To Poster Presenters
Schedule and Venue
Poster sessions will be held on August 5 (Tue) and August 6 (Wed) in rooms Y206 and Y306 (upstairs from the main auditorium; details will be provided upon arrival).
Poster Number and Location
Please check your name, session date, location, and assigned poster number in the Poster Presentations section below.
Poster Setup
Please put up your poster on the designated board before the first poster session on August 5 (Tue). Each board accommodates an A0-size portrait poster (86.8 cm width × 151.5 cm height). Only one side of each board may be used. Magnets will be available to affix posters. Posters should be removed after Poster Session 2 on August 6 (Wed).
Poster Presentations
August 5 (Tue) 15:00-16:30
Poster Session 1
- P1. Adwait Naravane (Ghent University)
TNRKit.jl: Open source software for Tensor Network Renormalization
Renormalization group is central to the study of quantum many body systems near criticality. Quantum Field Theories can be studied using the path integral formalism where they are described by summing over classical field configurations. Both these things can be numerically investigated through the use of Tensor Network Renormalisation. TNRKit.jl is an open source julia library designed to perform TNR simulations on two and three dimensional models of interest. As it is built on top of TensorKit.jl, it can handle Quantum models with discrete and continuous symmetries and also fermionic parity.
- P3. Masahiko Yamada (University of Tokyo)
Matrix product renormalization group
We have proposed a Matrix Product Renormalization Group (MPRG) as a new framework for solving various quantum many-body problems. MPRG can be regarded as a generalization of the Density Matrix Renormalization Group (DMRG) to high dimensions. Compared to DMRG, MPRG can be directly applied to infinite systems, high-dimensional systems, and systems at finite temperature. By utilizing continuous projected entangled pair states (cPEPS), we can also solve two-dimensional systems at finite temperatures. In terms of accuracy, cPEPS achieves approximately one order of magnitude higher accuracy than PEPS when using the same bond dimension. Observables at finite temperature, such as the specific heat, have also been compared with quantum Monte Carlo simulations. Since there are no sign problems, Trotter errors, or finite size effects, the observables can be easily extrapolated to the thermodynamic limit based solely on the scaling of the bond dimensions.
- P5. Haruki Yagi (University of Tokyo)
On Universality Classes of Typical Entanglement Under Symmetries
"Wigner showed that group symmetries in quantum mechanics are represented by unitary or anti-unitary operators, and Dyson demonstrated that typical Hamiltonians invariant under such symmetries fall into three robust universality classes. From a modern perspective, two puzzles remain. (i) While the classification of operators is well established, there are inconsistencies with that for states/entanglement. (ii) In the case of higher-form/non-invertible symmetries, which have recently attracted significant interest, the classification of universality classes remains unclear. In response to these questions, we discuss analogues of the universality classes for Haar-random quantum entanglement in two setups. Part I: We argue that random matrix universality is completed by symmetry fractionalization. Part II: We examine whether the universality classes emerging under the action of higher-form/non-invertible symmetries are already known or not."
- P7. Zhian Jia (National University of Singapore)
- P9. Ce Shen (BIMSA)
Manufacturing Critical Lattice Models with SymTFT
We give a novel algorithm to generate critical 2D lattice models in a controlled and systematic way. These 2D models are realized by giving critical boundary conditions to 3D topological orders (symTOs/symTFTs) described by string-net models. We engineer these critical boundary conditions by introducing a commensurate amount of non-commuting anyon condensates. Our structured method generates an infinite family of critical lattice models, including the A-series minimal models, and uncovers previously unknown critical points with Haagerup symmetry.
- P11. Yuman He (Hong Kong University of Science and Technology)
Stacked Tree Construction for Free-Fermion Projected Entangled Pair States
The tensor network representation of a state in higher dimensions, say a projected entangled-pair state (PEPS), is typically obtained indirectly through variational optimization or imaginary-time Hamiltonian evolution. Here, we propose a divide-and-conquer approach to directly construct a PEPS representation for free-fermion states admitting descriptions in terms of filling exponentially localized Wannier functions. Our approach relies on first obtaining a tree tensor network description of the state in local subregions. Next, a stacking procedure is used to combine the local trees into a PEPS. Lastly, the local tensors are compressed to obtain a more efficient description. We demonstrate our construction for states in one and two dimensions, including the ground state of an obstructed atomic insulator on the square lattice.
