IIIT Hyderabad Publications 


A few limits to Quantum Information TheoryAuthor: Subhasree Patro Date: 20180926 Report no: IIIT/TH/2018/69 Advisor:Indranil Chakrabarty AbstractQuantum superposition and entanglement (a special case of superposition) play a pivotal role in achieving information processing tasks which could otherwise be not possible through any classical resource. It is further interesting to note that these very properties constrict us from performing some tasks which are otherwise achievable classically. As quantum entanglement has proven to be a key resource for various informationtheoretic tasks, it’s numerous applications makes it imperative to study it’s behaviour. Considerable studies have been done on how to generate entanglement, the chief of which is by using global unitary operations. The thesis further examines the limits imposed on quantum information theory due to the probability structure of mixed states. In mixed states the probability occurs at two levels, first it starts as a description of the system as a statistical mixture, second as the intrinsic superposition that is contained by each entity of the ensemble. We witness how the global unitaries, that can make any pure separable state entangled, fail to generate entanglement for a class of mixed states. The discussion begins with the definition of separable states and nonlocal states. It is then followed by a concise study on the absoluteness of the above mentioned class of states. Following which is an extensive study on absoluteness of nonnegative conditional von Neumann entropy, which happens to be the decisive part of the second chapter. The thesis concludes by discussing another limit that superposition imposes on quantum theory. The impossibility to clone coherence of an arbitrary state. It also addresses the logical implication of nocloning of coherence which is the famous nocloning theorem. Full thesis: pdf Centre for Security, Theory and Algorithms 

Copyright © 2009  IIIT Hyderabad. All Rights Reserved. 