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Physical Review A

Candidates for direct laser cooling of diatomic molecules with the simplest Σ1−Σ1 electronic system

Chuanliang Li, Yachao Li, Zhonghua Ji, Xuanbing Qiu, Yunzhong Lai, Jilin Wei, Yanting Zhao, Lunhua Deng, Yangqin Chen, Jinjun Liu

Published Jun 5, 2018• 28 citations
Publisher

Abstract

We propose to utilize the $^{1}\mathrm{\ensuremath{\Sigma}}{\ensuremath{-}}^{1}\mathrm{\ensuremath{\Sigma}}$ electronic transition system for direct laser cooling of heteronuclear diatomic molecules. AgH, as well as its deuterium isotopolog AgD, is used as an example to illustrate the cooling schemes. Potential-energy curves and relevant molecular parameters of both AgH and AgD, including the spin-orbit constants and the electronic transition dipole moments, are determined in internally contracted multiconfiguration-reference configuration interaction calculations. The highly diagonal Franck-Condon matrices of the $A{\phantom{\rule{0.16em}{0ex}}}^{1}{\mathrm{\ensuremath{\Sigma}}}^{+}\ensuremath{-}X{\phantom{\rule{0.16em}{0ex}}}^{1}{\mathrm{\ensuremath{\Sigma}}}^{+}$ transitions predicted by the calculations suggest the existence of quasi-closed-cycle transitions, which renders these molecules suitable for direct laser cooling. By solving rate equations numerically, we demonstrated that both AgH and AgD molecules can be cooled from 25 K to 2 mK temperature in approximately 20 ms. Our investigation elucidates and supports the hypothesis that molecules in the simplest $^{1}\mathrm{\ensuremath{\Sigma}}{\ensuremath{-}}^{1}\mathrm{\ensuremath{\Sigma}}$ system can serve as favorable candidates for direct laser cooling.

DOI
10.1103/physreva.97.062501

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