechanical gain, both optomechanically-induced transparency and anomalous dispersion can be observed around a critical point, which exhibits an ultra-long group delay. The time delay $\\tau$ can be optimized by regulating the optomechanical coupling strength through the control field and improved up to several orders of magnitude ($\\tau\\sim2$ $\\math...
Seeded QED cascades in counter propagating laser pulses
Grismayer, Thomas; Martins, Joana L; Fonseca, Ricardo; Silva, Luís O
2015-01-01
The growth rates of seeded QED cascades in counter propagating lasers are calculated with 2D/3D QED-PIC simulations. The dependence of the growth rate on laser polarisation and intensity are compared with analytical models that support simulations results. The models provide an insight regarding the qualitative trend of the cascade growth when the intensity of the laser field is varied. The results suggest that relativistic pair plasmas and efficient conversion from laser photons to gamma rays can be created with the typical intensities planned to operate on future ultra-intense laser facilities such as ELI or VULCAN.
An introduction to QED radiative corrections for experimentalists
International Nuclear Information System (INIS)
To experimentalists, radiative corrections (RC) may just look like a complication coming into their data analysis. But one should keep in mind that RC played a crucial role in the development of QED and in its establishment as a fundamental theory. These corrections enable one to make predictions of extreme precision which, up to now, have never been contradicted by experiment. Radiative corrections have gained a renewed importance in recent years, both in electroweak theory and in quantum chromodynamics (QCD). The scope of the following introduction to radiative corrections will be limited to QED
Extensible circuit QED processor architecture with vertical I/O
Bruno, Alessandro; Poletto, Stefano; Haider, Nadia; Dicarlo, Leonardo
Achieving quantum fault tolerance in an extensible architecture is an outstanding challenge across experimental quantum computing platforms today. Traditionally, circuit QED processors have millimeter dimensions and lateral coupling for all input/output (I/O) signals, precluding the increase in qubit numbers beyond ~10. We present a scalable footprint for circuit QED processors with vertically coupled I/O. Our demonstration using centimeter scale chips can accommodate the ~50 qubits needed in next-generation processors targeting the experimental demonstration of quantum fault tolerance. We acknowledge funding from FOM, NWO and the EU FP7 Project SCALEQIT.
Scalar-QED ℎ-corrections to the Coulomb potential
International Nuclear Information System (INIS)
The leading long-distance 1-loop quantum corrections to the Coulomb potential are derived for scalar QED and their gauge-independence is explicitly checked. The potential is obtained from the direct calculation of the 2-particle scattering amplitude, taking into account all relevant 1-loop diagrams. Our investigation should be regarded as first step towards the same programme for effective Quantum Gravity. In particular, with our calculation in the framework of scalar QED, we are able to demonstrate the incompleteness of some previous studies concerning the quantum Gravity counterpart. (author)
Quantising general relativity using QED theory, an overview and extension
Bell, Sarah B. M.
2004-01-01
We summarise and discuss some of our previous results, which show that Bohr's theory of the one-electron atom may be derived from the theory underpinning Quantum ElectroDynamics (QED) or vice versa, and that General Relativity may also be derived from QED theory in the classical limit, if we use Newtonian mechanics in the right frame and self-similar tesseral hierarchies. We circumvent Newton's arguments against Descartes' vortex theory to show that the inverse square law for a force combined...
Bosonization of $QED_3$ with an induced Chern - Simons term
Kovner, A
1994-01-01
We extend the bosonization of $2+1$ - dimensional QED with one fermionic flavor performed previously to the case of QED with an induced Chern - Simons term. The coefficient of this term is quantized: $e^2n/8\\pi$, $n\\in {\\bf Z}$. The fermion operators are constructed in terms of the bosonic fields $A_i$ and $E_i$. The construction is similar to that in the $n=0$ case. The resulting bosonic theory is Lorentz invariant in the continuum limit and has Maxwell's equations as its equations of motion. The algebra of bilinears exhibits nontrivial operatorial mixing with lower dimensional operators, which is absent for $n=0$.
