能够突破标准量子极限的原子双数态的制备研究

所有经典的双模(两路径)干涉仪的相位测量精度都受限于1/N/(1/2)(其中N为参与干涉测量的总粒子数),这一极限被称为经典极限或标准量子极限.量子计量学最重要的目标之一是探索如何通过量子纠缠实现超越经典极限的测量精度.双数态是一种能突破经典极限的纠缠态,它由数目相等、不可区分的自旋朝上和朝下(双模)玻色粒子组成.通过光学自发参量下转换或囚禁离子内态的操控手段已实现了不到十个光子或离子的双数态.利用玻色-爱因斯坦凝聚体中原子的自旋混合过程,近年来也能产生多达几千个原子的双数态.但是这样制备的双数态的总粒子数的随机涨落过大,限制了它们的实际应用潜力.最近,我们通过调控原子凝聚体中的量子相变,实现了超过一万个原子的双数态的确定性制备.本文简要综述这一研究进展.     

A concise review of Rydberg atom based quantum computation and quantum simulation

Quantum information processing based on Rydberg atoms emerged as a promising direction two decades ago.Recent experimental and theoretical progresses have shined exciting light on this avenue.In this concise review,we will briefly introduce the basics of Rydberg atoms and their recent applications in associated areas of neutral atom quantum computation and simulation.We shall also include related discussions on quantum optics with Rydberg atomic ensembles,which are increasingly used to explore quantum computation and quantum simulation with photons.     

Quantum leakage of collective excitations of atomic ensemble induced by spatial motion

We generalize the conception of quantum leakage for the atomic collective excitation states. By making use of the atomic coherence state approach, we study the influence of the atomic spatial motion on the symmetric collective states of 2-level atomic ensemble due to inhomogeneous coupling. In the macroscopic limit, we analyze the quantum decoherence of the collective atomic state by calculating the quantum leakage for a very large ensemble at a finite temperature. Our investigations show that the fidelity of the atomic system will not be good in the case of atom numberN→∞. Therefore, quantum leakage is an inevitable problem in using the atomic ensemble as a quantum information memory. The detailed calculations shed theoretical light on quantum processing using atomic ensemble collective qubit.     

对被囚禁原子质心运动基态波包的有效分束

文章简要地介绍了原子干涉现象及原子光学的发展历史和现状．在对各种不同的原子干涉仪工作原理进行简单总结之后，文章描述了包括文章作者在内的研究小组一项最新的理论工作．这个工作提出了一个对被囚禁原子质心运动基态波包进行有效分束的物理方案．     

Ultra-High Efficiency Magnetic Transport of SZRb Atoms in a Single Chamber Bose-Einstein Condensation Apparatus

We report the ultra-high efficiency transport of cold ST Ftb atoms using a moving magnetic quadrupole potential generated by three overlapping pairs of fixed coils. The transfer etticiency is better than 97%, which is the highest ever reported to our knowledge. The temperature increase due to heating is less than IO #K when the initial cloud temperature is llO#K. Our setup is similar to the magnetic transferring belt design [Phys. ftev. A 63 （2001）031401（R）], although it is simpler because the push coil is not required. We use it to transport atoms away from a magneto-optical trap to very close to the wall of the glass cell, facilitating future experiments employing three-dimensional optical lattices, high resolution in-situ imaging, and magnetic Feshbach resonances.     

Measurement of S-Wave Scattering Length between ~6Li and ~(88)Sr Atoms Using Interspecies Thermalization in an Optical Dipole Trap

We report the creation of the first mixture of ~6 Li and ~(88) Sr atoms in an optical dipole trap. Using this mixture,a measurement of the interspecies thermalization process is carried out and the previously unknown interspecies s-wave scattering length between ~6 Li and ~(88) Sr atoms is extracted to be |~(a6) Li-~(88) Sr| =(380_(-100)~(+160))a_0 with a_0 being the Bohr radius from the rate of interspecies thermalization.