2026-06-08T08:26:56Zhttps://docta.ucm.es/rest/oai/requestoai:docta.ucm.es:20.500.14352/180852023-08-25T10:29:08Zcom_20.500.14352_14col_20.500.14352_15
Docta Complutense
author
Pérez Fernández, P.
author
Relaño Pérez, Armando
2023-06-17T22:06:59Z
2023-06-17T22:06:59Z
2017-07-12
2470-0045
10.1103/PhysRevE.96.012121
https://hdl.handle.net/20.500.14352/18085
http://dx.doi.org/10.1103/PhysRevE.96.012121
https://journals.aps.org/
We study the thermodynamics of the full version of the Dicke model, including all the possible values of the total angular momentum j, with bothmicrocanonical and canonical ensembles. We focus on both the excited-state quantum phase transition, appearing in the microcanonical description of the maximum angular momentum sector, j = N/2, and the thermal phase transition, which occurs when all the sectors are taken into account. We show that two different features characterize the full version of the Dicke model. If the system is in contact with a thermal bath and is described by means of the canonical ensemble, the parity symmetry becomes spontaneously broken at the critical temperature. In the microcanonical ensemble, and despite that all the logarithmic singularities which characterize the excited-state quantum phase transition are ruled out when all the j sectors are considered, there still exists a critical energy (or temperature) dividing the spectrum into two regions: one in which the parity symmetry can be broken, and another in which this symmetry is always well defined.
eng
From thermal to excited-state quantum phase transition: The Dicke model
journal article
URL
https://docta.ucm.es/bitstreams/a88bd31d-c6c7-4718-a897-5412ad6473da/download
File
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62db87c3248fcb9f7954ff8b2ad00929
743066
application/pdf
Relaño61libre.pdf