Preparing a GHZ state, or an EPR state, with the one-atom maser

Abstract

When operated suitably, the one-atom maser can entangle the cavity field with two atoms such that the resulting state is a superposition of a Greenberger–Horne–Zeilinger (GHZ) state and another component. This unwanted component can be suppressed substantially by exploiting trapping states. Alternatively, for another choice of parameters the second component is an Einstein–Podolsky–Rosen (EPR) state. In both cases, one can pick out either the EPR or the GHZ component by measuring the parity of the cavity field with the aid of a third atom.