Soutenance de thèse: Saptarshi Majumdar


14:00 - 18:00

Petit amphi, bâtiment Pascal n° 530
rue André Rivière, Orsay, 91405

Type d’évènement

Carte non disponible

Localisation in open quantum systems

We investigate the zero-temperature phase diagram of a one-dimensional XXZ spin chain coupled with local dissipative baths composed of simple harmonic oscillators. In a finite magnetization sector, we map this system onto a two-dimensional classical action using bosonization. From this classical field theory, we find the existence of a BKT phase transition between the pre-existing Luttinger liquid phase and a new dissipative phase at zero temperature. This new phase is a gapless spin density wave with unaltered susceptibility and vanishing spin stiffness. These analytical predictions are verified against numerical Langevin dynamics simulations of the action. The local baths in the spin chain can also be interpreted as annealed disorder and they affect the transport properties. Particularly for subohmic baths, the static conductivity vanishes, which can be interpreted as a localization effect induced by the presence of dynamical disorder. Moreover, we analyze the model at zero magnetization and argue that in that case, the gapless spin density wave is replaced by a gapped antiferromagnetic phase.

Jury : Rosario Fazio (rapporteur), Laura Foini (co-directrice de thèse), Edmond Orignac (rapporteur), Alberto Rosso (directeur de thèse), Inès Safi, Grégory Schehr.

Retour en haut