Limits to the sensitivity of a rare-earth-enabled cryogenic vibration sensor

TL;DR

This paper examines the fundamental and technical limits of a rare-earth-based cryogenic vibration sensor operating below 4K, aiming to improve sensitivity in environments with higher vibration levels from dry cryocoolers.

Contribution

It introduces a detailed analysis of the sensor's sensitivity limits, comparing different attachment methods and isolation techniques at cryogenic temperatures.

Findings

Spectral hole burning enhances sensor sensitivity below 4K.

Rigid attachment to cryocooler stage affects vibration measurement accuracy.

Isolation methods influence the sensor's fundamental sensitivity limits.

Abstract

Cryogenics is a pivotal aspect in the development of quantum technologies. Closed-cycle devices have recently emerged as an environmentally friendly and low-maintenance alternative to liquid helium cryostats. Yet the larger level of vibrations in dry cryocoolers forbids their use in most sensitive applications. In a recent work, we have proposed an inertial, broadband, contactless sensor based on the piezospectroscopic effect, ie the natural sensitivity of optical lines to strain exhibited by impurities in solids. This sensor builds on the exceptional spectroscopic properties of rare earth ions and operates below 4K, where spectral hole burning considerably enhances the sensitivity. In this paper, we investigate the fundamental and technical limitations of this vibration sensor by comparing a rigid sample attachment to cold stage of a pulse-tube cryocooler and a custom-designed exchange gas chamber for acoustic isolation.