Demonstration of a switchable damping system to allow low-noise operation of high-Q low-mass suspension systems

TL;DR

This paper presents a switchable damping system for high-Q low-mass suspensions, reducing damping noise and enabling low-noise quantum experiments with adjustable damping strength.

Contribution

Introduction of a passive, adjustable damping system that minimizes displacement noise in high-Q suspension systems for quantum experiments.

Findings

Damping factor reduced by a factor of 8 in tests

System can be optimized for various suspension configurations

Maintains low displacement noise during low-noise operation

Abstract

Low mass suspension systems with high-Q pendulum stages are used to enable quantum radiation pressure noise limited experiments. Utilising multiple pendulum stages with vertical blade springs and materials with high quality factors provides attenuation of seismic and thermal noise, however damping of these high-Q pendulum systems in multiple degrees of freedom is essential for practical implementation. Viscous damping such as eddy-current damping can be employed but introduces displacement noise from force noise due to thermal fluctuations in the damping system. In this paper we demonstrate a passive damping system with adjustable damping strength as a solution for this problem that can be used for low mass suspension systems without adding additional displacement noise in science mode. We show a reduction of the damping factor by a factor of 8 on a test suspension and provide a general optimisation for this system.