What can we learn from QED at large couplings?
International Nuclear Information System (INIS)
In order to understand QCD at the energies relevant to hadronic physics one requires analytical methods for dealing with relativistic gauge field theories at large couplings. Strongly coupled quenched QED provides an ideal laboratory for the development of such techniques, in particular as many calculations suggest that--like QCD--this theory has a phase with broken chiral symmetry. In this talk we report on a nonperturbative variational calculation of the electron propagator within quenched QED and compare results to those obtained in other approaches. We find surprising differences among these results
A Wearable Real-Time and Non-Invasive Thoracic Cavity Monitoring System
Salman, Safa
A surgery-free on-body monitoring system is proposed to evaluate the dielectric constant of internal body tissues (especially lung and heart) and effectively determine irregularities in real-time. The proposed surgery-free on-body monitoring system includes a sensor, a post-processing technique, and an automated data collection circuit. Data are automatically collected from the sensor electrodes and then post processed to extract the electrical properties of the underlying biological tissue(s). To demonstrate the imaging concept, planar and wrap-around sensors are devised. These sensors are designed to detect changes in the dielectric constant of inner tissues (lung and heart). The planar sensor focuses on a single organ while the wrap-around sensors allows for imaging of the thoracic cavity's cross section. Moreover, post-processing techniques are proposed to complement sensors for a more complete on-body monitoring system. The idea behind the post-processing technique is to suppress interference from the outer layers (skin, fat, muscle, and bone). The sensors and post-processing techniques yield high signal (from the inner layers) to noise (from the outer layers) ratio. Additionally, data collection circuits are proposed for a more robust and stand-alone system. The circuit design aims to sequentially activate each port of the sensor and portions of the propagating signal are to be received at all passive ports in the form of a voltage at the probes. The voltages are converted to scattering parameters which are then used in the post-processing technique to obtain epsilonr. The concept of wearability is also considered through the use of electrically conductive fibers (E-fibers). These fibers show matching performance to that of copper, especially at low frequencies making them a viable substitute. For the cases considered, the proposed sensors show promising results in recovering the permittivity of deep tissues with a maximum error of 13.5%. These sensors
Ruiz de Castañeda, Esther; Gatón Hernández, Patrícia; Rodriguez, E G; Silva, Raquel Assed Bezerra da; NELSON FILHO Paulo; Silva, Léa Assed Bezerra da
2012-01-01
Abstract OBJECTIVE: This study evaluated, histopathologically, the pulpal and periapical response to a silorane-based resin (Filtek Silorane) and a methacrylate-based nanoparticle resin (Filtek Supreme XT) in deep cavities in dogs, having zinc oxide and eugenol-based cement (ZOE) as a control. METHODS: The tooth/bone blocks were collected after 10 and 90 days and processed for microscopic analysis of the dentin, pulp, and periapical tissues using a score system. Data were analyzed statistical...
Zhang, Xufeng; Zou, Changling; Jiang, Liang; Tang, Hong X.
Mechanical oscillators have been recently widely utilized to couple with optical and microwave photons in a variety of hybrid quantum systems, but they all lack the tunability. The magnetostrictive force provides an alternative mechanism to allow phonon to couple with a different type of information carrier-magnon, the collective excitation of magnetization whose frequency can be tuned by a bias magnetic field. Here, we demonstrate an intriguing hybrid system that consists of a magnonic, a mechanical, and a microwave resonator. The magnon-phonon interaction results in hallmark coherent phenomena such as magnomechanically induced transparency/absorption and magnomechanical parametric amplification. The magnetic field dependence of magnon provides our system with unprecedented tunability. Moreover, the great flexibility of our system allows us to achieve triple resonance among magnon, phonon and photon, which drastically enhances the magnomechanical interaction. Our work demonstrates the fundamental principle of cavity magnetomechanics, opening up great opportunities in various applications, such as tunable microwave filter and amplifier, long-lifetime quantum memories, microwave-to-optics conversion.
Lisowski, Darius D.
