Emergent Phenomena in Quantum Matter: From Symmetry to Dynamics

Contribution List

3. Hamiltonian Lattice Gauge Theory via Topological Quantum Field Theory

Yoshimasa Hidaka (YITP)

6/29/26, 10:00 AM

Hamiltonian lattice gauge theory, free from the sign problem, is regarded as a promising framework for real-time dynamics and finite-density physics. In this talk I propose an analytical approach to it, based on techniques from topological quantum field theory (TQFT). The gauge-invariant Hilbert space is constructed naturally, with charges and fluxes organized by the quantum double $D(G)$, and...

6. Lattice Study of Critical and Symmetry Breaking Phases with Categorical Symmetry

Chenjie Wang (The University of Hong Kong)

6/29/26, 1:30 PM

I will present a construction of a family of 1D quantum lattice models with unitary fusion category symmetry. These models generalize the well-known anyon chain construction and can be viewed as edge theories of 2D symmetry-enriched topological states. They realize a variety of interesting phases, including gapless critical phases and phases with spontaneously broken categorical symmetries. A...

31. Discussion

6/29/26, 3:30 PM

4. Defining Mixed State Phases of Matter

Jong Yeon Lee (University of Illinois Urbana-Champaign)

6/30/26, 10:00 AM

In this talk, I will present the series of work that explores the landscape of mixed-state phases of matter, from axiomatic approaches to information-theoretic/hydrodynamic consequences. First, I will establish a systematic framework to study mixed-state phases of matter. This is achieved by identifying three information-theoretic quantities that can play the role analogous to the spectral gap...

7. Projector, Neural, and Tensor-Network Representations of $\mathbb{Z}_N$ Cluster and Dipolar-cluster SPT States

Jung Hoon Han (Sungkyunkwan University)

6/30/26, 1:30 PM

The $\mathbb{Z}_N$ cluster-state wavefunction, a paradigmatic example of symmetry-protected topological (SPT) order with $\mathbb{Z}_N \times \mathbb{Z}_N$ symmetry, is expressed in various equivalent ways. We identify the projector-based scheme called the $P$-representation as the efficient way to express cluster and dipolar cluster state's wavefunctions. Employing the restricted Boltzmann...

9. Bootstrapping problem in tensor-network contraction

Seishiro Ono (ISSP)

6/30/26, 3:30 PM

Accurate contraction of tensor networks beyond one dimension is essential in various fields including quantum many-body physics. However, existing approaches typically rely on approximate contraction schemes and do not provide certified error bars. In this talk, we introduce an alternative perspective on tensor-network contraction problems via the numerical bootstrap framework. This technique...

16. higher Berry phases in 1+1-dimensional systems

Shuhei Ohyama (RIKEN)

6/30/26, 4:00 PM

The Berry phase is a fundamental topological invariant associated with parameterized families of quantum mechanical systems. It has played a central role in the classification of topological phases, particularly in free fermion and other non-interacting systems. The higher Berry phase can be regarded as a many-body generalization of this idea, designed to capture topological information that...

14. Topological Order in Three Spatial Dimensions and Beyond: Continuum Topological Field Theory, Diagrammatics, and Microscopic Constructions

Peng Ye (Sun Yat-sen University)

7/1/26, 10:00 AM

Topological orders in three spatial dimensions and beyond can support spatially extended excitations, such as loops and membranes. These excitations give rise to exotic topological phenomena that have no direct counterparts in two-dimensional anyon systems. In this talk, I will give an overview of recent progress on higher-dimensional topological order, with a focus on continuum topological...

12. Generalized Symmetries, Unstable Nambu-Goldstone Modes, and Self-Similar Inverse Cascades

Naoki Yamamoto (Keio University)

7/1/26, 1:30 PM

Generalized global symmetries provide not only a classification of phases, but also a dynamical organizing principle for nonequilibrium phenomena. In this talk, I will discuss two related developments. First, I will show that Nambu-Goldstone modes associated with ordinary and higher-form symmetries can become unstable in the presence of background fields. Familiar examples include the chiral...

