Virtual Processes and Superradiance in Spin-Boson Models

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dc.creatorAlcalde, M. Aparicio
dc.creatorKullock, R.
dc.creatorSvaiter, N. F.
dc.date2008-07-03
dc.date.accessioned2026-07-07T12:39:07Z
dc.date.available2026-07-07T12:39:07Z
dc.descriptionWe consider spin-boson models composed by a single bosonic mode and an ensemble of $N$ identical two-level atoms. The situation where the coupling between the bosonic mode and the atoms generates real and virtual processes is studied, where the whole system is in thermal equilibrium with a reservoir at temperature $β^{-1}$. Phase transitions from ordinary fluorescence to superradiant phase in three different models is investigated. First a model where the coupling between the bosonic mode and the $j-th$ atom is via the pseudo-spin operator $σ^{,z}_{(j)}$ is studied. Second, we investigate the generalized Dicke model, introducing different coupling constants between the single mode bosonic field and the environment, $g_{1}$ and $g_{2}$ for rotating and counter-rotating terms, respectively. Finally it is considered a modified version of the generalized Dicke model with intensity-dependent coupling in the rotating terms. In the first model the zero mode contributes to render the canonical entropy a negative quantity for low temperatures. The last two models presents phase transitions, even when only Hamiltonian terms which generates virtual processes are considered.
dc.identifierhttps://arxiv.org/abs/0807.0639
dc.identifierhttp://arxiv.org/abs/0807.0639
dc.identifierJ.Math.Phys.50:013511,2009
dc.identifierdoi:10.1063/1.3040187
dc.identifier.urihttp://salesiana.dossiersoluciones.com/handle/123456789/218997
dc.subjectQuantum Physics
dc.titleVirtual Processes and Superradiance in Spin-Boson Models
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