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Diffuse laser cooling based on the 6P3/2 excited state of rubidium atoms via 420 nm blue light

Jia Zhang1, Xun Gao1, Zheng Xiao1, Xiaolei Guan1, Ruihang Chen1, Mengyuan Han1, Tiantian Shi2,3,*, and Jingbiao Chen1,2,4

  • 1Institute of Quantum Electronics, School of Electronics, Peking University, Beijing 100871, China
  • 2National Key Laboratory of Advanced Micro and Nano Manufacture Technology, School of Integrated Circuits, Peking University, Beijing 100871, China
  • 3Beijing Advanced Innovation Center for Integrated Circuits, Beijing 100871, China
  • 4Hefei National Laboratory, Hefei 230088, China

  • *Contact author: tts@pku.edu.cn
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Phys. Rev. Research 8, 033293 – Published 10 September, 2026

DOI: https://doi.org/10.1103/4jtk-471b

Abstract

To date, the laser cooling of rubidium atoms has inevitably relied on 780 nm cooling light corresponding to the first excited state 5P3/2. Here, we demonstrate diffuse laser cooling of Rb87 atoms using the 420 nm 5S1/2→6P3/2 transition without a preceding 780 nm cooling stage. A high-power 420nm laser is used as the cooling light to produce cold atoms in a 1-m-long diffuse-cooling cell. Absorption spectroscopy yields a cold-atom density of approximately 1.4×1011m−3. We compare the cooling performance of the 420 nm and conventional 780 nm diffuse-cooling schemes and verify the feasibility of using the high-excited-state transition as an independent cooling channel in this large-volume diffuse-cooling system. This approach provides an alternative cooling/pumping pathway for continuous cold-atom active optical clocks, where compatibility with the clock-lasing process and reduced cooling-light-induced perturbations are important. It is also expected to open up research directions and application prospects in frontier fields such as Rydberg atoms, quantum information, and so on.

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Phys. Rev. Research 8, 033293– Published 10 September, 2026
  • Received 24 September 2025
  • Accepted 18 August 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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