2025 SEUYC Theoretical Physics Seminars -- Upcoming

18th April, 2025

Friday, 16:00-17:00

Jin Chen

（Xiamen University）

Abstract

In recent years, our understanding of the generalized symmetries has been greatly evolved in terms of topological defect surfaces in QFTs. In this talk, I will focus on the generalized symmetries in 2d CFTs and the symTFTs associated with them. I will explain that gauging different generalized symmetries in a 2d CFT are one-to-one correspondence to various Lagrangian algebras in the symTFTs. Further applying these data, one can construct topological interfaces connecting the original theory and the orbifolded one. Finally, I will show how to use these interfaces to map boundary states in different orbifold phases.

11th April, 2025

Friday, 16:00-17:00

Tomas Reis

(SISSA, Trieste, Italy)

Abstract

I will talk about the recently published https://arxiv.org/abs/2412.04387, where we look at resurgence of the large charge expansion of the identity block in CFT2. Specifically, we do the resurgence analysis of four-point functions with degenerate operators at finite cross-ratio z, both for 4 heavy operators and two heavy two light “HHLL". We see how resurgence sheds light on semi-classical approximations and their regimes of validity. We expand on how Stokes phenomena in the asymptotic series in large c are controlled by the cross-ratio z, that they reveal the other block in the OPE, and that this solves the “forbidden singularities” of Kaplan et al., which might be related to information loss and suggest future directions for resurgence in CFT2.

28th March, 2025

Friday, 16:00-17:00

(Offline)

Abstract

We utilize the symmetry groups of regular tessellations on two-dimensional surfaces of different constant curvatures, including spheres, Euclidean planes and hyperbolic planes, to encode a qubit or qudit into the physical degrees of freedom on these surfaces. We show that the codes exhibit decent error correction properties by analysis via geometric considerations and the representation theory of the isometry groups on the corresponding surfaces. Interestingly, we demonstrate how this formalism enables the implementation of certain logical operations via geometric rotations of the surfaces. We provide a variety of concrete constructions of such codes  associated with different tessellations, which give rise to different logical groups.

21st March, 2025

Friday, 16:00-17:00

Rong-xin Miao

(Sun Yat-sen University)

Abstract

Inspired by the Kovtun-Son-Starinet bound, we propose that holography impose a lower bound on the Casimir effect. For simplicity, we focus on the Casimir effect between parallel planes for 3d conformal field theories and briefly comment on the generalizations to other boundary shapes and higher dimensions. Remarkably, all the holographic models impose a universal lower bound of the Casimir effect. We verify the holographic bound by free theories, the Ising model, and $O(N)$ models at critical points and prove it for the 2d case.

14th March, 2025

Friday, 10:00-11:00

Rafael Nepomechie

(University of Miami)

Abstract

The spin-1/2 Heisenberg quantum spin chain is a paradigmatic model of theoretical physics. We consider the problem of preparing exact eigenstates of this model on a quantum computer. We begin, after briefly reviewing the basics of quantum computing, by considering the simpler problem of preparing Dicke states, whose solution we then generalize to Bethe states. We use the latter construction to estimate Bethe roots.

10th March, 2025

Monday, 14:00-15:00

(Offline)

René Meyer

(Julius-Maximilians-Universität Würzburg)

Abstract

I will discuss recent new examples providing new links between quantum information, holography and quantum gravity. I will first introduce a refinement of the usual entanglement entropy for theories with global conserved charges, the so-called symmetry resolved entanglement entropy, and discuss its implementation in AdS3/CFT2 (2012.11274, 2108.09210). I will in particular discuss the structure of entanglement in different charge sectors, which turns out trivial in theories with U(1) Kac-Moody symmetry. This property is called equipartition of entanglement. I will then discuss how W3 symmetric CFTs (2202.11111) break this equipartition property. Finally, I will present recent work (2212.09767) which employs boundary conformal field theory techniques to obtain exact results for the symmetry-resolved entanglement and in particular for the equipartition property in U(1) Kac-Moody symmetric CFTs.

7th March, 2025

Friday, 16:00-17:00

Kazumi Okuyama

(Shinshu University)

Recent developments in double-scaled SYK

KO_DSSYK_2025.pdf

Abstract

SYK model is an interesting toy model of holographic duality. In particular, the so-called double-scaled SYK (DSSYK), defined by taking a large N limit with the number p of the p-body interaction scaled as p=N^(1/2),  has attracted a lot of attention recently since DSSYK is exactly solvable thanks to the underlying quantum group symmetry. In this talk, I will briefly review the recent developments in DSSYK.

17th January, 2025

16:00-17:00

Marco Serone

(SISSA)

Abstract

The study of non-abelian gauge theories in compact or non-flat spaces can be useful to gather insights and new perspectives on the confinement problem. We consider Yang-Mills theory on four dimensional Anti-de Sitter space and wonder how signals of confinement in the bulk can be detected from boundary observables. The Dirichlet boundary condition cannot exist at arbitrarily large radius because it would give rise to colored asymptotic states in flat space and hence a deconfinement-confinement transition has to occur as the radius is increased. By perturbative computations we provide evidence for the scenario of merger and annihilation. Namely, the theory with Dirichlet boundary condition stops existing because it merges and annihilates with another theory.  We also derive a general result for the leading-order anomalous dimension of the so called displacement operator for a generic perturbation in Anti-de Sitter, showing that it is related to the beta function of bulk couplings.

10th January, 2025

16:00-17:00

Christoph Uhlemann

（Vrije Universiteit Brussel）

Abstract

I will discuss recent work on N=4 super-Yang-Mills theory with Gaiotto-Witten boundary conditions. This broad class of theories with rich boundary dynamics comprises the most supersymmetric boundary conformal field theories in four dimensions, and in the context of string theory it allows for a proper realization of double holography. We will discuss their holographic description, a tight interplay between the holographic duals and the matrix models arising from supersymmetric localization, defect one-point functions, and large-charge operators.

3th January, 2025

16:00-17:00

Ideal Majtara

（SISSA）

Abstract

The low-energy theory of 4d N=2 supersymmetric gauge theories is encoded in the Seiberg-Witten (SW) curve which is naturally related to an integrable system. For SU(2) gauge theories, in presence of Omega-background this integrable system is given by Painlevé equations. In this talk we will show that the Nekrasov partition functions of 4d SU(2) susy gauge theories on the blowup of spacetime are tau functions which solve the Painlevé equations in Hirota bilinear form. These solutions can be expressed as expansions in terms of the moduli of the quantum SW curve and the construction can be applied also to non-Lagrangian theories. Furthermore, these solutions have manifest modular properties which provide a natural non-perturbative completion of the corresponding topological string partition function and they directly lead to the BCOV holomorphic anomaly equations of the topological string.