This experimental study investigated the thermal hydraulic behavior and boiling mechanisms present in a scaled reactor cavity cooling system (RCCS). The experimental facility reflects a ¼ scale model of one conceptual design for decay heat removal in advanced GenIV nuclear reactors. Radiant heaters supply up to 25 kW/m2 onto a three parallel riser tube and cooling panel test section assembly, representative of a 5° sector model of the full scale concept. Derived similarity relations have preserved the thermal hydraulic flow patterns and integral system response, ensuring relevant data and similarity among scales. Attention will first be given to the characterization of design features, form and heat losses, nominal behavior, repeatability, and data uncertainty. Then, tests performed in single-phase have evaluated the steady-state behavior. Following, the transition to saturation and subsequent boiling allowed investigations onto four parametric effects at two-phase flow and will be the primary focus area of remaining analysis. Baseline conditions at two-phase flow were defined by 15.19 kW of heated power and 80% coolant inventory, and resulted in semi-periodic system oscillations by the mechanism of hydrostatic head fluctuations. Void generation was the result of adiabatic expansion of the fluid due to a reduction in hydrostatic head pressure, a phenomena similar to flashing. At higher powers of 17.84 and 20.49 kW, this effect was augmented, creating large flow excursions that followed a smooth and sinusoidal shaped path. Stabilization can occur if the steam outflow condition incorporates a nominal restriction, as it will serve to buffer the short time scale excursions of the gas space pressure and dampen oscillations. The influences of an inlet restriction, imposed by an orifice plate, introduced subcooling boiling within the heated core and resulted in chaotic interactions among the parallel risers. The penultimate parametric examined effects of boil-off and
Tuner system for the s.c. 352 MHz LEP 4-cell cavities
International Nuclear Information System (INIS)
The s.c. 4-cell cavities for LEP are designed to operate at 5 MV/m with a beam current of at least twice 3 mA. The matched W/sub ext/ is then 4 106 resulting in a bandwidth of 90 Hz. The cavity has to be kept on its nominal frequency within a fraction of this bandwidth. The cavities are made from sheet metal and frequencies obtained after manufacturing have deviations of up to 200 kHz. An inelastic deformation to correct for the coarse manufacturing tolerances (200 kHz are corrected by a change of 5 mm in total length was foreseen. A specially designed tool allows even to change the length of each individual cell to correct deviations from the desired flat field distribution. The cavity is then mounted into the tuning support and the resonant frequency is adjusted with spacers to obtain the correct frequency at operational temperature with all vacua applied. 13 references, 8 figures
Studies of niobium and development of niobium resonant RF cavities for accelerator driven system
International Nuclear Information System (INIS)
The present approach for the fabrication of superconducting radio frequency (SRF) cavities is to roll and deep draw sheets of polycrystalline high-purity niobium. Jefferson Laboratory pioneered the use of large-grain/single-crystal Nb directly sliced from an ingot for the fabrication of single-crystal high-purity Nb SRF cavities. The large grain/single crystal niobium has several potential advantages over the polycrystalline niobium and has become a viable alternative to the standard fine grain (ASTM grain size>6 μm), high purity (RRR ≥ 250 ) niobium for the fabrication of high-performance SRF cavities for particle accelerators. The present study includes the prototype single cell low beta cavity design, fabrication, EB welding and low temperature RF test at 2K. In this study also the medium field Q-Slope has been analyzed with the help of an added non linear term in Heabel's analytical model and a linear increase of surface resistance Rs with the magnetic field
Deterministic nanoassembly of a coupled quantum emitter–photonic crystal cavity system
Van der Sar, T.; Hagemeier, J.; Pfaff, W.; Heeres, E.C.; Thon, S.M.; Kim, H.; Petroff, P.M.; Oosterkamp, T.H.; Bouwmeester, D.; Hanson, R.
