Publications
ResearcherID : C-5956-2008 (TY, h-index: 23) , AAZ-8749-2021 (RK, h-index: 6)
Google Scholar : TY (h-index: 32), RK (h-index: 7)
2020
Akihiro Kuwahata, Takahiro Kitaizumi, Kota Saichi, Takumi Sato, Ryuji Igarashi, Takeshi Ohshima, Yuta Masuyama, Takayuki Iwasaki, Mutsuko Hatano, Fedor Jelezko, Moriaki Kusakabe, Takashi Yatsui, Masaki Sekino
Magnetometer with nitrogen-vacancy center in a bulk diamond for detecting magnetic nanoparticles in biomedical applications Journal Article
In: Scientific Reports, 10 , pp. 2483, 2020.
Abstract | Links | BibTeX | Tags: Diamond, NV center
@article{Kuwahata2020,
title = {Magnetometer with nitrogen-vacancy center in a bulk diamond for detecting magnetic nanoparticles in biomedical applications},
author = {Akihiro Kuwahata and Takahiro Kitaizumi and Kota Saichi and Takumi Sato and Ryuji Igarashi and Takeshi Ohshima and Yuta Masuyama and Takayuki Iwasaki and Mutsuko Hatano and Fedor Jelezko and Moriaki Kusakabe and Takashi Yatsui and Masaki Sekino},
url = {https://www.altmetric.com/details/75906559},
doi = {10.1038/s41598-020-59064-6},
year = {2020},
date = {2020-02-01},
journal = {Scientific Reports},
volume = {10},
pages = {2483},
publisher = {Springer Nature},
abstract = {We developed a novel magnetometer that employs negatively charged nitrogen-vacancy (NV−) centers in diamond, to detect the magnetic field generated by magnetic nanoparticles (MNPs) for biomedical applications. The compact probe system is integrated into a fiber-optics platform allowing for a compact design. To detect signals from the MNPs effectively, we demonstrated, for the first time, the application of an alternating current (AC) magnetic field generated by the excitation coil of several hundred microteslas for the magnetization of MNPs in diamond quantum sensing. In the lock-in detection system, the minimum detectable AC magnetic field (at a frequency of 1.025 kHz) was approximately 57.6 nT for one second measurement time. We were able to detect the micromolar concentration of MNPs at distances of a few millimeters. These results indicate that the magnetometer with the NV− centers can detect the tiny amounts of MNPs, thereby offering potential for future biomedical applications.},
keywords = {Diamond, NV center},
pubstate = {published},
tppubtype = {article}
}
We developed a novel magnetometer that employs negatively charged nitrogen-vacancy (NV−) centers in diamond, to detect the magnetic field generated by magnetic nanoparticles (MNPs) for biomedical applications. The compact probe system is integrated into a fiber-optics platform allowing for a compact design. To detect signals from the MNPs effectively, we demonstrated, for the first time, the application of an alternating current (AC) magnetic field generated by the excitation coil of several hundred microteslas for the magnetization of MNPs in diamond quantum sensing. In the lock-in detection system, the minimum detectable AC magnetic field (at a frequency of 1.025 kHz) was approximately 57.6 nT for one second measurement time. We were able to detect the micromolar concentration of MNPs at distances of a few millimeters. These results indicate that the magnetometer with the NV− centers can detect the tiny amounts of MNPs, thereby offering potential for future biomedical applications.
2018
Felix Brandenburg, Ryosuke Nagumo, Kota Saichi, Kosuke Tahara, Takayuki Iwasaki, Mutsuko Hatano, Fedor Jelezko, Ryuji Igarashi, Takashi Yatsui
Improving the electron spin properties of nitrogen-vacancy centres in nanodiamonds by near-field etching Journal Article
In: Scientific Reports, 8 , pp. 15847, 2018.
