Abstract

Whether or not these Schrodinger cat states exist in a real physical system is still an open question. So far, no macroscopic superposition states have ever been observed experimentally. Recent work by Wolinsky and Carmichael [1,2] and Krippner, Munro and Reid have shown theoretically that a superposition of two macroscopically distinct coherent-states (a “Schrodinger-cat” state) may be produced in degenerate parametric oscillation in a transient regime. Interference fringes which indicate the existence of the macroscopic superposition states are indeed predicted in regimes where the parametric nonlinearity is sufficiently large compared to the signal cavity losses. Experimental criteria needed for the generationof macroscopic quantum superposition states using aparametric oscillation are thus established. The nonlinearity is too large to be experimentally viable and hence motivated by the work of Mecozzi and Tombesi [3] and Kennedy and Walls [4] who showed a definite improvement of the interference fringes visiblity to be possible in a χ³ nonlinearity medium in which the vacuum is replaced with a squeezed input. We analyse the effect of replacing the signal-mode vacuum input with a squeezed input and predict the fringes to be observable for lower nonlinearity values provided the squeezed field is sufficiently intense.

© 1996 Optical Society of America