Establishment of correlated pure states through decay in a squeezed reservoir.

Our normal understanding of the dissipative relaxation of a quantum system interacting with a reservoir or heat bath leads us to expect that the final state of the quantum system is a mixed state characteristic of one subsystem in equilibrium with the larger reservoir. We show that the broadband squeezed vacuum has such strong correlations in its quantum noise that, although it represents a true reservoir, the decay of subsystems, such as pairs of atoms or oscillators interacting with a squeezed reservoir, relaxes to a pure state that reflects these strong correlations. © 1989 The American Physical Society