Abstract | Links | BibTeX | Tags: Diamond, Nanophotonic fabrication, Near-field etching, NV center
@article{2018Felix,
title = {Improving the electron spin properties of nitrogen-vacancy centres in nanodiamonds by near-field etching},
author = {Felix Brandenburg and Ryosuke Nagumo and Kota Saichi and Kosuke Tahara and Takayuki Iwasaki and Mutsuko Hatano and Fedor Jelezko and Ryuji Igarashi and Takashi Yatsui},
doi = {10.1038/s41598-018-34158-4},
year = {2018},
date = {2018-10-01},
urldate = {2018-10-01},
journal = {Scientific Reports},
volume = {8},
pages = {15847},
publisher = {Springer Nature},
abstract = {The nitrogen-vacancy (NV) centre in diamond is a promising candidate for quantum computing applications and magnetic sensing applications, because it is an atomic-scale defect with stable coherence time (T2) and reliable accessibility at room temperature. We demonstrated a method for improving the NV spin properties (the full width half maximum (FWHM) value of the magnetic resonance spectrum and T2) through a near-field (NF) etching method under ambient conditions. The NF etching method, based on a He-Cd ultraviolet laser (325 nm), which is longer than the absorption edge of the oxygen molecule, enabled selective removal of defects on the nanodiamond surface. We observed a decrease in the FWHM value close to 15% and an increase in T2 close to 25%. Since our technique can be easily reproduced, a wide range of NV centre applications could be improved, especially magnetic sensing applications. Our results are especially attractive, because they have been obtained under ambient conditions and only require a light source with wavelength slightly above the O2 absorption edge.},
keywords = {Diamond, Nanophotonic fabrication, Near-field etching, NV center},
pubstate = {published},
tppubtype = {article}
}
The nitrogen-vacancy (NV) centre in diamond is a promising candidate for quantum computing applications and magnetic sensing applications, because it is an atomic-scale defect with stable coherence time (T2) and reliable accessibility at room temperature. We demonstrated a method for improving the NV spin properties (the full width half maximum (FWHM) value of the magnetic resonance spectrum and T2) through a near-field (NF) etching method under ambient conditions. The NF etching method, based on a He-Cd ultraviolet laser (325 nm), which is longer than the absorption edge of the oxygen molecule, enabled selective removal of defects on the nanodiamond surface. We observed a decrease in the FWHM value close to 15% and an increase in T2 close to 25%. Since our technique can be easily reproduced, a wide range of NV centre applications could be improved, especially magnetic sensing applications. Our results are especially attractive, because they have been obtained under ambient conditions and only require a light source with wavelength slightly above the O2 absorption edge.
2015
Ryosuke Nagumo, Felix Brandenburg, Anna Ermakova, Fedor Jelezko, Takashi Yatsui
Spectral control of nanodiamond using dressed photon-phonon etching Journal Article
In: Applied Physics A, 121 (4), pp. 1335-1339, 2015.
Abstract | Links | BibTeX | Tags: Diamond, Nanophotonic fabrication, Near-field etching, NV center
@article{2015NagumoAPA,
title = {Spectral control of nanodiamond using dressed photon-phonon etching},
author = {Ryosuke Nagumo and Felix Brandenburg and Anna Ermakova and Fedor Jelezko and Takashi Yatsui},
doi = {10.1007/s00339-015-9400-0},
year = {2015},
date = {2015-12-01},
journal = {Applied Physics A},
volume = {121},
number = {4},
pages = {1335-1339},
publisher = {Springer Nature},
abstract = {The luminescence of a nitrogen-vacancy (NV) center in a nanodiamond (ND) is of great interest because of its features, especially in the field of nanophotonics. When an NV center in an ND is located in the vicinity of the surface, the emission is often disturbed by any surface defects, resulting in non-radiative recombination. In this work, we performed dressed photon-phonon (DPP) etching of the NDs, and found that the size of the NDs decreased, while the cathodoluminescence (CL) intensity increased. We assume that this increase in the CL intensity originates from the removal of the surface protrusions and/or defects by DPP etching.},
keywords = {Diamond, Nanophotonic fabrication, Near-field etching, NV center},
pubstate = {published},
tppubtype = {article}
}
The luminescence of a nitrogen-vacancy (NV) center in a nanodiamond (ND) is of great interest because of its features, especially in the field of nanophotonics. When an NV center in an ND is located in the vicinity of the surface, the emission is often disturbed by any surface defects, resulting in non-radiative recombination. In this work, we performed dressed photon-phonon (DPP) etching of the NDs, and found that the size of the NDs decreased, while the cathodoluminescence (CL) intensity increased. We assume that this increase in the CL intensity originates from the removal of the surface protrusions and/or defects by DPP etching.
2014
Takashi Yatsui, Daisuke Takeuchi, Satoshi Koizumi, Kazuki Sato, Kohei Tsuzuki, Takayuki Iwasaki, Mutsuko Hatano, Toshiharu Makino, Masahiko Ogura, Hiromitsu Kato, Hideyo Okushi, Satoshi Yamasaki
Polarization-controlled dressed-photon–phonon etching of patterned diamond structures Journal Article
In: physica status solidi (a), 211 (10), pp. 2339-2342, 2014.
