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.

References in corpus (28)

• Quantum information with continuous variables
• Gaussian Quantum Information
• Peres-Horodecki separability criterion for continuous variable systems
• Inseparability criterion for continuous variable systems
• Squeezed states of light and their applications in laser interferometers
• Whispering gallery microsensors: a review
• On-Chip Optical Squeezing
• Quantum-enhanced optical phase tracking
• Squeezing in the audio gravitational wave detection band
• Quantum correlations between the light and kilogram-mass mirrors of LIGO
• A squeezed quantum microcomb on a chip
• Broadband quadrature-squeezed vacuum and nonclassical photon number correlations from a nanophotonic device
• Microsatellite-based real-time quantum key distribution
• Quantum Dynamics of Kerr Optical Frequency Combs below and above Threshold: Spontaneous Four-Wave-Mixing, Entanglement and Squeezed States of Light
• Squeezed light from a nanophotonic molecule
• Fabrication of low-loss quasi-single-mode PPLN waveguide and its application to a modularized broadband high-level squeezer
• Squeezing the quantum noise of a gravitational-wave detector below the standard quantum limit
• Integrated Quantum Optical Phase Sensor
• Room-temperature quantum optomechanics using an ultra-low noise cavity
• Over-8-dB squeezed light generation by a broadband waveguide optical parametric amplifier toward fault-tolerant ultra-fast quantum computers
• Tunable Squeezing Using Coupled Ring Resonators on a Silicon Nitride Chip
• Generation of squeezed vacuum state in the millihertz frequency band
• Deterministic quantum phase estimation beyond the ideal NOON state limit
• The first five years of gravitational-wave astrophysics
• Local-Oscillator Noise Coupling in Balanced Homodyne Readout for Advanced Gravitational Wave Detectors
• Strong nanophotonic quantum squeezing exceeding 3.5 dB in a foundry-compatible Kerr microresonator
• Efficient entanglement distillation without quantum memory
• Bright squeezed light in the kilohertz frequency band