Speaker
Description
We present unusual properties of the commercial quartz tuning forks (QTFs) operating at
resonance frequencies of 32 kHz, 77 kHz and 100 kHz at temperature range below 1K and in
high magnetic fields up to 7.5 T. We show that in millikelvin temperature range, the quartz
tuning forks exhibit the property of the coherent oscillations. These are manifested as a
temperature-dependent, extremely accurate tune-up of QFTs resonance frequencies in 9th
order with very high frequency stability characterized by the low values of the Allan
deviations comparable with those in lasers. Even more, we demonstrate that a normalized
resonance frequency of the tuning forks manifests a universal temperature dependence, which
is independent on the magnetic field strength. This feature make the QTFs a very promising
low temperature thermometer in high magnetic fields in temperature range below 1 K while
having the B/T ratio up to 1000. We also discuss the physical origin of the observed
dependencies.
