Enhanced Nonclassical Correlations in Entangled SU(1,1) Bosonic Coherent States

Abstract

Identification, characterization and manipulation of natural quantum resources play a pivotal role in assessing the possibilities of physical implementation and inherent bounds on the use of various quantum technologies. A very pertinent example of such resources is the nonclassicality a single particle system, for instance, that may arise due to quantum superposition of various eigenstates of the quantum system. In a multipartite systems, the nonclassicality of the constituent subsystems may be converted in to their mutual nonclassical correlation, such as quantum entanglement. These nonclassical properties and resulting nonclassical correlations are regarded as a key resource for a large variety of tasks related to quantum information, quantum computation protocols and various related technologies. However, the practical implementation of such quantum technologies does require some physical quantum system as an essential component. For instance, quantum optical systems, prepared in nonclassical states, have been proved as a testing ground for such physical implementations. Here we are aimed to present a resource theoretic formalism for nonclassical properties and resulting correlations in a special class of quantum optical field states. In this thesis, we consider a large class of optical coherent field states, namely bosonic su(1,1) coherent states, which models a large variety of physical situations of matter-field interaction and their nonclassical properties have been analyzed. In the case of multimode fields, we discuss the bipartite entanglement generation in the bosonic su(1,1) CSs using dichotomic observables and analyze their various nonclassical correlated properties using concurrence, joint excitation probability distribution and higher order quadrature squeezing, such as sum-squeezing and difference squeezing. In general, one of the main and important features of the CSs is that,being a quantum superposition of a set of discrete basis states by construction, they are yet represented by a continuous-variable which ascribe them ability to represent various physical situations in optical fields. In our work we introduce the discrete excitation of continuously parameterized bosonic su(1,1) CSs as tool to engineer their various nonclassical properties. Furthermore, we extend this formalism of discrete excitation to our previously constructed entangled su(1,1) CSs and analyze their nonclassical correlation. It has been observed that the nonclassical properties and resulting nonclassical correlations can be controlled (enhanced) by discrete excitation of continuously parameterized entangled su(1,1) CSs of light.