Abstract

Although classical models of feedback schemes have been used for a long time to control dynamical noise, an analogous quantum theory of feedback has been developed only in the last fifteen years.^1-7 Recently there has been considerable interest in quantum feedback as a way to fight decoherence in isolated quantum systems, using the approach of Refs.^4-5 For example, it has been suggested as a way to create optical squeezed states,⁸ to create micromaser number states,⁹ to correct errors in quantum bits,¹⁰ and to protect optical and microwave Schrodinger cat states against dissipation.^11-13

© 2001 Optical Society of America