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arXiv · 2609.11004

On-chip squeezed light in the audio frequency band

Xuezhi Zhu·Yunyun Cao·Rui Liu·Yaya He·Fan Zhang·Yaqing Zhang·Shiwei Du·Meihong Wang·Xiaoshun Jiang·Xiaolong Su
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Abstract

Squeezed light in the audio-frequency band is a key resource for quantum metrology and quantum sensing. However, realizing stable audio-frequency squeezed light on integrated photonic platforms remains challenging due to technical noise and the difficulty of scalable phase referencing. Here, we demonstrate on-chip generation of audio-band two-mode squeezed states down to 60 Hz in a silica microcavity. To enable phase-stable operation without directly locking fragile quantum modes, we develop a coherent-comb control method in which a weak electro-optic reference comb co-propagates with the vacuum at the quantum frequency modes in an orthogonal polarization. This scheme provides quadrature measurement and long-timescale phase stability, thereby enabling covariance-matrix reconstruction. We verify the entanglement with the positive partial transposition criterion, which confirms inseparability via a minimum symplectic eigenvalue of 0.395 ($<0.5$). Our results establish an experimentally accessible route toward on-chip phase-stable audio-band squeezing and support the scalable framework for continuous-variable quantum information processing with integrated photonics.

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Xuezhi Zhu, Yunyun Cao, Rui Liu, Yaya He, Fan Zhang, Yaqing Zhang, Shiwei Du, Meihong Wang, Xiaoshun Jiang, Xiaolong Su. 2026-09-10. On-chip squeezed light in the audio frequency band. https://doi.org/10.1016/j.scib.2026.08.054

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