Condensed Matter Theory Seminar | February 01, 09:15
Aspects of quantum matter in and out of equilibrium
The talk is in three parts. Part 1: Universal spectral signatures of many-body-localization The notion of universality is enormously powerful in understanding equilibrium phases and phenomena. At the most practical level, it allows us to substitute a complicated problem for a much simpler one. A surprising notion of universality has been observed for quantum chaotic systems, which are said to constitute a non-equilibrium 'eigenstate phase' of matter. Correlations in the spectrum are observed to be reproduced by a particularly simple system- random matrix ensembles, which predict universal signatures, such as a `ramp' in the spectral-form-factor. I will argue the existence of analogous universal signatures for a different eigenstate phase constituted by many-body-localized systems. Based on joint work with Manas Kulkarni (ICTS-TIFR) and Jedediah Pixley (Rutgers). Part 2: Eigenstate phases with non-Abelian symmetry. A long-standing open question is whether there exist any eigenstate phases beyond the now-well-known examples of many-body-localized or quantum-chaotic systems. A promising possibility presents itself for systems with finite non-Abelian symmetries. By numerically studying a spin-chain with such a symmetry in the presence of disorder, we see some evidence for the presence of a novel eigenstate phase of matter. Based on joint work with Tzu-Chieh Wei (Stony Brook), Sriram Ganeshan (CCNY) and Lukasz Fidkowski (University of Washington). Part 3: Emergent supersymmetry in fermionic symmetry-protected-topological phases. Symmetry-protected topological phases are characterized by an almost trivial insulating bulk but exotic boundaries due to the presence of 't Hooft anomalies. These anomalies present themselves in manifold ways- protected gapless phases, Landau-forbidden deconfined quantum critical transitions and the absence of a trivial order. I will demonstrate that for a large class of fermionic SPT phases, the boundary anomaly presents itself in a fascinating manner- emergent supersymmetry with no fine tuning of any kind! This might present the most robust realization of supersymmetry in solid-state and cold atomic systems. Based on joint work with Juven Wang (Harvard)
ICTS, Bengaluru, Karnataka, Indiai
Zoom ( URL https://uni-koeln.zoom.us/j/92374710227 )
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