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HIGH-ORDER QUANTUM BERRY’S ADIABATIC PHASE AND ITS OBSERVABLE EFFECT

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Chinese Physics Letters 1989年第3期6卷 97-100页

作者： sun changpu Department of Physics Northeast Normal UniversityChangchun

New high-order adiabatic approximate method is proposed for the study of non-adiabatic evolution of a quantum system with slowly-changing *** corresponding high-order Berry’s adiabatic phases are used to describe the... 详细信息

关键词： adiabatic quantum Berry

CLASSICAL ANALOGUES OF QUANTUM BERRYS PHASE

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Chinese Physics Letters 1989年第11期6卷 481-483页

作者： sun changpu Physics Department Northeast Normal UniversityChangchun

With the classical generalized harmonic oscillator as an example,we show that the analogues of the quantum Berry's phase can appear in the classical mechanic systems with adiabatically-changing parameters,which have t... 详细信息

关键词： equations CLASS analogues

Dynamic generation of entangling wave packets in XY spin system with decaying long-range couplings

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Science China(Physics,Mechanics & Astronomy) 2008年第1期51卷 45-55页

作者： YANG Shuo SONG Zhi sun changpu Department of Physics Nankai UniversityTianjin 300071China Institute of Theoretical Physics Chinese Academy of SciencesBeijing 100080China

The dynamic generation of spin entanglement between two distant sites in a XY model with 1/r 2 decay long-range couplings was *** to the linear dispersion relationε(k)~|k|of magnons in such a model,a well-located spin state can be dynamically split into two moving entangled local wave packets without changing their ***,when such two wave packets meet at the diametrically opposite site after the fast periodτ=Nπ/J,the initial well-located state is completely *** calculation was performed to confirm the analytical result even if the ring system of sizes N up to several thousands is *** truncation approximation for the coupling strengths was also *** simulation shows that the above conclusions still hold even if the range of the coupling strength is truncated to a relatively short scale compared with the size of the spin system.

关键词： quantum information entanglement spin model

A quantum solution to Gibbs paradox with few particles

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Science China(Physics,Mechanics & Astronomy) 2012年第10期55卷 1727-1733页

作者： DONG Hui CAI ChengYun sun changpu Department of Chemistry University of CaliforniaBerkeleyCA 94720USA Institute of Theoretical Physics Chinese Academy of SciencesBeijing 100190China

We present a fully quantum solution to the Gibbs paradox (GP) with an illustration based on a gedanken experiment with two particles trapped in an infinite potential well. The well is divided into two cells by a solid wall, which could be removed for mixing the particles. For the initial thermal state with correct two-particle wavefunction according to their quantum statistics, the exact calculations show the entropy changes are the same for boson, fermion and non-identical particles. With the observation that the initial unmixed state of identical particles in the conventional presentations actually is not of a thermal equilibrium, our analysis reveals the quantum origin of the paradox, and confirms Jaynes' observation that entropy increase in Gibbs mixing is only due to the including more observables. To further show up the subtle role of the quantum mechanism in the GP, we study the different finite size effect on the entropy change and show the work performed in the mixing process is different for various types of particles.

关键词： Gibbs paradox identical particles mixing entropy

Spontaneous decoherence of coupled harmonic oscillators confined in a ring

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Science China(Physics,Mechanics & Astronomy) 2018年第4期61卷 17-29页

作者： ZhiRui Gong ZhenWei Zhang DaZhi Xu Nan Zhao changpu sun College of Physics and Energy Shenzhen UniversityShenzhen 518060China Beijing Computational Science Research Center Beijing 100084China Center for Quantum Technology Research School of PhysicsBeijing Institute of TechnologyBeijing 100081China

We study the spontaneous decoherence of coupled harmonic oscillators confined in a ring container, where the nearest-neighbor harmonic potentials are taken into consideration. Without any external symmetry-breaking field or surrounding environment, the quantum superposition state prepared in the relative degrees of freedom gradually loses its quantum coherence *** spontaneous decoherence is interpreted by the gauge couplings between the center-of-mass and the relative degrees of freedoms, which actually originate from the symmetries of the ring geometry and the corresponding nontrivial boundary *** particular, such spontaneous decoherence does not occur at all at the thermodynamic limit because the nontrivial boundary conditions become the trivial Born-von Karman boundary conditions when the perimeter of the ring container tends to *** investigation shows that a thermal macroscopic object with certain symmetries has a chance for its quantum properties to degrade even without applying an external symmetry-breaking field or surrounding environment.

