Quantum-enhanced sensing via spectral noise reduction

TL;DR

This paper demonstrates quantum-enhanced sensing in the Fourier domain by showing that quantum correlations reduce noise floor and improve signal-to-noise ratio, enabling super-sensitivity in interferometric measurements.

Contribution

It provides the first direct experimental comparison of single- and two-photon interference under identical noise, establishing Fourier-domain quantum super-sensitivity as a practical sensing resource.

Findings

3 dB improvement in signal-to-noise ratio due to quantum correlations

Quantum enhancement persists in sub-shot-noise regime

Spectral noise reduction enables super-sensitivity in interferometry

Abstract

We report a direct demonstration of quantum-enhanced sensing in the Fourier domain by comparing single- and two-photon interference in a fiber-based interferometer under strictly identical noise conditions. The simultaneous acquisition of both signals provides a common-mode reference that enables a fair and unambiguous benchmark of quantum advantage. Spectral analysis of the interferometric outputs reveals that quantum correlations do not increase the amplitude of the modulation peak, but instead lower the associated noise floor, resulting in the expected 3 dB improvement in signal-to-noise ratio. This enhancement persists in the sub-shot-noise regime, where the classical signal becomes buried in the spectral background while the two-photon contribution remains resolvable. These observations establish Fourier-domain quantum super-sensitivity as an operational and broadly applicable resource for precision interferometric sensing.