Toshiharu Makino’s research while affiliated with National Institute of Advanced Industrial Science and Technology and other places

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Publications (264)


Heteroepitaxial (111) CVD diamond process with preferentially aligned NV centers. a) Process flow. b) Top‐view of heteroepitaxial diamond (iii). c) Inverse pole figure map of heteroepitaxial diamond (iii).
Electric vehicle (EV) battery monitor with heteroepitaxial (111) diamond sensors. a) Diamond sensor glued to the fiber top. b) Microwave guide surrounding the fiber top to generate a microwave magnetic field perpendicular to the [111] NV‐axis of the diamond sensor. c) Circuit for tracking the resonance frequencies of two sensors A and B for the gradiometer. The higher and lower resonance frequencies of each sensor, RH and RL, are tracked by two microwave generators’ frequencies FH and FL at the same time using integral feedback control from the normal and quadrature two‐phase outputs of the lock‐in amplifier, PN and PQ. d) Illustration of the tilt angle θ between two sensors A and B. e) Dependence of the CMRR (Common Mode Rejection Ratio) on θ. f) Illustration of the tilt correction mechanism in the sensor holder. The sensor holder consists of the base and the mounting fixture. The base is attached to the bus bar. The base and the mounting fixture are connected by the flexible pillar. The sensor is fixed to the mounting fixture. The tilt angle between the sensor surface and the busbar was fine‐tuned using these screws. The top half of the upper sensor holder is shown as a dashed outline line to clearly show the area around sensor B. Sensor A is located under the busbar and is not visible in this illustration.
Fundamental physical properties of the heteroepitaxial CVD diamond sensor were measured with a confocal microscope. a) CW‐ODMR spectrum, b) PL spectrum, c) Rabi oscillation, d) Hahn echo decay.
Fundamental performance of the heteroepitaxial (111) CVD diamond sensor glued onto the fiber‐top and installed in the sensor holder for busbar current measurement. a) CW‐ODMR spectrum showing NV‐axes preferentially aligned to (111). The dashed line represents the Gaussian fit. b) FFT spectra of the magnetic field noise observed as (PQ–PN)/2γS, where PQ and PN are the normal and quadrature two‐phase outputs of the lock‐in amplifier, γ is the gyromagnetic ratio and S is the rate of change (slope) of the derivative of the ODMR spectrum at the resonance frequency. The blue and orange lines represent independent sensors A and B, respectively, while the dark blue represents their difference as the gradiometer.
Common mode noise rejection characteristics of heteroepitaxial CVD diamond sensors as the gradiometer measured in the laboratory noise environment. a) Allan deviation of the magnetic field without the busbar current, where the magnetic field was evaluated as the sum of Δ(PQ–PN)/2γS which is major at shorter time range than CR and Δ(FH–FL)/2γ which is major at longer time range. The blue and orange lines represent independent sensors A and B, respectively, while the dark blue represents their difference as the gradiometer. b) Busbar current from 100 to 1 mA for pulse measurement. c) Measured magnetic field in pulse measurement. Blue, orange, and dark blue lines are the same as in (a). A 10 mA pulse could be recognized.
Heteroepitaxial (111) Diamond Quantum Sensors with Preferentially Aligned Nitrogen‐Vacancy Centers for an Electric Vehicle Battery Monitor
  • Article
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January 2025

