Thermoelastic effects at low temperatures and quantum limits in displacement measurements

TL;DR

This paper investigates how thermoelastic effects influence displacement measurements in optomechanical systems at low temperatures, highlighting conditions where thermal fluctuations can be reduced below quantum noise levels for advanced quantum experiments.

Contribution

It provides an analysis showing that thermoelastic displacement fluctuations can be minimized below quantum fluctuations in specific low-temperature, high-reflectivity, high-power regimes.

Findings

Thermoelastic fluctuations can be suppressed below quantum noise at low temperatures.

Design guidelines for quantum-limited gravitational-wave detectors are proposed.

Implications for observing quantum mechanical motion in macroscopic objects.

Abstract

The displacement fluctuations of mirrors in optomechanical devices, induced via thermal expansion by temperature fluctuations due either to thermodynamic fluctuations or to fluctuations in the photon absorption, can be made smaller than quantum fluctuations, at the low temperatures, high reflectivities and high light powers needed to readout displacements at the standard quantum limit. The result is relevant for the design of quantum limited gravitational-wave detectors, both "interferometers" and "bars", and for experiments to study directly mechanical motion in the quantum regime.