- P13. Atis Yosprakob (YITP, Kyoto University)
Clifford-augmented MPS technique for fermionic systems
Reducing entanglement entropy is a key strategy for improving the efficiency of Matrix Product States (MPS), especially when simulating highly entangled quantum systems. Clifford-augmented MPS (CAMPS) is a recent approach that incorporates Clifford gates into the MPS ansatz to transform the basis in a way that compresses entanglement without altering the physical content of the state. This enhancement enables better classical simulability by exploiting the efficient representation of stabilizer-like structures, while preserving accuracy for non-stabilizer states. In this talk, we develop a fermionic counterpart of CAMPS using Grassmann tensor networks, which naturally encode fermionic statistics. This framework allows us to explore the impact of Clifford transformations on entanglement and computational cost in fermionic systems directly without relying on the fermion-spin transformation. Some benchmark results for the tight-binding model are presented.
- P15. Chao LI (RIKEN-AIP)
Toward a Tensor Brain: Tractable Quantum-Informatic Modeling of Brain Twins
We propose Tensor Brain, a quantum-informatic proposal for modeling and generating discrete-time neuronal spike trains using tensor network structures inspired by quantum probability theory. By encoding brain activity as quantum events within a tensorized Hilbert space and leveraging tensor networks, our approach enables compact, expressive modeling of high-dimensional neural activity. To overcome the exponential scaling in multi-neuron systems, we introduce structured sparsity and entanglement control, allowing tractable yet flexible representations. We integrate the Free Energy Principle (FEP) into this quantum setting, deriving a loss function grounded in quantum measurement theory and information content. Training is performed via Stiefel-manifold optimization to maintain unitarity constraints, ensuring both physical plausibility and efficient learning. Our method supports biologically interpretable sampling and inference aligned with the Born rule, and demonstrates promising performance on synthetic and benchmark neural data. This proposal establishes a scalable, theoretically grounded foundation for quantum-aware brain modeling and opens new directions for "digital brain" using tensor networks.
- P17. Haruki Shimizu (University of Tokyo, ISSP)
Complex entanglement entropy for complex conformal field theory
Conformal field theory underlies critical ground states of quantum many-body systems. While conventional conformal field theory is associated with positive central charges, nonunitary conformal field theory with complex-valued central charges has recently been recognized as physically relevant. Here, we demonstrate that complex-valued entanglement entropy characterizes complex conformal field theory and critical phenomena of open quantum many-body systems. This is based on non-Hermitian reduced density matrices constructed from the combination of right and left ground states. Applying the density matrix renormalization group to non-Hermitian systems, we numerically calculate the complex entanglement entropy of the non-Hermitian five-state Potts model, thereby confirming the scaling behavior predicted by complex conformal field theory.
- P19. Wenqing Xie (Hong Kong University of Science and Technology)
Unitary Network: Tensor network unitaries with local unitarity
We propose a novel structure for tensor network unitaries, called \textit{unitary network}. In contrast to the existing matrix product unitary architecture, each local tensor in a unitary network is required to be a unitary matrix upon suitable reshaping. Unitary networks can express global unitary operators without invariance, and can represent unitaries that do not preserve locality even with finite bond dimensions. In particular, we show that the class of unitary network encompasses global unitaries which preserve locality up to exponentially suppressed tails, as in those that naturally arise from the finite-time evolution of local Hamiltonians. Unitary networks also exhibit net entropy flow, extending the corresponding index defined for quantum cellular automata to situations where locality is not preserved.
- P21. Canceled
- P23. Yiting Mao (Zhejiang University)
Diagnosing thermalization dynamics of non-Hermitian quantum systems via GKSL master equations
The application of the eigenstate thermalization hypothesis to non-Hermitian quantum systems has become one of the most important topics in dissipative quantum chaos, recently giving rise to intense debates. The process of thermalization is intricate, involving many time-evolution trajectories in the reduced Hilbert space of the system. By considering two different expansion forms of the density matrices adopted in the biorthogonal and right-state time evolutions, we have derived two versions of the Gorini-Kossakowski-Sudarshan-Lindblad master equations describing the non-Hermitian systems coupled to a bosonic heat bath in thermal equilibrium. By solving the equations, we have identified a sufficient condition for thermalization under both time evolutions, resulting in Boltzmann biorthogonal and right-eigenstate statistics, respectively. This finding implies that the recently proposed biorthogonal random matrix theory needs an appropriate revision. Moreover, we have exemplified the precise dynamics of thermalization and thermodynamic properties with test models.
