Ultranarrow bandwidth tunable atomic filter via quantum interference-induced polarization rotation in Rb vapor

We report the experimental demonstration of an ultranarrow bandwidth atomic filter by optically induced polarization rotation in multilevel electromagnetically induced transparency systems in hot Rb vapor. With a coupling intensity of 2.3 W/cm^2, the filter shows a peak transmission of 33.2% and a bandwidth of 10 MHz. By altering the coupling frequency, a broad tuning range of several Doppler linewidths of the D1 line transitions of STRb atoms can be obtained. The presented atomic filter has useful features of ultranarrow bandwidth, and the operating frequency can be tuned resonance with the atomic transition. Such narrowband tunable atomic filter can be used as an efficient noise rejection tool in classical and quantum optical applications.     

操作腔外原子可控制腔内原子的压缩特性

原子偶极压缩效应的研究一直是量子光学领域中的一个十分活跃的课题,而且这些研究中多限于初始处于单原子的单态或叠加态、双原子的直积态或相干态与光场的相互作用.近年来,原子的纠缠态引起了人们极大的研究兴趣.因为纠缠态不仅证明了量子力学的非局域性,而且被广泛应用于量子计算、量子密码术、量子隐形传态等方面.最近, Yang等人研究了初始处于EPR态的两个两能级原子,其中一个注入真空态腔中,然后通过对腔外原子的操作可以控制腔内原子的发射性质.Lin等人考虑了初始处于GHZ态的三个两能级原子,让其中两个原子分别注入两个处于真空态的共振腔中.在本文中,我们分别考虑原子初始处于EPR态或GHZ态,将其中一个或两个原子同时注入一个处于相干态的光腔中,在共振条件下通过操纵腔外原子来研究腔内原子的偶极压缩效应.结果表明:对腔外原子执行一次旋转操纵和测量,可以改变腔内原子存在的偶极压缩特性.这方面的研究工作对量子态的制备和腔场的辐射控制具有一定的实际意义.     

一维原子刻蚀的数值模拟

通过直接的数值模拟，分析了原子束在激光驻波场下传播的动力学行为．估计了Cr原子沉积在基片上的焦点的大小，同时还发现一些实验参数会影响原子刻蚀的精度：如原子束的速度分布、激光的失谐量和激光束的直径等．     

Evolution of spin-dependent atomic wave packets in a harmonic potential

We have investigated theoretically the evolution of spin-dependent atomic wave packets in a harmonic magnetic trapping potential. For a Bose-condensed gas, which undergoes a Mott insulator transition and a spin-dependent transport, the atomic wavefunction can be described by an entangled single-atom state. Due to the confinement of the harmonic potential, the density distributions exhibit periodic decay and revival, which is different from the case of free expansion after switching off the combined harmonic and optical lattice potential.     

对抛式冷原子陀螺仪中原子运动轨迹的控制

冷原子具有很小的速度,很窄的速度分布以及良好的相干特性,利用冷原子物质波干涉特性可实现原子干涉仪,具有萨格奈克效应的原子干涉仪即原子陀螺仪,可精密测量转动速率. 冷原子轨迹的精确控制对提高冷原子陀螺仪的测量精度有着重要的意义,文章报道了利用直接数字频率综合器,实现对双向对抛冷原子运动轨迹的精确控制. 关键词： 冷原子 原子陀螺仪 直接数字频率综合器     

利用原子的塞曼光谱对半导体激光器进行稳频

中性原子的超精细能级在磁场中产生塞曼分裂 ,另外 ,左旋和右旋圆偏振光激发下原子的跃迁选择定则不同 ,因此 ,原子在超精细塞曼能级间的吸收谱峰相对无磁场条件下的吸收谱峰有一定的移动。利用这一点 ,验证了一种简单、灵活的方法对半导体激光器进行稳频 ,使激光器的线宽稳到小于 1MHz。通过对实验结果的分析 ,发现由左旋和右旋圆偏振光激发引起的原子吸收谱峰移动之和与饱和吸收峰半高宽相等时 ,稳频效果最好     

Microwave coherent manipulation of cold atoms in optically induced fictitious magnetic traps on an atom chip

We propose a novel on-chip platform for controlling and manipulating cold atoms precisely and coherently. The scheme is achieved by producing optically induced fictitious magnetic traps(OFMTs) with 790 nm(for ~(87)Rb) circularly polarized laser beams and state-dependent potentials simultaneously for two internal atomic states with microwave coplanar waveguides. We carry out numerical calculations and simulations for controlled collisional interactions between OFMTs and addressable single atoms' manipulation on our designed hybrid atom chips. The results show that our proposed platform is feasible and flexible, which has wide applications including collisional dynamics investigation, entanglement generation,and scalable quantum gates implementation.     

超球方法计算范德瓦尔斯三聚体Ar_2Kr和Ar_3基态性质

利用新近发展的耦合道超球方法和最新的Tang-Toennies(TT)模型势,计算了由重惰性原子Ar和Kr构成的范德瓦尔斯三聚体Ar2Kr和Ar3的基态性质.本文系统的研究了超球势曲线、道函数的特征与收敛性,实现了有复杂多通道耦合时重惰性原子三聚体的精确求解,得到了Ar2Kr和Ar3惰性原子三聚体精确的基态能量、结构参数及转动常数.     

Cavity-Induced Enhancement of Squeezing in Resonance Fluorescence of a V-Type Three-Level Atom

The quadrature squeezing spectra in the resonance fluorescence of a V-type three-level atom driven by a coherent field and coupled to a single-mode cavity is investigated. For weak excitation, the fluorescence field exhibit squeezing in the out-of-phase quadrature. The coupling between the atom and the cavity mode can greatly enhance the squeezing centred at the laser frequency. More importantly, for strong excitation, under the effect of the cavity-atom coupling, the in-phase quadrature of fluorescence can exhibit two-mode squeezing at the two inner sideband frequencies. By working in the dressed-state representation and hiring secular approximation, we give an analytical explanation for the effect. The result shows, under appropriate conditions, the squeezing can be greatly enhanced by appropriately tuning the cavity resonant frequency.     

Rb原子磁光阱中囚禁原子数目与实验参数的依赖关系

研究表明，Rb原子磁光阱中所囚禁的原子数目对囚禁光的光强和失谐量，回泵光的强度以及磁场梯度有很大的依赖关系.用二能级系统模型对囚禁原子数目随囚禁光的光强和失谐量的变化关系进行了预估，理论预测的结果与实验结果定性符合.实验结果也展示了囚禁原子数目随回泵光的强度和磁场梯度的变化关系，要定量解释这些实验结果则需要更复杂的理论模型.通过囚禁原子数目对实验参数依赖关系的研究，得到特定的实验参数，来获得最大数目的冷原子. 关键词： 磁光阱 冷原子