Entanglement dynamics of a moving multi-photon Jaynes-Cummings model in mixed states

Using the algebraic dynamical method,the entanglement dynamics of an atom-field bipartite system in a mixed state is investigated.The atomic center-of-mass motion and the field-mode structure are also included in this system.We find that the values of the detuning and the average photon number are larger,the amplitude of the entanglement is smaller,but its period does not increase accordingly.Moreover,with the increase of the field-mode structure parameter and the transition photon number,the amplitude of the entanglement varies slightly while the oscillation becomes more and more fast.Interestingly,a damping evolution of the entanglement appears when both the detuning and the atomic motion are considered simultaneously.     

Demonstration of the approximation of eliminating atomic excited populations in an atom-cavity system

Using the master equation approach to a V-type three-level atom inside a high-finesse single-mode cavity in the strong coupling condition,we demonstrate the approximation of eliminating populations of atomic excited states,which is widely used in the field of the atom-cavity systems [Hechenblaikner G,Gangl M,Horak P and Ritsch H 1998 Phys.Rev.A 58 3030];Liu L W,Tan T and Xu Y 2008 J.Mod.Opt.56 968;Cho J,Angelakis D G and Bose S 2008 Phys.Rev.A 78 062338.This is reflected in the deviation of the population δ,of which the value is 10～(-3)～10～(-2).We further find the deviation of the dipole force and demonstrate that the deviation of atomic population will not notably affect the dipole force of the atom in the strong coupling condition.A relevant experimental case is also presented.     

Quantum Fluids of Self-Assembled Chains of Polar Molecules at Finite Temperature

The finite temperature properties of self-assembled dipole chains of polar molecules in strongly confined pancake traps are investigated. The single-chain vibrations at finite temperature, which become important for long chains in a strongly interacting regime, are found to lower the transition temperature and to shift the chain distribution by less than 10%. We also propose experimental parameters to observe such quantum phase transition.     

偶极旋量玻色-爱因斯坦凝聚体在外场中的自旋混合动力学

探讨了外场中偶极旋量玻色-爱因斯坦凝聚体的静态和动力学行为.研究结果表明，可以调节外场、自旋交换相互作用和偶极-偶极相互作用来调控三组分之间的隧穿,控制布居数动力学演化范围和相对相位动力学行为. 关键词： 玻色-爱因斯坦凝聚 偶极-偶极相互作用 自旋混合动力学     

失谐对耗散耦合腔阵列体系超流-绝缘相变的影响

利用平均场理论和微扰论解析求解了失谐存在且环境作用下Jaynes-Cummings-Hubbard模型的哈密顿量,得到了体系序参量的解析表达式,并讨论了失谐对体系超流一绝缘相变的影响,研究结果表明:调节失谐可以改变腔间的有效排斥势和系统的临界隧穿率,实现系统在超流态和绝缘态之间转变,结合耗散耦合腔阵列的输运性质探讨了失谐对序参量取值的影响,结果显示:沿失谐负支随着失谐的增大,序参量会经历先增后减的变化。     

Bloch Oscillations of Two-Component Bose-Einstein Condensates in Optical Lattices

We study the Bloch oscillations of two-component Bose-Einstein condensates trapped in spin-dependent optical lattices. The influence of the intercomponent atom interaction on the system is discussed in detail Accelerated breakdown of the Bloch oscillations and revival phenomena are found respectively for the repulsive and attractive case. For both the cases, the system will finally be set in a quantum self-trapping state due to dynamical instability.     

亲疏水性可控纤维素基相变纤维的制备与性能研究

以棉花为支撑材料,丙烯酰氯(AC)作为中间体,在异相条件下制备纤维素基丙烯酸酯(CA);后利用过氧化苯甲酰(BPO)作为引发剂,通过自由基聚合法接枝疏水性丙烯酸十八酯(A18)、亲水性聚乙二醇单甲醚甲基丙烯酸酯(OEGMA)及其共聚物,制备具有亲疏水性可控的纤维素基固-固相变纤维(solid-solid phase change fibers, SSPCFs)。利用傅里叶变换红外光谱(FTIR)、差示扫描量热仪(DSC)、热重分析(TG)和X射线衍射(XRD)对SSPCFs的结构和热性能进行了表征;通过形态稳定性测试研究接枝共聚物在不同温度下的形态;最后对相变纤维进行水接触角测试研究其亲疏水可控性。结果表明：成功将A18和OEGMA接枝到纤维素表面,制备出具有一定储能特性的固-固相变材料;五种CA-g-P(A18-co-OEGMA)共聚物的耐热温度初始分解温度最低为348℃,最高为368℃,均比CA的初始分解温度高,增加了纤维素基产物的热稳定性;通过水接触角测试表面,随着OEGMA含量的增加,接枝共聚物的水接触角逐渐减小,呈现出逐渐亲水的状态。以上结果说明CA-g-P(A18-co-O...     

Electromagnetically induced transparency of single Λ-type three-level atoms in a high-finesse optical cavity

We study the features of electromagnetically induced transparency(EIT) in a single Λ-type three-level atom placed in a high-finesse cavity under the action of a coupling laser and a probe laser.Our calculations show that three transparency windows appear when the pump strength is large enough.This can be explained by the residual pump in the cavity mostly resulting in energy splitting.The level |3 is split into four slightly different energy levels,and interference takes place between the excitation pathways.Furthermore,it is also shown that the frequencies of the EIT windows can be tuned by changing the coupling field detuning 2,and that the reflection profile is very sensitive to the cavity field detuning △c.     

Enhanced cooling of a V-type three-level atom in an optical cavity

We have studied theoretically and numerically the enhanced cooling of a V-type three-level atom in a high-finesse optical cavity and shown that the cooling rate can be increased by one order of magnitude over that of a two-level atom, and the momentum amplitude tends to a stationary state much smaller than that of a two-level atom. We have further shown that the cooling rate can be significantly improved by using feedback and a time-dependent pump.     

Mechanical effects of light on the Ξ-type three-level atom in a high-finesse optical cavity

A theoretical study is carried out for the modification and implication of the effect on the Ξ-type three level atom in a high-finesse optical cavity driven by light field including spontaneous emission and the cavity decay. Analytic expressions for the dipole force, the friction force, the optical potentials and the friction coefficient are obtained. Then the numerical and graphical methods are used to investigate the friction coefficient with the controlling parameters. It is shown that the friction coefficient is strongly dependent on the controlling parameters. The cooling rate can increase by one order of magnitude more than that of a two-level atomic system. The reason can be given using the dressed states and the Sisyphus cooling mechanism, which would stimulate further experimental investigations.