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arXiv:2609.28294

A photonic integrated comb engine for ultracold quantum gases

Wei Sun, Xiaoying Yan, Jinbao Long, Sanli Huang, Zhixin Duan, Zhenyuan Shang, Zeying Zhong, Jiahao Sun, Yue Hu, Shichang Li, Baoqi Shi, Yi-Han Luo, Shuyi Li, Hao Tan, Chen Shen, Zhichuan Niu, Shengjun Yang, Junqiu Liu

physics.opticscond-mat.quant-gasquant-phSubmitted Sep 23, 2026• Announced Sep 24, 2026• 0 citations
v1 · Sep 23, 2026v2 · Oct 6, 2026
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Abstract

Cold atoms underpin quantum sensing, simulation and computation, but their coherent control demands highly stable optical fields whose generation, referencing and power scaling remain formidable integration challenges. While photonic integrated circuits have yielded compact visible lasers and high-$Q$ microresonators have enabled chip-scale optical frequency combs, these crucial technologies have largely remained functionally fragmented. Consequently, the coherent manipulation of ultracold quantum gases using a fully integrated laser-comb source has yet to be realized. Here we demonstrate a scalable, hybrid-integrated microcomb engine at 780 nm that seamlessly bridges frequency synthesis, atomic referencing and power amplification to achieve quantum state control of a Bose--Einstein condensate. By self-injection locking of electrically driven III--V lasers to high-$Q$ Si$_3$N$_4$ microresonators, we generate coherent platicon microcombs featuring 20- and 100-GHz mode spacings. Absolute referencing of the microcomb to an $^{85}$Rb transition actively suppresses long-term frequency drift from over 200 MHz to the 100-kHz level across 2,000 s. A selected comb tooth is subsequently injection-amplified to 102 mW, entirely preserving the microcomb's pristine coherence and stability. We utilize this synthesized field to construct an optical lattice, drive coherent two-photon Raman transitions, and prepare stationary spin-orbit-coupled and Raman-lattice states within an $^{87}$Rb condensate. By providing a synchronized optical grid, this atom-referenced microcomb allows multiple optical-control channels to scale without a proportional multiplication of independent frequency references. Our work establishes a transformative, fully integrated frequency-synthesis architecture essential for realizing deployable, large-scale atomic quantum systems.

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