83 citations · 287 across the 44 of their papers we have counts for
45 papers
First-quantized quantum simulation with non-local potentials by matrix-product-state encoding
Kazuki Tsuoka, Taichi Kosugi, Masari Watanabe +2
Quantum simulations based on first-quantized approaches can offer lower space and gate complexities than second-quantized approaches. The gate requirements for these simulations ca…
An efficient quantum Hadamard product algorithm for functions
Xinchi Huang, Hirofumi Nishi, Tomofumi Zushi +1
We propose an efficient quantum algorithm for preparing the Hadamard product state of two quantum states whose amplitudes are generated by functions on a uniform grid with grid num…
End-to-End Molecular Dynamics with a Langevin Thermostat on Quantum Circuits
Masari Watanabe, Hirofumi Nishi, Taichi Kosugi +3
We construct a quantum-circuit framework for finite-temperature molecular dynamics in the canonical ensemble (NVT) with a Langevin thermostat, connecting canonical state preparatio…
Koopman--von Neumann Molecular Dynamics for Green--Kubo Transport Coefficients
Masari Watanabe, Hirofumi Nishi, Taichi Kosugi +3
We formulate the Green--Kubo transport coefficients of classical molecular dynamics as a readout problem for quantum algorithms using the Koopman--von Neumann (KvN) representation.…
Overcoming the Matrix-Product-State Encoding Barrier via DMRG-Guided Probabilistic Imaginary-Time Evolution
Masari Watanabe, Hirofumi Nishi, Taichi Kosugi +2
Ground-state preparation is a fundamental task in quantum simulation, because the overlap of the prepared state with the true ground state significantly affects the overall cost of…
Quantum algorithms for density functional theory with minimal readout
Yuansheng Zhao, Hirofumi Nishi, Taichi Kosugi +5
While quantum computers have shown significant promise for electronic structure calculations, their potential to accelerate density functional theory (DFT) calculations remains unc…
Channel-agnostic finite-temperature phase estimation averaged over variable grids: reconstruction of Green's function for dynamical mean-field theory
Taichi Kosugi, Hirofumi Nishi, Keito Kasebayashi +2
For treating correlated electronic systems on quantum computers, we propose a quantum-classical hybrid scheme for dynamical mean-field theory (DMFT). In the quantum part of the sch…
Error-corrected phase estimation averaged over variable grids on a trapped-ion quantum computer: hyperacuity spectra of a CO molecule adsorbed onto -FeC
Taichi Kosugi, Hirofumi Nishi, Keito Kasebayashi +2
Quantum phase estimation (QPE) is an underlying technology for extracting the excitation spectra of many-electron systems, yet its practical use on current hardware is hindered by…
Problem-Specific Basis Quantum State Readout via Proper Orthogonal Decomposition
Kota Ichiki, Xinchi Huang, Gekko Budiutama +7
Quantum computing offers a promising approach to accelerating partial differential equation (PDE) solvers for large-scale, real-world problems. However, reconstructing the classica…
Approximate Amplitude Encoding with the Adaptive Interpolating Quantum Transform
Gekko Budiutama, Shunsuke Daimon, Xinchi Huang +2
Amplitude encoding of real-world data on quantum computers is often the workflow bottleneck: direct amplitude encoding scales poorly with input size and can offset any speedups in…
Real and Fourier space readout methods: Comparison of complexity and applications to CFD problems
Xinchi Huang, Hirofumi Nishi, Yoshifumi Kawada +2
Quantum computing is a promising technology that accelerates the partial differential equations solver for practical problems. The reconstruction of solutions (i.e., the readout of…
Adaptive Interpolating Quantum Transform: A Quantum-Native Framework for Efficient Transform Learning
Gekko Budiutama, Shunsuke Daimon, Hirofumi Nishi +3
Machine learning on quantum computers has attracted attention for its potential to deliver computational speedups in different tasks. However, deep variational quantum circuits req…
Fourier space readout method for efficiently recovering functions encoded in quantum states
Xinchi Huang, Hirofumi Nishi, Yoshifumi Kawada +2
Applying quantum computing in the computer-aided engineering (CAE) problems are highly expected since quantum computers yield potential exponential speedups for the operations betw…
Accelerated spin-adapted ground state preparation with non-variational quantum algorithms
Takumi Kobori, Taichi Kosugi, Hirofumi Nishi +2
Various methods have been explored to prepare the spin-adapted ground state, the lowest energy state within the Hilbert space constrained by externally specified values of the tota…
Quantum State Readout via Overlap-Based Feature Extraction
Hirofumi Nishi, Taichi Kosugi, Xinchi Huang +3
In this study, a method for quantum state readout and feature extraction is developed using quantum-overlap-based fitting of function expansions. The approach involves the quantum…
General Transform: A Unified Framework for Adaptive Transform to Enhance Representations
Gekko Budiutama, Shunsuke Daimon, Hirofumi Nishi +1
Discrete transforms, such as the discrete Fourier transform, are widely used in machine learning to improve model performance by extracting meaningful features. However, with numer…
Demonstration of logical quantum phase estimation for X-ray absorption spectra
Hirofumi Nishi, Taichi Kosugi, Satoshi Hirose +2
In this study, we employed Fourier-based quantum phase estimation (QPE) to calculate X-ray absorption spectroscopy (XAS) spectra. The primary focus of this study is the calculation…
Towards Improved Quantum Machine Learning for Molecular Force Fields
Yannick Couzinié, Shunsuke Daimon, Hirofumi Nishi +3
This study explores the use of equivariant quantum neural networks (QNN) for generating molecular force fields, focusing on the rMD17 dataset. We consider a QNN architecture based…
Tensor decomposition technique for qubit encoding of maximal-fidelity Lorentzian orbitals in real-space quantum chemistry
Taichi Kosugi, Xinchi Huang, Hirofumi Nishi +1
To simulate the real- and imaginary-time evolution of a many-electron system on a quantum computer based on the first-quantized formalism, we need to encode molecular orbitals (MOs…
A probabilistic imaginary-time evolution quantum algorithm for advection-diffusion equation: Explicit gate-level implementation and comparisons to quantum linear system algorithms
Xinchi Huang, Hirofumi Nishi, Taichi Kosugi +2
Simulating differential equations on classical computers becomes an intractable problem if the grid size is extremely large. Quantum computers are believed to achieve a possibly ex…
Machine learning supported annealing for prediction of grand canonical crystal structures
Yannick Couzinie, Yuya Seki, Yusuke Nishiya +4
This study investigates the application of Factorization Machines with Quantum Annealing (FMQA) to address the crystal structure problem (CSP) in materials science. FMQA is a black…
Approximate real-time evolution operator for potential with one ancillary qubit and application to first-quantized Hamiltonian simulation
Xinchi Huang, Taichi Kosugi, Hirofumi Nishi +1
In this article, we compare the methods implementing the real-time evolution operator generated by a unitary diagonal matrix where its entries obey a known underlying real function…
Orbital-free density functional theory with first-quantized quantum subroutines
Yusuke Nishiya, Hirofumi Nishi, Taichi Kosugi +1
In this study, we propose a quantum-classical hybrid scheme for performing orbital-free density functional theory (OFDFT) using probabilistic imaginary-time evolution (PITE), desig…
Encoded probabilistic imaginary-time evolution on a trapped-ion quantum computer for ground and excited states of spin qubits
Hirofumi Nishi, Yuki Takei, Taichi Kosugi +4
In this study, we employed a quantum computer to solve a low-energy effective Hamiltonian for spin defects in diamond (so-called NV centre) and wurtzite-type aluminium nitride, whi…