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Development of Tensor Network Algorithms for Studying Classical and Quantum Many-Body Systems


Fishman, Matthew Theodore (2018) Development of Tensor Network Algorithms for Studying Classical and Quantum Many-Body Systems. Dissertation (Ph.D.), California Institute of Technology. doi:10.7907/44s6-0q68.


The field of tensor networks, kicked off in 1992 by Steve White's invention of the spectacularly successful density matrix renormalization group (DMRG) algorithm, has exploded in popularity in recent years. Tensor networks are poised to play a role in helping us solve some of the greatest open physics problems of our time, such as understanding the nature of high-temperature superconductivity and illuminating a theory of quantum gravity. DMRG and extensions based on a class of variational states known as tensor network states have been indispensable tools in helping us understand both numerically and theoretically the properties of complicated classical and quantum many-body systems. However, practical challenges to these techniques still remain, and algorithmic developments are needed before tensor network algorithms can be applied to more physics problems. In this thesis we present a variety of recent advancements to tensor network algorithms.

First we describe a DMRG-like algorithm for noninteracting fermions. Noninteracting fermions, naturally being gapless and therefore having high levels of entanglement, are actually a challenging setting for standard DMRG algorithms, and we believe this new algorithm can help with tensor network calculations in that setting.

Next we explain a new algorithm called the variational uniform matrix product state (VUMPS) algorithm that is a DMRG-like algorithm that works directly in the thermodynamic limit, improving upon currently available MPS-based methods for studying infinite 1D and quasi-1D quantum many-body systems.

Finally, we describe a variety of improvements to algorithms for contracting 2D tensor networks, a common problem in tensor network algorithms, for example for studying 2D classical statistical mechanics problems and 2D quantum many-body problems with projected entangled pair states (PEPS). One is a new variant of the corner transfer matrix renormalization group (CTMRG) algorithm of Nishino and Okunishi that improves the numerical stability for contracting asymmetric two-dimensional tensor networks compared to the most commonly used method. Another is the application of the VUMPS algorithm to contracting 2D tensor networks. The last is a new alternative to CTMRG, where the tensors are solved for with eigenvalue equations instead of a power method, which we call the fixed point corner method (FPCM). We present results showing the transfer matrix VUMPS algorithm and FPCM significantly improve upon the convergence time of CTMRG. We expect these algorithms will play an important role in expanding the set of 2D classical and 2D quantum many-body problems that can be addressed with tensor networks.

Item Type:Thesis (Dissertation (Ph.D.))
Subject Keywords:Tensor networks; entanglement; quantum many-body systems; matrix product states; projected entangled pair states; density matrix renormalization group; corner transfer matrix renormalization group; tensor product states
Degree Grantor:California Institute of Technology
Division:Physics, Mathematics and Astronomy
Major Option:Physics
Thesis Availability:Public (worldwide access)
Research Advisor(s):
  • Preskill, John P. (co-advisor)
  • White, Steven R. (co-advisor)
Group:Institute for Quantum Information and Matter
Thesis Committee:
  • Preskill, John P. (chair)
  • White, Steven R.
  • Chan, Garnet K.
  • Motrunich, Olexei I.
Defense Date:24 May 2018
Errata:In the updated version, it is clarified in Chapters 4 and 5 that higher accuracy can be obtained in a method we compare against in benchmarks if an alternative, higher accuracy SVD algorithm is used.
Funding AgencyGrant Number
NSF Graduate Research FellowshipDGE-1144469
Austrian Science Fund (FWF)GRW 1-N36
Record Number:CaltechTHESIS:05312018-184631141
Persistent URL:
Related URLs:
URLURL TypeDescription for chapter 2 for chapter 3 for chapter 5
Default Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:10992
Deposited By: Matthew Fishman
Deposited On:08 Jun 2018 20:31
Last Modified:02 Jun 2020 21:43

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