By introducing a fictitious mode to be a counterpart mode of the system mode under review we introduce the entangled state representation （η｜, which can arrange master equations of density operators p（t） in quant...By introducing a fictitious mode to be a counterpart mode of the system mode under review we introduce the entangled state representation （η｜, which can arrange master equations of density operators p（t） in quantum statistics as state-vector evolution equations due to the elegant properties of （η｜. In this way many master equations （respectively describing damping oscillator, laser, phase sensitive, and phase diffusion processes with different initial density operators） can be concisely solved. Specially, for a damping process characteristic of the decay constant k we find that the matrix element of p（t） at time t in 〈η｜ representation is proportional to that of the initial po in the decayed entangled state （ηe^-kt｜ representation, accompanying with a Gaussian damping factor. Thus we have a new insight about the nature of the dissipative process. We also set up the so-called thermo-entangled state representation of density operators, ρ = f（d^2η/π）（η｜ρ〉D（η）, which is different from all the previous known representations.展开更多
By exposing deficiency of the usual superoperators that have no explicit operator-expression in quantuminformation theory we introduce thermo entangled state representation to endow each of these superoperators a defi...By exposing deficiency of the usual superoperators that have no explicit operator-expression in quantuminformation theory we introduce thermo entangled state representation to endow each of these superoperators a definiteoperator-expression in an enlarged space in which one mode is a fictitious.This helps us to directly derive the role ofexponential of superoperators and the solutions of some master equations.展开更多
We have theoretically studied the nucleation of superconductivity in doubly connected superconductors in the form of long superconducting cylinders. The giant vortex states are investigated with the nonlinear Ginzburg...We have theoretically studied the nucleation of superconductivity in doubly connected superconductors in the form of long superconducting cylinders. The giant vortex states are investigated with the nonlinear Ginzburg-Landau theory. The solutions of Ginzburg-Landau equations are solved numerically with relaxation method. The quantum size effect is clearly shown through the calculation of free energy.展开更多
The non-Markovian dynamics of quantum entanglement is studied by the Shabani-Lidar master equation when one of entangled quantum systems is coupled to a local reservoir with memory effects.The completely positive redu...The non-Markovian dynamics of quantum entanglement is studied by the Shabani-Lidar master equation when one of entangled quantum systems is coupled to a local reservoir with memory effects.The completely positive reduced dynamical map can be constructed in the Kraus representation.Quantum entanglement decays more slowly in the non-Markovian environment.The decoherence time for quantum entanglement can be markedly increased with the change of the memory kernel.It is found out that the entanglement sudden death between quantum systems and entanglement sudden birth between the system and reservoir occur at different instants.展开更多
We extend the approach of solving master equations for density matrices by projecting it onto the thermal entangled state representation(Hong-Yi Fan and Jun-Hua Chen,J.Phys.A35(2002)6873)to two-mode case.In this appro...We extend the approach of solving master equations for density matrices by projecting it onto the thermal entangled state representation(Hong-Yi Fan and Jun-Hua Chen,J.Phys.A35(2002)6873)to two-mode case.In this approach the two-photon master equations can be directly and conveniently converted into c-number partial differential equations.As an example,we solve the typical master equation for two-photon process in some limiting cases.展开更多
In this paper, we give a direct method for calculating the partition function, and hence the equation of state （EOS） of QCD at finite chemical potential and zero temperature. In the EOS derived in this paper the pre...In this paper, we give a direct method for calculating the partition function, and hence the equation of state （EOS） of QCD at finite chemical potential and zero temperature. In the EOS derived in this paper the pressure density is the sum of two terms： the first term P（μ）｜μ=0 （the pressure density at μ = 0） is a μ-independent constant; the second term, which is totally determined by G[μ] （p） （the dressed quark propagator at finite μ）, contains all the nontrivial μ-dependence. By applying a general result in the rainbow-ladder approximation of the Dyson-Schwinger approach obtained in our previous study [Phys. Rev. C 71 （2005） 015205], G[μ]（p） is calculated from the meromorphic quark propagator proposed in [Phys. Rev. D 67 （2003） 054019]. From this the full analytic expression of the EOS of QCD at finite μ and zero T is obtained （apart from the constant term P（μ）｜μ=0, which can in principle be caJculated from the CJT effective action）. A comparison between our EOS and the cold, perturbative EOS of QCD of Fraga, Pisarski and Schaffner-Bielich is made. It is expected that our EOS can provide a possible new approach for the study of neutron stars.展开更多