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34 Reads

Kenichi Kajiyama

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Moriyoshi Haruyama

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Mutsuko Hatano

A platform for heteroepitaxial (111) chemical vapor deposition (CVD) diamond quantum sensors with preferentially aligned nitrogen vacancy (NV) centers on a large substrate is developed, and its operation as an electric vehicle (EV) battery monitor is demonstrated. A self‐standing heteroepitaxial CVD diamond film with a (111) orientation and a thickness of 150 µm is grown on a non‐diamond substrate and subsequently separated from it. The high uniformity and crystallinity of the (111)‐oriented diamond is confirmed. A 150‐µm thick NV‐diamond layer is then deposited on the heteroepitaxial diamond. The T2 value measured by confocal microscopy is 20 µs, which corresponds to substitutional nitrogen defect concentration of 8 ppm. The nitrogen‐vacancy concentration and T2* are estimated to be 0.05 ppm and 0.05 µs by continuous wave optically detected magnetic resonance (CW‐ODMR) spectroscopy in a fiber‐top sensor configuration. In a gradiometer, where two sensors are placed on both sides of the busbar, the noise floor is 17 nT/Hz0.5 in the frequency range of 10–40 Hz without magnetic shielding. The Allan deviation of the magnetic field noise in the laboratory is below 0.3 µT, which corresponds to a busbar current of 10 mA, in the accumulation time range of 10 ms to 100 s.

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FIG. 1. Energy level structure of NV 0 and its characterization. (a) Schematic of the energy levels of NV 0 with some static strain under a zero magnetic field. The ground state exhibits energy splitting on the order of 10 GHz. The optical transition occurs at 575 nm. |±⟩ o and |↑⟩ s are the eigenstate of the orbital (o) and spin (s) operators. The prime symbol (|± ′ ⟩) indicates the orbital eigenstates are hybridized under the static strain [29]. |0⟩ o represents that the state does not have the orbital angular momentum. (b) Measurement sequence for PLE spectrum of NV 0 . The 637-nm laser that is resonant with the zero-phonon line of NV − is used to initialize the charge state to NV 0 , while the 575-nm laser is used to observe the optical transition. (c) PLE spectrum of NV 0 . The 575-nm laser is horizontally polarized to maximize counts from |0⟩. (d) Measurement sequence for ODER. After the charge initialization, the driving microwave pulse is applied between initialization (Init.) and readout (RO) optical pulses. The initialization pulse pumps the orbital state from |0⟩ to |1⟩. Changes in population induced by the driving pulse are estimated from the ratio of the maximum counts (B/A) obtained from the first (A) and second (B) pulses. In the following analysis, the dark counts are subtracted from the PL counts. The PL counts are then smoothed by the five-point moving average. (e) The ODER spectrum corresponding to the |1⟩ → |0⟩ transition, which is fitted by a Gaussian curve. The error bars correspond to the standard deviation considering the photon shot noise.
FIG. 2. Temperature dependence of the orbital relaxation time and rate. (a) Temperature dependence of the orbital relaxation time. The fitting function for T orb 1 is shown in the main text. The inset shows how T orb 1
FIG. S1. Optical setup for the confocal microscopy with the microwave input and the control system using a field programmable gate array (FPGA). Pictures of the structure around the sample and the objective lens, the sample mounted on a printed-circuit-board, the diamond sample with the electrodes are shown. (1) Objective lens, (2) sample holder, (3) thermal link, (4) piezo xyz scanner, (5) piezo xyz positioner. APD : avalanche photodiode, AWG : arbitrary waveform generator, PM : power meter, AOM : acousto-optic modulator, VOA : variable optical attenuator, λ-meter : wavelength meter, FPGA : field programmable gate array.
FIG. S4. T orb 1 in different average (a) laser and (c) microwave (MW) powers. T sample estimated
Quantum Orbital-State Control of a Neutral Nitrogen-Vacancy Center at Millikelvin Temperatures

November 2024

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10 Reads

A neutral nitrogen-vacancy center (NV0^0) is promising for realizing strong coupling with a single microwave photon due to its large electric field sensitivity, although it is susceptible to environmental phonon noise at 5 K. Decreasing the temperature to 15 mK results in a tenfold increase in orbital relaxation time compared to that at 5 K. Dynamical decoupling pulses significantly increase the orbital coherence time to around 1.8 μ\mus, representing a 30-fold improvement compared to that without decoupling pulses. Based on these results, a single NV0^0 can reach the strong coupling regime when coupled with a high-impedance microwave resonator, thus opening up the possibility of microwave quantum electrodynamics using a single optically-active defect center in diamond.




