Nonclassicality and entanglement in continuous variable systems[HBNI Th34]

Abstract

Nonclassicality and entanglement are two important features exhibited by continuous variable quantum states. This thesis is centered on the connection between nonclassicality and entanglement in the context of continuous variable quantum systems. It is well explored in the context of Gaussian states, - in the context of squeezing nonclassicality. The connection in the context of nonclassical photon number statistics and antibunching is studied. Having brought out the connection between nonclassicality and entanglement, and having exposed nonclassicality as a resource, it is useful to understand this resource as being Gaussian and non-Gaussian. Chapters 2 and 3 primarily dealt with non-Gaussian states, and the non classicality associated with them. Chapter 7 brings out the essential difference between these two very different resources through the consideration of cumulants. A new measure for non-Gaussianity based on the negentrophy of the Q function is introduced. Chapter 6 shows that the scale invariance of the measure is demanded by the fact that scaling of Q function is a valid physical transformation.