Research Projects

This proposal primarily aims to investigate the types of quantum correlations responsible for enabling (prohibiting) discrimination of bipartite quantum states under local operations and classical communication (LOCC). In particular, we intend to quantify the success rate of bipartite as well as multipartite state discrimination in terms of what we call the generalized nonlocal and contextual correlations and use them as resources in different information processing tasks such as the device-independent quantum key distribution, randomness certification and secure quantum communication. It is a well known result in quantum information that nonorthogonal quantum states cannot be discriminated with certainty. Moreover, discrimination with certainty is not even possible for multipartite orthogonal states, if only LOCC is allowed. Given a set of multipartite orthogonal states, it is not always possible to say whether they can be discriminated or not under the LOCC. It is famously known that any two multipartite orthogonal states can be distinguished with certainty by LOCC. Researchers have also shown that for inconclusive discrimination of any two multipartite pure nonorthogonal states the optimal probability of error can be attained by using LOCC only. Furthermore, the same has been shown to be true even in the case of conclusive discrimination. Against the backdrop, it is also proven that four Bell states cannot be discriminated even in probabilistic way. It then seems that neither the orthogonality of two bipartite quantum states nor the entanglement content has a direct relation with the such discrimination tasks using LOCC. Thus it remains an open question what is the viable quantum correlation that permits the perfect discrimination of two Bell states in one hand and in other hand restricts one to discriminate between more than two bipartite orthogonal entangled states through LOCC. Another important question is that whether this correlation exists only in case of discrimination of bipartite orthogonal pure states or it also explains the multipartite orthogonal state discrimination tasks. Once we get the answers of the aforementioned questions, we may also investigate the characteristics of such quantum correlation for the case of multipartite non-orthogonal state discrimination tasks using LOCC. It is already known that conventional forms of nonlocal and contextual correlations offer advantages in various device-independent quantum information processing protocols. Notably, different facets of quantum correlations find important applications across a range of communication protocols. Therefore, even a partial characterization of the proposed, yet unexplored, form of nonlocal and contextual correlation—relevant to multipartite state discrimination protocols—could potentially lead to useful applications in a range of such communication protocols as well as other information processing tasks.