Tomoya Hayata

We explore the applicability of a stochastic time-evolution algorithm based on probabilistic angle interpolation. To simplify the preprocessing of the algorithm, we take the continuous-time limit, thereby explicitly eliminating Trotter errors and streamlining the resource analysis. We also introduce a noise-mitigation method tailored to it. As demonstrations, we apply the algorithm to two representative problems: estimating the ground-state energy of the H 3 + molecular Hamiltonian and computing out-of-time-ordered correlators in the sparse Sachdev-Ye-Kitaev model. We evaluate the protocol's performance through numerical simulations and experiments on a trapped-ion quantum computer, Quantinuum Reimei.

Given the rapid advances in quantum computing hardware, establishing strategies for verifying the correctness of quantum computations has become increasingly important. Exploiting the fact that the axial anomaly in gauge theories is exact to all orders in perturbation theory, we propose the axial anomaly as a nontrivial benchmark for quantum simulations of lattice gauge theories. We simulate axial charge production in Z N lattice gauge theories on the trapped-ion quantum computer “Reimei.” After taking the U(1), infinitesimal time, and infinite volume limits, we successfully reproduce the anomaly coefficient within statistical uncertainties, even without error mitigation. Our results demonstrate that the axial anomaly can be simulated on current quantum computers and serves as a verification test of quantum computations.

Nonequilibrium dynamics of quantum many-body systems is one of the main targets of quantum simulations. This focus—together with rapid advances in quantum-computing hardware—has driven increasing applications in high-energy physics, particularly in lattice gauge theories. However, most existing experimental demonstrations remain restricted to (1+1)-dimensional and/or Abelian gauge theories, such as the Schwinger model and the toric code. It is essential to develop quantum simulations of non-Abelian gauge theories in higher dimensions, addressing realistic problems in high-energy physics. To fill the gap, we demonstrate a quantum simulation of real-time dynamics in a (2+1)-dimensional q -deformed SU ( 2 ) 3 Yang-Mills theory using a trapped-ion quantum computer. By restricting the irreducible representations of the gauge fields to the integer-spin sector of SU ( 2 ) 3 , we obtain a simplified yet nontrivial model described by Fibonacci anyons, which preserves the essential non-Abelian fusion structure of the gauge fields. As a demonstration, we simulate the real-time dynamics of this model using quantum circuits that explicitly implement F -moves. In our demonstrations, the quantum circuits execute up to 47 sequential F -moves. We identify idling errors as the dominant error source, which can be effectively mitigated using dynamical decoupling combined with a parallelized implementation of F -moves.

We investigate the ( 2 + 1 )-dimensional q -deformed SU ( N ) k Yang-Mills theory in the lattice Hamiltonian formalism, which is characterized by three parameters: the number of colors N , the coupling constant g , and the level k . By treating these as tunable parameters, we explore how key properties of the theory, such as confinement and topological order, emerge in different regimes. Employing a variational mean-field analysis that interpolates between the strong- and weak-coupling regimes, we determine the large- N phase structure in terms of the ’t Hooft coupling λ tH = g 2 N and the ratio k / N . We find that the topologically ordered phase remains robust at large N under appropriate scalings of these parameters. This result indicates that the continuum limit of large- N gauge theory may be more intricate than naively expected, and it motivates studies beyond the mean-field theory, both to achieve a further understanding of confinement in gauge theories and to guide quantum simulations of large- N gauge theories.

Nonequilibrium dynamics of quantum many-body systems is one of the main targets of quantum simulations. This focus – together with rapid advances in quantum-computing hardware – has driven increasing applications in high-energy physics, particularly in lattice gauge theories. However, most existing experimental demonstrations remain restricted to (1+1)-dimensional and/or abelian gauge theories, such as the Schwinger model and the toric code. It is essential to develop quantum simulations of nonabelian gauge theories in higher dimensions, addressing realistic problems in high-energy physics. To fill the gap, we demonstrate a quantum simulation of thermalization dynamics in a (2+1)-dimensional q-deformed SU(2)3 Yang–Mills theory using a trapped-ion quantum computer. By restricting the irreducible representations of the gauge fields to the integer-spin sector of SU(2)3, we obtain a simplified yet nontrivial model described by Fibonacci anyons, which preserves the essential nonabelian fusion structure of the gauge fields. We successfully simulate the real-time dynamics of this model using quantum circuits that explicitly implement F-moves. In our demonstrations, the quantum circuits execute up to 47 sequential F-moves. We identify idling errors as the dominant error source, which can be effectively mitigated using dynamical decoupling combined with a parallelized implementation of F-moves.

We demonstrate a dissipative protocol for ground-state preparation of a quantum spin chain on a trapped-ion quantum computer. As a first step, we derive a Kraus representation of a dissipation channel for the protocol recently proposed by Ding et al. [Phys. Rev. Res. 6, 033147 (2024)] that still holds for arbitrary temporal discretization steps, extending the analysis beyond the Lindblad dynamics regime. The protocol guarantees that the fidelity with the ground state monotonically increases (or remains unchanged) under repeated applications of the channel to an arbitrary initial state, provided that the ground state is the unique steady state of the dissipation channel. Using this framework, we implement dissipative ground-state preparation of a transverse-field Ising chain for up to 19 spins on the trapped-ion quantum computer Reimei provided by Quantinuum. Despite the presence of hardware noise, the dynamics consistently converges to a low-energy state far away from the maximally mixed state even when the corresponding quantum circuits contain as many as 4110 entangling gates, demonstrating the intrinsic robustness of the protocol. By applying zero-noise extrapolation, the resulting energy expectation values are systematically improved to agree with noiseless simulations within statistical uncertainties.