Darrick Chang
Caltech
One of the most intriguing questions associated with quantum theory is whether effects such as quantum coherence and entanglement can be observed at macroscopic scales. As a first step towards resolving this question, recently much effort has been directed toward quantum state preparation of high-Q modes of nano-mechanical oscillators -- in particular, cooling such modes to their quantum ground state. To reach the quantum regime, it is necessary to minimize the thermalization and decoherence rates of these systems, which thus far has necessitated the use of cryogenic operating environments. Here we propose a fundamentally different approach, where one optically levitates an entire mechanical system inside an optical cavity, thus eliminating any contact of the system with the environment through clamping or material supports. Such an approach should facilitate the emergence of quantum behavior even in room-temperature environments. In particular, we show theoretically that the center-of-mass motion of an optically levitated nanosphere can be laser-cooled to its quantum ground state starting from room temperature. We also describe a technique to transfer quantum states of motion onto light or vice versa. This can be used to entangle two spheres separated by large distances in different cavities, starting from a pair of entangled optical beams generated using conventional nonlinear optics. Conversely, the optical trapping fields can be manipulated to create highly non-classical states of motion, which subsequently can be mapped onto light. As two examples, we show that an optically levitated sphere can be used to generate squeezed states of light and single photons. These examples suggest tremendous potential to realize nonlinear optical processes or quantum information processing of light using opto-mechanical systems.
Thursday, January 21st at 4:00 PM
Room F235, Technological Institute
Refreshments are served at 3:30 PM
