Phys. Rev. Lett. 111, 183001 (2013)

Credit: © 2013 AUSTRALIAN NATIONAL UNIVERSITY

Controlling optomechanical interactions at the quantum level is challenging. The main barrier to reaching the quantum regime is thermal coupling to the surrounding environment. If a system can be effectively isolated, it will be free from thermal fluctuations. Now, Giovanni Guccione and co-workers from the Australian National University and Tianjin University, China, propose the use of a tripod-shaped optical cavity that enables a mirror to be optically levitated by radiation pressure associated with the intra-cavity fields. Calculations suggest that if the levitated mirror is made of fused silica with a mass of 0.3 mg, a diameter of 2 mm, and a reflectivity of 99.998%, a total power of 3 W in the three cavity beams and a cavity finesse of 1,000 will provide a sufficiently large force to suspend the mirror. The levitation region was estimated to be 30 nm wide in the horizontal directions, and 1 nm high in the vertical direction. The researchers say that the approach provides a useful platform for not only studying quantum and classical optomechanics but also performing gravitational field sensing and quantum state generation.