Energy level structure of NV⁰, device image, photoluminescence excitation (PLE) spectrum, and DC voltage dependence of the PLE spectrum
a Schematic of the energy level of NV⁰ with some static strain under a zero magnetic field. The ground state exhibits energy splitting in the order of 10 GHz owing to the combined effects of spin-orbit interaction and strain. Moreover, the optical transition occurs at 575 nm. b Optical microscope image of the electrical circuit on the diamond used in the experiments. The upper electrodes are used to apply low (<1 MHz) or high (~10 GHz) electric fields. Moreover, the color map shows the photoluminescence (PL) counts around the center of the circuit. The red-circled NV center is used for experiments. c PLE spectrum of NV⁰ and its measurement sequence. The 637 nm laser resonant at the zero-phonon line of NV⁻ is used to initialize the charge state to NV⁰, and the 575 nm laser is used to observe the transition. d PLE spectrum shifts as a function of the DC voltage. The green and blue circles correspond to the lower (0\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\left\vert 0\right\rangle$$\end{document}) and upper (1\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\left\vert 1\right\rangle$$\end{document}) branches, respectively, and the inset shows the difference in the PLE frequencies of the upper (0\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\left\vert 0\right\rangle$$\end{document}) and lower (1\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\left\vert 1\right\rangle$$\end{document}) branches. Additionally, the horizontal axis is the same as that of the main graph.
Measurement of the orbital relaxation time of NV⁰
a Schematic of the experimental sequence for measuring the orbital relaxation time of NV⁰. After charge initialization (Init.) using the 637 nm laser, the first 575 nm laser pulse initializes 0\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\left\vert 0\right\rangle$$\end{document} to 1\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\left\vert 1\right\rangle$$\end{document}, and the population in 0\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\left\vert 0\right\rangle$$\end{document} is read out (RO) by the second 575 nm pulse after some delay time. The peak counts, A and B, at each pulse are used to estimate the population in 0\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\left\vert 0\right\rangle$$\end{document}. The repetition time for each measurement, N, is 150, and is determined by measuring the decay of the PL counts as a function of the duration of the 575 nm laser irradiation. b Normalized counts, B/A, as a function of the delay time. The red dots are the experimental data and the orange curve is the results of curve fitting using the exponential function. The inset shows the time-resolved PL counts of two pulses with a 100 ns gap in between. Additionally, the PL counts are smoothed using the Savitzky-Golay filter with 17 points before the calculation of the peak height, and the background is subtracted using the data when the laser is absent. Error bars correspond to standard deviation error after the smoothing.
Optically detected electrical resonance (ODER) and the Autler-Townes splitting measurements
a Schematic of the experimental sequence used in measuring the ODER and the Autler-Townes splitting. After charge conversion using the 637 nm laser, the 575 nm laser is simultaneously applied with microwave application at the transition between 0\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\left\vert 0\right\rangle$$\end{document} and 2\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\left\vert 2\right\rangle$$\end{document}. The microwave frequencies are then swept for ODER measurement, and the power of the microwave is swept for the measurement of the Autler-Townes splitting. b ODER spectrum of NV⁰. The orange dots represent the data and the red curve is the Gaussian fit. Error bars correspond to standard deviation error. c The Autler-Townes splitting as a function of the square root of the power of the applied microwave electric fields.
Rabi oscillation and microwave power dependence of the Rabi frequency
a Schematic of the experimental sequence for Rabi oscillation. The microwave pulse is applied between the first (initialization) and second (readout) laser pulses, and the microwave frequency is set to the resonance frequency obtained from ODER measurement. The repetition times, N, are 100. b Normalized counts as a function of the microwave pulse width. The orange dots represent the data and the brown curve is the cosinusoidal fit. Error bars correspond to standard deviation error. The Rabi frequency is 87.8 MHz. c Rabi frequency as a function of the square root of the input power. The slope is 3.86 MHz/μW1/2.
Ramsey interference
a Schematic of the experimental sequence for Ramsey interference, where the two microwave pulses are applied between the first (initialization) and second (readout) laser pulses. The microwave width for the π/2 pulse is determined to be 4.6 ns based on the Rabi oscillation measurement. The repetition times, N, are 100. b Normalized counts as a function of the delay time of the microwave pulse (free precession time). The blue dots represent the data and the blue curve represents the fitting using the function, Asin(Δt+ϕ)exp(−t/T2*)+B\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$A\sin (\Delta t+\phi )\exp (-t/{T}_{2}^{*})+B$$\end{document}, where A, B, and ϕ are constants, Δ is the detuning from the transition between 0\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\left\vert 0\right\rangle$$\end{document} and 1\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\left\vert 1\right\rangle$$\end{document}, and T2*\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$${T}_{2}^{*}$$\end{document} is the orbital coherence time. Error bars correspond to standard deviation error. T2*\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$${T}_{2}^{*}$$\end{document} is 31.0 ns.
Coherent electric field control of orbital state of a neutral nitrogen-vacancy center

