Quantum control of optomechanical systems

The field of quantum optomechanics, concerned with systems composed of electromagnetic and macroscopic mechanical oscillators in the quantum regime, has developed rapidly. Recent achievements include the demonstration of cooling of a mechanical oscillator to its quantum ground state and squeezing of the quantum noise of a quadrature of the mechanical oscillator below its ground-state value. We have recently described an efficient approach to the generation of (quantum entangled) two-mode squeezed states of two macroscopic mechanical oscillators via coupling to a single auxiliary electromagnetic cavity mode [Physical Review A89, 063805 (2014)]. The approach, relying on multi-tone driving of the cavity mode, is based on a form of quantum control known as reservoir engineering. The state has a clear signature in the cavity output spectrum. Beyond being of fundamental interest, such states are useful in sensing and quantum information processing applications. This work has been supported by a Travel Fellowship to Japan from the Australian Academy of Science.