- P25. Canceled
- P27. Masano Keisuke (Nihon University)
Exactly solvable multi-band model of correlated lattice electrons
"We propose an exact solvable Hamiltonian that introduces long-range interactions into the Harper model with spin degrees of freedom. The Harper model is a two-dimensional tight-binding model in a magnetic field in which the magnetic field is taken in the Peierls substitution and the periodic modulation potential is obtained by eliminating the one-dimensional direction by a Fourier transform. The hopping terms form multi-bands due to their periodic modulation. The ground state and thermodynamic quantities are analytically obtained. If the interaction is an attraction, the ground state consists of electron pairs of opposite spin. However, the low-energy excitations are not of the particle-hole type in the non-interacting case, but rather pairwise excitations across the Fermi surface. In the repulsive case, there are always zero-energy excitations at the general filling level, and the system is metallic. Depending on the magnitude of the repulsive interactions, there are two types of Fermi surfaces in the ground state: the Fermi surfaces of electron pairs with opposite spins and the Fermi surfaces of single spins. References [1] Hatsugai and Kohmoto, J. Phys. Soc. Jpn. 61, 2056 (1992) [2] Dmitry Manning-Coe and Barry Bradlyn, Phys. Rev. B 108, 165136 (2023)"
- P29. Ayumi Ukai (Kyoto University / RIKEN RQC)
Effective Hamiltonian for an Equilibrium State
An approximate ground state projector (AGSP) for a gapped ground state is often constructed as a polynomial of the Hamiltonian. However, when the Hamiltonian has a large norm, technical difficulties arise, especially in infinite systems, and the computational efficiency of polynomial approximations can decline. To overcome these issues, the idea of the effective Hamiltonian is employed. Here, the effective Hamiltonian refers to one in which the contributions from energy regions significantly far from the target equilibrium state are cut off, resulting in a smaller norm. In this work, we rigorously prove that the spectra of the original Hamiltonian and the effective Hamiltonian remain almost unchanged near the equilibrium state. In particular, we show that a ground state with a spectral gap can be considered as a gapped ground state for the effective Hamiltonian as well.
- P31. Canceled
- P33. Mingcheng Yi (The University of Tokyo)
Monte Carlo Tomography: Estimating Von Neumann Entanglement Entropy
We present a general framework for estimating ground-state von Neumann entanglement entropy in quantum many-body systems, inspired by the idea of quantum tomography. Reduced density matrices for small subsystems are first sampled via Monte Carlo simulations. These local data are then compressed into a global tensor network representation using machine learning techniques. We validate the reconstructed global state by examining various physical observables, and find strong evidence that our method enables accurate and scalable estimation of von Neumann entanglement entropy.
August 6 (Wed) 15:00-16:30
Poster Session 2
- P2. Canceled
- P4. Kevin Vervoort (Ghent University)
Extracting Average Properties of Disordered Spin chains with translationally invariant tensor networks
We develop a tensor network-based method for calculating disorder-averaged expectation values in random spin chains without having to explicitly sample over disorder configurations. The algorithm exploits statistical translation invariance and works directly in the thermodynamic limit. We benchmark our method on the infinite-randomness critical point of the random transverse field Ising model.
- P6. Ching-Yu Yao (University of Tokyo, ISSP)
Lattice Translation Modulated Symmetries and Modulated SymTFT
Tensor networks have been a powerful tool for studying generalized symmetries. In this presentation, I will introduce how to describe the information of lattice translation modulated symmetries in 1+1D using tensor networks, and classify the gapped phases. Furthermore, I will discuss how to encode the modulation in the corresponding bulk theory.
- P8. Weicheng Ye (University of British Columbia)
- P10. Kaixin Ji (Fudan University)
New CFTs with Categorical Symmetric Loop-TNR
In the 1+1d generalized Landau paradigm, there is a gapped phase associated to each Frobenius algebra of a spherical category. In this poster, we present a canonical construction of critical theories from their phase transitions. It is represented as a strange correlator between the F symbols and Frobenius data. A new tensor network renormalization scheme is introduced to calculate the phase diagram and critical data, which explicitly preserve the category symmetry embedded in the F symbols.
