arXiv subjects

Hiroshi Yukawa

Publications and source records attributed to Hiroshi Yukawa.

5 recordsLinked to original sources

arXiv2022

Glass-patternable notch-shaped microwave architecture for on-chip spin detection in biological samples

We report a notch-shaped coplanar microwave waveguide antenna on a glass plate designed for on-chip detection of optically detected magnetic resonance (ODMR) of fluorescent nanodiamonds (NDs). A lithographically patterned thin wire at the center of the notch area in the coplanar waveguide realizes a millimeter-scale ODMR detection area (1.5 x 2.0 mm^2) and gigahertz-broadband characteristics with low reflection (about 8%). The ODMR signal intensity in the detection area is quantitatively predictable by numerical simulation. Using this chip device, we demonstrate a uniform ODMR signal intensity over the detection area for cells, tissue, and worms. The present demonstration of a chip-based microwave architecture will enable scalable chip integration of ODMR-based quantum sensing technology into various bioassay platforms.

physics.app-ph↗

arXiv2020

Wide-field fluorescent nanodiamond spin measurements toward real-time large-area intracellular quantum thermometry

In this study, we analyze the operational process of nanodiamond (ND) quantum thermometry based on wide-field detection of optically detected magnetic resonance (ODMR) of nitrogen vacancy centers, and compare its performance with that of confocal ODMR detection. We found that (1) the thermometry results are significantly affected by the shape and size of the camera region of interest (ROI) surrounding the target NDs and that (2) by properly managing the ROI and acquisition parameters of the camera, a temperature precision comparable to confocal detection in living cells can be obtained by wide-field ODMR. Our results are significant to the development of camera-based real-time large-area quantum thermometry of living cells.

physics.app-ph↗

arXiv2019

Monitoring spin coherence of single nitrogen-vacancy centers in nanodiamonds during pH changes in aqueous buffer solutions

We report on sensing stability of nanodiamond (ND) quantum sensors in various pH aqueous buffer solutions for the two detection schemes of quantum decoherence spectroscopy and thermometry. The electron spin properties of single nitrogen-vacancy (NV) centers in 25-nm-sized NDs have been characterized by a spin-measurement compatible perfusion (SMCP) chamber where observing the same individual NDs in different buffer solutions is possible. With this system, we have determined the stability of the NV quantum sensors during the pH change from 4 to 11 as the fluctuations of +- 12% and +- 0.2 MHz for the spin coherence time ($T_2$) and the resonance frequency ($ω_0$) of their mean values, which are comparable to the instrumental error of the measurement system. Here, we discuss the importance of characterizing the sensing stability during pH changes and how the present observations affect ND-based NV quantum sensing.

cond-mat.mes-hall↗

arXiv1998

Spiral Structure in IP Peg: Confronting Theory and Observations

The first convincing piece of evidence of spiral structure in the accretion disc in IP Pegasi was found by Steeghs et al. (1997). We performed two kinds of 2D hydrodynamic simulations, a SFS finite volume scheme and a SPH scheme, with a mass ratio of 0.5. Both results agreed well with each other. We constructed Doppler maps and line flux-binary phase relations based on density distributions, the results agreeing well with those obtained by observation.

astro-ph↗

arXiv1997

Spiral Shocks in 3D Accretion Discs

We have performed three-dimensional numerical simulations of accretion discs in a close binary system using the Smoothed Particle Hydrodynamics method. Our result show that, contrary to previous claims, 3D discs do exist even when the specific heat ratio of the gas is as large as gamma=1.2. Although the disc is clearly more spread in the z-direction in this case than it is for the quasi-isothermal one, the disc height is compatible with the hydrostatic balance equation. Our numerical simulations with gamma=1.2 also demonstrate that spiral shocks exist in 3D discs. These results therefore confirm previous 2D simulations.

astro-ph↗