Alex Szorkovszky, George A. Brawley, Andrew C. Doherty, Warwick P. Bowen
While cooling techniques are commonly used to remove thermal noise in an oscillator, parametric modulation of the oscillator can reduce both thermal and zero-point noise in one quadrature of motion. This "noise squeezing" property has been widely demonstrated, but has found little use in practice due to a well-known 3dB limit to the squeezing in equilibrium. Using a standard AFM cantilever, we experimentally break this limit by combining optimal estimation and detuned parametric amplification. We observe squeezing of the noise by more than 5dB when the parametric modulation is applied. This squeezing - limited only by the oscillator Q-factor - could be used at room temperature to improve the stability and resolution of sensors, as well as in the low temperature regime to achieve mechanical squeezing below the quantum zero-point motion.
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http://arxiv.org/abs/1210.1657
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