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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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