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Decoherence, discord, and the quantum master equation for cosmological perturbations

Jamie McDonald, Timothy Hollowood Orcid Logo

Physical Review D, Volume: 95, Issue: 10

Swansea University Authors: Jamie McDonald, Timothy Hollowood Orcid Logo

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DOI (Published version): 10.1103/physrevd.95.103521

Abstract

We examine environmental decoherence of cosmological perturbations in order to study the quantum-to-classical transition and the impact of noise on entanglement during inflation. Given an explicit interaction between the system and environment, we derive a quantum master equation for the reduced den...

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Published in: Physical Review D
ISSN: 2470-0010 2470-0029
Published: American Physical Society (APS) 2017
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URI: https://cronfa.swan.ac.uk/Record/cronfa33006
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spelling 2020-07-30T09:26:06.3285617 v2 33006 2017-04-20 Decoherence, discord, and the quantum master equation for cosmological perturbations b9cddd775bd9658e28636c6f26f18a97 Jamie McDonald Jamie McDonald true false ea9ca59fc948276ff2ab547e91bdf0c2 0000-0002-3258-320X Timothy Hollowood Timothy Hollowood true false 2017-04-20 SBI We examine environmental decoherence of cosmological perturbations in order to study the quantum-to-classical transition and the impact of noise on entanglement during inflation. Given an explicit interaction between the system and environment, we derive a quantum master equation for the reduced density matrix of perturbations, drawing parallels with quantum Brownian motion, where we see the emergence of fluctuation and dissipation terms. Although the master equation is not in Lindblad form, we see how typical solutions exhibit positivity on super-horizon scales, leading to a physically meaningful density matrix. This allows us to write down a Langevin equation with stochastic noise for the classical trajectories which emerge from the quantum system on super-horizon scales. In particular, we find that environmental decoherence increases in strength as modes exit the horizon, with the growth driven essentially by white noise coming from local contribution to environmental correlations. Finally, we use our master equation to quantify the strength of quantum correlations as captured by discord. We show that environmental interactions have a tendency to decrease the size of the discord and that these effects are determined by the relative strength of the expansion rate and interaction rate of the environment. We interpret this in terms of the competing effects of particle creation versus environmental fluctuations, which tend to increase and decrease the discord respectively. Journal Article Physical Review D 95 10 American Physical Society (APS) 2470-0010 2470-0029 30 5 2017 2017-05-30 10.1103/physrevd.95.103521 COLLEGE NANME Biosciences COLLEGE CODE SBI Swansea University 2020-07-30T09:26:06.3285617 2017-04-20T11:59:01.0409989 Faculty of Science and Engineering School of Biosciences, Geography and Physics - Physics Jamie McDonald 1 Timothy Hollowood 0000-0002-3258-320X 2 0033006-20042017115959.pdf PRD_Final_13_Apr2017.pdf 2017-04-20T11:59:59.3070000 Output 1664457 application/pdf Accepted Manuscript true 2017-04-20T00:00:00.0000000 true eng
title Decoherence, discord, and the quantum master equation for cosmological perturbations
spellingShingle Decoherence, discord, and the quantum master equation for cosmological perturbations
Jamie McDonald
Timothy Hollowood
title_short Decoherence, discord, and the quantum master equation for cosmological perturbations
title_full Decoherence, discord, and the quantum master equation for cosmological perturbations
title_fullStr Decoherence, discord, and the quantum master equation for cosmological perturbations
title_full_unstemmed Decoherence, discord, and the quantum master equation for cosmological perturbations
title_sort Decoherence, discord, and the quantum master equation for cosmological perturbations
author_id_str_mv b9cddd775bd9658e28636c6f26f18a97
ea9ca59fc948276ff2ab547e91bdf0c2
author_id_fullname_str_mv b9cddd775bd9658e28636c6f26f18a97_***_Jamie McDonald
ea9ca59fc948276ff2ab547e91bdf0c2_***_Timothy Hollowood
author Jamie McDonald
Timothy Hollowood
author2 Jamie McDonald
Timothy Hollowood
format Journal article
container_title Physical Review D
container_volume 95
container_issue 10
publishDate 2017
institution Swansea University
issn 2470-0010
2470-0029
doi_str_mv 10.1103/physrevd.95.103521
publisher American Physical Society (APS)
college_str Faculty of Science and Engineering
hierarchytype
hierarchy_top_id facultyofscienceandengineering
hierarchy_top_title Faculty of Science and Engineering
hierarchy_parent_id facultyofscienceandengineering
hierarchy_parent_title Faculty of Science and Engineering
department_str School of Biosciences, Geography and Physics - Physics{{{_:::_}}}Faculty of Science and Engineering{{{_:::_}}}School of Biosciences, Geography and Physics - Physics
document_store_str 1
active_str 0
description We examine environmental decoherence of cosmological perturbations in order to study the quantum-to-classical transition and the impact of noise on entanglement during inflation. Given an explicit interaction between the system and environment, we derive a quantum master equation for the reduced density matrix of perturbations, drawing parallels with quantum Brownian motion, where we see the emergence of fluctuation and dissipation terms. Although the master equation is not in Lindblad form, we see how typical solutions exhibit positivity on super-horizon scales, leading to a physically meaningful density matrix. This allows us to write down a Langevin equation with stochastic noise for the classical trajectories which emerge from the quantum system on super-horizon scales. In particular, we find that environmental decoherence increases in strength as modes exit the horizon, with the growth driven essentially by white noise coming from local contribution to environmental correlations. Finally, we use our master equation to quantify the strength of quantum correlations as captured by discord. We show that environmental interactions have a tendency to decrease the size of the discord and that these effects are determined by the relative strength of the expansion rate and interaction rate of the environment. We interpret this in terms of the competing effects of particle creation versus environmental fluctuations, which tend to increase and decrease the discord respectively.
published_date 2017-05-30T03:40:37Z
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score 11.013731

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