Breakdown of Angular Momentum Selection Rules in High Pressure Optical Pumping Experiments

Efficient polarization of high-angular-momentum systems

We propose methods of optical pumping that are applicable to open, high-angular-momentum transitions in atoms and molecules, for which conventional optical pumping would lead to significant population loss. Instead of applying circularly polarized cw light, as in conventional optical pumping, we propose to use techniques for coherent population transfer (e.g., adiabatic fast passage) to arrange the atoms so as to increase the entropy removed from the system with each spontaneous decay from the upper state. This minimizes the number of spontaneous-emission events required to produce a stretched…

Hubbard-Thouless泵中的量子化及其失效

Quantisation and its breakdown in a Hubbard-Thouless pump

本文在光晶格中实验实现了具有可调Hubbard相互作用的拓扑Thouless泵，揭示了弱相互作用下泵浦的稳健性、强吸引相互作用下束缚对驱动的量子化输运，以及强排斥相互作用下泵浦失效但可通过修改泵浦轨迹恢复的现象。

Two-Orders-of-Magnitude Improvement in the Total Spin Angular Momentum of 131Xe Nuclei Using Spin Exchange Optical Pumping

We report on hyperpolarization of quadrupolar (I=3/2) 131Xe via spin-exchange optical pumping. Observations of the 131Xe polarization dynamics show that the effective alkali-metal/131Xe spin-exchange cross-sections are large enough to compete with 131Xe spin relaxation. 131Xe polarization up to 7.6 p/m 1.5 percent was achieved in ca. 8.5EE20 spins--a ca. 100-fold improvement in the total spin angular momentum--enabling applications including measurement of spin-dependent neutron-131Xe s-wave scattering and sensitive searches for time-reversal violation in neutron-131Xe interactions beyond the …

Transverse optical pumping of spin states

Optical pumping is an efficient method for initializing and maintaining atomic spin ensembles in a well-defined quantum spin state. Standard optical-pumping methods orient the spins by transferring photonic angular momentum to spin polarization. Generally the spins are oriented along the propagation direction of the light due to selection rules of the dipole interaction. Here we present and experimentally demonstrate that by modulating the light polarization, angular momentum perpendicular to the optical axis can be transferred efficiently to cesium vapor. The transverse pumping scheme employs…

高角动量原子的高效冷却

Efficient cooling of high-angular-momentum atoms

针对高角动量原子，本文提出结合光泵浦、受激跃迁和磁力的快速平动冷却方法，可压缩相空间密度并保持粒子数守恒，为替代蒸发冷却制备量子简并气体提供方案。

Doppler-free approach to optical pumping dynamics in the $6S_{1/2}- 5D_{5/2}$ electric quadrupole transition of Cesium vapor

The $6S_{1/2}-5D_{5/2}$ electric quadrupole transition is investigated in Cesium vapor at room temperature via nonlinear Doppler-free 6P-6S-5D three-level spectroscopy. Frequency-resolved studies of individual E2 hyperfine lines allow one to analyze optical pumping dynamics, polarization selection rules and line intensities. It opens the way to studies of transfer of light orbital angular momentum to atoms, and the influence of metamaterials on E2 line spectra.