Entanglement - A Queer In The World Of Quantum

The work is directed to represent some interesting and apparently peculiar features of entangled system in both pure as well as mixed state level. In pure state level we largely concentrated on the existence and different characteristics of bipartite incomparable pair of states. We proposed some schemes for deterministic local conversion of one pure bipartite state to another, incomparable in nature, by exploiting free unpreserved entanglement. Our next attempt is to probe the physics behind the existence of such incomparable pair of states. Then we connect incomparability to some fundamental no-go theorems of quantum mechanics. Assuming the existence of some physically impossible operations and then applying those operations locally, we are able to show a pair of incomparable states could be comparable with certainty. In the next part, we provide a new class of multipartite mixed states which are bound entangled but activable. We explore some interesting features of this class like, Bell correlation, local Pauli connection, local indistinguishability, etc. Lastly, we attempt to propose a data hiding scheme using that class of states.