On-chip squeezed light in the audio frequency band

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.

Quantum Physics (quant-ph); Optics (physics.optics)

arXiv:2609.11004 [quant-ph]

(or arXiv:2609.11004v1 [quant-ph] for this version)

https://doi.org/10.48550/arXiv.2609.11004 Focus to learn more arXiv-issued DOI via DataCite (pending registration)

On-chip squeezed light in the audio frequency band. Science Bulletin 2026, 71(19)

https://doi.org/10.1016/j.scib.2026.08.054 Focus to learn more DOI(s) linking to related resources

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