2011-01-01
Controlling the interaction of a single quantum emitter with its environment is a key challenge in quantum optics. Here, we demonstrate deterministic coupling of single nitrogen-vacancy (NV) centers to high-quality photonic crystal cavities. We preselect single NV centers and position their 50-nm-si
Quantum phase transition and degeneracy of a circuit-QED vacuum
Nataf, Pierre
2009-01-01
We investigate theoretically the quantum vacuum properties of a transmission line resonator inductively coupled to a chain of $N$ superconducting qubits. We derive the quantum Hamiltonian for such circuit-QED system, showing that, due to the type and strength of the interaction, a quantum phase transition occurs in the limit of large $N$, with a twice degenerate quantum vacuum above a critical coupling. The phase diagram can be fully explored thanks to the controllable ultrastrong coupling of the qubits with the modes of the transmission line resonator. For finite values of $N$, an energy splitting occurs, which becomes exponentially small with increasing size and coupling.
Transverse Vector Vertex Function and Transverse Ward-Takahashi Relations in QED
Institute of Scientific and Technical Information of China (English)
HE Han-Xin
2006-01-01
The transverse vector vertex function in momentum space in four-dimensional QED is derived in terms of a set of transverse Ward-Takahashi relations for the vector and the axial-vector vertices in the case of massless fermion.It is demonstrated explicitly that the transverse vector vertex function derived this way to one-loop order leads to the same result as one obtained in perturbation theory. This provides a basic approach to determine the transverse part of basic vertex function from the symmetry relations of the system.
Kelisani, M. Dayyani; Doebert, S.; Aslaninejad, M.
2016-08-01
The critical process of beam loading compensation in high intensity accelerators brings under control the undesired effect of the beam induced fields to the accelerating structures. A new analytical approach for optimizing standing wave accelerating structures is found which is hugely fast and agrees very well with simulations. A perturbative analysis of cavity and waveguide excitation based on the Bethe theorem and normal mode expansion is developed to compensate the beam loading effect and excite the maximum field gradient in the cavity. The method provides the optimum values for the coupling factor and the cavity detuning. While the approach is very accurate and agrees well with simulation software, it massively shortens the calculation time compared with the simulation software.
International Nuclear Information System (INIS)
The Reactor Cavity Cooling System (RCCS) of the Modular High- Temperature Gas-Cooled Reactor (MHTGR) proposed by the U.S. Department of Energy is designed to remove the nuclear afterheat passively in the event that neither the heat transport system nor the shutdown cooling circulator subsystem is available. A computer dynamic simulation for the physical and mathematical modeling of and RCCS is described here. Two conclusions can be made form computations performed under the assumption of a uniform reactor vessel temperature. First, the heat transferred across the annulus from the reactor vessel and then to ambient conditions is very dependent on the surface emissivities of the reactor vessel and RCCS panels. These emissivities should be periodically checked to ensure the safety function of the RCCS. Second, the heat transfer from the reactor vessel is reduced by a maximum of 10% by the presence of steam at 1 atm in the reactor cavity annulus for an assumed constant in the transmission of radiant energy across the annulus can be expected to result in an increase in the reactor vessel temperature for the MHTGR. Further investigation of participating radiation media, including small particles, in the reactor cavity annulus is warranted. 26 refs., 7 figs., 1 tab
DEFF Research Database (Denmark)
Reitzenstein, S.; Schneider, C.; Albert, F.;
2011-01-01
Semiconductor quantum dots (QDs) are fascinating nanoscopic structures for photonics and future quantum information technology. However, the random position of self-organized QDs inhibits a deterministic coupling in devices relying on cavity quantum electrodynamics (cQED) effects which complicates...
QCD and QED corrections to light-by-light scattering
International Nuclear Information System (INIS)
We present the QCD and QED corrections to the fermion-loop contributions to light-by-light scattering, γγ→γγ, in the ultrarelativistic limit where the kinematic invariants are much larger than the masses of the charged fermions. (author)
Landau singularity and the instability of vacuum state in QED
Azam, Mofazzal
2008-01-01
Quantum Eletrodynamics (QED) is considered as the most successful of all physical theories. It can predict numerical values of physical quantities to a spectacular degree of accuracy. However, from the very early days it has been known that, in QED, there are two important problems which are linked with the very foundation of the theory. In 1952, Dyson put forward strong argumnts to suggest that the perturbation seires in quantum electrodynamics can not be convergent. Just three years latter, in 1955, Landau argued that the effective running coupling constant in QED has a pole (Landau singularity) albeit at some very high energy scale. This paper addresses, in details, the question of stability of perturbative vacuum state of QED in the light of these two well known problems. Landau has been a cult-like figure for many of us who studied theoretical physics in the former Soviet Union. As an undergraduate student in the department of theoretical physics of People's Friendship University, Moscow, in 1970's, I gr...