Black lenses with L(n,1) horizon topology in five dimensions have many unusual properties shared by neither Myers-Perry black holes with event-horizon topology S 3,nor 5-dimensional black rings with event-horizon topo...Black lenses with L(n,1) horizon topology in five dimensions have many unusual properties shared by neither Myers-Perry black holes with event-horizon topology S 3,nor 5-dimensional black rings with event-horizon topology S 2 × S 1.In this work,by constructing appropriate matrices γμ for the general covariant Dirac equation,we further extend the fermion tunnelling method to 5-dimensional static and rotating black lenses.As a result,it is interesting to find as in black hole cases,fermions tunnelling can also result in correct Hawking temperatures for the static and rotating black lenses.展开更多
From Bethe-Salpeter equation,we deduce the equation which describes the two-body system consisting of a scalar meson and a vector meson.This equation is applied to investigate the exotic narrow state X (3872) assumed ...From Bethe-Salpeter equation,we deduce the equation which describes the two-body system consisting of a scalar meson and a vector meson.This equation is applied to investigate the exotic narrow state X (3872) assumed as a molecule state composed of D 0 0.The contribution of the resonance 0 is the attractive interaction between two heavy mesons in this molecule state.The calculated mass of X is consistent with the experimental data.展开更多
In this paper, we investigate the escape of Brownian particles and stochastic resonance (SR) with low-temperatures quantum fluctuations by using the quantum Smoluchowski equations at low-temperature. Two specific exam...In this paper, we investigate the escape of Brownian particles and stochastic resonance (SR) with low-temperatures quantum fluctuations by using the quantum Smoluchowski equations at low-temperature. Two specific examples have been considered: one is the example of bistable system, and the other is the example of metastable system. The explicit expressions of the mean-first passage time (MFPT) and signal-to-noise ratio (SNR) for both specific examples are obtained, respectively. Based on the numerical computations, we compare the quantum case with its classical counterpart. Our research results show that: (i) the quantum effect accelerates the escape of the Brownian particle in comparison with the classical result and (ii) the quantum effect enhances the SR in the SNR as a function of β for a bistable system (i.e., β = 1/kBT, kB is the Boltzmann constant and T is the temperature), while for a metastable system, the β amplifies the quantum effects, and the quantum effect weakens the SNR as a function of β.展开更多
基金supported by President Foundation of Chinese Academy of Sciences and National Natural Science Foundation of China under Grant Nos. 10775097 and 10874174
文摘By introducing a fictitious mode to be a counterpart mode of the system mode under review we introduce the entangled state representation （η｜, which can arrange master equations of density operators p（t） in quantum statistics as state-vector evolution equations due to the elegant properties of （η｜. In this way many master equations （respectively describing damping oscillator, laser, phase sensitive, and phase diffusion processes with different initial density operators） can be concisely solved. Specially, for a damping process characteristic of the decay constant k we find that the matrix element of p（t） at time t in 〈η｜ representation is proportional to that of the initial po in the decayed entangled state （ηe^-kt｜ representation, accompanying with a Gaussian damping factor. Thus we have a new insight about the nature of the dissipative process. We also set up the so-called thermo-entangled state representation of density operators, ρ = f（d^2η/π）（η｜ρ〉D（η）, which is different from all the previous known representations.
基金Supported by the President Foundation of Chinese Academy of Science
文摘By exposing deficiency of the usual superoperators that have no explicit operator-expression in quantuminformation theory we introduce thermo entangled state representation to endow each of these superoperators a definiteoperator-expression in an enlarged space in which one mode is a fictitious.This helps us to directly derive the role ofexponential of superoperators and the solutions of some master equations.
基金The project supported by Natural Science Foundation from Beijing Normal University.Acknowledgments H. Zhao wishes to thank Profs. Fang-Lin Peng, Jue- Lian Shen, and Jia-Cai Nie for helpful discussions
文摘We have theoretically studied the nucleation of superconductivity in doubly connected superconductors in the form of long superconducting cylinders. The giant vortex states are investigated with the nonlinear Ginzburg-Landau theory. The solutions of Ginzburg-Landau equations are solved numerically with relaxation method. The quantum size effect is clearly shown through the calculation of free energy.
