Nanomechanical motion measured with an imprecision below that at the standard quantum limit (original) (raw)

2009, Nature Nanotechnology

Nanomechanical oscillators are at the heart of ultrasensitive detectors of force , mass [2] and motion . As these detectors progress to even better sensitivity, they will encounter measurement limits imposed by the laws of quantum mechanics. For example, if the imprecision [8] of a measurement of an oscillator's position is pushed below the standard quantum limit (SQL), quantum mechanics demands that the motion of the oscillator be perturbed by an amount larger than the SQL. Minimizing this quantum backaction noise and nonfundamental, or technical, noise requires an information efficient measurement. Here we integrate a microwave cavity optomechanical system [9] and a nearly noiseless amplifier into an interferometer to achieve an imprecision below the SQL. As the microwave interferometer is naturally operated at cryogenic temperatures, the thermal motion of the oscillator is minimized, yielding an excellent force detector with a sensitivity of 0.51 aN/ √ Hz. In addition, the demonstrated efficient measurement is a critical step towards entangling mechanical oscillators with other quantum systems .

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