Hamiltonian formulation of QED in the superaxial gauge
International Nuclear Information System (INIS)
A Hamiltonian formulation of QED in a fully fixed axial gauge is presented. The equal-time commutators for all field variables are computed and are shown to lead to the correct equations of motion. The constraints and gauge conditions hold as strong operator relations. (Author)
Orbital Angular Momentum in Scalar Diquark Model and QED
BC, Hikmat; Burkardt, Matthias
2011-01-01
We compare the orbital angular momentum of the 'quark' in the scalar diquark model as well as that of the electron in QED (to order {\\alpha}) obtained from the Jaffe-Manohar de- composition to that obtained from the Ji relation. We estimate the importance of the vector potential in the definition of orbital angular momentum.
Orbital Angular Momentum in Scalar Diquark Model and QED
International Nuclear Information System (INIS)
We compare the orbital angular momentum of the 'quark' in the scalar diquark model as well as that of the electron in QED (to order α) obtained from the Jaffe-Manohar decomposition to that obtained from the Ji relation. We estimate the importance of the vector potential in the definition of orbital angular momentum. (author)
APFEL: A PDF Evolution Library with QED corrections
Bertone, Valerio; Rojo, Juan
2014-01-01
Quantum electrodynamics and electroweak corrections are important ingredients for many theoretical predictions at the LHC. This paper documents APFEL, a new PDF evolution package that allows for the first time to perform DGLAP evolution up to NNLO in QCD and to LO in QED, in the variable-flavor-number scheme and with either pole or MSbar heavy quark masses. APFEL consistently accounts for the QED corrections to the evolution of quark and gluon PDFs and for the contribution from the photon PDF in the proton. The coupled QCD+QED equations are solved in x-space by means of higher order interpolation, followed by Runge-Kutta solution of the resulting discretized evolution equations. APFEL is based on an innovative and flexible methodology for the sequential solution of the QCD and QED evolution equations and their combination. In addition to PDF evolution, APFEL provides a module that computes Deep-Inelastic Scattering structure functions in the FONLL general-mass variable-flavor-number scheme up to O($\\alpha_s^2...
Forward scattering amplitude of the virtual longitudinal photon in QED
Samsonov, A. V.
1997-01-01
Forward scattering amplitude of the virtual longitudinal photon at zero energy on electron in QED in the limit of small photon virtualities is calculated. The first radiation corrections are taken into account. Two terms in the expansion over photon virtualities are obtained.
Critical Mass of Gauge Boson in Rainbow QED3
Institute of Scientific and Technical Information of China (English)
FENG Hong-Tao; HU Fei; SUN Wei-Min; ZONG Hong-Shi
2005-01-01
In three-dimensional quantum electrodynamics (QED3) with a massive gauge boson, we investigate the coupled Dyson-Schwinger equations for the fermion and photon propagators in the rainbow approximation, and obtain the critical gauge boson mass for various numbers of the fermion flavors. A comparision with the previous results is presented.
QED in external fields: A functional point of view
International Nuclear Information System (INIS)
A functional partial differential equation is set for the proper graphs generating functionals of QED in external electromagnetic fields. This equation leads to the evolution of the proper graphs with the external field amplitude and the external field gauge dependence of the complete fermion propagator and vertex is derived nonperturbatively
1974-01-01
The main RF-system of the SPS comprises four cavities: two of 20 m length and two of 16.5 m length. They are all installed in one long straight section (LSS 3). These cavities are of the travelling-wave type operating at a centre frequency of 200.2 MHz. They are wideband, filling time about 700 ns and untuned. A power of up to 790 kW can be supplied to each giving a total accelerating voltage of about 8 MV. The power amplifiers, using tetrodes are installed in a surface building 200 m from the cavities.