May 2024

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72 Reads

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6 Citations

The coherent control of the orbital state is crucial for realizing the extremely-low power manipulation of the color centers in diamonds. Herein, a neutrally-charged nitrogen-vacancy center, NV⁰, is proposed as an ideal system for orbital control using electric fields. The electric susceptibility in the ground state of NV⁰ is estimated, and found to be comparable to that in the excited state of NV⁻. Also, the coherent control of the orbital states of NV⁰ is demonstrated. The required power for orbital control is three orders of magnitude smaller than that for spin control, highlighting the potential for interfacing a superconducting qubit operated in a dilution refrigerator.



The fabrication process flow, the schematic of the water vapor annealing system, and the schematic and optical microscope image of the Al2O3/diamond MOS capacitors.
Cycle C–V curves at 1 MHz for different samples of (a) without water vapor annealing and (b)–(d) with water vapor annealing for 30 min, 1 h, and 2 h, respectively.
Simultaneous C–V curves at quasi-static and 1 MHz for different samples of (a) without water vapor annealing and (b)–(d) with water vapor annealing for 30 min, 1 h, and 2 h, respectively.
Energy distribution of interface trap density (Dit) for the four Al2O3/diamond MOS capacitors without and with water vapor annealing treatments for 30 min, 1 h, and 2 h, respectively.
(a) The flatband voltage shift and (b) the effective fixed charge for different samples without water vapor annealing, with water vapor annealing for 30 min, 1 h, and 2 h, respectively.
Impact of water vapor annealing treatments on Al2O3/diamond interface

March 2024

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59 Reads

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1 Citation

Our group developed the first inversion-type p-channel diamond metal–oxide–semiconductor field-effect transistor, which featured normally off properties by employing water vapor annealing treatments for the oxygen-terminated diamond surface. Despite the comprehensive device-grade characterization, the impact of water vapor annealing treatments on the Al2O3/diamond interface has not been investigated in detail. In this work, we fabricated four diamond metal–oxide–semiconductor (MOS) capacitors without and with water vapor annealing treatments for various times of 30 min, 1 h, and 2 h and conducted the cycle capacitance–voltage (C–V) and simultaneous C–V measurements. The large cycle C–V shift existed in the sample without water vapor annealing treatment, whereas it was significantly suppressed by water vapor annealing treatments, indicating the effective passivation of the traps with long time constants. The simultaneous C–V results showed a similar trend that the frequency dispersion of the simultaneous C–V was dramatically reduced with water vapor annealing treatments, and the interface quality of Al2O3/diamond had a slight dependence on the water vapor annealing times. Based on simultaneous C–V measurements, the interface state density (Dit) at an energy level of 0.2–0.6 eV from the valence band edge of diamond was extracted for the different MOS capacitors. The Dit was reduced by one order of magnitude with water vapor annealing treatments, and it almost did not change with the water vapor annealing times. Besides, the flat band voltage shift and effective fixed charge were also dramatically reduced by water vapor annealing. The possible physical reason for the interface improvement by water vapor annealing treatments was discussed.


