A5026548929- Quantum Information and Cryptography
- Quantum Computing Algorithms and Architecture
- Quantum optics and atomic interactions
- Quantum and electron transport phenomena
- Neural Networks and Reservoir Computing
- Photonic and Optical Devices
- Mechanical and Optical Resonators
- Quantum Mechanics and Applications
- Advanced Fiber Laser Technologies
- Quantum-Dot Cellular Automata
- Advanced Memory and Neural Computing
- Photorefractive and Nonlinear Optics
- Laser-Matter Interactions and Applications
- Cold Atom Physics and Bose-Einstein Condensates
- Spectroscopy and Quantum Chemical Studies
- Copper-based nanomaterials and applications
- Atomic and Subatomic Physics Research
- Shoulder Injury and Treatment
- Physics of Superconductivity and Magnetism
- Musculoskeletal pain and rehabilitation
- Error Correcting Code Techniques
- Quantum many-body systems
- Spectroscopy and Laser Applications
- Myofascial pain diagnosis and treatment
- Advanced Photocatalysis Techniques
Toshiba (Japan)
2016-2025
RIKEN Center for Quantum Computing
2024-2025
RIKEN
2025
RIKEN Center for Advanced Photonics
2024
Keio University
1997-2024
Foro Italico University of Rome
2021
Japanese Red Cross Medical Center
2021
Shivaji University
2020
Tohoku University
2018-2019
University of Yamanashi
2018
Combinatorial optimization problems are ubiquitous but difficult to solve. Hardware devices for these have recently been developed by various approaches, including quantum computers. Inspired proposed adiabatic using a nonlinear oscillator network, we propose new algorithm simulating evolutions of classical Hamiltonian systems exhibiting bifurcation phenomena, which call simulated (SB). SB is based on and chaotic (ergodic) systems. also suitable parallel computing because its simultaneous...
The dynamics of nonlinear systems qualitatively change depending on their parameters, which is called bifurcation. A quantum-mechanical oscillator can yield a quantum superposition two oscillation states, known as Schrödinger cat state, via adiabatic evolution through its bifurcation point. Here we propose computer comprising such oscillators, instead bits, to solve hard combinatorial optimization problems. network finds optimal solutions evolution, where terms are increased slowly, in...
Massively parallel implementations of algorithms based on classical mechanics realize high-performance combinatorial optimization.
Abstract In the ‘Beyond Moore’s Law’ era, with increasing edge intelligence, domain-specific computing embracing unconventional approaches will become increasingly prevalent. At same time, adopting a variety of nanotechnologies offer benefits in energy cost, computational speed, reduced footprint, cyber resilience, and processing power. The time is ripe for roadmap to guide future research, this collection aims fill that need. authors provide comprehensive neuromorphic using electron spins,...
We theoretically show that a nonlinear oscillator network with controllable parameters can be used for universal quantum computation. The initialization is achieved by quantum-mechanical bifurcation based on adiabatic evolution, which yields Schr\"odinger cat state. All the elementary gates are also in dynamical phases accompanying evolutions controlled system parameters. Numerical simulation results indicate high gate fidelities achieved, where no dissipation assumed.
Quantum computers with Kerr-nonlinear parametric oscillators (KPOs) have recently been proposed by the author and others. computation using KPOs is based on quantum adiabatic bifurcations of KPOs, which lead to superpositions coherent states, such as Schrodinger cat states. Therefore, these are referred "quantum bifurcation machines (QbMs)." QbMs can be used for qauntum optimization universal computation. Superconducting circuits Josephson junctions, (JPOs) in particular, promising physical...
We numerically study reservoir computing on a spin-torque oscillator (STO) array, describing the magnetization dynamics of STO array by nonlinear model. The STOs exhibit synchronized oscillation due to coupling magnetic dipolar fields. show that can be performed using state. performance improved increasing number STOs. becomes highest at boundary between and disordered states. Using an we achieve higher than echo-state network with similar units. This result indicates arrays are promising...
A network of driven nonlinear oscillators without dissipation has recently been proposed for solving combinatorial optimization problems via quantum adiabatic evolution through its bifurcation point. Here we investigate the behavior machine in presence dissipation. Our numerical study suggests that output probability distribution dissipative is Boltzmann-like, where energy Boltzmann corresponds to cost function problem. We explain by generalizing concept heating a single oscillator case...
We study microwave response of a Josephson parametric oscillator consisting superconducting transmission-line resonator with an embedded dc-SQUID. The dc-SQUID allows to control the magnitude Kerr nonlinearity over ranges where it is smaller or larger than photon loss rate. Spectroscopy measurements reveal change from classical Duffing in single device. In single-photon regime, we observe oscillations well-defined phase either $0$ $\pi$, whose probability can be controlled by externally...
Kerr cat qubits are a promising candidate for fault-tolerant quantum computers owing to the biased nature of their errors. The $ZZ$ coupling between can be utilized two-qubit entangling gate, but residual called crosstalk is detrimental precise computing. In order resolve this problem, we propose tunable $ZZ$-coupling scheme using two transmon couplers. By setting detunings couplers at opposite values, couplings via cancel each other out. We also apply our...
