Thursday 28 April 2016
to 13:00 at
Muhammad Sadiq (Stockholm University, Department of Physics)
Quantum mechanics is undoubtedly a weird field of science, which violates
many deep conceptual tenets of classical physics, requiring reconsideration of
the concepts on which classical physics is based. For instance, it permits persistent
correlations between classically separated systems, that are termed as
entanglement. To circumvent these problems and explain entanglement, hidden
variables theories–based on undiscovered parameters–have been devised.
However, John S. Bell and others invented inequalities that can distinguish between
the predictions of local hidden variable (LHV) theories and quantum
mechanics. The CHSH-inequality (formulated by J. Clauser, M. Horne, A.
Shimony and R. A. Holt), is one of the most famous among these inequalities.
In the present work, we found that this inequality actually contains an even
simpler logical structure, which can itself be described by an inequality and
will be violated by quantum mechanics. We found 3 simpler inequalities and
were able to violate them experimentally.
Furthermore, the CHSH inequality can be used to devise games that can
outperform classical strategies. We explore CHSH-games for biased and unbiased
cases and present their experimental realizations. We also found a remarkable
application of CHSH-games in real life, namely in the card game
of duplicate Bridge. In this thesis, we have described this application along
with its experimental realization. Moreover, non-local games with quantum
inputs can be used to certify entanglement in a measurement device independent
manner. We implemented this method and detected entanglement in a set
of two-photon Werner states. Our results are in good agreement with theory.
A peculiar form of entanglement that is not distillable through local operations
and classical communication (LOCC) is known as bound entanglement
(BE). In the present work, we produced and studied BE in four-partite Smolin
states and present an experimental violation of a Bell inequality by such states.
Moreover we produced a three-qubit BE state, which is also the first experimental
realization of a tripartite BE state. We also present its activation, where
we experimentally demonstrate super additivity of quantum information resources