Upper Bound Imposed upon Responsivity of Optical Modulators

We study theoretically the responsivity of optical modulators. For the case of linear response we find using perturbation theory an upper bound imposed upon the responsivity. For the case of two mode modulator we find a lower bound imposed upon the optical path required for achieving full modulation when the maximum birefringence strength is given

Sensing Dispersive and Dissipative Forces by an Optomechanical Cavity

We experimentally study an optomechanical cavity that is formed between a mechanical resonator, which serves as a movable mirror, and a stationary on-fiber dielectric mirror. A significant change in the behavior of the system is observed when the distance between the fiber's tip and the mechanical resonator is made smaller than about 1 micrometer. The observed effects are attributed to the combined influence of Casimir force, Coulomb interaction due to trapped charges, and optomechanical coupling. The comparison between experimental results and theory yields a partial agreement

Damping in a Superconducting Mechanical Resonator

We study a mechanical resonator made of aluminum near the normal to super conductivity phase transition. A sharp drop in the rate of mechanical damping is observed below the critical temperature. The experimental results are compared with predictions based on the Bardeen Cooper Schrieffer theory of superconductivity and a fair agreement is obtained

Decoherence and Recoherence in a Vibrating RF SQUID

We study an RF SQUID, in which a section of the loop is a freely suspended beam that is allowed to oscillate mechanically. The coupling between the RF SQUID and the mechanical resonator originates from the dependence of the total magnetic flux threading the loop on the displacement of the resonator. Motion of the latter affects the visibility of Rabi oscillations between the two lowest energy states of the RF SQUID. We address the feasibility of experimental observation of decoherence and recoherence, namely decay and rise of the visibility, in such a system.Comment: 9 pages, 2 figure