Abstract | Links | BibTeX | Tags: Diamond, First, Nanophotonic fabrication, Near-field etching
@article{doi:10.1002/pssa.201431161,
title = {Polarization-controlled dressed-photon–phonon etching of patterned diamond structures},
author = {Takashi Yatsui and Daisuke Takeuchi and Satoshi Koizumi and Kazuki Sato and Kohei Tsuzuki and Takayuki Iwasaki and Mutsuko Hatano and Toshiharu Makino and Masahiko Ogura and Hiromitsu Kato and Hideyo Okushi and Satoshi Yamasaki},
doi = {10.1002/pssa.201431161},
year = {2014},
date = {2014-10-01},
journal = {physica status solidi (a)},
volume = {211},
number = {10},
pages = {2339-2342},
abstract = {To realize an ultra-flat diamond surface with a three-dimensional (3D) structure, we performed dressed-photon–phonon (DPP) etching. A DPP is generated on nano-scale protrusions. Hence, the generation of DPPs results in selective removal of nano-scale protrusions, thereby achieving an ultra-flat surface even on the sidewall of a diamond mesa structure. By controlling the polarization of the incident light, a smooth diamond mesa structure sidewall was obtained, and a higher etching rate was obtained with a perpendicular polarization on the corrugations. In addition, by selective deposition of n-layer diamond on the p-layer diamond mesa structure, smooth n-layer diamond was confirmed on the DPP etched sidewall. Schematic of dressed-photon–phonon (DPP) etching on the sidewall: (a) before and (b) after etching, in which DPP selectively generates on the corrugations and etching automatically stops when the surface was smooth. Scanning electron microscopy image of the selective deposition of the n-layer (c) without and (d) with the DPP etched sidewall.},
keywords = {Diamond, First, Nanophotonic fabrication, Near-field etching},
pubstate = {published},
tppubtype = {article}
}
To realize an ultra-flat diamond surface with a three-dimensional (3D) structure, we performed dressed-photon–phonon (DPP) etching. A DPP is generated on nano-scale protrusions. Hence, the generation of DPPs results in selective removal of nano-scale protrusions, thereby achieving an ultra-flat surface even on the sidewall of a diamond mesa structure. By controlling the polarization of the incident light, a smooth diamond mesa structure sidewall was obtained, and a higher etching rate was obtained with a perpendicular polarization on the corrugations. In addition, by selective deposition of n-layer diamond on the p-layer diamond mesa structure, smooth n-layer diamond was confirmed on the DPP etched sidewall. Schematic of dressed-photon–phonon (DPP) etching on the sidewall: (a) before and (b) after etching, in which DPP selectively generates on the corrugations and etching automatically stops when the surface was smooth. Scanning electron microscopy image of the selective deposition of the n-layer (c) without and (d) with the DPP etched sidewall.
2012
Takashi Yatsui, Wataru Nomura, Makoto Naruse, Motoichi Ohtsu
Realization of an atomically flat surface of diamond using dressed photon–phonon etching Journal Article
In: Journal of Physics D: Applied Physics, 45 (47), pp. 475302, 2012.
Abstract | Links | BibTeX | Tags: Diamond, First, Nanophotonic fabrication, Near-field etching
@article{Yatsui_2012,
title = {Realization of an atomically flat surface of diamond using dressed photon–phonon etching},
author = {Takashi Yatsui and Wataru Nomura and Makoto Naruse and Motoichi Ohtsu},
url = {https://doi.org/10.1088%2F0022-3727%2F45%2F47%2F475302},
doi = {10.1088/0022-3727/45/47/475302},
year = {2012},
date = {2012-11-01},
journal = {Journal of Physics D: Applied Physics},
volume = {45},
number = {47},
pages = {475302},
publisher = {IOP Publishing},
abstract = {We obtained an atomically flat diamond surface following dressed photon–phonon (DPP) etching using 3.81 eV light and O2 gas. We obtained a surface roughness (Ra) of 0.154 nm for Ib-type (1 1 1) diamond and 0.096 nm for Ib-type (1 0 0) diamond. To evaluate the surface roughness, we grouped the surface into bins of width l and introduced the standard deviation of the height difference function for a given separation l, which allowed us to determine the height variation of the surface. Based on the calculation of standard deviation, the conventional adiabatic photochemical reaction did not remove the small surface features, while DPP etching decreased the surface roughness for all length scales.},
keywords = {Diamond, First, Nanophotonic fabrication, Near-field etching},
pubstate = {published},
tppubtype = {article}
}
We obtained an atomically flat diamond surface following dressed photon–phonon (DPP) etching using 3.81 eV light and O2 gas. We obtained a surface roughness (Ra) of 0.154 nm for Ib-type (1 1 1) diamond and 0.096 nm for Ib-type (1 0 0) diamond. To evaluate the surface roughness, we grouped the surface into bins of width l and introduced the standard deviation of the height difference function for a given separation l, which allowed us to determine the height variation of the surface. Based on the calculation of standard deviation, the conventional adiabatic photochemical reaction did not remove the small surface features, while DPP etching decreased the surface roughness for all length scales.