A5058426871- Theoretical and Computational Physics
- Physics of Superconductivity and Magnetism
- Quantum many-body systems
- Advanced Condensed Matter Physics
- Quantum and electron transport phenomena
- Markov Chains and Monte Carlo Methods
- Magnetic properties of thin films
- Machine Learning in Materials Science
- Magnetic Properties and Synthesis of Ferrites
- Parallel Computing and Optimization Techniques
- Advanced Thermodynamics and Statistical Mechanics
- Spectroscopy and Quantum Chemical Studies
- Quantum Computing Algorithms and Architecture
- Stochastic processes and statistical mechanics
- X-ray Diffraction in Crystallography
- Metallic Glasses and Amorphous Alloys
- Iron oxide chemistry and applications
- Tensor decomposition and applications
- Quantum Information and Cryptography
- Quantum, superfluid, helium dynamics
- Black Holes and Theoretical Physics
- Quantum Chromodynamics and Particle Interactions
- Magnetic Properties and Applications
- Advanced Chemical Physics Studies
- Distributed and Parallel Computing Systems
The University of Tokyo
2016-2025
Bunkyo University
2024
Japan Graduate School of Education University
2020
National Institute for Materials Science
2018-2019
Japan Science and Technology Agency
2006-2012
Japan External Trade Organization
2009
Adam Mickiewicz University in Poznań
2006
Institute of Physics
2006
Board of the Swiss Federal Institutes of Technology
2001-2003
ETH Zurich
2002-2003
We present release 2.0 of the ALPS (Algorithms and Libraries for Physics Simulations) project, an open source software project to develop libraries application programs simulation strongly correlated quantum lattice models such as magnets, bosons, fermion systems. The code development is centered on common XML HDF5 data formats, simplify speed up development, evaluation plotting tools, programs. enable non-experts start carrying out serial or parallel numerical simulations by providing basic...
We propose a sequential minimal optimization method for quantum-classical hybrid algorithms, which converges faster, is robust against statistical error, and hyperparameter-free. Specifically, the problem of parameterized quantum circuits divided into solvable subproblems by considering only subset parameters. In fact, if we choose single parameter, cost function becomes simple sine curve with period $2\pi$, hence can exactly minimize respect to chosen parameter. Furthermore, even in general...
We present a general strategy to extend quantum cluster algorithms for S = 1 / 2 spin systems, such as the loop algorithm, those with an arbitrary size of spins. The partition function high- system is generally represented by path integral model special boundary conditions in imaginary-time direction. introduce additional graphs part and give labeling probability explicitly, which completes algorithm together existing algorithm. As demonstration, we simulate integer-spin antiferromagnetic...
The N\'eel temperature ${T}_{\mathrm{N}}$ of quasi-one- and quasi-two-dimensional antiferromagnetic Heisenberg models on a cubic lattice is calculated by Monte Carlo simulations as function interchain (interlayer) to intrachain (intralayer) coupling ${J}^{\ensuremath{'}}/J$ down ${J}^{\ensuremath{'}}/J\ensuremath{\simeq}{10}^{\ensuremath{-}3}$. We find that obeys modified random-phase approximationlike relation for small with an effective universal renormalized coordination number,...
We present a specific algorithm that generally satisfies the balance condition without imposing detailed in Markov chain Monte Carlo. In our algorithm, average rejection rate is minimized, and even reduced to zero many relevant cases. The absence of also introduces net stochastic flow configuration space, which further boosts up convergence. demonstrate autocorrelation time Potts model becomes more than 6 times shorter by conventional Metropolis algorithm. Based on same concept, bounce-free...
To examine the validity of scenario deconfined critical phenomena, we carry out a quantum Monte Carlo simulation for SU($N$) generalization Heisenberg model with four-body and six-body interactions. The phase transition between N\'eel valence-bond solid phases is characterized $N=2$, 3, 4 on square honeycomb lattices. While finite-size scaling analysis works well up to maximum lattice size ($L=256$) indicates continuous nature transition, clear systematic change towards first-order observed...
The $S=1/2$ and $S=1$ two-dimensional quantum Heisenberg antiferromagnets on the anisotropic dimerized square lattice are investigated by Monte Carlo method. By finite-size-scaling analyses correlation lengths, ground-state phase diagram parametrized strengths of dimerization spatial anisotropy is determined much more accurately than previous works. It confirmed that critical phenomena boundaries belong to same universality class as classical three-dimensional model. Furthermore, for $S=1,$...
