arXiv:2401.04940 · Physical Review Letters

Quantum Enhanced Balanced Heterodyne Readout for Differential Interferometry

Daniel W. Gould, V. B. Adya, S. Chua, J. Junker, D. M. Wilken, T. McRae, Bram J. J. Slagmolen, M. J. Yap, Robert L. Ward, M. Heurs, David E. McClelland

Published Aug 8, 2024• 8 citations

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Abstract

Conventional heterodyne readout schemes are now under reconsideration due to the realization of techniques to evade its inherent 3 dB signal-to-noise penalty. The application of high-frequency, quadrature-entangled, two-mode squeezed states can further improve the readout sensitivity of audio-band signals. In this Letter, we experimentally demonstrate quantum-enhanced heterodyne readout of two spatially distinct interferometers with direct optical signal combination, circumventing the 3 dB heterodyne signal-to-noise penalty. Applying a high-frequency, quadrature-entangled, two-mode squeezed state, we show further signal-to-noise improvement of an injected audio band signal of 3.5 dB. This technique is applicable for quantum-limited high-precision experiments, with application to searches for quantum gravity, searches for dark matter, gravitational wave detection, and wavelength-multiplexed quantum communication.

DOI: 10.1103/physrevlett.133.063602

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