30 research outputs found
Quantum Correlations, Chaos and Information
Quantum chaos is the study of quantum systems whose classical description is
chaotic. How does chaos manifest itself in the quantum world? In this spirit,
we study the dynamical generation of entanglement as a signature of chaos in a
system of periodically kicked coupled-tops, where chaos and entanglement arise
from the same physical mechanism. The long-time entanglement as a function of
the position of an initially localized wave packet very closely correlates with
the classical phase space surface of section - it is nearly uniform in the
chaotic sea, and reproduces the detailed structure of the regular islands. The
uniform value in the chaotic sea is explained by the random state conjecture.
As classically chaotic dynamics take localized distributions in phase space to
random distributions, quantized versions take localized coherent states to
pseudo-random states in Hilbert space. Such random states are highly entangled,
with an average value near that of the maximally entangled state. Continuing on
our journey to find the footprints of chaos in the quantum world, we explore
quantum signatures of classical chaos by studying the rate of information gain
in quantum tomography. We find an increase in the rate of information gain and
hence higher fidelities in the process when the Floquet maps employed increase
in chaoticity. We make predictions for the information gain using random matrix
theory in the fully chaotic regime and show a remarkable agreement between the
two. The last part of this thesis is devoted to the study of the nature of
quantum correlations themselves. We present an operational interpretation of
quantum discord based on the quantum state merging protocol. Quantum discord is
the markup in the cost of quantum communication in the process of quantum state
merging, if one discards relevant prior information.Comment: Dissertatio