Superradiant Quantum Phase Transition in Open Systems: System-Bath Interaction at the Critical Point

Fuente: arXiv
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Autori principali: Lamberto, Daniele, Orlando, Gabriele, Savasta, Salvatore
Natura: Preprint
Pubblicazione: 2024
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author Lamberto, Daniele
Orlando, Gabriele
Savasta, Salvatore
author_facet Lamberto, Daniele
Orlando, Gabriele
Savasta, Salvatore
contents The occurrence of a second-order quantum phase transition in the Dicke model is a well-established feature. On the contrary, a comprehensive understanding of the corresponding open system, particularly in the proximity of the critical point, remains elusive. When approaching the critical point, the system inevitably enters first the system-bath ultrastrong coupling regime and finally the deepstrong coupling regime, causing the failure of usual approximations adopted to describe open quantum systems. We study the interaction of the Dicke model with bosonic bath fields in the absence of additional approximations, which usually relies on the weakness of the system-bath coupling. We find that the critical point is not affected by the interaction with the environment. Moreover, the interaction with the environment is not able to affect the system ground-state condensates in the superradiant phase, whereas the bath fields are infected by the system and acquire macroscopic occupations. The obtained reflection spectra display lineshapes which become increasingly asymmetric, both in the normal and superradiant phases, when approaching the critical point.
format Preprint
id arxiv_https___arxiv_org_abs_2411_16514
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle Superradiant Quantum Phase Transition in Open Systems: System-Bath Interaction at the Critical Point
Lamberto, Daniele
Orlando, Gabriele
Savasta, Salvatore
Quantum Physics
The occurrence of a second-order quantum phase transition in the Dicke model is a well-established feature. On the contrary, a comprehensive understanding of the corresponding open system, particularly in the proximity of the critical point, remains elusive. When approaching the critical point, the system inevitably enters first the system-bath ultrastrong coupling regime and finally the deepstrong coupling regime, causing the failure of usual approximations adopted to describe open quantum systems. We study the interaction of the Dicke model with bosonic bath fields in the absence of additional approximations, which usually relies on the weakness of the system-bath coupling. We find that the critical point is not affected by the interaction with the environment. Moreover, the interaction with the environment is not able to affect the system ground-state condensates in the superradiant phase, whereas the bath fields are infected by the system and acquire macroscopic occupations. The obtained reflection spectra display lineshapes which become increasingly asymmetric, both in the normal and superradiant phases, when approaching the critical point.
title Superradiant Quantum Phase Transition in Open Systems: System-Bath Interaction at the Critical Point
topic Quantum Physics
url https://arxiv.org/abs/2411.16514