On the Measure of Nonclassicality of Field States

Abstract

The degree of nonclassicality of states of a field mode is analysed\nconsidering both phase-space and distance-type measures of nonclassicality. By\nworking out some general examples, it is shown explicitly that the phase-space\nmeasure is rather sensitive to superposition of states, with finite\nsuperpositions possessing maximum nonclassical depth (the highest degree of\nnonclassicality) irrespective to the nature of the component states. Mixed\nstates are also discussed and examples with nonclassical depth varying between\nthe minimum and the maximum allowed values are exhibited. For pure Gaussian\nstates, it is demonstrated that distance-type measures based on the\nHilbert-Schmidt metric are equivalent to the phase-space measure. Analyzing\nsome examples, it is shown that distance-type measures are efficient to\nquantify the degree of nonclassicality of non-Gaussian pure states.\n