Pantheon SEMPARIS Le serveur des séminaires parisiens Paris

Statut Confirmé
Série LPTMS
Domaines cond-mat.stat-mech
Date Mardi 21 Mars 2023
Heure 14:00
Institut LPTMS
Salle Salle des séminaires du FAST et du LPTMS, bâtiment Pascal n°530
Nom de l'orateur Baldwin
Prenom de l'orateur Christopher
Addresse email de l'orateur
Institution de l'orateur University of Maryland
Titre Self-averaging and the replica trick in quantum spin glasses and SYK
Résumé The structure of the Sachdev-Ye-Kitaev (SYK) model is strikingly similar to the canonical mean-field models of spin glass theory, yet the resulting behavior is quite different --- the SYK model is "maximally chaotic" and has connections to quantum gravity at low temperature, whereas spin glasses instead have frozen dynamics and an intricate equilibrium structure. In the first part of this talk, we present some explanation as to why, by proving the following result: in any bosonic model with all-to-all random interactions, there must be a breakdown of self-averaging of the partition function, and thus the analysis used to study the (fermionic) SYK model cannot directly apply. In this sense, the fermionic nature of the SYK model is a necessary ingredient for its physics. In the second part of the talk, we consider the physical implications of a breakdown of self- averaging in more detail. We show that, surprisingly, self-averaging transitions need *not* be related to any spin glass physics. Doing so requires resolving some ambiguities in the replica trick that appear to have gone unaddressed until now.
Numéro de preprint arXiv
Commentaires Hybrid: onsite seminar + zoom. For zoom, please write to valentina.ros@universite-paris-saclay.fr or check http://lptms.u-psud.fr/fr/activites/seminaires/
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