非简谐振子湮没算符高次幂的本征态及其高阶压缩性质

构造出了非简谐振子湮没算符N次幂(N≥3)的N正交归一本征态,并且研究了它们的数学性质及其高次方压缩特性.其结果表明,它们能组成一个完备的希尔伯特(Hibert)空间;且当N为偶数时,这些本征态均可呈现M次方压缩效应[M=(n 1/2)N,n=0,1,2,…]     

各向异性量子点单光子发射的高偏振度特性

研究了线偏振脉冲光场激发下,单个各向异性InGaAs量子点的高偏振光发射. 给出其偏振因子与两个正交本征态之间的交叉弛豫之间的关系式. 分析表明，交叉弛豫随激发场强度增大，并导致偏振因子随激发场入射脉冲面积减小. 关键词： 量子点 单光子发射 偏振度     

单原子在两个远红失谐光偶极阱中的转移

在光偶极阱中实现单个中性原子的囚禁及其操控在量子信息处理中具有重要的应用.为此在使用强聚焦远红失谐激光形成的光偶极阱囚禁单个中性铷原子后,通过一个空间可移动的光偶极阱从静止的光偶极阱上掠过,实现了将静止的光偶极阱中的单原子以94%的概率转移到可移动的光偶极阱中,并将该原子移动到焦平面上指定的位置.该实验对于实现光偶极阱阵列中任意两个原子的纠缠以及光偶极阱中原子外在自由度的操控等研究有着潜在的应用.     

超冷费米气体研究的新进展

近几年,人们在超冷费米气体的实验和理论研究方面取得了一系列激动人心的进展,比如分子玻色—爱因斯坦凝聚的成功实现和BCS-BEC渡越过程的大量研究。在本文中,我们对超冷费米气体中的这些进展进行了介绍,并讨论了今后几年的发展趋势。     

冷原子的横向推载与探测

文中在获得温度低,数目多的冷原子基础上,研究了冷原子传输速度与推的脉冲光各种参数之间的关系.     

Rb原子激发态碰撞能量转移

报道了用连续单模激光激发Rb原子至特定的激发态，从而观察激发态间的碰撞形成更高Rb原子激发态的实验结果.实验观察到Rb原子激发态的自发辐射与高激发态的碰撞形成通道之间的明显竞争，测得了高激发态的形成概率与激发光功率、原子蒸气温度及激光失谐的关系，所提出的碰撞能量转移机理较好地解释了实验结果. 关键词：     

利用量子密钥的加密／解密实现身份认证

目前的量子密钥分发（QKD）协议都是在通信双方均为合法的前提下提出的，为了防止窃听者（Eve）假冒任意一方进行通信、保证量子通信的安全胜，需要对QKD的通信双方（Alice和Bob）进行合法身份确认。     

A COMPREHENSIVE PROOF OF THE GREENBERGER-HORNE-ZEILINGER THEOREM FOR THE FOUR-QUBIT SYSTEM

Greenberger-Horne-Zeilinger(GHZ)theorem asserts that there is a set of mutually commuting nonlocal observables with a common eigenstate on which those ob- servables assume values that refute the attempt to assign values only required to have them by the local realism of Einstein,Podolsky,and Rosen(EPR).It is known that for a three-qubit system.there is only one form of the GHZ-Mermin-like argument with equiva- lence up to a local unitary transformation,which is exactly Mermin's version of the GHZ theorem.This article for a four-qubit system,which was originally studied by GHZ,the authors show that there are nine distinct forms of the GHZ-Mermin-like argument.The proof is obtained using certain geometric invariants to characterize the sets of mutually commuting nonlocal spin observables on the four-qubit system.It is proved that there are at most nine elements(except for a different sign)in a set of mutually commuting nonlocal spin observables in the four-qubit system,and each GHZ-Mermin-like argument involves a set of at least five mutually commuting four-qubit nonlocal spin observables with a GHZ state as a common eigenstate in GHZ's theorem.Therefore,we present a complete construction of the GHZ theorem for the four-qubit system.     

Entropy evolution properties in a system of two entangled atoms interacting with light field

In this paper, we use the field entropy as a measurement of the degree of entanglement between the light field and the atoms of the system which is composed of two dipole—dipole interacting two-level atoms initially in an entangled state interacting with the single mode coherent field in a Kerr medium. The influence of the coupling constant of dipole—dipole interaction between atoms and the coupling strength of the Kerr medium with the light field and the intensity of the light field on the field entropy are discussed by numerical calculations. It is shown that when the coupling strength of the Kerr medium with the light field is large enough, and the light field is strong, the degree of entanglement between the atoms with the light field becomes weaker. The degree of entanglement only changes slightly with the change of the coupling constant of dipole—dipole interaction between atoms.     

Coherent Population Trapping-Ramsey Interference in Cold Atoms

We demonstrate an experimental observation of coherent population trapping-Ramsey interference in cold 87Rb atoms by employing the time-domain separated oscillatory fields＇ method. The interference fringe with line width of 80 Hz is obtained. We propose a novel method to measure the cold atom number. The measurement is insensitive to the pump beam intensity, the single photon detuning and even the initial state population. We use this method to normalize the interference signal and to improve the signal-to-noise ratio significantly.