  The position variance of a single-mode Yuen states can go below the standard
quantum limit. For two-mode squeezed states, it is shown that the
time-dependent evolution of the entanglement of formation can be contractive,
going below that of the squeezed state with minimum Einstein-Podolsky-Rosen
dispersions, and increasing thereafter. The rate of change of the
Einstein-Podolsky-Rosen dispersions as a function of the two-mode phases
control this process. Contractive entanglement is shown to be equivalent to a
rotating phase space accompanied by time-dependent single-mode squeezing.

Quantum Physics