Optical probes of angular momentum and energy transport in spin-exchange optical pumping systems

Kevin Wright, Andrew B. Kowalik, L. Suzanne Leslie +2 more

Ge Jin, Tao shi, Yuxin Chen +2 more

Abstract We investigate angular-momentum transfer efficiencies in hybrid Rb–Cs– 129 Xe vapor cells with different alkali compositions. Experiments were performed at a pump power of 40 mW and a cell temperature of 110 ∘ C, where the Rb–Cs spin-exchange rate is comparable to the alkali electron-spin relaxation rate and complete spin-temperature equilibrium is not established. Using Rb-rich cells under Cs pumping and Cs-rich cells under Rb pumping, we measured the steady-state 129 Xe polarization and build-up time and determined the corresponding spin-exchange and photon efficiencies. Within each cell series, both efficiencies exhibit systematic composition-dependent trends arising from the combined effects of optical pumping, incomplete Rb–Cs polarization transfer, alkali relaxation, and alkali–Xe spin exchange. The Rb–Cs polarization-transfer factor converts the nominal alkali density ratio into an effective polarization-weighted ratio, which governs the relative contributions of the Rb–Xe and Cs–Xe spin-exchange channels. These results clarify angular-momentum transfer in hybrid Rb–Cs– 129 Xe systems and provide guidance for optimizing low-power hybrid spin-exchange optical pumping and alkali–noble-gas sensor platforms.

Ian A. Nelson

Patrick Bevington, R. Gartman, Witold Chałupczak

Traditionally, atomic spin orientation is achieved by the transfer of angular momentum from polarized light to an atomic system. We demonstrate the mechanism of orientation generation in room-temperature caesium vapors that combines three elements: optical pumping, nonlinear spin dynamics, and spin-exchange collisions. Through the variation of the spin-exchange relaxation rate, the transition between an aligned and an oriented atomic sample is presented. The observation is performed by monitoring the atomic radio-frequency spectra. The measurement configuration discussed paves the way to simple and robust radio-frequency atomic magnetometers that are based on a single low-power laser diode that approach the performance of multilaser pump-probe systems.

Bien Chann

Thad G Walker, W. Happer

Spin-exchange optical pumping of mixtures of alkali-metal vapors and noble gases can be used to efficiently polarize the nuclei of the noble-gas atoms. Liters of noble gases at standard temperature and pressure and with nuclear spin polarizations of several tens of percent are now used in many applications. The authors describe the basic phenomena that govern the spin-exchange process and review the physics of angular momentum transfer and loss in optical pumping and spin-exchange collisions.