A two-carrier scheme: evading the 3dB quantum penalty of heterodyne readout in gravitational-wave detectors

TL;DR

This paper introduces a two-carrier scheme for gravitational-wave detectors that overcomes the 3dB quantum noise penalty of heterodyne readout, enabling more precise measurements and compatibility with quantum nondemolition techniques.

Contribution

The paper proposes a novel two-carrier detector design that evades the quantum penalty and enables frequency-dependent squeezing using two-mode squeezing.

Findings

Achieves noise performance comparable to homodyne readout

Enables more precise audio frequency measurements

Compatible with quantum nondemolition techniques

Abstract

Precision measurements using traditional heterodyne readout suffer a 3dB quantum noise penalty compared with homodyne readout. The extra noise is caused by the quantum fluctuations in the image vacuum. We propose a two-carrier gravitational-wave detector design that evades the 3dB quantum penalty of heterodyne readout. We further propose a new way of realising frequency-dependent squeezing utilising two-mode squeezing in our scheme. It naturally achieves more precise audio frequency signal measurements with radio frequency squeezing. In addition, the detector is compatible with other quantum nondemolition techniques.