Wehrl's entropy and a measure of intermode correlations in phase space
Krzysztof Piątek, W. Leoński · Journal of Physics A Mathematical and General · 2001
The properties of the entangled pure states in phase space are analysed using the classical entropy introduced by Wehrl. The general entropy inequalities for non-entangled pure states are derived, which are violated by any entangled state . To measure the strength of intermode correlations in phase space the parameters related to these inequalities are proposed. As an example we study the correlations between amplitudes and phases for two-mode Fock states. We find that the amplitudes as well as phases of different modes are correlated. It is also shown that the degree of the intermode correlation strongly depends on the photon number difference in two-mode Fock states.