We determine the finite-temperature phase diagram of square lattice hard-core boson Hubbard model with nearest neighbor repulsion using quantum Monte Carlo simulations. This is equivalent to an anisotropic spin-1/2 XXZ in a magnetic field. present rich first order transition between solid and superfluid phase, instead previously conjectured supersolid tricritical end point separation. Unusual reentrant behavior ordering upon increasing temperature found, similar Pomeranchuk effect 3He.
We present the ALPS (Algorithms and Libraries for Physics Simulations) project, an international open source software project to develop libraries application programs simulation of strongly correlated quantum lattice models such as magnets, bosons, fermion systems. Development is centered on common XML binary data formats, simplify speed up code development, full-featured programs. The enable non-experts start carrying out numerical simulations by providing basic implementations important...
HΦ [aitch-phi ] is a program package based on the Lanczos-type eigenvalue solution applicable to broad range of quantum lattice models, i.e., arbitrary models with two-body interactions, including Heisenberg model, Kitaev Hubbard model and Kondo-lattice model. While it works well PCs PC-clusters, also runs efficiently massively parallel computers, which considerably extends tractable system size. In addition, unlike most existing packages, supports finite-temperature calculations through...
We propose a new tensor renormalization group algorithm, Anisotropic Tensor Renormalization Group (ATRG), for lattice models in arbitrary dimensions. The proposed method shares the same versatility with Higher-Order (HOTRG) i.e., it preserves topology after renormalization. In comparison HOTRG, both of computation cost and memory footprint our are drastically reduced, especially higher dimensions, by renormalizing tensors an anisotropic way singular value decomposition. demonstrate ability...
We study the first-order Verwey transition in single-crystal ${\mathrm{Fe}}_{3}$${\mathrm{O}}_{4}$ using high-resolution temperature-dependent (100--300 K) photoemission spectroscopy. The near-Fermi-level (${\mathit{E}}_{\mathit{F}}$) spectrum exhibits a clear gap of \ensuremath{\sim}70 meV occupied part density states (DOS) low-temperature semiconducting phase. is closed above temperature ${\mathit{T}}_{\mathit{V}}$=122 K, establishing metal-semiconductor transition. Fe 3d derived features...
We propose an order parameter to characterize valence-bond-solid (VBS) states in quantum spin chains, given by the ground-state expectation value of a unitary operator appearing Lieb-Schultz-Mattis argument. show that changes sign according number valence bonds (broken bonds) at boundary for periodic (open) systems. This allows us determine phase transition point between different VBS states. demonstrate this theory successive dimerization transitions bond-alternating Heisenberg using Monte...
We propose an improved tensor renormalization-group (TRG) algorithm, the bond-weighted TRG (BTRG). In BTRG, we generalize conventional by introducing bond weights on edges of network. show that BTRG outperforms and higher-order renormalization group with same dimension, whereas its computation time is almost as TRG. Furthermore, can have nontrivial fixed-point tensors at optimal hyperparameter. demonstrate singular value spectrum obtained invariant under procedure in case two-dimensional...
Quantum Monte Carlo (QMC) methods for the frustrated quantum spin systems occasionally suffer from negative sign problem, which makes simulations exponentially harder larger at lower temperatures and severely limits QMC's application across a wide range of systems. This problem is known to depend on choice representation basis. We propose systematic approach mitigating independent given Hamiltonian or lattice structure. first introduce concept negativity characterize severity problem. then...
Variational Quantum Algorithms (VQAs) are being highlighted as key quantum algorithms for demonstrating advantage on Noisy Intermediate-Scale (NISQ) devices, which limited to executing shallow circuits because of noise. However, the barren plateau problem, where gradient loss function becomes exponentially small with system size, hinders this goal. Recent studies suggest that embedding tensor networks into and initializing parameters can avoid plateau. Yet, is generally difficult, methods...
The $(1+1)$-dimensional two-color lattice QCD is studied with the Grassmann tensor renormalization group. We construct network representations of theories staggered fermion and Wilson show that networks can describe both cases same bond dimension. also propose an efficient initial compression scheme to gauge degrees freedom. compute number density, chiral condensate, diquark condensate at finite employing fermions. For theory fermion, a critical point in negative mass region identified by...
A bstract We construct a Grassmann tensor network representing the partition function of (1+1)-dimensional two-color QCD with staggered fermions. The path integral is rewritten as trace by introducing two-component auxiliary fields on every edge lattice. introduce an efficient initial compression scheme to reduce size tensors. bond-weighted renormalization group approach adopted evaluate quark number density, fermion condensate, and diquark condensate at different gauge couplings chemical...