Combining quantum noise reduction resources: a practical approach

TL;DR

This paper explores combining quantum noise reduction techniques like squeezing and QND measurements in optomechanical sensors to improve high-bandwidth impulse detection, aiming to detect weak signals such as dark matter interactions.

Contribution

It provides theoretical limits for quantum noise reduction at higher frequencies and demonstrates how QND techniques simplify broadband force detection with squeezed light.

Findings

QND techniques significantly reduce technical challenges in broadband force detection.

Combining quantum noise reduction methods enhances sensitivity for dark matter signal detection.

Theoretical limits established for quantum noise reduction at higher, broader frequencies.

Abstract

Optomechanical sensors are capable of transducing external perturbations to resolvable optical signals. A particular regime of interest is that of high-bandwidth force detection, where an impulse is delivered to the system over a short period of time. Exceedingly sensitive impulse detection has been proposed to observe very weak signals like those due to long range interactions with dark matter that require much higher sensitivities than current sensors can provide. Quantum resources to go beyond the traditional standard quantum limit of these sensors include squeezing of the light used to transduce the signal, backaction evasion by measuring the optimal quadrature, and quantum non-demolition (QND) measurements that reduce backaction directly. These methods have been developed in the context of gravitational wave detection for target frequencies in the audio band range. Here, we provide the theoretical limits to quantum noise reduction for higher and broader frequency targets, such as those from dark matter signals, while combining quantum enhanced readout techniques based on squeezed light and QND measurements with optomechanical sensors. We demonstrate that backaction evasion through QND techniques dramatically reduces the technical challenges presented when using squeezed light for broadband force detection, paving the way for combining multiple quantum noise reduction techniques for enhanced sensitivity in the context of impulse metrology.