Abstract
We propose a scheme that combines velocity-selective coherent population trapping (CPT) and Raman sideband cooling (RSC) for subrecoil cooling of optically trapped atoms outside the Lamb-Dicke regime. This scheme is based on an inverted Y configuration in an alkali-metal atom. It consists of a Λ formed by two Raman transitions between the ground hyperfine levels and the D transition, allowing RSC along two paths and formation of a CPT dark state. Using the state-dependent difference in vibration frequency of the atom in a circularly polarized trap, we can tune the Λ to make only the motional ground state a CPT dark state. We call this scheme motion-selective coherent population trapping (MSCPT). We write the master equations for RSC and MSCPT and solve them numerically for a Rb87 atom in a one-dimensional optical lattice when the Lamb-Dicke parameter is 1. Although MSCPT reaches the steady state slowly compared with RSC, the former consistently produces colder atoms than the latter. The numerical results also show that subrecoil cooling by MSCPT outside the Lamb-Dicke regime is possible under a favorable, yet experimentally feasible, condition. We explain this performance quantitatively by calculating the relative darkness of each motional state. Finally, we discuss the application of the MSCPT scheme to an optically trapped diatomic polar molecule whose Stark shift and vibration frequency exhibit large variations depending on the rotational quantum number.
Original language | English |
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Article number | 023324 |
Journal | Physical Review A |
Volume | 106 |
Issue number | 2 |
DOIs | |
Publication status | Published - 2022 Aug |
Bibliographical note
Funding Information:This work was supported by the National Research Foundation of Korea (Grant No. 2019M3E4A1080382). We thank Q-Han Park for help with the numerical work, D. G. Lee for assisting in the computer setup, and Eunmi Chae for discussions and information on molecules.
Publisher Copyright:
© 2022 American Physical Society.
ASJC Scopus subject areas
- Atomic and Molecular Physics, and Optics