International Nuclear Information System (INIS)
This paper presents a lower-hybrid cavity detection system, CDS, for measurements of electron plasma density on the FREJA satellite wave experiment. The system can reduce the amount of data to be analysed by as much as 96% and still retain more than 85% of the desired information. The CDS is a combination of a hybrid neural network, HNN and expert rules. The HNN is a Self Organizing Map, SOM, combined with a feed forward back propagation neural net, BP. The CDS can be controlled by the user to operate with various degrees of sensitivity. Maximum detection capability is as high as 95% with data reduction lowered to 85%. 10 refs
Quantum Information Transfer in Circuit QED with Landau-Zener Tunneling
Institute of Scientific and Technical Information of China (English)
LI Jun-Wang; WU Chun-Wang; DAI Hong-Yi
2011-01-01
We propose a scheme to implement quantum information transfer between Cooper-pair boxes (CPBs) in a circuit quantum electrodynamic (QED) system with Landau-Zener tunneling. The system consists of two CPB qubits and a one-dimensional transmission line resonator (TLR). By analytically solving the eigenequation and numerically calculating the transition probability, the results show the quantum state transfer from one qubit to another via a fast adiabatic passage. The coupling mechanism is robust against decoherence effects.%@@ We propose a scheme to implement quantum information transfer between Cooper-pair boxes(CPBs)in a circuit quantum electrodynamic(QED)system with Landau-Zener tunneling.The system consists of two CPB qubits and a one-dimensional transmission line resonator(TLR).By analytically solving the eigenequation and numeri-cally calculating the transition probability,the results show the quantum state transfer from one qubit to another via a fast adiabatic passage.The coupling mechanism is robust against decoherence effects.
... leading to cavities. Treatment may involve: Fillings Crowns Root canals Dentists fill teeth by removing the decayed tooth ... gold, porcelain, or porcelain attached to metal. A root canal is recommended if the nerve in a tooth ...
1979-01-01
This picture shows one of the 2 new cavities installed in 1978-1979. The main RF-system of the SPS comprises four cavities: two of 20 m length and two of 16.5 m length. They are all installed in one long straight section (LSS 3). These cavities are of the travelling-wave type operating at a centre frequency of 200.2 MHz. They are wideband, filling time about 700 ns and untuned. The power amplifiers, using tetrodes are installed in a surface building 200 m from the cavities. Initially only two cavities were installed, a third cavity was installed in 1978 and a forth one in 1979. The number of power amplifiers was also increased: to the first 2 MW plant a second 2 MW plant was added and by end 1979 there were 8 500 kW units combined in pairs to feed each of the 4 cavities with up to about 1 MW RF power, resulting in a total accelerating voltage of about 8 MV. See also 7412016X, 7412017X, 7411048X
1975-01-01
The picture shows one of the two initially installed cavities. The main RF-system of the SPS comprises four cavities: two of 20 m length and two of 16.5 m length. They are all installed in one long straight section (LSS 3). These cavities are of the travelling-wave type operating at a centre frequency of 200.2 MHz. They are wideband, filling time about 700 ns and untuned. The power amplifiers, using tetrodes are installed in a surface building 200 m from the cavities. Initially only two cavities were installed, a third cavity was installed in 1978 and a forth one in 1979. The number of power amplifiers was also gradually increased: by end 1980 there were 8 500 kW units combined in pairs to feed each of the 4 cavities with up to about 1 MW RF power, resulting in a total accelerating voltage of about 8 MV. See also 7412017X, 7411048X, 7505074.