10. Topological structure of sigma models

Kazuya Yonekura (Tohoku University)

7/2/26, 10:00 AM

I will discuss general topological structure of sigma model actions which are useful for both actions and sigma model anomalies. Modulo continuous deformations, those terms are classified by the Anderson dual of bordism. If time permits, I will also discuss generalization of sigma models by combining symmetries in a nontrivial way.

18. Effective field theory of operator scrambling from strong-to-weak symmetry breaking

Zhicheng Yang (Peking University)

7/2/26, 1:30 PM

Operator scrambling is usually diagnosed through the growth of out-of-time-ordered correlators (OTOCs), yet a general symmetry principle underlying their effective dynamics has remained elusive. We develop a symmetry-based effective field theory for operator scrambling, organized by a strong-to-weak U(1) symmetry breaking in operator space. The key observation is that the four-fold Keldysh...

11. Transport and puzzle of the old SU(2) anomaly at finite temperature

Nick Poovuttikul (Chulalongkorn University)

7/3/26, 10:00 AM

I will give a brief overview on the method on how to extract the the anomaly induced transport coefficients of finite temperature/density QFT starting from the bordism group and mapping torus that governed its global anomaly. After that, I will focus on the puzzling case of SU(2) anomaly where the anomaly matching forbid a naive analytic continuation of DC conductivities and enforce nontrivial...

28. Random Local Stabilizer Codes in Three Dimensions without String or Self-Similar Fractal Logical Operators

Han Yan (The University of Tokyo)

7/3/26, 1:30 PM

Quantum error-correcting codes (QECs) are essential components of quantum computation and have deep connections to quantum phases of matter. A key obstruction to passive self-correcting QECs is the presence of string logical operators, which can generate logical errors through constant-energy-barrier processes. Haah's Codes (fracton codes) showed that three-dimensional stabilizer codes can...

19. Effective theory of surface oscillations in self-bound superfluid droplets

Masaru Hongo (Niigata Universiity)

7/6/26, 10:00 AM

We investigate the low-energy dynamics of small-amplitude surface oscillations of spherical superfluid droplets in vacuum. Starting from the effective field theory of superfluid phonons, we derive an effective action governing the surface oscillations under a fixed particle-number constraint. The normal-mode eigenfrequencies $\omega_{\ell}$ for each angular momentum quantum number $\ell$ are...

29. Conformal invariance in non-Hermitian free-fermion critical system

Chang-Tse Hsieh (National Taiwan University)

7/6/26, 1:30 PM

Conformal invariance typically emerges in critical systems where the correlation length diverges, which is generally the case for Hermitian quantum systems without a spectral gap (in the thermodynamic limit). However, the situation becomes more subtle when Hermiticity is broken. In this talk, I will discuss when a non-Hermitian gapless quantum system can exhibit conformal invariance, focusing...

22. Classifying Finite-Temperature Phases Beyond Symmetry Breaking

Haruki Watanabe (The Hong Kong University of Science and Technology)

7/7/26, 10:00 AM

The classification of phases of matter at finite temperature has traditionally rested on Landau's paradigm of spontaneous symmetry breaking and local order parameters. At absolute zero, this paradigm has been decisively enlarged over the past decades: topologically ordered and symmetry-protected topological phases sharply distinguish ground states that share exactly the same symmetries. Most...

21. Topological lines in 1+1d chiral fermions

Kantaro Ohmori (RIKEN iTHEMS)

7/7/26, 1:30 PM

I will talk about a construction of topological lines in 1+1d holomorphic CFT in terms of symmetry TFT. In particular, the method is applied to a construction of topological lines in the chiral free fermion theory that intertwines the global symmetry currents nontrivially. Upon folding, this construction in turn provides a boundary condition in the non-chiral fermion theory that preserves a...

