Quantum optomechanics beyond the quantum coherent oscillation regime

Interaction with a thermal environment decoheres the quantum state of a mechanical oscillator. When the interaction is sufficiently strong, such that more than one thermal phonon is introduced within a period of oscillation, quantum coherent oscillations are prevented. This is generally thought to preclude a wide range of quantum protocols. Here we show that the combination of pulsed optomechanics techniques with coherent control can overcome this limitation, allowing ground-state cooling, general linear quantum nondemolition measurements, optomechanical state swaps, and quantum-state preparation and tomography without requiring quantum coherent oscillations. Finally, we show how the protocol can break the usual thermal limit for classical sensing of impulse forces. (C) 2017 Optical Society of America