SearcharxivSearch

arXiv subjects

H. Kutsuma

Publications and source records attributed to H. Kutsuma.

2 recordsLinked to original sources

NbTiN Nanowire Resonators for Spin-Photon Coupling on Solid Neon

Electrons floating on a solid neon exhibit long charge coherence times, making them attractive for hybrid quantum systems. When combined with high-quality, high-impedance superconducting resonators and a local magnetic field gradient, this platform enables strong charge--photon and spin--charge coupling-key ingredients for scalable spin qubit architectures. In this work, we demonstrate that NbTiN nanowire resonators maintain high quality factors around 10^5 after depositing solid neon onto the resonators and subsequently loading electrons onto the neon surface, validating their suitability for electrons-on-neon platforms. Building on these experimental results, we theoretically analyze micromagnet designs and coupling strategies that can enable spin-photon interactions in this platform. Our analysis outlines performance targets for next-generation devices, showing that, at the charge sweet spot, spin qubit gate fidelities exceeding 99.99% for single-qubit operations and 99.9% for two-qubit operations are achievable with natural neon.

cond-mat.mes-hall

Pointing calibration of GroundBIRD telescope using Moon observation data

Understanding telescope pointing (i.e., line of sight) is important for observing the cosmic microwave background (CMB) and astronomical objects. The Moon is a candidate astronomical source for pointing calibration. Although the visible size of the Moon ($\ang{;30}$) is larger than that of the planets, we can frequently observe the Moon once a month with a high signal-to-noise ratio. We developed a method for performing pointing calibration using observational data from the Moon. We considered the tilts of the telescope axes as well as the encoder and collimation offsets for pointing calibration. In addition, we evaluated the effects of the nonuniformity of the brightness temperature of the Moon, which is a dominant systematic error. As a result, we successfully achieved a pointing accuracy of $\ang{;3.3}$. This is one order of magnitude smaller than an angular resolution of $\ang{;36}$. This level of accuracy competes with past achievements in other ground-based CMB experiments using observational data from the planets.

astro-ph.IM