Quantum-enhanced optical phase-insensitive heterodyne detection beyond 3-dB noise penalty of image band

TL;DR

This paper introduces a quantum technique using squeezed light to surpass the 3-dB noise limit in optical heterodyne detection, enhancing measurement sensitivity in various applications.

Contribution

It presents a novel method to eliminate shot noise from all bands in heterodyne detection using squeezed light, achieving beyond-3-dB noise reduction experimentally.

Findings

Successfully reduced shot noise from all bands

Achieved beyond-3-dB noise reduction

Enhanced sensitivity in optical measurements

Abstract

Optical phase-insensitive heterodyne (beat-note) detection, which measures the relative phase of two beams at different frequencies through their interference, is a key sensing technology for various spatial/temporal measurements, such as frequency measurements in optical frequency combs. However, its sensitivity is limited not only by shot noise from the signal frequency band but also by the extra shot noise from an image band, known as the 3-dB noise penalty. Here, we propose a method to remove shot noise from all these bands using squeezed light. We also demonstrate beyond-3-dB noise reduction experimentally, confirming that our method actually reduces shot noise from both the signal and extra bands simultaneously. Our work should boost the sensitivity of various spatial/temporal measurements beyond the current limitations.