We report a velocity selective bi-polarization spectroscopy (VS-BPS) technique to generate a background-free, dispersion-like reference signal which is tunable over a wide range of frequency. In this technique, a pair of linearly polarized weak probe beams passing through a gas cell of metastable Krypton (Kr*) atoms, overlaps with a pair of counter-propagating circularly polarized strong pump beams derived from an independently tunable control laser. The polarization spectroscopy signals from the two probe beams, after subtraction, result in VS-BPS signal. The spectral shifting in VS-BPS signal can be achieved by tuning the frequency of the control laser. The dependence of the amplitude and slope of the VS-BPS signal on the RF power used for excitation of Kr atoms in the gas cell and on the power of pump beams has been studied. The frequency stability of a diode laser locked with VS-BPS signal has been found to be better than the frequency stability of the laser locked with a saturated absorption spectroscopy (SAS) signal. The VS-BPS signal is finally used for stabilization and tuning of the cooling laser frequency for a magneto-optical trap (MOT) for Kr* atoms.
A Thermal Beam of Metastable Krypton Atoms Produced by Optical Excitation
利用光激发方法，在室温下获得了亚稳5s[3/2]2能级的氪原子束。用氪放电灯产生124 nm的真空紫外光子，作为从基态4p 6 1 S 0到5s[3/2]1能级的第一步激发。使用819 nm Ti：Sapphire激光器进行从5s[3/2]1到5 p [3/2]1的第二步激发，随后自发衰减到5s[3/2]2亚稳能级。在总气体流速为0.01 cm^3 STP/s（或3 x 10^17 atoms/s）时，获得了角通量密度为3 x 10^14 /s/sr的亚稳态原子束。研究了流量与气体流量、激光功率和灯参数的关系。
Spin dependent inelastic collisions between metastable state two-electron atoms and ground state alkali-atoms
实验上研究了低磁场下亚稳3 P 0态的镱（Yb）与处于Li基态流形的锂（Li）之间的非弹性碰撞的自旋依赖性。使用选择性激发，174 Yb（3 P0）的所有磁子级mJ的访问和四个最低的躺在磁子级的6Li的光泵浦制备。一方面，发现了Li（F=1/2）原子碰撞的mJ无关性，另一方面，发现了Li（F=3/2）原子碰撞的系统mJ依赖性，特别是拉伸碰撞态的抑制损失.此外，MJ变化过程被认为是次要的相关性。观测到的非弹性碰撞速率范围在1*10^{-11} cm ^3/s ~ 40*10^{-11} cm ^3/s之间，并讨论了观测行为的可能起源.
Cavity-enhanced Ramsey spectroscopy at a Rydberg-atom-superconducting-circuit interface
利用里德堡氦原子与微波场在$λ/4$超导共面波导谐振腔中的相干相互作用，研究了腔模的光谱特性。这是通过从亚稳态1 s2 s $^3$ S $_1$能级共振增强双色双光子激发制备1 s55 s $^3$ S $_1$ Rydberg能级的原子来实现的。然后原子在谐振腔中运动，其中频率为$ω_{\mathrm{res}}=2π\times19.556$ GHz的三次谐波微波场驱动双光子1 s55 s $^3$ S $_1\rightarrow$ 1 s56 s $^3$ S $_1$跃迁。通过将一系列Ramsey脉冲注入谐振器中，并通过状态选择性脉冲电场电离来监测里德堡态布居的相干演化，作为微波场的频率被调谐，记录光谱，其允许谐振器谐振频率和品质因数被确定，其中原子充当微观量子传感器。
