Pairing and entanglement: quantum Monte Carlo studies

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

Yang, David Chang-Mo

关键词: 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;   

Others  :  https://www.ideals.illinois.edu/bitstream/handle/2142/90737/YANG-DISSERTATION-2016.pdf?sequence=1&isAllowed=y

美国|英语

来源: The Illinois Digital Environment for Access to Learning and Scholarship

【 摘 要 】

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.