QFS 2016 Book of Abstracts

Abstracts

O4.2 High Q-value quartz tuning fork in vacuum as a potential thermometer in millikelvin temperature range ˇCloveˇcko Marcel, Kupka Martin, Skyba Peter, Vavrek Frantiˇsek Institute of Experimental Physics, Slovak Academy of Sciences, Watsonova 47, 04001 Koˇsice, Slovakia The results of a newly developed pulse-demodulation (P-D) technique introduced to measure high Q-value quartz tuning forks (QTF) in vacuum and millikelvin (mK) temperature range are presented. By applying P-D technique with extremely low excitation energy ( ≈ fJ) to a standard 32 kHz QTF, we were able to measure the resonance frequency of fork’s decay signal with resolution better than 10 μ Hz. We’ve found a continuous and reproducible temperature dependence of the fork’s resonance frequency in mK range. Observed dependence suggests a potential application for the QTFs to be used as thermometers in mK range. We also discuss the physical origin of the observed phenomenon. O4.3 Dissipation mechanisms in a superfluid micromechanical resonator Fabien Souris(1), Xavier Rojas(2), John Davis(1) 1) University of Alberta, Department of Physics, Edmonton, Alberta, Canada 2) Royal Holloway, University of London, Department of Physics, Egham, Surrey, United Kingdom There has been significant interest in micro and nanomechanical systems as quantum resources, and recently it has been realized that superfluid 4 He is among the most promising candidates for studying mechanics in the quantum regime. Here we performed a careful analysis of the dissipation mechanisms in our microfabricated superfluid mechanical resonator. We show that despite already reaching a quality factor up to 900,000, it has the potential to reach quality factors as high as 108 at 100 mK. Coupled to a microwave resonator this architecture would be in an ideal position to harness mechanical quantum effects and study the effect of confinement on superfluid 3 He.

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