Quantum amplification of motion of a mechanical oscillator
Shaun C. Burd, Raghavendra Srinivas, John J. Bollinger, Andrew C. Wilson, David J. Wineland, Dietrich G. Leibfried, Daniel H. Slichter, David T. Allcock
Detection of the weakest forces in nature and the search for new physics demand increasingly sensitive measurements of the motion of mechanical oscillators. However, the attainable knowledge of an oscillators motion is limited by quantum fluctuations that exist even if the oscillator is in its lowest possible energy state. Here we demonstrate a widely applicable technique for amplifying coherent displacements of a mechanical oscillator with magnitudes well below these zero-point fluctuations. The method involves applying two orthogonal squeezing interactions before and after a small displacement, resulting in an amplified coherent state, ideally with no added quantum noise. We implement this protocol with a trapped-ion mechanical oscillator and measure metrological enhancements of up to 17.5(2) dB.