基金Supported by the Project of Teaching Quality in SUST under Grant No. 2010JGB-27the National Natural Science Foundation under Grant No. 10774108
文摘The non-Markovian dynamics of quantum entanglement is studied by the Shabani-Lidar master equation when one of entangled quantum systems is coupled to a local reservoir with memory effects.The completely positive reduced dynamical map can be constructed in the Kraus representation.Quantum entanglement decays more slowly in the non-Markovian environment.The decoherence time for quantum entanglement can be markedly increased with the change of the memory kernel.It is found out that the entanglement sudden death between quantum systems and entanglement sudden birth between the system and reservoir occur at different instants.
基金The project supported by National Natural Science Foundation of China under Grant No.10175057the President Foundation of the Chinese Academy of Sciences
文摘We extend the approach of solving master equations for density matrices by projecting it onto the thermal entangled state representation(Hong-Yi Fan and Jun-Hua Chen,J.Phys.A35(2002)6873)to two-mode case.In this approach the two-photon master equations can be directly and conveniently converted into c-number partial differential equations.As an example,we solve the typical master equation for two-photon process in some limiting cases.
基金supported in part by the National Natural Science Foundation of China under Grant No.10575050the Research Fund for the Doctoral Program of Higher Education under Grant No.20060284020
文摘In this paper, we give a direct method for calculating the partition function, and hence the equation of state （EOS） of QCD at finite chemical potential and zero temperature. In the EOS derived in this paper the pressure density is the sum of two terms： the first term P（μ）｜μ=0 （the pressure density at μ = 0） is a μ-independent constant; the second term, which is totally determined by G[μ] （p） （the dressed quark propagator at finite μ）, contains all the nontrivial μ-dependence. By applying a general result in the rainbow-ladder approximation of the Dyson-Schwinger approach obtained in our previous study [Phys. Rev. C 71 （2005） 015205], G[μ]（p） is calculated from the meromorphic quark propagator proposed in [Phys. Rev. D 67 （2003） 054019]. From this the full analytic expression of the EOS of QCD at finite μ and zero T is obtained （apart from the constant term P（μ）｜μ=0, which can in principle be caJculated from the CJT effective action）. A comparison between our EOS and the cold, perturbative EOS of QCD of Fraga, Pisarski and Schaffner-Bielich is made. It is expected that our EOS can provide a possible new approach for the study of neutron stars.
基金supported by the Scientific Research Foundation of the Education Department of Liaoning Province,China (Grant No.L2011195)
文摘Black lenses with L(n,1) horizon topology in five dimensions have many unusual properties shared by neither Myers-Perry black holes with event-horizon topology S 3,nor 5-dimensional black rings with event-horizon topology S 2 × S 1.In this work,by constructing appropriate matrices γμ for the general covariant Dirac equation,we further extend the fermion tunnelling method to 5-dimensional static and rotating black lenses.As a result,it is interesting to find as in black hole cases,fermions tunnelling can also result in correct Hawking temperatures for the static and rotating black lenses.
文摘From Bethe-Salpeter equation,we deduce the equation which describes the two-body system consisting of a scalar meson and a vector meson.This equation is applied to investigate the exotic narrow state X (3872) assumed as a molecule state composed of D 0 0.The contribution of the resonance 0 is the attractive interaction between two heavy mesons in this molecule state.The calculated mass of X is consistent with the experimental data.
基金supported by the Natural Science Foundation of Yunnan Province (Grant No. 2010CD031)the National Natural Science Foun-dation of China (Grant Nos. 50906035, 51066002 and U0937604)
文摘In this paper, we investigate the escape of Brownian particles and stochastic resonance (SR) with low-temperatures quantum fluctuations by using the quantum Smoluchowski equations at low-temperature. Two specific examples have been considered: one is the example of bistable system, and the other is the example of metastable system. The explicit expressions of the mean-first passage time (MFPT) and signal-to-noise ratio (SNR) for both specific examples are obtained, respectively. Based on the numerical computations, we compare the quantum case with its classical counterpart. Our research results show that: (i) the quantum effect accelerates the escape of the Brownian particle in comparison with the classical result and (ii) the quantum effect enhances the SR in the SNR as a function of β for a bistable system (i.e., β = 1/kBT, kB is the Boltzmann constant and T is the temperature), while for a metastable system, the β amplifies the quantum effects, and the quantum effect weakens the SNR as a function of β.
