C R Locke et al 2002 Class. Quantum Grav. 19 1877 doi:10.1088/0264-9381/19/7/388
C R Locke, M E Tobar and E N Ivanov
Show affiliationsTo measure the standard quantum limit (SQL) a high quality transducer must be coupled to a high quality mechanical system. Due to its monolithic nature, the monolithic sapphire transducer (MST) has high quality factors for both types of resonances. Single loop suspension is shown to yield a mechanical quality factor of 6 × 108 at 4 K and Whispering Gallery electromagnetic modes display a quality factor of 2 × 106 at 4 K. From standard analysis we show that the MST has the potential to measure the noise fluctuations of the mechanical oscillator at the SQL. Also, we point out a new way to determine if the transducer back-action is quantum limited. We show that if the fluctuations are at the quantum limit, then the amplitude of the oscillations will be amplified by the ratio of the ringdown time to the measurement time, which is an inherently easier measurement.
03.65.Ta Foundations of quantum mechanics; measurement theory
Issue 7 (7 April 2002)
Received 5 October 2001, in final form 13 November 2001
Published 18 March 2002
C R Locke et al 2002 Class. Quantum Grav. 19 1877
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