Abstract

Decoherence, i.e., the rapid destruction of the phase relation between two quantum states of a system caused by the entanglement of these two states with two different states of the environment,¹ is the main limiting factor for quantum information processing. For this reason, decoherence control is now becoming a rapidly expanding field of investigation. Decoherence control would be particularly useful in high-Q electromagnetic cavities. In fact, one of the few experimental realizations of a quantum gate is the Caltech’s “quantum phase gate,”² demonstrating conditional quantum dynamics between polarized modes in a high-finesse optical cavity. Moreover, the progressive decoherence of a mesoscopic Schrödinger cat state has been observed for the first time in the experiment of Brune et al.,³ where the linear superposition of two coherent states of a field in a microwave cavity, with classically distinct phases, has been generated and detected.

© 1998 Optical Society of America