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Efficient Λ-enhanced gray molasses using an electromagnetically-induced-transparency-based laser locking scheme

Timothy Leese1,2, Siobhan Patrick1, Silvia Bergamini1, and Calum MacCormick1,*

  • 1School of Physical Sciences, Faculty of STEM, The Open University, Walton Hall, Milton Keynes MK7 6AA, United Kingdom
  • 2Department of Physics, University of Oxford, Parks Road, Oxford OX1 3PU, United Kingdom

  • *Contact author: c.maccormick@open.ac.uk
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Phys. Rev. A 113, 053113 – Published 20 May, 2026

DOI: https://doi.org/10.1103/gb69-pvt4

Abstract

We present a low-cost implementation of lambda-enhanced gray molasses cooling in a nonstandard beam geometry and with an inexpensive laser locking setup that only provides limited coherence of the Raman laser beams. In contrast to the established use of resource-intensive phase-locking methods, our laser system uses two independent lasers, frequency- locked to a spectral feature produced by an electromagnetically induced transparency (EIT) resonance. We show that this approach achieves sufficient coherence to enable effective gray molasses cooling without the need for costly GHz electronics, significantly reducing the complexity and cost of experimental setups and represents a step toward more accessible cold atom technologies. Furthermore, the cooling remains efficient even with a nonoptimal beam geometry, typical of cold-atoms quantum computing platforms based on optical tweezers. A wave-function Monte Carlo analysis supports the experimental findings, offering insight into the cooling dynamics of this unconventional scheme.

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Phys. Rev. A 113, 053113– Published 20 May, 2026
  • Received 9 October 2025
  • Accepted 31 March 2026
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Published by the American Physical Society under the terms of the Creative Commons Attribution 4.0 International license. Further distribution of this work must maintain attribution to the author(s) and the published article's title, journal citation, and DOI.

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