- P12. Che-Chia Hsu (National Tsing Hua University)
Matrix Product States for Discrete Scale Invariant Solutions in Efimov Physics
In Efimov physics, the discrete invariant solutions and the limit cycle behavior are crucial features that must be considered at different length scales. To solve the large-scale challenge, we consider the matrix product state (MPS) with the quantized tensor train (QTT) framework that was developed recently. In the scale-invariant Hamiltonian of Efimov physics, we propose the gauge transformation method to represent the scaling potential without any approximation in the matrix product operator (MPO) stage and give the uniform rescaling for the renormalization group (RG) transformation to identify the limit cycle. In addition, we also propose two additional methods for constructing related types of functions in MPS. The first method can use the function to construct its reciprocal function with the aid of density matrix renormalization group (DMRG), and the second method provides an applicable expansion in QTT representation. In summary, these techniques can be used to construct reciprocal functions, identify scaling functions, and study RG transformations.
- P14. Ryo Watanabe (Osaka University)
Quantum-inspired computation with 2D tensor networks
"Variational quantum algorithms (VQAs) have been considered as current approaches for exploiting noisy quantum hardware. We expect that their usefulness stems from enabling the simulation of unitary dynamics and the measurement of expectation values in large $n$-qubit systems, and there have been numerous reports where current quantum hardware could surpass numerical simulations using conventional (classical) computers. Following this, a range of refined classical simulation approaches has been developed that refute these results. For contrast, the Quantum Approximate Optimization Algorithm (QAOA) is known as one of the most promising practical uses of quantum computers among VQAs, because QAOAs rely on sampling bitstrings from quantum states. We benchmarked with these 2D-TN techniques for Quantum Approximate Optimization Algorithm (QAOA) for an Ising spin glass Hamiltonian. In the experiment, we employed the transfer learning where parameters are optimized in small problem instances. By simulating circuits at depths well beyond what the state of the art can physically run, we clearly showed that TN simulation could be reasonable to sample the solutions better than those from current quantum hardwares, and shade light on the effect of transfer learning applied to the instance with large system size."
- P16. Canceled
- P18. Kimia Masoudifar (Sharif University of Technology)
Non-Equilibrium Dynamics of One-Dimensional Quantum Systems under Quench
Quantum quenches in one-dimensional spin systems offer a powerful probe of entanglement growth, information propagation, and thermalization in closed many-body systems. In this study, we perform both global and local quenches of the transverse field in the Ising model and the anisotropy ¢ in the spin-? XXZ (Heisenberg) chain. In global quenches, the entire external field or ¢ is suddenly changed across the chain, whereas in local quenches we perturb a single bond or site. We evolve initial product or weakly entangled states via Time-Evolving Block Decimation (TEBD), first benchmarking against Exact Diagonalization for N ? 20 to calibrate bond dimension Ô and time]step before simulating larger systems (N > 20). We compute the half-chain von Neumann entropy, two-point correlations, mutual information, and state fidelity. Our global-quench results reveal an early linear rise of entropy up to a saturation time t*åL/(2v)?in agreement with Lieb-Robinson light-cone bounds?and a saturation plateau scaling with subsystem length and interaction strength. Correlation heatmaps display clear causal glight cones,h with mutual information peaks along their edges. Fidelity remains near unity, showing damped oscillations tied to spectral gaps. In local quenches, entanglement spreads more slowly, producing a glight-coneh with a narrower front and sublinear S(t) growth at early times. By tuning ¢ and introducing weak disorder, we identify transitions from rapid thermalization in chaotic regimes to logarithmic entanglement growth characteristic of many-body localization. These comprehensive benchmarks illuminate the interplay between integrability, chaos, and information propagation under both global and local perturbations, validating tensor-network methods for quench dynamics.
