Shot-Noise Limited Homodyne Detection for MHz Quantum Light Characterisation in the 2 {\mu}m Band

TL;DR

This paper demonstrates a shot-noise limited homodyne detector operating at 2.07 μm, enabling quantum state characterization in the 2 μm band with high efficiency and bandwidth, suitable for MHz quantum light analysis.

Contribution

It introduces a high-performance homodyne detector optimized for the 2 μm band, with detailed characterization of its bandwidth, efficiency, and noise clearance capabilities.

Findings

Achieved 13.2 MHz bandwidth for the detector.

Demonstrated 58% conversion efficiency at 2.07 μm.

Obtained 9 dB shot-noise clearance at 5 MHz.

Abstract

Characterising quantum states of light in the 2 ${\mu}m$ band requires high-performance shot-noise limited detectors. Here, we present the characterisation of a homodyne detector that we use to observe vacuum shot-noise via homodyne measurement with a 2.07 ${\mu}m$ pulsed mode-locked laser. The device is designed primarily for pulsed illumination. It has a 3 dB bandwidth of 13.2 MHz, total conversion efficiency of 58% at 2.07 ${\mu}m$ and a common-mode rejection ratio of 48 dB at 39.5 MHz. The detector begins to saturate at 1.8 mW with 9 dB of shot-noise clearance at 5 MHz. This demonstration enables the characterisation of megahertz-quantum optical behaviour in the 2 ${\mu}m$ band.