Please use this identifier to cite or link to this item: https://doi.org/10.1007/s00220-017-2973-z
Title: Rigorous RG Algorithms and Area Laws for Low Energy Eigenstates in 1D
Authors: Arad, I 
Landau, Z
Vazirani, U
Vidick, T 
Issue Date: 2017
Publisher: Springer New York LLC
Citation: Arad, I, Landau, Z, Vazirani, U, Vidick, T (2017). Rigorous RG Algorithms and Area Laws for Low Energy Eigenstates in 1D. Communications in Mathematical Physics 356 (1) : 65-105. ScholarBank@NUS Repository. https://doi.org/10.1007/s00220-017-2973-z
Rights: Attribution 4.0 International
Abstract: One of the central challenges in the study of quantum many-body systems is the complexity of simulating them on a classical computer. A recent advance (Landau et al. in Nat Phys, 2015) gave a polynomial time algorithm to compute a succinct classical description for unique ground states of gapped 1D quantum systems. Despite this progress many questions remained unsolved, including whether there exist efficient algorithms when the ground space is degenerate (and of polynomial dimension in the system size), or for the polynomially many lowest energy states, or even whether such states admit succinct classical descriptions or area laws. In this paper we give a new algorithm, based on a rigorously justified RG type transformation, for finding low energy states for 1D Hamiltonians acting on a chain of n particles. In the process we resolve some of the aforementioned open questions, including giving a polynomial time algorithm for poly(n) degenerate ground spaces and an nO(logn) algorithm for the poly(n) lowest energy states (under a mild density condition). For these classes of systems the existence of a succinct classical description and area laws were not rigorously proved before this work. The algorithms are natural and efficient, and for the case of finding unique ground states for frustration-free Hamiltonians the running time is O~ (nM(n) ) , where M(n) is the time required to multiply two n × n matrices. © 2017, The Author(s).
Source Title: Communications in Mathematical Physics
URI: https://scholarbank.nus.edu.sg/handle/10635/179082
ISSN: 00103616
DOI: 10.1007/s00220-017-2973-z
Rights: Attribution 4.0 International
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