11 citations · 32 across the 17 of their papers we have counts for
18 papers
Chern-number estimation: nearly optimal quantum algorithm and provable quantum speedup
Soichiro Imamura, Shintaro Ae, Kazuki Sakamoto +2
Topological phases of matter are characterized by global properties of quantum states beyond conventional local order parameters. The Chern number is a central invariant in this ch…
Structure-Aware Variance Reduction for Unbiased Randomized Hamiltonian Simulation
Joshua W. Dai, Fredrik Hasselgren, Chusei Kiumi
Randomized Hamiltonian simulation methods are often governed by a trade-off between systematic bias and sampling overhead. We study how classical variance-reduction techniques can…
Adiabatic Error Cancellation in Berry Phase Estimation
Chusei Kiumi
The Berry phase encodes the geometry of a closed Hamiltonian path, complementing the dynamical phase determined by the accumulated energy. We uncover an adiabatic error-cancellatio…
Introducing a Kondo-type interaction to the model of quantum walkers
Manami Yamagishi, Naomichi Hatano, Kohei Kawabata +4
We introduce a model of discrete-time quantum walkers interacting with a lozalized magnetic impurity. Each quantum walker interacts with an impurity, through which multiple quantum…
Low-Resource Quantum Energy Gap Estimation via Randomization
Hugo Pages, Chusei Kiumi, Yuto Morohoshi +2
Estimating the energy spectra of quantum many-body systems is a fundamental task in quantum physics, with applications ranging from chemistry to condensed matter. Algorithmic shado…
Computational complexity of Berry phase estimation in topological phases of matter
Ryu Hayakawa, Kazuki Sakamoto, Chusei Kiumi
The Berry phase is a fundamental quantity in the classification of topological phases of matter. In this paper, we present a new quantum algorithm and several complexity-theoretica…
TE-PAI: Exact Time Evolution by Sampling Random Circuits
Chusei Kiumi, Bálint Koczor
Simulating time evolution under quantum Hamiltonians is one of the most natural applications of quantum computers. We introduce TE-PAI, which simulates time evolution exactly by sa…
Quantum Calculation for Two-Stream Instability and Advection Test of Vlasov-Maxwell Equations: Numerical Evaluation of Hamiltonian Simulation
Hayato Higuchi, Juan W. Pedersen, Kiichiro Toyoizumi +3
The Vlasov-Maxwell equations provide kinetic simulations of collisionless plasmas, but numerically solving them on classical computers is often impractical. This is due to the comp…
Operator quantum singular value transformation: Spectral mapping, design and topological invariants
Chusei Kiumi, Akito Suzuki, Yohei Tanaka
Quantum singular value transformation (QSVT) provides a unifying framework for quantum algorithms by applying the polynomials of quantum signal processing (QSP) to block-encoded ma…
Spectral analysis of three-state quantum walks with general coin matrices
Chusei Kiumi, Jirô Akahori, Takuya Watanabe +1
Mathematical analysis of the spectral properties of the time evolution operator in quantum walks is essential for understanding key dynamical behaviors such as localization and lon…
IPS/Zeta Correspondence for the Domany-Kinzel model
Chusei Kiumi, Norio Konno, Yuki Oshima
Previous studies presented zeta functions by the Konno-Sato theorem or the Fourier analysis for one-particle models, including random walks, correlated random walks, quantum walks,…
Spectral Analysis of Non-unitary Two-phase Quantum Walks in One Dimension
Chusei Kiumi, Kei Saito, Yohei Tanaka
It is recently shown by Asahara-Funakawa-Seki-Tanaka that existing index theory for chirally symmetric (discrete-time) quantum walks can be extended to the setting of non-unitary q…
Return probability of quantum and correlated random walks
Chusei Kiumi, Norio Konno, Shunya Tamura
The analysis of the return probability is one of the most essential and fundamental topics in the study of classical random walks. In this paper, we study the return probability of…
Localization in quantum walks with periodically arranged coin matrices
Chusei Kiumi
There is a property called localization, which is essential for applications of quantum walks. From a mathematical point of view, the occurrence of localization is known to be equi…
Localization of space-inhomogeneous three-state quantum walks
Chusei Kiumi
Mathematical analysis on the existence of eigenvalues is essential because it is equivalent to the occurrence of localization, which is an exceptionally crucial property of quantum…
Strongly trapped space-inhomogeneous quantum walks in one dimension
Chusei Kiumi, Kei Saito
Localization is a characteristic phenomenon of space-inhomogeneous quantum walks in one dimension, where particles remain localized around their initial position. The existence of…
A new type of quantum walks based on decomposing quantum states
Chusei Kiumi
In this paper, the 2-state decomposed-type quantum walk (DQW) on a line is introduced as an extension of the 2-state quantum walk (QW). The time evolution of the DQW is defined wit…
Eigenvalues of two-phase quantum walks with one defect in one dimension
Chusei Kiumi, Kei Saito
We study space-inhomogeneous quantum walks (QWs) on the integer lattice which we assign three different coin matrices to the positive part, the negative part, and the origin, respe…