Slow Decoherence of Superpositions of Macroscopically Distinct States

Linear superpositions of macroscopically distinct quantum states (sometimes also called Schr\"odinger cat states) are usually almost immediately reduced to a statistical mixture if exposed to the dephasing influence of a dissipative environment. Couplings to the environment with a certain symmetry can lead to slow decoherence, however. We give specific examples of slowly decohering Schr\"odinger cat states in a realistic quantum optical system and discuss how they might be constructed experimentally.