Pantheon SEMPARIS Le serveur des séminaires parisiens Paris

Statut Confirmé
Série LPENS-MDQ
Domaines cond-mat
Date Lundi 16 Avril 2018
Heure 13:30
Institut LPA
Salle L363-365
Nom de l'orateur Iadecola
Prenom de l'orateur Thomas
Addresse email de l'orateur
Institution de l'orateur
Titre Many-body spectral reflection symmetries and protected infinite-temperature degeneracy
Résumé Symmetry-protected zero modes in quantum physics traditionally arise in the context of ground states of many-body Hamiltonians, and are especially prominent in noninteracting problems. In this talk, I will discuss how protected zero modes can arise in otherwise generic interacting quantum many-body systems with spectral reflection symmetries. These many-body zero modes exist at finite energy densities above the ground state, and can even appear when conservation of energy is disposed of altogether; as such, they give rise to a notion of protected many-body degeneracy at "infinite temperature." I will discuss index theorems that protect these zero modes, and give examples of many-body systems that host them. In particular, I will introduce a class of nonintegrable spin chains that includes the so-called "Fibonacci chain" that was recently realized in Rydberg-atom quantum simulators, and show how the presence of zero modes can be definitively inferred from the long-time dynamics of certain operators. I will also show how this situation generalizes to periodically-driven (or "Floquet") quantum systems, where protected degenerate states can give rise to subharmonic response reminiscent of, but distinct from, that of discrete time crystals.
Numéro de preprint arXiv
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