Thermal noise and mechanical loss of SiO${}_2$/Ta${}_2$O${}_5$ optical coatings at cryogenic temperatures

Abstract

Mechanical loss of dielectric mirror coatings sets fundamental limits for both gravitational wave detectors and cavity-stabilized optical local oscillators for atomic clocks. Two approaches are used to determine the mechanical loss: ringdown measurements of the coating quality factor and direct measurement of the coating thermal noise. Here we report a systematic study of the mirror thermal noise from room temperature to 4 K by operating reference cavities at these temperatures. The directly measured thermal noise is used to extract the corresponding mechanical loss for SiO${}_2$/Ta${}_2$O${}_5$ coatings, which are compared with previously reported values.

References in corpus (3)

• Exploring the Sensitivity of Next Generation Gravitational Wave Detectors
• An ultrastable silicon cavity in a continuously operating closed-cycle cryostat at 4 K
• Broadband Measurement of Coating Thermal Noise in Rigid Fabry-Perot Cavities

Cited by in corpus (1)

• Engineering the sensitivity of macroscopic physical systems to variations in the fine-structure constant