25. Rethinking Lattice QFT: from Category Theoretic Framework to Machine Learning Renormalization

Jing-Yuan Chen (Institute for Advanced Study Tsinghua University)

7/8/26, 10:00 AM

I will introduce a systematic way to rethink and refine lattice QFT, in order to make better connection to continuum QFT, by elevating the idea behind the Villain model into the language of higher category theory. Our primary purpose is to find unambiguous definitions for topological operators (and hence the associated symmetries and anomalies) on the lattice---the most notable example is the...

23. Gaplessness of charge- and neutral-excitations under Lieb-Schultz-Mattis constraints

Yasuhiro Tada (Hiroshima University)

7/8/26, 1:30 PM

We study gaplessness in one-dimensional quantum many-body systems with U(1) and translation symmetries under Lieb–Schultz–Mattis (LSM)–type constraints. While the LSM theorem imposes strong restrictions on the low-energy spectrum, the relation between charge- and neutral-excitations remains nontrivial in general interacting systems.

In this work, we show that, under physically reasonable...

15. An algorithm to generate two-dimensional critical lattice models using competing anyon condensation

Yu Zhao (Fudan University)

7/8/26, 2:00 PM

The critical behaviour at a second-order phase transition is often described by a conformal field theory. The restrictions imposed by conformal symmetry give rise to a number of important theoretical techniques that have made these theories central to the understanding of critical phenomena. However, efforts to classify conformal field theories have run into the challenge of identifying...

26. Non-Abelian phases and anyon superconductivity in twisted bilayer MoTe2: from numerics to theory

Gil Young Cho (KAIST)

7/9/26, 10:00 AM

In this talk, we present our recent theoretical studies of twisted bilayer MoTe(_2), where we have discovered non-Abelian fractional Chern insulators, fractional spin Hall insulators, and anyon superconductivity. Motivated by these findings, we then introduce a unified categorical framework that provides a common theoretical description of anyon superconductivity and the quantum Hall...

20. Dissipative Field Theories for Nambu-Goldstone Modes of Higher-Form Symmetries

Yuji Hirono (Tsukuba University)

7/9/26, 1:30 PM

Symmetry provides a powerful organizing principle for low-energy effective theories. Higher-form symmetries extend this idea to systems with extended charged objects, such as lines and surfaces. From this viewpoint, photons can be regarded as Nambu-Goldstone modes of a spontaneously broken U(1) one-form symmetry. In this talk, I will discuss how this symmetry-based picture can be extended to...

27. Quantum Geometry in Fractional Quantum Hall

Dung Nguyen (Institute For Interdisciplinary Research in Science and Education, Quy Nhon, Vietnam)

7/10/26, 10:00 AM

I will present an effective field theory for higher-spin chiral collective modes in fractional quantum Hall states, constructed on the basis of the guiding-center (W∞) algebra. The low-energy excitations are described as area-preserving deformations of the quantum Hall fluid, forming a hierarchy of chiral modes that includes the spin-2 graviton and higher-spin excitations. The report derives...

30. Monopole versus center vortex through the lens of twisted partition functions

Yuya Tanizaki (YITP, Kyoto)

7/10/26, 1:30 PM

We propose the gauge-invariant criteria for the center-vortex and monopole condensation using the twisted partition functions: Center vortex condensation is characterized by the torus twisted partition function, and the monopole condensation is by the lens-space twisted partition function. After presenting its physical justification, we prove that, under the presence of the mass gap, the...

5. Universal decay of mutual information and conditional mutual information in gapped quantum phases of matter

Liujun Zou (National University of Singapore)

Mutual information (MI) and conditional mutual information (CMI) are central tools to characterize the correlation and entanglement in quantum systems. However, their universal properties in quantum many-body systems were poorly understood before. In this talk, I will present our recent rigorous results on the universal properties of MI and CMI in gapped quantum matter, and discuss their...