缀饰原子系统中双光子共振非简并四波混频

本文研究了缀饰原子系统中的双光子共振非简并四波混频.理论上我们研究了多普勒增宽的四能级系统中耦合光场对双光子共振非简并四波混频的影响,发现加入强耦合场后,非简并四波混频频谱出现Autler-Townes分裂;在不同双光子共振失谐时,由于量子干涉双光子共振非简并四波混频的信号能够被抑制或增强.实验上我们在Ba原子蒸汽中,通过引入基态6s2和自电离里德堡态6pnd之间的原子相干证实了该现象.本方法提供了一种不仅可以测得共振频率和横向弛豫,而且可以测得两个高激发原子态之间的跃迁的偶极矩阵元的新的光谱学工具.     

Atomic coherence in nondegenerate four-wave mixing

Two-photon resonant nondegenerate four-wave mixing (NFWM) with the addition of a coupling field in Ba atomic vapour has been studied. We find that coherence of the atomic level transitions leads to suppression of the NFWM signal, giving rise to a dip with a linewidth that is linearly proportional to the intensity of the coupling field.     

受激Raman谱中的宏观极化干涉

研究了Rb⁸⁵原子蒸气D1线系统中的受激Raman增益与损耗现象. 实验中观察到 随着抽运光失谐量的增大, 受激Raman谱明显地呈现出一个从增益到损耗的陡峭转变. 从缀饰态模型出发, 我们提出这是对探测光有相反贡献的不同速度原子群之间极化干涉的结果. 关键词： 受激Raman谱 电磁感应透明 极化干涉     

Enhanced Loading of ~(40)K from Natural Abundance Potassium Source with a High Performance 2D~+ MOT

~(40)K is one of the most important atomic species for ultra-cold atomic physics. Due to the extremely low concentration(0.012%) of ~(40)K in natural abundance of potassium, most experiments use 4–10% enriched potassium source, which have greatly suffered from the extremely low annual production and significant price hikes in recent years. Using naturally abundant potassium source, we capture 5.4 × 10~6 cold ~(40)K atoms with the help of a high performance of two-dimensional magneto-optical trap(2D~+MOT), which is almost three orders of magnitude greater than previous results without the 2D~+ MOT. The number of the ~(40)K atoms is sufficient for most ultra-cold ~(40)K experiments, and our approach provides an ideal alternative for the field.     

Autler–Townes spectroscopy of high-lying state by phase conjugate six-wave mixing

An Autler-Townes(AT) spectroscopy based on phase conjugate six-wave mixing(SWM) is proposed to detect AT doublet of high-lying state in a Doppler-broadened cascade four-level system.It is found that the SWM spectrum is dependent strongly on the ratios between the magnitudes of the wave vectors.We discuss how the Doppler broadening affects the SWM spectrum from a time-domain viewpoint and find that,due the atomic motion,the atomic polarizations acquire different phases for atoms with different velocities as time evolves.The Doppler free SWM spectrum can be obtained only when the atomic polarization can be rephasing again at certain time after the interactions of all the incident fields.     

Large Photoluminescence Enhancement by an Out-of-Plane Magnetic Field in Exfoliated WS2 Flakes

We report an out-of-plane magnetic field induced large photoluminescence enhancement in WS₂ flakes at 4 K, in contrast to the photoluminescence enhancement provided by an in-plane field in general. Two mechanisms for the enhancement are proposed. One is a larger overlap of the electron and hole caused by the magnetic field induced confinement. The other is that the energy difference between ■ and K valleys is reduced by magnetic field, and thus enhancing the corresponding indirect-tra...     

Rb87冷原子电磁感应透明吸收曲线不对称性的分析

研究了耦合光共振时Rb⁸⁷冷原子D1线Λ形能级体系中电磁感应透明吸收曲线的不对称现象.发现间隔为814 MHz的另一个激发态能级导致了不对称现象.不对称现象的根本原因是受激拉曼散射, 同时发现透明窗口两侧不对称的吸收峰的幅值比与耦合光强成正比.理论拟合与实验数据符合得较好.     

Three-Photon Resonant Six-Wave Mixing with Phase-Conjugation Geometry in Na Atomic Vapour

We report a three-photon resonant six-wave mixing (SWM) with phase- conjugation geometry. It has advantages that phase matching condition is not critical and the generation of SWM signal is efficient. This technique provides a new spectroscopic tool for studying the highly excited atomic or molecular states with high resolution. The feasibility of this technique is demonstrated in sodium vapour.     

T-C模型中三体纠缠态纠缠量的演化特性

本文研究两个全同定态二能级原子与单模场相互作用的T-C模型中的量子纠缠量的随时间的演化特性.     

Tavis-Cummings模型中三体纠缠态纠缠量的演化特性

研究两个全同二能级原子与单模场相互作用的Tavis-Cummings模型中的量子纠缠.在场和两原子初始分别为真空场和纠缠或非纠缠状态下，得出体系状态将演化为三体近似W纠缠态.通过对纠缠量的计算得出：该三体近似W纠缠态纠缠量的演化特性将随三体所处的初始状态、原子间及原子与场间的耦合系数、失谐程度、原子反转粒子数的变化而变化.值得一提的是可得出原子间耦合作用强度对纠缠量的非线性效应，并且纠缠量展现出与原子反转粒子数一致的周期振荡现象. 关键词： W纠缠态 纠缠量 反转粒子数