Please note that the list below only shows forthcoming events, which may not include regular events that have not yet been entered for the forthcoming term. Please see the past events page for a list of all seminar series that the department has on offer.

 

Past events in this series


Tue, 10 Nov 2026
13:00
L2

Non-invertible symmetry: from rational CFTs to the lattice

Corey Jones
(North Carolina State University )
Abstract

Finite non-invertible symmetries have been extensively studied in both (1+1)-dimensional conformal field theories and quantum lattice systems. The kinematics of these settings look very different. We will show that nevertheless, for a class of rational CFT symmetries preserving a common rational chiral algebra, the continuum and lattice descriptions are exactly equivalent in a precise sense. The main idea is to encode symmetry through the inclusion of symmetry-invariant observables into the full observable algebra. After adjoining symmetry-trivial infinite-dimensional degrees of freedom to an anyon chain, these inclusions can be identified by an isomorphism of algebras that preserves locality up to a uniformly bounded enlargement of regions in both directions. Starting from familiar examples of CFT defects and anyon chains, we will explain this equivalence, the resulting classification of local symmetry structures by fusion categories, and its implications for transporting states and dynamics between the continuum and the lattice.

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Tue, 17 Nov 2026
13:00
L2

The Rise and Fall of Black Hole Interiors: From Geometry to Krylov Complexity

Nicolo Bragagnolo
(Swansea)
Abstract
What happens to the interior of a black hole as it evaporates? In this talk, I will address this question in a model of Jackiw–Teitelboim gravity with an end-of-the-world brane entangled with an auxiliary radiation system. By studying a renormalized geodesic length and incorporating non-perturbative contributions from spacetime and replica wormholes, we find that the black hole interior initially grows, reaches a maximum near the Page time, and subsequently shrinks.
I will then present a complementary approach based on the Krylov spread complexity of the canonical purification of the black hole reduced density matrix. Using random matrix techniques, we find a Page-time crossover that becomes sharp in the semiclassical limit, reproducing the characteristic growth and subsequent suppression found in the gravitational description.
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Tue, 24 Nov 2026
13:00
L2

Emergent Hamiltonians from boundary symmetries

Jose Garre Rubio
(Vienna)
Abstract

We introduce a systematic framework for constructing emergent local commuting Hamiltonians in (d+1) dimensions from symmetries defined on a d-dimensional boundary. Starting from a generic d-dimensional symmetry, we gauge it by introducing layers of gauge fields carrying dual symmetries, which can in turn be gauged. The fixed points of this iterative gauging procedure yield (d+1)-dimensional stabilizer Hamiltonians built from local Gauss-law constraints. These Hamiltonians encode the emergent bulk order while realizing the original symmetry on the boundary.

I will show how, starting in one dimension, this construction reproduces familiar two-dimensional topological codes, such as the toric code, and naturally realizes all gapped boundary conditions as different one-dimensional symmetric phases at the boundary. The framework extends to higher-form and subsystem symmetries in arbitrary dimensions, yielding, for example, three-dimensional fracton models.

If time permits, I will also discuss how these symmetries can be classified within the framework of tensor networks.

Based on arXiv: 2403.07575, 2410.09044, and 2203.12563.
 

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