IIIT Hyderabad Publications
Nonlocality and complementarity of quantum correlations and issues related to closed time like curves in quantum framework
Report no: IIIT/TH/2017/2
The thesis is based upon two important concepts of foundation of quantum mechanics, locality and complementarity. Violation of locality and presence of complementarity are key features of “quantumness” of a system distinguishing it from all classical systems that conform to the idea of local realism. The first part of the thesis is devoted to the investigations of issues related to non locality and complementarity of quantum correlations in multipartite scenarios, in particular, the Svetlichny model. Our investigations are based upon device independent approach valid irrespective of any theoretical setting. We show that there exists a complementary relationship in terms of the genuine non-locality as a principle between the system and subsystems. We investigate Svetlichny games in a multiparty binary input and output scenario with a threshold value of the winning probability as a signature of genuine multiparty non locality. We analytically show that in the Svetlichny games setup, there exists complementary relationship between Svetlichny correlations of n party versus Svetlichny correlations of k ≤ n party which arise due to no-signaling principle. In other words, the violation of locality for multiparty systems can not be arbitrary, it comes at the price of non violation of locality in the reduced subsystem. The latter is one of the major findings of the thesis. In addition to Svetlichny games, we consider many non local games like Mermin games, Bancal et. al’s IP, Guess Your Neighbors Input game and present the details of our numerical investigations in case of No-signaling and quantum correlations. We demonstrate that the numerical findings support of our main result obtained analytically. In the second part of the thesis, we have considered hypothetical yet theoretically possible situation, by considering the existing models of closed time like curves. It had been noted in the literature earlier that these models of closed time like curves give enormous power to achieve things which are computationally and physically impossible with the existing structure of quantum mechanics in the causality respecting region. Specifically, we show that it is possible to create an arbitrary superposition of unknown states in case CTCs are invoked in the quantum framework which is otherwise impossible. This is an important finding which should be added to the list of no-go results which become permissible by the allowance of closed time like curves in quantum framework.
Full thesis: pdf
Centre for Security, Theory and Algorithms
Copyright © 2009 - IIIT Hyderabad. All Rights Reserved.