Talks

Kiseok Kim 

Title: Dual holography as functional renormalization group

Abstract: We investigate the relationship between the functional renormalization group (RG) and the dual holography framework in the path integral formulation, highlighting how each can be understood as a manifestation of the other. Rather than employing the conventional functional RG formalism, we consider a functional RG equation for the probability distribution function, where the RG flow is governed by a Fokker-Planck-type equation. The central idea is to reformulate the solution of Fokker-Planck type functional RG equation in a path integral representation. Within the semiclassical approximation, this leads to a Hamilton-Jacobi equation for an effective renormalized on-shell action. We then examine our framework for an Einstein-Hilbert action coupled to a scalar field. Ap plying standard techniques, we derive a corresponding functional RG equation for the distribution function, where the dual holographic path integral serves as its formal solution. By synthesizing these two perspectives, we propose a generalized dual holography framework in which the RG flow is explicitly incorporated into the bulk effective action. This generalization naturally introduces RG β-functions and reveals that the RG flow of the distribution function is essentially identical to that of the functional RG equation. 

Sungbin Lee

Title: All to all interaction via multifractal wavefunctiom geometry

Abstract: We uncover a generic mechanism through which the intrinsic geometry of multifractal quantum wavefunctions generates effective all-to-all interactions in many-body systems. By analyzing the multifractal spectrum, we demonstrate that the simultaneous participation of widely separated length scales creates a global connectivity that bypasses local interaction constraints. This nonlocality leads to fast information scrambling, evidenced by sharp changes in the quenched dynamics of the quantum Fisher information and bipartite mutual information with the onset of negative tripartite mutual information. Such rapid scrambling is a defining feature of strongly chaotic quantum dynamics, and our results identify the systems with multifractal states as a promising solid-state platform for realizing this regime. More broadly, they reveal a new paradigm in which complex, multiscale wavefunction structure intrinsically generates long-range connectivity, providing a natural route to achieving nonlocal behavior in strongly correlated quantum materials. 

Jae-Yoon Choi

Title: The fate of ergodicity breaking in two-dimensions

Abstract: Disordered quantum many-body systems pose a central challenge in condensed matter physics, as their nonequilibrium dynamics are generally intractable for classical computation. Many-body localization (MBL), which is hypothesized to evade thermalization under strong disorder, represents an extreme limit of such behavior. In this talk, I will introduce the recent experimental results that investigate the stability of MBL in two dimensions using ultracold atoms in optical lattices with controllable system sizes up to 24x24sites. We probe the long-time dynamics through the decay of an initially prepared density-wave imbalance under two distinct disorder realizations: random and quasiperiodic disorder. For random disorder, the MBL crossover shifts to higher disorder strengths with increasing system size, consistent with avalanche-induced destabilization. In contrast, for quasiperiodic disorder, we observe no clear system-size dependence, suggesting a stable localized phase in two dimensions and highlighting the role of disorder correlations beyond one dimension.

Yili Wang

Title:  Strange Metals from Disorder 

Abstract: Without a satisfactory theoretical description, strange metals remain among the most puzzling problems in modern physics. In this talk, I will show how strange-metal behaviour can arise from disorder. It has been demonstrated that Yukawa-type all-to-all interactions between electrons and scalar bosons lead to linear-in-temperature resistivity, a key hallmark of strange metals. Building on this result, I will consider QED-type random interactions, as well as more general multi-field interactions in arbitrary dimensions. I will argue that Yukawa-type and QED-type interactions in (2+1) dimensions may constitute the fundamental building blocks underlying linear resistivity.

Debabrata Ghorai

Title: Holographic transport from quantum geometry

Abstract: In this talk, we present a new method to compute holographic transport directly from the fermionic retarded Green’s function using the quantum geometric tensor (QGT). This framework links fermionic spectral functions to transport in strongly coupled systems, with the black-hole background effectively playing the role of a Fermi–Dirac distribution. We demonstrate an insulator–to–metal transition from the DC conductivity and briefly discuss a holographic flat-band model and its transport properties using QGT formalism.

Jeong-Won Seo

Title: Discrete Symmetries and Holographic Weyl Systems

Abstract: We construct a holographic model of Weyl semimetals in which the emergence and organization of Weyl phases are dictated by discrete symmetries. A two-flavor Dirac field in asymptotically AdS(_5) serves as a minimal dual description of a boundary four-band structure (orbital/node (\otimes) spin), while Yukawa-type bulk deformations are classified by their transformation properties under (C), (P), (\mathcal T), and CPT. Imposing symmetry-compatible boundary conditions, the analysis shows that breaking either (P) or (\mathcal T) generically resolves a Dirac-like degeneracy into separated Weyl nodes with quantized chirality, and the resulting nodal arrangement is characterized through the boundary fermionic spectral response.

Seung Beom Hong

Title: Self-similar, altermagnetic spin texture in Ammann--Beenker quasicrystal

Abstract: Recently, a new class of collinear magnetism, known as altermagnetism(AM), has been reported, exhibiting interesting features arising from effective time-reversal symmetry associated with rotational symmetry. Existing classifications, however, are largely confined to periodic lattices with translational symmetry. Here we investigate AM in a quasiperiodic setting by studying the classical Heisenberg model on the Ammann-–Beenker (AB) tiling with eight-fold rotational symmetry. By introducing a family of exchange couplings associated with characteristic length scales of the AB tiling, we identify a set of analytically solvable points relevant to AM, at which the tiling decomposes into uncoupled spin segments. The segments fall into two classes under a specific exchange coupling. One class realizes perfectly collinear altermagnetic configurations, which imprint an alternating spin texture on the spin-resolved local density of states (LDOS) and thereby give rise to alternating spin-up and spin-down transport signals. The other class forms steering-wheel–like fractal clusters whose fractal depth controls the emergence of higher-generation segments and gives rise to size-dependent hidden peaks in the spin structure factor reflecting the hierarchical geometry of the tiling. Taken together, our results support the view that AM can occur without translational symmetry in segmented quasiperiodic lattices, and suggest that size-dependent features in spin-resolved LDOS, structure factor, and transport provide a natural diagnostic for distinguishing AM from other magnetic orders in quasicrystalline systems.