Cavity-quantized optical states—exploiting both polarization and quadrature degrees of freedom—offer a practical and accessible platform to encode, process, and decode information beyond the capabilities of classical resources. Polarization modes, which belong to discrete-variable (DV) systems, and quadrature observables, characteristic of continuous-variable (CV) systems, each provide distinct advantages in quantum information processing. However, they also present unique challenges in terms of implementation and integration with existing technological infrastructure.

My research primarily addresses the theoretical aspects of information processing using such quantum optical states. A central focus is to understand the role of exotic nonclassical and non-Gaussian features of these states, and how these characteristics contribute to various tasks in quantum information science and technology. More specifically, my work is largely directed toward quantum communication and its extensions into quantum computation.

A key part of this endeavor is identifying and quantifying the intrinsic "quantumness" of these optical states, particularly when such features act as resources in applied optics. An important strand of my research is the development of an experimentally viable, resource-theoretic framework to characterize this quantumness—commonly referred to as nonclassicality—within CV optical systems. Furthermore, I aim to extend this framework to DV systems, such as polarization- or spin-based optical modes, thereby providing a unified understanding of nonclassical resources across both domains.

Quantum Communication with optical hybrid states

Alongside the spin/polarization based DV systems and quadrature based CV systems, there exists another class of physical systems, formally known as the optical hybrid states, that possess both the DV and CV components. In recent times, such states are found to be highly efficient in various tasks of current-day interest ranging from quantum error-correction to error mitigation, quantum sensing to measurement-based-quantum-computation. However, despite their experimental realization in various setups and existance of a strong intrinsic correlation, such states are largely unexplored in quantum communication. 

In the current project, we analyze the role of such optical hybrid states in distributing quantum correlations over large distance - a major obstacle in developing sustainable and resource-efficient quantum network. By bringing forth the best of both DV and CV worlds we have already shown the superiority of these states in sharing high-quality quantum entanglement over long distances compared to the DV-only and CV-only approaches. Next, we focus on higher order tasks such as sharing Bell non-locality, loophole free Bell tests and so on.

Resource theory of optical nonclassicality

Quantum states of light tht can't be sampled with a positive definite distribution over the set of classical pure states--coherent states, are known to nonclassical states. Such optical states  possesing pseudo-probability distributions, in phase space, that could be negative or highly singular play a crucial role in understanding the fundamental character of the nature as well as enable non-trivial information processing tasks which are otherwise not possible. As a consequence, on the backdrop of an extensive analysis ever since its first mathematically consistent formulation in 1963 by Sudarshan and Glauber, obtaining a resource theoretic description of such exotic character of optical states has been a centre of interest over last few  decades. While such formulations provide a deeper understanding of the nonclassical character and their practical utility, most of them require convex optimization or lack the experimental feasibility. This necessitates further attention to the formulation of convex resource theory of optical nonclassicality.

In the current project, we analyze the possibility of obtaining such a mathematically rigorous formulation without any use of optimization that further admits experimental verification. Moreover, we also focus on extending such ideas to the case of entnglement theory as well as systems in finite dimension.