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Title:Pairing and entanglement: quantum Monte Carlo studies
Author(s):Yang, David Chang-Mo
Director of Research:Ceperley, David M
Doctoral Committee Chair(s):Stone, Michael
Doctoral Committee Member(s):DeMarco, Brian L; Gollin, George D
Department / Program:Physics
Degree Granting Institution:University of Illinois at Urbana-Champaign
Subject(s):quantum Monte Carlo
degenerate Fermi gas
path integral Monte Carlo
variational Monte Carlo
quantum entanglement
inhomogeneous superfluidity
many-body correlation
computational physics
density matrix
chemical bond
one-dimensional system
molecular physics
Abstract:Described in this dissertation is the use of quantum Monte Carlo methods to study two ideas in quantum many-body problems: superfluidity and entanglement. Density matrices are presented a central tool in the analysis, as are discussed in the review of path integral Monte Carlo (PIMC) and variational Monte Carlo (VMC) methods. PIMC is used to model a one-dimensional system of fermionic lithium atoms according to existing experiments, including a realistic temperature. New estimators of the pair momentum distribution are implemented, yielding in a clear in-situ signature of a pairing mechanism (dubbed FFLO after its first proposers) which implies a microscopic phase fluctuation in space between a normal fluid and a superfluid. VMC is used to model homonuclear diatomic molecules of period-2 elements. The degree of entanglement and the responsible electronic configurations in real space are quantified in terms of the entanglement spectra. Calculating the reduced denstity matrix as an intermediate step reveals a novel way of understanding chemical bonds, as exemplified by Be2 and C2 . Possible implications of these results in integrable many-body models and in quantum chemistry are discussed, as well as direction for future investigation.
Issue Date:2016-04-07
Rights Information:Copyright 2016 David Chang-Mo Yang
Date Available in IDEALS:2016-07-07
Date Deposited:2016-05

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