arXiv subjects

Yoshinori Kurimoto

Publications and source records attributed to Yoshinori Kurimoto.

7 recordsLinked to original sources

arXiv2026

QuBE/Qubex: an integrated hardware-software system for superconducting qubit experiments with broadband control

Achieving high-fidelity operation in large-scale superconducting qubit systems requires not only control hardware with broad frequency coverage, low crosstalk, and tight synchronization but also software that coordinates system configuration, experiment execution, and data analysis. Here we present an integrated qubit-control system that combines broadband microwave hardware with a pulse-level software stack for scalable superconducting qubit experiments. The hardware provides broadband microwave coverage, including an instantaneous span of up to 1.6 GHz from a control output, while the software reduces setup and calibration overhead through automated configuration and built-in experiment workflows. We validate the system on a 64-qubit fixed-frequency transmon chip through full-chip frequency identification and representative demonstrations, including multi-unit far-detuned cross-resonance calibration and benchmarking that yields a measured two-qubit gate fidelity of 98.34%, and multilevel readout beyond the computational subspace. By disclosing the hardware architecture and releasing the software stack as open source, this work provides an inspectable hardware-software foundation for scalable superconducting qubit control experiments.

quant-ph↗

arXiv2026

Cryogenic Time-Division-Multiplexed Voltage Control for Scalable Trapped-Ion Quantum Processors

Trapped-ion quantum computers based on the quantum charge-coupled device architecture require on the order of ten trap electrodes per qubit, making the number of vacuum feedthroughs a bottleneck at the system scale. Time-division multiplexed (TDM)-based voltage control for trap electrodes provides a natural route to alleviate this constraint. However, previous studies have been limited to architectural proposals for static trap-potential compensation and room-temperature demonstrations of dynamic-electrode control, leaving cryogenic operation of TDM-based voltage control for static and dynamic electrodes experimentally unexplored. In this study, we develop and cryogenically validate TDM-based voltage control schemes for two distinct electrode classes. For static electrodes used in trap-potential compensation, we implement a 32-channel demultiplexed system operating at approximately 27~K, achieving an effective voltage update rate of 37.5~kHz with an output range of $\pm10~\mathrm{V}$ per channel. For dynamic electrodes used in ion operations, such as shuttling, we implement a four-channel demultiplexed system operating at approximately 14~K, achieving an effective voltage update rate of 1~MHz with a comparable output range. These results establish TDM-based voltage control as a practical approach for both electrode classes, providing a path for mitigating the vacuum feedthrough bottleneck in scalable trapped-ion quantum processors.

quant-ph↗

arXiv2026

Microwave Output Stabilization of a Qubit Controller via Device-Level Temperature Control

We present the design and performance of QuEL-1 SE, which is a multichannel qubit controller developed for superconducting qubits. The system incorporates the active thermal stabilization of critical analog integrated circuits, such as phase-locked loops, amplifiers, and mixers, to suppress the long-term amplitude and phase drift. To evaluate the amplitude and phase stability, we simultaneously monitor 15 microwave output channels over 24 h using a common analog-to-digital converter. Across the channels, the normalized amplitude exhibits standard deviations of 0.09\%--0.22\% (mean: 0.15\%), and the phase deviations are 0.35$^\circ$--0.44$^\circ$ (mean: 0.39$^\circ$). We further assess the impact of these deviations on quantum gate operations by estimating the average fidelity of an $X_{π/2}$ gate under the coherent errors corresponding to the deviations. The resulting gate infidelities are $2\times 10^{-6}$ for amplitude errors and $2\times 10^{-5}$ for phase errors, which are significantly lower than typical fault-tolerance thresholds such as those of the surface code. These results demonstrate that the amplitude and phase stability of QuEL-1 SE enables reliable long-duration quantum operations, thus highlighting its utility as a scalable control platform for superconducting and other qubit modalities.

quant-ph↗

arXiv2025

Selective Excitation of Superconducting Qubits with a Shared Control Line through Pulse Shaping

In conventional architectures of superconducting quantum computers, each qubit is connected to its own control line, leading to a commensurate increase in the number of microwave lines as the system scales. Frequency-multiplexed qubit control addresses this problem by enabling multiple qubits to share a single microwave line. However, it can cause unwanted excitation of non-target qubits, especially when the detuning between qubits is smaller than the pulse bandwidth. Here, we propose a selective-excitation-pulse (SEP) technique that suppresses unwanted excitations by shaping a drive pulse to create null points at non-target qubit frequencies. In a proof-of-concept experiment with three fixed-frequency transmon qubits, we demonstrate that the SEP technique achieves single-qubit gate fidelities comparable to those obtained with conventional Gaussian pulses while effectively suppressing unwanted excitations in non-target qubits. These results highlight the SEP technique as a promising tool for enhancing frequency-multiplexed qubit control.

quant-ph↗

arXiv2021

Particle Tracking with Space Charge Effects using Graphics Processing Unit

Particle tracking simulations with space charge effects are very important for high-intensity proton rings. Since they include not only Hamilton mechanics of a single particle but constructing charge densities and solving Poisson equations to obtain the electromagnetic field due to the space charge, they are extremely time-consuming. We have newly developed a particle tracking simulation code that can be used in Graphics Processing Units (GPU). GPUs have strong capacities of parallel processing so that the calculation of single-particle mechanics can be done very fast by complete parallelization. Our new code also includes the space charge effect. It must construct charge densities, which cannot be completely parallelized. For the charge density construction, we can use shared memory which can be accessed very fast from each thread. The usage of shared memory is another advantage of GPU computing. As a result of our new development, we increase the speed of our particle tracking including space charge effect approximately 10 times faster than that in the case of our conventional code used in CPU.

physics.acc-ph↗

arXiv2018

A Control System of New Magnet Power Converter for J-PARC Main Ring Upgrade

Japan Proton Accelerator Research Complex (J-PARC) aims at a MW-class proton accelerator facility. One of the promising solutions for increasing the beam power of the Main Ring (MR) is converters of the main magnets with new ones for this upgrade. We have a plan to replace and develop the power converters of main magnets for this upgrade. According to develop the new power converter. We have developed a new control system for the new power converters. This control system consists of four parts : the current measuring device, the feedback control system, the gate pulse generator and the slow control system. Considering a reproducibility in the mass-production and the facilitation of the control algorithm, the digital control system is adopted. We will report the design of this control system and some test result with a new power converter for small quadrupole magnets.

physics.acc-ph↗

arXiv2018

Real-Time Betatron Tune Correction with the Precise Measurement of Magnet Current

The betatron tune, which is defined as the number of transverse oscillations in one turn of a ring accelerator, is one of the most important parameters. An undesired betatron tune increases the amplitude of the transverse oscillation so that many particles are lost from the ring sooner than designed. Since a betatron tune is controlled by the magnetic fields in the ring, the ripple of the magnet current directly displaces the betatron tune from its designated value. We have developed a system that corrects the betatron tune displacement using the measured magnet current at the J-PARC (Japan Proton Accelerator Research Complex) Main Ring. We adopted Field Programmable Gated Arrays (FPGA) to convert from the measured magnet current to the betatron tune in real time. Using the system, we have decreased the fluctuation of the betatron tune from 5.2e-4 to 3.3e-4 at the frequencies less than 250 Hz.

physics.acc-ph↗