1988-01-01
The pulse of a particle accelerator. 128 of these radio frequency cavities were positioned around CERN's 27-kilometre LEP ring to accelerate electrons and positrons. The acceleration was produced by microwave electric oscillations at 352 MHz. The electrons and positrons were grouped into bunches, like beads on a string, and the copper sphere at the top stored the microwave energy between the passage of individual bunches. This made for valuable energy savings as it reduced the heat generated in the cavity.
Modeling the thermal–hydraulic behavior of the reactor cavity cooling system using RELAP5-3D
International Nuclear Information System (INIS)
Highlights: • The RCCS complex geometry and heat transfer mechanisms were modeled with RELAP5-3D. • Code limitations were overcome by applying special heat structures modeling techniques. • The simulation results were found to be in good agreement with the experimental data. • RELAP5-3D was found to be an adequate tool for analysis of HTGR components. - Abstract: The Very High Temperature Gas-Cooled Reactor (VHTR), one of the six proposed designs for the next generation nuclear reactor, was conceived to achieve high temperatures to support industrial applications and power generation. Due to the high temperature reached during normal operation, the design included new passive safety systems. The Reactor Cavity Cooling System (RCCS) is a new passive safety system designed to remove the heat from the reactor cavity during normal operation (steady-state) and accident scenarios. Computational tools such as system codes have been selected to simulate the reactor system and, in particular, the new safety components. The capabilities of these codes are being investigated to verify their ability in predicting the phenomena involved in the RCCS operation during steady-state and accident conditions. A RELAP5-3D input model of a small scale water-cooled experimental facility was prepared to simulate steady-state. The simulation results were compared with data produced during the experimental steady-state run. The results obtained and presented in the paper showed a good agreement of the code prediction with the experimental data. The paper also provides a set of modeling techniques to overcome some of the limitations of the current version of the computer code in simulating complex geometries with combined heat transfer mechanisms in the reactor cavity of the VHTR
Combining NNPDF3.0 and NNPDF2.3QED through the APFEL evolution code
Bertone, V
2016-01-01
We present sets of parton distribution functions (PDFs), based on the NNPDF3.0 family, which include the photon PDF from the NNPDF2.3QED sets, and leading-order QED contributions to the DGLAP evolution as implemented in the public code APFEL. The aim is to combine our state-of-the-art determination of quark and gluon PDFs with the so far only direct determination of the photon PDF from LHC data. In addition, the use of APFEL allowed us to employ a solution of the DGLAP equation that, differently from that used for the NNPDF2.3QED sets, includes QED corrections in a more accurate way. We briefly discuss how these sets are constructed and investigate the effect of the inclusion of the QED corrections on PDFs and parton luminosities. Finally, we compare the resulting sets, which we dubbed NNPDF3.0QED, to the older NNPDF2.3QED sets and to all presently available PDF sets that include QED corrections, namely CT14QED and MRST2004QED.
1976-01-01
The SPS started up with 2 accelerating cavities (each consisting of 5 tank sections) in LSS3. They have a 200 MHz travelling wave structure (see 7411032 and 7802190) and 750 kW of power is fed to each of the cavities from a 1 MW tetrode power amplifier, located in a surface building above, via a coaxial transmission line. Clemens Zettler, builder of the SPS RF system, is standing at the side of one of the cavities. In 1978 and 1979 another 2 cavities were added and entered service in 1980. These were part of the intensity improvement programme and served well for the new role of the SPS as proton-antiproton collider. See also 7411032, 8011289, 8104138, 8302397.
Electro-optical channel drop switching in a photonic crystal waveguide-cavity side-coupling system
Chang, Kao-Der; Liu, Cheng-Yang
2014-04-01
The electro-optical channel drop switching in a photonic crystal waveguide-cavity side-coupling system is reported. The line waveguide is formed by removing a single row of dielectric cylinders. The twin optical microcavities side coupled between linear waveguides is studied by solving Maxwell's equations. We determine the general characteristics of the coupling element required to achieve channel drop tunneling. By modulating the conductance of the twin microcavities, the electrical tunability of the resonant modes is observed in the transmission spectrum. The spectral characteristics suggest a potential application for this switching device as an efficient multichannel optical switch in the photonic integrated circuits.