关键词： spontaneous quantum decoherence periodic boundary condition gauge interaction

Fermion System with Quantum Group Symmetry and Usual Fermion Realizations of S1_(q)(2)

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Chinese Physics Letters 1992年第12期9卷 633-636页

作者： sun changpu LI Jianming Department of Physics Northeast Normal UniversityChangchun 130024 Department of Physics Jilin UniversityChangchun 130023

The usual fermion realizations of quantum algebra S1_(q)(2) defining higher-dimensional representations are built in this *** them,we construct a usual fermion system with quantum group symmetry of S1_(q)(2) as a q-deformation of the pairing correlation model in many-body *** energy spectra are exactly solved out from the representation theory of S1_(q)(2).

关键词： Fermi quantum usual

Thermodynamic witness of quantum probing

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Chinese Science Bulletin 2010年第29期55卷 3256-3260页

作者： DONG Hui LIU XuFeng sun changpu Institute of Theoretical Physics Chinese Academy of Sciences Beijing 100190 China Department of Mathematics Peking University Beijing 100871 China

The thermodynamic influence of quantum probing on an object is ***,quantum probing is understood to be a pre-measurement based on a non-demolition interaction,which records some information of the probed object but does not change its energy state when both the probing apparatus and the probed object are isolated from the *** is argued that when the probing apparatus and the probed object are immersed in the same equilibrium environment,the probing can affect the effective temperature of the object or induce a quantum isothermal process for the object to transfer its *** thermodynamic feature can be regarded as a witness of quantum probing.

关键词：热力学特性探测仪器量子能量转移等温过程有效积温环境

Photonic Feshbach resonance

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Science China(Physics,Mechanics & Astronomy) 2010年第7期53卷 1234-1238页

作者： XU DaZhi IAN Hou SHI Tao DONG Hui sun changpu Institute of Theoretical Physics Chinese Academy of SciencesBeijing 100190China Department of Modern Physics University of Science and Technology of ChinaHefei 230026China

Feshbach resonance is a resonance for two-atom scattering with two or more channels,in which a bound state is achieved in one *** show that this resonance phenomenon not only exists during the collisions of massive particles,but also emerges during the coherent transport of massless particles,that is,photons confined in the coupled resonator arrays linked by a separated cavity or a tunable two level system(TLS).When the TLS is coupled to one array to form a bound state in this setup,the vanishing transmission appears to display the photonic Feshbach *** process can be realized through various experimentally feasible solid state systems,such as the couple defected cavities in photonic crystals and the superconducting qubit coupled to the transmission *** numerical simulation based on the finite-different time-domain(FDTD) method confirms our assumption about the physical implementation.

关键词： Feshbach resonance bound state single-photon transistor

Dynamics of quantum zeno and anti-zeno efects in an open system

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Science China(Physics,Mechanics & Astronomy) 2014年第2期57卷 194-207页

作者： ZHANG Peng AI Qing LI Yong XU DaZhi sun changpu Department of Physics Renmin University of China Department of Chemistry and Center for Quantum Science and Engineering National Taiwan University Beijing Computational Science Research Center Institute of Theoretical Physics Chinese Academy of Sciences

We provide a general dynamical approach for the quantum Zeno and anti-Zeno effects in an open quantum system under repeated non-demolition measurements. In our approach the repeated measurements are described by a general dynamical model without the wave function collapse postulation. Based on that model, we further study both the short-time and long-time evolutions of the open quantum system under repeated non-demolition measurements, and derive the measurement-modified decay rates of the excited state. In the cases with frequent ideal measurements at zero-temperature, we re-obtain the same decay rate as that from the wave function collapse postulation （Nature, 2000, 405： 546）. The correction to the ideal decay rate is also obtained under the non-ideal measurements. Especially, we find that the quantum Zeno and anti-Zeno effects are possibly enhanced by the non-ideal natures of measurements. For the open system under measurements with arbitrary period, we generally derive the rate equation for the long-time evolution for the cases with arbitrary temperature and noise spectrum, and show that in the long-time evolution the noise spectrum is effectively tuned by the repeated measurements. Our approach is also able to describe the quantum Zeno and anti-Zeno effects given by the phase modulation pulses, as well as the relevant quantum control schemes.

关键词： quantum Zeno effect quantum anti-Zeno effect quantum measurement