Quantum Measurements in Cavity Optomechanics

Over the last several years, research in the field of cavity optomechanics has developed extraordinarily sensitive and low loss devices as well as clever measurement techniques to probe macroscopic mechanical systems in the quantum regime.  If one observes carefully, the noise in optically detected mechanical resonators can reveal a remarkable tale of the fundamental quantum mechanics of measurement embodied by Heisenberg’s microscope type physics.  In this talk, I will review the basic consequences of quantum measurement backaction in the context of recent cavity optomechanics experiments ranging from nanoscale integrated photonic devices, to millimeter scale vibrating membranes, to extremely large interferometric gravitational wave observatories.  I will then discuss how these effects are being harnessed for useful purposes.  One set of applications consists of manipulating the quantum state of light with a mechanically mediated nonlinearity to generate squeezed light for quantum metrology or to coherently convert quantum information between vastly different frequency domains.   Another type of application involves carefully measuring the size of quantum noise for use as a fundamental scale for temperature metrology.