By using the Wei-Norman's method,the deflection of an atomic beam with a large period quantized standing light wave is analyzed for the case with two-level atom and single-mode cavity field.It is concluded that af...By using the Wei-Norman's method,the deflection of an atomic beam with a large period quantized standing light wave is analyzed for the case with two-level atom and single-mode cavity field.It is concluded that after passing through the standing light wave in cavity,the atomic beam is split into infinite beams symmetrically,and each momentum shift for a split component is proportional to the interaction time.It is also shown that the output momentum distribution of atoms is sensitive to the statistical properties of the cavity field.展开更多
The usual fermion realizations of quantum algebra S1_(q)(2) defining higher-dimensional representations are built in this letter.Using them,we construct a usual fermion system with quantum group symmetry of S1_(q)(2) ...The usual fermion realizations of quantum algebra S1_(q)(2) defining higher-dimensional representations are built in this letter.Using 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 problems.Its energy spectra are exactly solved out from the representation theory of S1_(q)(2).展开更多
The dynamic generation of spin entanglement between two distant sites in a XY model with 1/r 2 decay long-range couplings was studied.Due to the linear dispersion relationε(k)~|k|of magnons in such a model,a well-loc...The dynamic generation of spin entanglement between two distant sites in a XY model with 1/r 2 decay long-range couplings was studied.Due 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 shapes.Interestingly,when such two wave packets meet at the diametrically opposite site after the fast periodτ=Nπ/J,the initial well-located state is completely recurrent.Numerical calculation was performed to confirm the analytical result even if the ring system of sizes N up to several thousands is considered.The truncation approximation for the coupling strengths was also studied.Numerical 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.展开更多
The thermodynamic influence of quantum probing on an object is studied.Here,quantum probing is understood to be a pre-measurement based on a non-demolition interaction,which records some information of the probed obje...The thermodynamic influence of quantum probing on an object is studied.Here,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 environment.It 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 energy.This thermodynamic feature can be regarded as a witness of quantum probing.展开更多
We provide a general dynamical approach for the quantum Zeno and anti-Zeno efects in an open quantum system under repeated non-demolition measurements.In our approach the repeated measurements are described by a gener...We provide a general dynamical approach for the quantum Zeno and anti-Zeno efects 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 efects 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 efectively tuned by the repeated measurements.Our approach is also able to describe the quantum Zeno and anti-Zeno efects given by the phase modulation pulses,as well as the relevant quantum control schemes.展开更多
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...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.展开更多
Feshbach resonance is a resonance for two-atom scattering with two or more channels,in which a bound state is achieved in one channel.We show that this resonance phenomenon not only exists during the collisions of mas...Feshbach resonance is a resonance for two-atom scattering with two or more channels,in which a bound state is achieved in one channel.We 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 resonance.This 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 line.The numerical simulation based on the finite-different time-domain(FDTD) method confirms our assumption about the physical implementation.展开更多
基金Partially supported by the National Natural Science Foundation of China,and the Fok Yin-Tung Education Foundation.
文摘By using the Wei-Norman's method,the deflection of an atomic beam with a large period quantized standing light wave is analyzed for the case with two-level atom and single-mode cavity field.It is concluded that after passing through the standing light wave in cavity,the atomic beam is split into infinite beams symmetrically,and each momentum shift for a split component is proportional to the interaction time.It is also shown that the output momentum distribution of atoms is sensitive to the statistical properties of the cavity field.
基金Supported by the National Natural Science Foundation of China.
文摘The usual fermion realizations of quantum algebra S1_(q)(2) defining higher-dimensional representations are built in this letter.Using 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 problems.Its energy spectra are exactly solved out from the representation theory of S1_(q)(2).
基金Supported by the National Natural Science Foundation of China(Grant Nos.90203018,10474104 and 60433050)the National FundamentalResearch Program of China(Grant Nos.2001CB309310 and 2005CB724508)
文摘The dynamic generation of spin entanglement between two distant sites in a XY model with 1/r 2 decay long-range couplings was studied.Due 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 shapes.Interestingly,when such two wave packets meet at the diametrically opposite site after the fast periodτ=Nπ/J,the initial well-located state is completely recurrent.Numerical calculation was performed to confirm the analytical result even if the ring system of sizes N up to several thousands is considered.The truncation approximation for the coupling strengths was also studied.Numerical 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.
基金supported by the National Natural Science Foundation of China (10874091)National Basic Research Program of China (2006CB921205)
文摘The thermodynamic influence of quantum probing on an object is studied.Here,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 environment.It 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 energy.This thermodynamic feature can be regarded as a witness of quantum probing.
基金supported by the National Natural Science Foundation of China(Grant Nos.11074305,10935010,11074261 and 11121403)the National Basic Research Program of China(Grant Nos.2012CB922104 and 2014CB921402)
文摘We provide a general dynamical approach for the quantum Zeno and anti-Zeno efects 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 efects 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 efectively tuned by the repeated measurements.Our approach is also able to describe the quantum Zeno and anti-Zeno efects given by the phase modulation pulses,as well as the relevant quantum control schemes.
基金supported by the National Natural Science Foundation of China (Grant Nos. 11121403,10935010 and 11074261)
文摘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.
基金supported by the National Natural Science Foundation of China (Grant Nos.10474104,60433050 and10704023)the National Basic Research Program of China (Grant Nos.2006CB921205 and 2005CB724508)
文摘Feshbach resonance is a resonance for two-atom scattering with two or more channels,in which a bound state is achieved in one channel.We 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 resonance.This 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 line.The numerical simulation based on the finite-different time-domain(FDTD) method confirms our assumption about the physical implementation.
