97 citations · 439 across the 20 of their papers we have counts for
21 papers
Quantum-echo Markov process for combinatorial optimization
Tatsuhiko Shirai
We introduce a quantum-echo Markov process for combinatorial optimization. Quantum dynamics based on quantum annealing (QA) or the quantum approximate optimization algorithm (QAOA)…
Quasi-adiabatic thermal ensemble preparation in the thermodynamic limit
Tatsuhiko Shirai
We investigate a quasi-adiabatic thermal process for preparing finite-temperature ensembles in the thermodynamic limit. The process gradually transforms a thermal ensemble of a non…
Out-of-time-order correlator computation based on discrete truncated Wigner approximation
Tatsuhiko Shirai, Takashi Mori
We propose a method based on the discrete truncated Wigner approximation (DTWA) for computing out-of-time-order correlators. This method is applied to long-range interacting quantu…
Compressed space quantum approximate optimization algorithm for constrained combinatorial optimization
Tatsuhiko Shirai, Nozomu Togawa
Combinatorial optimization is a promising area for achieving quantum speedup. Quantum approximate optimization algorithm (QAOA) is designed to search for low-energy states of the I…
Toward Practical Benchmarks of Ising Machines: A Case Study on the Quadratic Knapsack Problem
Kentaro Ohno, Tatsuhiko Shirai, Nozomu Togawa
Combinatorial optimization has wide applications from industry to natural science. Ising machines bring an emerging computing paradigm for efficiently solving a combinatorial optim…
Post-processing variationally scheduled quantum algorithm for constrained combinatorial optimization problems
Tatsuhiko Shirai, Nozomu Togawa
We propose a post-processing variationally scheduled quantum algorithm (pVSQA) for solving constrained combinatorial optimization problems (COPs). COPs are typically transformed in…
Accelerated Decay due to Operator Spreading in Bulk-Dissipated Quantum Systems
Tatsuhiko Shirai, Takashi Mori
Markovian open many-body quantum systems display complicated relaxation dynamics. The spectral gap of the Liouvillian characterizes the asymptotic decay rate towards the stationary…
Symmetrized Liouvillian Gap in Markovian Open Quantum Systems
Takashi Mori, Tatsuhiko Shirai
Markovian open quantum systems display complicated relaxation dynamics. The spectral gap of the Liouvillian characterizes the asymptotic decay rate towards the steady state, but it…
Tensor-network approach to thermalization in open quantum many-body systems
Hayate Nakano, Tatsuhiko Shirai, Takashi Mori
We investigate the relaxation dynamics of open non-integrable quantum many-body systems in the thermodynamic limit by using a tensor-network formalism. We simulate the Lindblad qua…
Guiding Principle for Minor-Embedding in Simulated-Annealing-Based Ising Machines
Tatsuhiko Shirai, Shu Tanaka, Nozomu Togawa
We propose a novel type of minor-embedding (ME) in simulated-annealing-based Ising machines. The Ising machines can solve combinatorial optimization problems. Many combinatorial op…
Exact bounds for dynamical critical exponents of transverse-field Ising chains with a correlated disorder
Tatsuhiko Shirai, Shu Tanaka
This study investigates the dynamical critical exponent of disordered Ising chains under transverse fields to examine the effect of a correlated disorder on quantum phase transitio…
Resolving Discrepancy between Liouvillian Gap and Relaxation Time in Boundary-Dissipated Quantum Many-Body Systems
Takashi Mori, Tatsuhiko Shirai
The gap of the Liouvillian spectrum gives the asymptotic decay rate of a quantum dissipative system, and therefore its inverse has been identified as the slowest relaxation time. I…
Dynamical phase transition in Floquet optical bistable systems: An approach from finite-size quantum systems
Tatsuhiko Shirai, Synge Todo, Seiji Miyashita
We study a dynamical phase transition in optical bistable systems subject to a time-periodic driving field. The phase transition occurs in the structure of limit cycle as a functio…
Thermalization in open many-body systems based on eigenstate thermalization hypothesis
Tatsuhiko Shirai, Takashi Mori
We investigate steady states of macroscopic quantum systems under dissipation not obeying the detailed balance condition. We argue that the Gibbs state at an effective temperature…
Optical Bistability in a Low Photon-Density Regime
Tatsuhiko Shirai, Synge Todo, Hans de Raedt +1
We give a microscopic description of the optical bistability, where the transmission coefficient has two different values as a function of input light intensity, and the system exh…
Floquet-Gibbs state in open quantum systems
Tatsuhiko Shirai, Takashi Mori, Seiji Miyashita
We study long-time asymptotic states of periodically driven quantum systems coupled to a thermal bath. In order to describe a class of such a system, we introduce the Floquet-Gibbs…
Microscopic Description of Yielding in Glass Based on Persistent Homology
Tatsuhiko Shirai, Takenobu Nakamura
Persistent homology (PH) was applied to probe the structural changes of glasses under shear. PH associates each local atomistic structure in an atomistic configuration to a geometr…
Effective Floquet-Gibbs states for dissipative quantum systems
Tatsuhiko Shirai, Juzar Thingna, Takashi Mori +3
A periodically driven quantum system, when coupled to a heat bath, relaxes to a non-equilibrium asymptotic state. In the general situation, the retrieval of this asymptotic state p…
Condition for emergence of the Floquet-Gibbs state in periodically driven open systems
Tatsuhiko Shirai, Takashi Mori, Seiji Miyashita
We study probability distribution of a steady state of a periodically driven system coupled to a thermal bath by using a quantum master equation in the weak coupling limit. It is p…
Photon and spin dependence of the resonance lines shape in the strong coupling regime
S. Miyashita, T. Shirai, T. Mori +3
We study the quantum dynamics of a spin ensemble coupled to cavity photons. Recently, related experimental results have been reported, showing the existence of the strong coupling…
Novel symmetry-broken phase in a driven cavity system in the thermodynamic limit
Tatsuhiko Shirai, Takashi Mori, Seiji Miyashita
We study non-equilibrium stationary states of a cavity system consisting of many atoms interacting with a quantized cavity field mode, under a driving field in a dissipative enviro…