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Fluctuations and non-Hermiticity in the stochastic approach to quantum spins

Begg, SE; Green, AG; Bhaseen, MJ; (2020) Fluctuations and non-Hermiticity in the stochastic approach to quantum spins. Journal of Physics A: Mathematical and Theoretical , 53 (50) , Article 50LT02. 10.1088/1751-8121/abbf87. Green open access

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Abstract

We investigate the non-equilibrium dynamics of isolated quantum spin systems via an exact mapping to classical stochastic differential equations. We show that one can address significantly larger system sizes than recently obtained, including two-dimensional systems with up to 49 spins. We demonstrate that the results for physical observables are in excellent agreement with exact results and alternative numerical techniques where available. We further develop a hybrid stochastic approach involving matrix product states. In the presence of finite numerical sampling, we show that the non-Hermitian character of the stochastic representation leads to the growth of the norm of the time-evolving quantum state and to departures for physical observables at late times. We demonstrate approaches that correct for this and discuss the prospects for further development.

Type: Article
Title: Fluctuations and non-Hermiticity in the stochastic approach to quantum spins
Open access status: An open access version is available from UCL Discovery
DOI: 10.1088/1751-8121/abbf87
Publisher version: https://doi.org/10.1088/1751-8121/abbf87
Language: English
Additional information: Original content from this work may be used under the terms of the Creative Commons Attribution 4.0 licence (https://creativecommons.org/licenses/by/4.0/). Any further distribution of this work must maintain attribution to the author(s) and the title of the work, journal citation and DOI.
UCL classification: UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Maths and Physical Sciences
UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Maths and Physical Sciences > London Centre for Nanotechnology
UCL > Provost and Vice Provost Offices > UCL BEAMS
UCL
URI: https://discovery.ucl.ac.uk/id/eprint/10158054
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