Hyperfine and electric quadrupolar interaction-driven loschmidt echo in nanoscale nuclear spin baths
Author
Güldeste, Ekrem Taha
Advisor
Bulutay, Ceyhun
Date
2018-07Publisher
Bilkent University
Language
English
Type
ThesisItem Usage Stats
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Abstract
Environmental dynamics in solid state matrix is of much importance for quantum
information processing and storage purposes. Here, we first give a basic recipe to
get Loschmidt echo (LE) which is a measure of decoherence (loss of information
from the qubit) in heterogeneously interacting nuclear spin bath (NSB) in the
presence of Fermi-contact hyperfine and nuclear spin dipole-dipole interactions.
Then, by dropping the latter we discuss the basic dependencies of pure-dephasing
regime on size, initial polarization, hyperfine coupling inhomogeneity, spin quantum
number in nuclear spin environments, and arrive at a phenomenological
expression that governs all these attributes. For NSBs consisting of spin-I ≥ 1,
the effect of nuclear electric quadrupole interaction is also considered where its
biaxiality term has an in
uence on the decoherence process. Furthermore, a general
decoherence channel is also employed to see how phase-
ip rate affects LE.
After insights gained from these models, we consider two generic realistic systems,
namely, donor center and quantum dot and explain the power spectral density of
LE in these cases.