Transform-Limited Photon Emission from a Lead-Vacancy Center in Diamond above 10 K

February 2024

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54 Reads

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15 Citations

Physical Review Letters

Transform-limited photon emission from quantum emitters is essential for high-fidelity entanglement generation. In this Letter, we report the coherent optical property of a single negatively charged lead-vacancy (PbV) center in diamond. Photoluminescence excitation measurements reveal stable fluorescence with a linewidth of 39 MHz at 6 K, close to the transform limit estimated from the lifetime measurement. We observe 4 orders of magnitude different linewidths of the two zero-phonon lines, and find that the phonon-induced relaxation in the ground state contributes to this huge difference in the linewidth. Because of the suppressed phonon absorption in the PbV center, we observe nearly transform-limited photon emission up to 16 K, demonstrating its high temperature robustness compared to other color centers in diamond.


FIG. 1. (a) Image of a SAW resonator used in this experiment. The IDTs and reflectors made of Al were fabricated on the AlN/diamond heterostructure. (b) Schematic of the S-parameter measurement setup: the SAW resonator is attached to a printed circuit board, and the coplanar waveguide (CPW) and electrodes on the board are coupled by wire bonding. The sample is cooled to 5 K by using a cryogen-free cryostat. (c) mBVD model with wire and electrode impedances connected in series.
FIG. 2. Before the temperature correction of (a) magnitude and (b) phase of S 11 . The wiring loss decreases with decreasing temperature, and the phase at the region away from the resonant frequency jS 11 j is decreasing.
FIG. 3. (a) Real and (b) imaginary parts of admittance at room temperature (300 K) and (c) real and (d) imaginary parts of admittance at 5 K. The solid lines are experimental data, and dashed lines are fitting curves.
 View Online  Export Citation CrossMark Low-temperature characteristics of an AlN/Diamond surface acoustic wave resonator  Low-temperature characteristics of an AlN/Diamond surface acoustic wave resonator

December 2023

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50 Reads

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2 Citations

Phonons confined in mechanical resonators can be coupled to a variety of quantum systems and are expected to be applied to hybrid quantum systems. Diamond surface acoustic wave (SAW) devices are capable of high efficiency in phonon interaction with color centers in diamond. The temperature dependence of the quality factor is crucial for inferring the governing mechanism of coupling efficiency between phonons and color centers in diamond. In this paper, we report on the temperature dependence of the quality factor of an AlN/diamond SAW device from room temperature to 5 K. The temperature dependence of the quality factor and resonant frequency suggests that the mechanism of SAW dissipation in the AlN/diamond SAW resonator at 5 GHz is the phonon-phonon scattering in the Akheiser regime and that further cooling can be expected to improve the quality factor. This result provides a crucial guideline for the future design of AlN/diamond SAW devices. Published under an exclusive license by AIP Publishing. https://doi.


Citations (64)


... Since nanodiamonds (NDs) can be prepared in a wide range of sizes, NV defects can be studied in materials with size ranging from about 10-100 nm. Although coherent control using electric fields has been demonstrated for the neutral NV (0) centres, [9] and potential applications as qubits have been considered, [10] most research into quantum applications has been focused on the negatively charged NV (−) centres. NV (−) centres in diamond structures possess unique electronic properties that are crucial for their application in quantum technology. ...

Reference:

The influence of surface properties on colour centres in diamond
Coherent electric field control of orbital state of a neutral nitrogen-vacancy center

... On top of that, the linewidth of the target resonance can undergo homogeneous broadening, which can be caused by nonradiative decay [117], or phonon-induced dephasing [118] and depolarization [117]. In our model, we group these phenomena into an additional rate Γ ′ hom ≲ Γ 0 , whose value qualitatively accounts for the fact that nearly transform-limited linewidths have been observed at cryogenic temperatures (we also notice that encouraging paths have been suggested to extend this property up to much higher temperatures [121]). At the same time, we consider the possibility that local properties (such as strain, or spectral diffusion) randomly shift the resonance frequencies of the individual emitters, thus resulting in an additional inhomogeneous broadening. ...

