U(2) invariant squeezing properties of pair coherent states

Abstract

The U(2) invariant approach is delineated for the pair coherent states to explore their squeezing properties. This approach is useful for a complete analysis of the squeezing properties of these two-mode states. We use the maximally compact subgroup U(2) of Sp(4,R) to mix the modes, thus allowing us to search over all possible quadratures for squeezing. The variance matrix for the pair coherent states turns out to be analytically diagonalisable, giving us a handle over its least eigenvalue, through which we are able to pin down the squeezing properties of these states. In order to explicitly demonstrate the role played by U(2) transformations, we connect our results to the previous analysis of squeezing for the pair coherent states.