Nonclassical Properties in the Resonant Interaction of a Three Level A-type Atom with Two-mode Coherent state

A potential scheme is proposed to deterministically generate complete sets of entangled photons in the context of cavity quantum electrodynamics （QED）. The scheme includes twice interactions of atoms with cavities, in which the first interaction is made in two-mode optical cavities and the second one exists in a microwave cavity. In the optical cavities the atoms are resonant with the cavity modes, while the detuned interaction of the atoms with a singlemode of the microwave cavity is driven by a classical field. The favorable features of our scheme include ： （ 1 ） it is very straightforward in implementation because we carry out the scheme by only sending atoms through the cavities. The requirement for the implementation is very close to the reach of current cavity QED techniques. （2） The com- plete set of the entangled two- or more-photon states can be generated deterministically by our scheme, and the implementation time remains constant with the size of the entangled photon states. （3） Our scheme is more efficient than previous proposals with cavities, and the generated photons may be collected much more efficiently, due to cavities, than previous proposals by spontaneous emission.     

Nonclassical properties in the resonant interaction of a three level Λ-type atom with two-mode field in coherent state

In this paper, we study the nonclassical properties of the electromagnetic field resulting from the interaction of a three-level Λ-type atom with a two-mode field initially in the coherent state, such as squeezing properties and sub-Poisson statistics. We show that the squeezing can be enhanced by selective atomic measurement.     

The atomic Wehrl entropy of a <Emphasis Type="Italic">V</Emphasis>-type three-level atom interacting with two-mode squeezed vacuum state

We study the interaction of a V-type three-level atom with a two-mode field through the two-photon interaction when the atom is initially in the upper state and the initial field is in the two-mode squeezed vacuum state. The influence of the atomic motion on the evolution of the atomic Q-function and atomic Wehrl entropy is examined. The results show that the atomic motion and the mode structure play important roles in the evolution of the atomic Q-function, atomic Wehrl entropy, and marginal atomic Wehrl entropy.     

Kerr介质腔中非关联双模热光场与V型三能级原子相互作用中的场关联特性

研究了Kerr介质腔中非关联双模热光场与V型三能级原子相互作用过程中的场关联特性.通过数值计算和图形分析,讨论了平均光子数、Kerr介质、失谐量以及耦合系数对场的关联特性的影响.结果发现:当V型三能级原子与两模光场发生相互作用时,非关联双模热光场将发生关联,且关联强度与耦合强度、失谐量和Kerr系数有关.当两模热光场和裸原子发生对称相互作用时,两模光场始终处于正关联;增加一模光场的平均光子数,两模光场的关联减弱;Kerr介质和失谐量的增加将削弱两模场的关联;当两模光场与原子发生不对称相互作用时,假设g1>g2,两模光场的关联特性在正关联和反关联之间交替出现.保持场一模的平均光子数不变,增加场另一模的平均光子数,反关联特性消失.     

Optical selection rules and phase-dependent adiabatic state control in a superconducting quantum circuit

We analyze the optical selection rules of the microwave-assisted transitions in a flux qubit superconducting quantum circuit (SQC). We show that the parities of the states relevant to the superconducting phase in the SQC are well defined when the external magnetic flux phi(e) = phi(0)/2; then the selection rules are the same as the ones for the electric-dipole transitions in usual atoms. When phi(e) does not = phi(0)/2, the symmetry of the potential of the artificial "atom" is broken, a so-called delta-type "cyclic" three-level atom is formed, where one- and two-photon processes can coexist. We study how the population of these three states can be selectively transferred by adiabatically controlling the electromagnetic field pulses. Different from lambda-type atoms, the adiabatic population transfer in our three-level delta atom can be controlled not only by the amplitudes but also by the phases of the pluses.     