Transform-Limited Photon Emission from a Lead-Vacancy Center in Diamond above 10 K
  • Citing Article
  • February 2024

Physical Review Letters

... The essential step is mapping the coupled acoustic (mechanical) and electric degrees of freedom to a single anharmonic oscillator. The results from published data for an AlN-on-diamond piezoelectric resonator 14 are analyzed with this model and found to be in reasonable agreement. ...

 View Online  Export Citation CrossMark Low-temperature characteristics of an AlN/Diamond surface acoustic wave resonator  Low-temperature characteristics of an AlN/Diamond surface acoustic wave resonator

... Although the NV − center is stable in bulk diamond and in nanodiamonds with diameter > 10 nm, unfortunately, it is converted to its neutral state upon optical excitation if it resides close (< 10 nm) to the surface. 29,31,32 Proposed strategies [33][34][35][36][37][38][39][40][41] to stabilize NV − -centers close to a diamond surface include doping and surface modification through chemical functionalization, adsorption of molecules, and surface coating. So far, most studies focused on surfaces terminating bulk diamonds, while strategies for stabilizing NV − centers within USNDs remain unexplored. ...

Charge stabilization of shallow nitrogen-vacancy centers using graphene/diamond junctions

... Just by comparing the spectra collected for comparable ion currents, it is clear that there is a distinct NV − peak visible in the spectra where laser excitation is present. Since it has been established that the NV − center is not optically active as a trap/recombination center, as was reported in other IL [28], electroluminescence (EL) [29], and cathodoluminescence (CL) [30] experiments, it shouldn't be possible to observe NV − emission unless some articulated and proactive charge stabilization is applied [31]. This, along with the results shown in Fig. 2, shows that the LIBIL setup could resolve some spectral features not distinguishable only with ion excitation. ...

Electroluminescence of negatively charged single NV centers in diamond

... Delta(δ)-doping studies [41][42][43] have demonstrated vacancy diffusion-limited spatially localized NV centers, while avoiding the crystal damage and processing inherent to aperture mask or focused implantation [42,[44][45][46][47][48][49]. PECVD of diamond quantum systems has enabled engineering of NV center spin environ- * These two authors contributed equally ments via isotopic purification [41,50,51], dimensionality control [41,52,53], and co-doping techniques [54][55][56]. However, the development of these techniques has outpaced computational efforts to model spin bath-induced decoherence [57,58], and theoretical approaches have not yet been applied to investigate diamond qubit synthesis. ...

n -type diamond synthesized with tert -butylphosphine for long spin coherence times of perfectly aligned NV centers
  • Citing Article
  • November 2022

... In addition, the atomically flat diamond can be formed by lateral growth techniques and can be employed to fabricate diamond MOS capacitors to further improve the surface and interface qualities. 25,35,36 IV. CONCLUSION ...

Selectively buried growth of heavily B doped diamond layers with step-free surfaces in N doped diamond (111) by homoepitaxial lateral growth
  • Citing Article
  • April 2022

Applied Surface Science

... 19) The bulk diamond was then polished to 50 μm thick and was cut into isosceles triangularshaped prisms (measured 30 μm in base, 50 μm on both sides). 20) A magnetic sample, 3 μm diameter core-shell superparamagnetic microbead named Magnosphere MS300/ Carboxyl (JSR Life Science Co.) was used. The magnetic bead consists of a non-magnetic core covered by magnetite nanoparticles (Fe 3 O 4 ) as a shell [ Fig. 1(a)]. ...

Scanning diamond NV center magnetometer probe fabricated by laser cutting and focused ion beam milling
  • Citing Article
  • December 2021

... Matsumoto et al. at Kanazawa University developed a normally off inversion p-channel metal-oxide-semiconductor field-effect transistor (MOSFET) on top of a nitrogen (N)-doped diamond body. 53 The nitrogen doping was realized by microwave plasma-enhanced chemical vapor deposition with intention to replace the currently often used phosphorus (P) doping and reduce environmental fabrication risks of diamond devices. The results are compared to phosphorus doped diamond. ...

Fabrication of inversion p-channel MOSFET with a nitrogen-doped diamond body