Intrinsic flicker floor of cryogenic quartz resonators above Q = 10^9

Determine the intrinsic 1/f frequency-noise floor of cryogenic quartz resonators operated above a quality factor of 10^9, and establish why further increases in quality factor have not produced the anticipated improvement in frequency stability.

Background

The paper discusses the prediction that cooling quartz resonators should reduce their flicker-frequency-noise floor. Cryogenic measurements achieved quality factors exceeding 109, but the expected improvement in stability was not observed.

The authors explicitly state that the intrinsic flicker floor in this high-quality-factor regime remains unresolved. Further measurements or a theory are needed to characterize the floor and explain its apparent independence from the quality factor in this regime.

References

The prediction that cooling quartz should lower its flicker floor did not survive cryogenic measurement. Quality factors past $10{9}$ were attained, but improved stability did not follow, and the intrinsic flicker floor above $Q=10{9}$ remains unresolved.

— 1/f frequency noise in mechanical resonators scales inversely with volume, not with quality factor  (2609.16668 - Roukes, 15 Sep 2026) in End Matter, subsection “The cryogenic test of the Q law”