非简并双光子Jaynes-Cummings模型中贝尔非定域性的演化

基于赝自旋算符的关联所对应的贝尔算符期待值,研究了各种双模非经典态(纠缠相干态、对相干态以及双模压缩真空态)在非简并双光子Jaynes-Cummings模型中贝尔非定域性的动力学特性.结果表明:对于纠缠相干态,贝尔非定域性的演化与双模场平均光子数的大小息息相关;对于对相干态和双模压缩真空态,贝尔非定域性会在有限的时间内完全消失,之后又基本上复原到初始值,呈现出周期性振荡现象.     

类Kerr介质中双模SU(1,1)相干态场与Λ型三能级原子相互作用的量子统计性质

导出了类Kerr介质中双模SU(1,1)相干态场与Λ型三能级原子相互作用系统的态函数,研究了Kerr效应对Λ型三能级原子布居概率、双模SU(1,1)相干态场的互关联函数、Cauchy-Schwartz不等式及二阶相干度的影响.结果表明:Kerr效应使原子与光场的耦合减弱,原子布居的崩塌与复苏的周期缩短;在初始光场较弱和较强两种情况下,类Kerr介质对双模SU(1,1)相干态场两模间的相关性、相关程度以及光子的聚束与反聚束效应产生的作用有明显的区别.     

与双模光场作用的Λ型三能级原子及其二能级近似

从多能级原子与多模光场的相互作用哈密顿量出发,导出了Λ型三能级原子与双模光场的相互作用哈密顿量。在大失谐条件下将其化成等效的二能级形式-双模喇曼耦合模型。提出了该模型的一个改进型等效哈密顿量。该哈密顿量由两部分构成:一部为通常所谓的等效哈密顿量,另一部分描述原子能级的动态斯塔克移动。研究表明,在双模喇曼耦合模型的研究中,只考虑前者是不够的,还必须考虑后者。最后,我们研究了该系统中原子的动力学行为,发现崩塌-复苏的数目、崩塌时间和复苏时间均呈现新的特性。     

与双模光场作用的Λ型三能级原子及其二能级近似

从多能级原子与多模光场的相互作用哈密顿量出发,导出了Λ型三能级原子与双模光场的相互作用哈密顿量．在大失谐条件下将其化成等效的二能级形式－双模喇曼耦合模型．提出了该模型的一个改进型等效哈密顿量．该哈密顿量由两部分构成：一部为通常所谓的等效哈密顿量,另一部分描述原子能级的动态斯塔克移动．研究表明,在双模喇曼耦合模型的研究中,只考虑前者是不够的,还必须考虑后者．最后,我们研究了该系统中原子的动力学行为,发现崩塌－复苏的数目、崩塌时间和复苏时间均呈现新的特性．     

双模SU(2)相干态场与一个Λ型三能级原子共振相互作用的光场非经典性质

采用全量子理论和数值计算方法, 研究了初始处于SU(2)相干态的双模腔场与一个Λ型三能级原子共振相互作用的光场非经典性质,讨论了在没有对原子进行态选择测量、 直接对原子进行态选择测量和应用经典微波场并对原子进行态选择测量的三种情况下,两个腔模总光子数、配分参量和耦合系数对光场非经典性质的影响.结果表明,增加两个腔模的总光子数M或对原子进行态选择测量,双模差压缩明显增强;减小配分参量和应用经典场并对原子进行态选择测量,a模光子的亚Poisson统计分布的平均程度变浅,而b模变深;两模间的反相关特征保持不变,增加M或直接对原子进行态选择测量,反相关平均程度变浅;直接对原子进行态选择测量,违背Cauchy-Schwartz不等式. 关键词： SU(2)相干态场')" href="#">SU(2)相干态场 Λ型三能级原子 态选择测量     

双模压缩场与V型原子相互作用光场的性质

研究了双模压缩真空场与V型三能级运动原子的相互作用,得到光场二阶相干度和模间相干度的解析表达式;通过数值计算分析了原子运动速度、场模结构参数和平均光子数对光场二阶相干度和模间相干度的影响.结果表明:平均光子数的增加使得二阶相干度和模间相干度显著增大;而原子运动速度、模场结构参数的增加虽然对光子聚束效应和反聚束效应的强度影响不大,却使其演化周期大大减小.     