- P20. Canceled
- P22. Pei-Yuan Cai (Institute of Physics, Chinese Academy of Sciences)
Symmetry-protected topological order identified via Gutzwiller-guided density-matrix-renormalization-group: $\mathrm{SO}(n)$ spin chains
We present a comprehensive study of topological phases in the SO($n$) spin chains using a combination of analytical parton construction and numerical techniques. For even $n=2l$, we identify a novel SPT$^2$ phase characterized by two distinct topological sectors, exhibiting exact degeneracy at the matrix product state (MPS) exactly solvable point. Through Gutzwiller-projected mean-field theory and density matrix renormalization group (DMRG) calculations, we demonstrate that these sectors remain topologically degenerate in close chains throughout the SPT$^2$ phase, with energy gaps decaying exponentially with system size. For odd $n=2l+1$, we show that the ground state remains unique in close chains. We precisely characterize critical states using entanglement entropy scaling, confirming the central charges predicted by conformal field theories. Our results reveal fundamental differences between even and odd $n$ cases, provide numerical verification of topological protection, and establish reliable methods for studying high-symmetry quantum systems. The Gutzwiller-guided DMRG is demonstrated to be notably efficient in targeting specific topological sectors.
- P24. Canceled
- P26. Ryo Minakawa (Kyoto University)
Simulating stochastic process using dynamical low-rank approximation in matrix product state representation
"In recent years, research into non-equilibrium many-body dynamics has broadened to encompass not only steady states, but also relaxation processes and dynamical phase transitions. There is now increasing attention being paid to information-theoretic observables, such as entanglement/Renyi entropy and mutual information, that probe a systemfs wavefunction or probability distribution beyond the simple Monte Carlo method. Direct simulation remains prohibitive, however, because the associated degrees of freedom grow exponentially with system size. To overcome this barrier, the quantum information community has developed tensor network representations that achieve exponential compression while maintaining high fidelity. This enables precise calculations of ground states and equilibrium partition functions. By contrast, time evolution is still dominated by Suzuki?Trotter operator splitting, and practical algorithms remain comparatively immature. Meanwhile, the applied mathematics community has revitalized the dynamical low-rank approximation (DLRA) as a general framework for approximating time-dependent equations on manifolds of fixed rank. Despite its promise, DLRA has only been applied to a few large many-body problems. In this study, we evaluate the effectiveness of DLRA using the one-dimensional contact process, which is a canonical model of absorbing-state phase transitions."
- P28. Yuto Sugimoto (Tohoku University)
The acceleration of the Tensor Renormalization Group method in higher dimensions
The tensor renormalization group (TRG) method is a promising tool for overcoming the sign problem in Monte Carlo simulations. However, its application to higher-dimensional systems?particularly in four dimensions?is challenging due to the rapidly increasing computational cost. In this research, we explore several acceleration techniques from both algorithmic and hardware perspectives. Our results demonstrate a significant reduction in computational cost and a substantial speed-up compared to conventional TRG methods. In addition, we also investigate a method that significantly improves the accuracy of the algorithm.
- P30. Canceled
- P32. Yida Chu (Beijing Computational Science Research Center)
Realization of a period-3 coplanar state in one-dimensional spin-orbit-coupled optical lattices
" In ultracold atoms, achieving a period-3 structure poses a significant challenge. In this work, we propose a three-sublattice spin-flop transition mechanism, differing from the two-sublattice counterpart used to explain the emergence of ferrimagnetic orders in higher dimensions. Guided by this mechanism, we design a setup of alkaline-earth-metal atoms to create a spin-orbit-coupled optical lattice, where we identify a triplefold degenerate YXY state with a period-3 coplanar spin ordering within the deep Mott-insulating phase region of the ground- state phase diagram. The Y X Y state is protected by a finite gap, and its characteristic angle can be finely tuned by specific setup parameters. Moreover, we use the Rabi spectroscopy technique to detect the Y X Y state. Our work not only shows the feasibility of achieving a period-3 structure via the new mechanism but also suggests its potential applications for exploring other periodic structures in optical lattices."
- P34. Ken Shiozaki (YITP, Kyoto University)
Equivariant Parameter Family of Spin Chains
We present a framework for analyzing topological phase transitions and higher Berry curvature in 1D quantum spin systems, incorporating explicit symmetry actions on the parameter space. A $G$-compatible discretization combines group cochains with parameter-space differentials, enabling the construction of equivariant topological invariants. For symmetry actions with isolated fixed points, we derive a fixed-point formula showing that the transition between Haldane and trivial phases behaves as a monopole-like source of higher Berry curvature.