Measurement of the squeezed vacuum state by a bichromatic local oscillator

TL;DR

This paper demonstrates an experimental method to measure a squeezed vacuum state using a bichromatic local oscillator, enabling detection of quantum states with sensitivity below the shot-noise limit, which is significant for quantum information applications.

Contribution

The work introduces a novel measurement technique employing a bichromatic local oscillator for enhanced detection of squeezed vacuum states.

Findings

Successful detection of squeezed vacuum with sensitivity below shot-noise limit.

Use of phase-locked bichromatic local oscillators at ±5 MHz.

Potential applications in quantum state measurement and quantum information.

Abstract

We present the experimental measurement of a squeezed vacuum state by means of a bichromatic local oscillator (BLO). A pair of local oscillators at $\pm$5 MHz around the central frequency $\omega_{0}$ of the fundamental field with equal power are generated by three acousto-optic modulators and phase-locked, which are used as a BLO. The squeezed vacuum light are detected by a phase-sensitive balanced-homodyne detection with a BLO. The baseband signal around $\omega_{0}$ combined with a broad squeezed field can be detected with the sensitivity below the shot-noise limit, in which the baseband signal is shifted to the vicinity of 5 MHz (the half of the BLO separation). This work has the important applications in quantum state measurement and quantum information