利用Ξ型三能级原子与双模光场的非共振相互作用制备双模Schrdinger猫态

提出了一种利用Ξ型三能级原子与双模光场的非共振相互作用制备双模Schrdinger猫态的方法. 关键词：     

对双模反关联光场非经典特性的远程控制

考虑初始处于纠缠态的两个V型三能级原子之一注入腔场中,并且与初始处于SU(2)相干态的双模场发生共振相互作用的情况。采用数值计算方法研究了双模关联场的非经典特性。讨论了对腔外原子选择性测量、双模总光子数和配分参量对双模关联场的差压缩、柯西-施瓦茨(Cauchy-Schwarz)不等式、模间相干性以及光子亚泊松(sub-Poisson)分布的影响。研究结果表明:对腔外原子的选择性测量或增加两模的总光子数,a模的差压缩和光子sub-Poisson分布都明显地增强,但两模之间的反相关明显地减弱。     

Berry phases in the three-level atoms driven by quantized light fields

A theoretical analysis of Berry’s phases is given for the three-level atoms interacting with external one-mode and two-mode quantized light fields. Three main results are obtained: (i) There is a Berry phase which vanishes in the classical limit or this Berry phase is completely induced by the field quantization; (ii) Berry’s phases for the one-mode field and the two-mode field can be equal so long as the photon numbers of the two-mode field are properly chosen; (iii) In the two-mode case, Berry phases of the atom interacting with one mode is affected by the other mode even if the photon number of the other mode is zero.      

Emission and absorption spectra of a Λ type three-level atom driven by a two-mode cavity field with nonlinearities

An analytical expression of the emission and absorption spectra for a Λ type three-level cavity-bound atom interacting with a two-mode cavity field is given using the dressed states of the system. We take into account explicitly the nonlinearities of both the field and the intensity-dependent atom-field coupling. The characteristics of the emission and absorption spectra when one of the two-mode cavity fields is in a binomial state and the other is in a squeezed coherent state are exhibited. The effects of the mean number of photons, detuning, and the kinds of nonlinearities on the spectra are analyzed.     

Generation of strongly squeezed states for a cavity field with a single atom

We propose a scheme to realize strong squeezing for a cavity field with a single three-level atom. In the scheme the atom is sent through the cavity initially filled with a coherent field. The atom dispersively interacts with the cavity field, which is displaced by a microwave resource during the interaction. Then, a selective measurement on the atom collapses the field to a superposition of an even coherent state with a vacuum state, which exhibits strong squeezing. The scheme can also be generalized to the two-mode case.     

Ξ型三能级原子玻色-爱因斯坦凝聚体单模光场系统中双模原子激光的压缩性质

研究了Ξ型三能级原子玻色-爱因斯坦凝聚体单模光场系统中双模原子激光的压缩性质.结果表明:双模原子激光能被周期性压缩,并且具有量子Rabi振荡和崩塌-回复现象两种形式的振荡.最大压缩深度和崩塌-回复振荡频率主要依赖于光场与原子间相互作用强度,量子Rabi振荡频率主要由光场圆频率决定.     

原子相干性对 V型三能级原子自发辐射的影响

本文分别就两种模型,即三能级原子与单模场和双模场的V型相互作用,研究了原子相干性对原子自发辐射的影响.发现在单模情况,原子相干性导致原子自发辐射的消除;而在双模情况,两个跃迁通道的自发辐射是相互独立的,原子相干性不导致原子自发辐射的消除.     

利用V-型三能级原子与双模腔场双光子大失谐相互作用制备W纠缠态

本文提出利用V-型三能级原子与双模腔场的双光子大失谐相互作用制备W纠缠态,该方案要求三个三能级原子和一个双模腔场,第一个与腔场作用的原子最初处于激发态,第二个和第三个原子均处于基态,腔场最初处于真空态,合适地选择原子与腔场之间的相互作用时间即可获得三原子W纠缠态.并且此方案可以推广至多原子W纠缠态和多腔场W纠缠态的制备;通过计算共生纠缠度研究系统中态的纠缠演化以及热纠缠现象.