Abstract

Quantum computing requires that coherent superpositions of pure states be protected from decoherence¹ or, if not protected, at least the resulting errors can be corrected.- Recently Schrodinger cat states, i.e., linear superpositions of coherent states with opposite phases of a radiation mode inside a microwave cavity, with small separation of the components, were created and their exponential decoherence in time were experimentally detected.³ Last year, similar nonclassical superposition states with "mesoscopic" separation were created in the center-of-mass motion of a single trapped ion.⁴ Cat states are very fragile with respect to the decoherent effects of damping. Any attempt to create cat states with larger separation will necessarily involve some attempt to mitigate the effects of decoherence. There is thus considerable motivation for considering schemes to preserve cat states in the presence of dissipation.

© 1997 Optical Society of America