A new implementation of quantum gates by adiabatic passage with an optical cavity is proposed. This allows one to perform not only elementary gates, such as one-qubit and a controlled-NOT gate, but also multiqubit controlled unitary gates. Some are numerically simulated. From the simulation results, it concluded that this three-qubit more efficient than decomposing into
Since many combinatorial optimization problems can be mapped onto ground-state search of Ising models, special-purpose machines for have attracted intense attention. Simulated bifurcation (SB) is a recently proposed algorithm to solve these problems. One the remarkable features SB high-degree parallelism underlying in algorithm, providing an opportunity very fast by massively parallel processing. In this work, we implement on FPGAs designing custom circuits. We then compare FPGA-based with...
Abstract A two-dimensional array of Kerr-nonlinear parametric oscillators (KPOs) with local four-body interactions is a promising candidate for realizing an Ising machine all-to-all spin couplings, based on adiabatic quantum computation in the Lechner–Hauke–Zoller (LHZ) scheme. However, its performance has been evaluated only symmetric network three KPOs, and thus it unclear whether such works general cases asymmetric networks. By numerically simulating more KPOs LHZ scheme, we find that...
A Kerr nonlinear parametric oscillator (KPO) can stabilize a quantum superposition of two coherent states with opposite phases, which be used as qubit. In universal gate set for computation KPOs, an $R_x$ gate, interchanges the states, is relatively hard to perform owing stability states. We propose method high-fidelity by exciting KPO outside qubit space parity-selective transitions, implemented only adding driving field. this method, utilization higher effective excited leads faster rather...
Tunable couplers, which turn on and off the interaction between qubits, have emerged as a key means to achieve low error rates in superconducting quantum computers. Conventional devices using one transmon qubit exhibit unwanted residual coupling, though, especially at high detuning that is desirable for suppressing crosstalk errors. To solve this critical problem, author proposes tunable coupler based two transmons satisfies ideal conditions of no coupling fast two-qubit gate operations...
Kerr parametric oscillators (KPOs), two-photon driven Kerr-nonlinear resonators, can stably hold coherent states with opposite-sign amplitudes and are promising devices for quantum computing. Recently, we have theoretically proposed a two-qubit gate Rzz highly detuned KPOs called it conditional-driving [Chono et al., Phys. Rev. Res. 4, 043054 (2022)]. In this study, analyzing its superconducting-circuit model deriving corresponding static model, find that an AC-Zeeman shift due to the flux...
Abstract The seven-qubit quantum error-correcting code originally proposed by Steane is one of the best known codes. has a desirable property that most basic operations can be performed easily in fault-tolerant manner. A major obstacle to computation with preparation encoded states, which requires large computational resources. Here we propose efficient state methods for zero and magic states code, where basis allows us achieve universality computation. minimize resource overheads therefore...
Abstract Various kinds of Ising machines based on unconventional computing have recently been developed for practically important combinatorial optimization. Among them, the implementing a heuristic algorithm called simulated bifurcation achieved high performance, where Hamiltonian dynamics are by massively parallel processing. To further improve performance bifurcation, here we introduce thermal fluctuation to its relying Nosé–Hoover method, which has used simulate at finite temperatures....
Kerr parametric oscillators (KPOs), which can be implemented with superconducting parametrons possessing large nonlinearity, have been attracting much attention in terms of their applications to quantum annealing, universal computation, and studies many-body systems. It is practical importance for these realize fast accurate tunable coupling between KPOs a simple manner. We develop scheme high tunability speed amplitude using the transitionless rotation KPO phase space based on shortcuts...
Kerr parametric oscillators (KPOs) can stabilize the superpositions of coherent states, which be utilized as qubits, and are promising candidates for realizing hardware-efficient quantum computers. Although elementary gates universal computation with KPO qubits have been proposed, these usually based on adiabatic operations thus need long gate times, result in errors caused by photon loss KPOs realized by, e.g., superconducting circuits. In this work we accelerate experimentally feasible...
We theoretically propose a method for on-demand generation of traveling Schr\"odinger cat states, namely, quantum superpositions distinct coherent states fields. This is based on deterministic intracavity using Kerr-nonlinear parametric oscillator (KPO) via adiabatic evolution. show that the generated inside KPO can be released into an output mode by controlling pump amplitude dynamically. further quality improved shortcut-to-adiabaticity technique.
We analytically derive the upper bound on overall efficiency of single-photon generation based cavity quantum electrodynamics (QED), where internal loss is treated explicitly. The leads to a tradeoff relation between and escape efficiency, which results in fundamental limit efficiency. corresponding lower failure probability expressed only with an "internal cooperativity," introduced here as cooperativity parameter respect rate. obtained by optimizing external rate, can be experimentally...
Adiabatic quantum computation (AQC), which is particularly useful for combinatorial optimization, becomes more powerful by using excited states, instead of ground states. However, the excited-state AQC prone to errors due dissipation. Here we propose started with most stable state, i.e., vacuum state. This counterintuitive approach possible a driven system, or precisely, network Kerr-nonlinear parametric oscillators (KPOs). By numerical simulations, show that some hard instances, where...