Single-crystal sapphire resonator at millikelvin temperatures: Observation of thermal bistability in high-Q factor whispering gallery modes
- School of Physics (M013), University of Western Australia, 35 Stirling Hwy, Crawley, Western Australia 6009 (Australia)
Resonance modes in single crystal sapphire ({alpha}-Al{sub 2}O{sub 3}) exhibit extremely high electrical and mechanical Q factors ({approx_equal}10{sup 9} at 4 K), which are important characteristics for electromechanical experiments at the quantum limit. We report the cool down of a bulk sapphire sample below superfluid liquid-helium temperature (1.6 K) to as low as 25 mK. The electromagnetic properties were characterized at microwave frequencies, and we report the observation of electromagnetically induced thermal bistability in whispering gallery modes due to the material T{sup 3} dependence on thermal conductivity and the ultralow dielectric loss tangent. We identify ''magic temperatures'' between 80 and 2100 mK, the lowest ever measured, at which the onset of bistability is suppressed and the frequency-temperature dependence is annulled. These phenomena at low temperatures make sapphire suitable for quantum metrology and ultrastable clock applications, including the possible realization of the quantum-limited sapphire clock.
- OSTI ID:
- 21421411
- Journal Information:
- Physical Review. B, Condensed Matter and Materials Physics, Vol. 82, Issue 10; Other Information: DOI: 10.1103/PhysRevB.82.104305; (c) 2010 The American Physical Society; ISSN 1098-0121
- Country of Publication:
- United States
- Language:
- English
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SUPERCONDUCTIVITY AND SUPERFLUIDITY
ALUMINIUM OXIDES
DIELECTRIC MATERIALS
HELIUM
MICROWAVE RADIATION
MONOCRYSTALS
RESONANCE
RESONATORS
SAPPHIRE
SUPERFLUIDITY
TEMPERATURE DEPENDENCE
TEMPERATURE RANGE 0000-0013 K
THERMAL CONDUCTIVITY
ALUMINIUM COMPOUNDS
CHALCOGENIDES
CORUNDUM
CRYSTALS
ELECTROMAGNETIC RADIATION
ELECTRONIC EQUIPMENT
ELEMENTS
EQUIPMENT
FLUIDS
GASES
MATERIALS
MINERALS
NONMETALS
OXIDE MINERALS
OXIDES
OXYGEN COMPOUNDS
PHYSICAL PROPERTIES
RADIATIONS
RARE GASES
TEMPERATURE RANGE
THERMODYNAMIC PROPERTIES