Show simple item record

dc.contributor.authorBao, Chenfeng
dc.date.accessioned2019-05-22 17:22:20 (GMT)
dc.date.available2019-05-22 17:22:20 (GMT)
dc.date.issued2019-05-22
dc.date.submitted2019
dc.identifier.urihttp://hdl.handle.net/10012/14674
dc.description.abstractLoop optimization for tensor network renormalization (loop-TNR) is a real-space renormalization group algorithm suitable for studying 1+1D critical systems. While the original proposal by Yang et al. focused on classical models, we extend this algorithm with new techniques to enable accurate and efficient extraction of conformal data from critical quantum models. Benchmark results are provided for a number of quantum models, including ones described by non-minimal or non-unitary conformal field theories, showcasing both the strengths and limitations of loop-TNR. We discuss the subtle issue of non-analytic finite size effect in quantum lattice models and its impact on loop-TNR, and propose the use of virtual-space transfer-matrix to circumvent it, using the XY model as a demonstration. We then generalize loop-TNR to fermionic systems by incorporating Grassmann numbers, and benchmark the generalized algorithm on the t-V model. Next, we demonstrate a non-trivial application of loop-TNR by studying the 1D domain wall between untwisted and twisted 2D lattice gauge theories of finite groups G. We numerically study such domain walls for G = Z_N (with N<6) using loop-TNR, and discover a large class of gapless models. We also study the physical mechanism for these gapless domain walls and propose quantum field theory descriptions that agree perfectly with our numerical results. By taking advantage of the classification and construction of twisted gauge models using group cohomology theory, we systematically construct general lattice models to realize gapless domain walls for arbitrary finite symmetry group G. Such constructions can be generalized into arbitrary dimensions and might provide us a systematical way to study gapless domain walls and topological quantum phase transitions.en
dc.language.isoenen
dc.publisherUniversity of Waterlooen
dc.subjecttensor networksen
dc.subjectmany-body physicsen
dc.subjectquantum physicsen
dc.subjectstatistical physicsen
dc.titleLoop Optimization of Tensor Network Renormalization: Algorithms and Applicationsen
dc.typeDoctoral Thesisen
dc.pendingfalse
uws-etd.degree.departmentPhysics and Astronomyen
uws-etd.degree.disciplinePhysicsen
uws-etd.degree.grantorUniversity of Waterlooen
uws-etd.degreeDoctor of Philosophyen
uws.contributor.advisorTurok, Neil
uws.contributor.affiliation1Faculty of Scienceen
uws.published.cityWaterlooen
uws.published.countryCanadaen
uws.published.provinceOntarioen
uws.typeOfResourceTexten
uws.peerReviewStatusUnrevieweden
uws.scholarLevelGraduateen


Files in this item

Thumbnail

This item appears in the following Collection(s)

Show simple item record


UWSpace

University of Waterloo Library
200 University Avenue West
Waterloo, Ontario, Canada N2L 3G1
519 888 4883

All items in UWSpace are protected by copyright, with all rights reserved.

DSpace software

Service outages