Production of oriented nitrogen-vacancy color centers in synthetic diamond

We present a promising method for creating high-density ensembles of nitrogen-vacancy centers with narrow spin-resonances for high-sensitivity magnetic imaging. Practically, narrow spinresonance linewidths substantially reduce the optical and RF power requirements for ensemble-based sensing. The method combines isotope purified diamond growth, in situ nitrogen doping, and helium ion implantation to realize a 100 nm-thick sensing surface. The obtained 10 17 cm −3 nitrogen-vacancy density is only a factor of 10 less than the highest densities reported to date, with an observed spin resonance linewidth over 10 times more narrow. The 200 kHz linewidth is most likely limited by dipolar broadening indicating even further reduction of the linewidth is desirable and possible.The nitrogen-vacancy (NV) center in diamond is a versatile room-temperature magnetic sensor which can operate in a wide variety of modalities, from nanometerscale imaging with single centers [1, 2] to sub-picotesla sensitivities using ensembles [3]. Ensemble-based magnetic imaging, utilizing a two-dimensional array of NV centers [4][5][6], combines relatively high spatial resolution with high magnetic sensitivity. These arrays are ideal for imaging applications ranging from detecting magnetically tagged biological specimens [7,8] to fundamental studies of magnetic thin films [9]. A key challenge for array-based sensors is creating a high density of NV centers while still preserving the desirable NV spin properties. Here we report on a promising method which combines isotope purified diamond growth, in situ nitrogen doping and helium ion implantation. In the 100 nmthick sensor layer, we realize an NV density of 10 17 cm −3 with a 200 kHz magnetic resonance linewidth. This corresponds to a a DC magnetic sensitivity ranging from 170 nT (current experimental conditions) to 10 nT (optimized experimental conditions) for a 1 µm 2 pixel and 1 second measurement time.Magnetic sensing utilizing NV centers is based on optically-detected magnetic resonance (ODMR) [10][11][12]. In the ideal shot-noise limit, the DC magnetic sensitivity is given by [9] in which h/gµ B = 36 µT/MHz, C is the resonance dip contrast, η is the photon collection efficiency, δν is the full-width at half maximum resonance linewidth, n N V is the density of NV centers in imaging pixel volume V , and t is the measurement time. From Eq. 1, it is apparent that to minimize δB ideal for a given linewidth δν, one would like to maximize the NV density n N V . Increasing n N V , however, can also increase δν. For example, lattice damage during the NV creation process can create inhomogeneous strain-fields [13]. More fundamentally, eventually NV-NV and NV-N dipolar interactions will contribute to line broadening. This dipolar broadening, δν dp , is proportional to the nitrogen density n N [14,15]. Since n N V is typically proportional to n N , we can divide δ ν into two components, δν = δν 0 + δν dp = δν 0 + An N V , to obtainin which δν 0 depends on factors independent of NV density (e.g. hyperfi...

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confidence: 81%

High density nitrogen-vacancy sensing surface created via He+ ion implantation of 12C diamond

Kleinsasser

Stanfield

Banks

et al. 2016

“…In (111)-oriented synthetic diamond, it has been reported that the NV centers can be preferentially oriented along the [111] crystallographic axis. [18][19][20][21] Attracting enormous attention, such a special diamond substrate will lead to enhanced sensitivity in metrology as well as atomically precise quantum information devices. Our resonator circuit design will be fully compatible with these applications.…”

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confidence: 99%

Polarization- and frequency-tunable microwave circuit for selective excitation of nitrogen-vacancy spins in diamond

Herrmann

Appleton

Sasaki

et al. 2016

We report on a planar microwave resonator providing arbitrarily polarized oscillating magnetic fields that enable selective excitation of the electronic spins of nitrogen-vacancy (NV) centers in diamond. The polarization plane is parallel to the surface of diamond, which makes the resonator fully compatible with (111)-oriented diamond. The field distribution is spatially uniform in a circular area with a diameter of 4 mm, and a near-perfect circular polarization is achieved. We also demonstrate that the original resonance frequency of 2.8 GHz can be varied in the range of 2−3.2 GHz by introducing varactor diodes that serve as variable capacitors.In recent years, the nitrogen-vacancy (NV) center in diamond has emerged as a promising platform for quantum information processing and nanoscale metrology. 1-7At the heart of both technologies lies an exquisite control of the NV electronic spin.8 The ground state of the negatively charged NV center is an S = 1 spin triplet with the m S = ±1 sublevels lying D gs = 2.87 GHz above the m S = 0 sublevel under zero magnetic field. The external static magnetic field B dc applied parallel to the quantization axis n NV (along one of the 111 crystallographic axes) further splits the m S = ±1 levels by 2γB dc , with γ = 28 GHz/T being the gyromagnetic ratio of the NV electronic spin [see Fig. 1].Initialization, control, and readout of this three-level V system are accomplished by an optically detected magnetic resonance (ODMR) technique, in which opticalLin. pol.Cir. pol. pumping by a green (∼500 nm) laser serves to initialize and read out the NV spin and short pulses of oscillating magnetic fields B ac (∼2.87 GHz) drive it into an arbitrary quantum-mechanical superposition. In ideal magnetic resonance experiments, B ac and B dc ( n NV ) should be orthogonal, 9,10 whereas in reality the direction of B ac at the location of the target NV center is hard to control or even know about. This is because a metal wire or a microfabricated stripline, commonly used for experiments with NV centers, generates B ac that is highly dependent on the positions. Moreover, B ac from these sources is linearly polarized, while the NV spin has clear transition selection rules; The m S = 0 ↔ 1 (−1) transition is driven by σ + (σ − ) circularly polarized fields. To fully exploit the S = 1 nature of the NV spin for quantum information and metrology applications, 11-14 it is highly desired to have a reliable means to generate arbitrarily polarized microwave fields.A few configurations for polarization-controlled B ac have been adopted for the NV system. A popular one is a pair of crisscrossed striplines, which generates desired fields only beneath the crossing point.15,16 A pair of parallel striplines may be a simpler alternative.17 In both examples, however, it is by design difficult or impossible to make the polarization plane perpendicular to n NV and thus to B dc .In this paper, we present a simple planar resonator circuit providing spatially uniform, arbitrarily polarized, and in-plane microwave magne...

“…Additionally, high-density surface defects formed during implantation affect the spin coherence time and the ensembles show a random orientation with this technique 12,13,14 . Existing studies include reports of CVD growth that demonstrated a narrow distribution in the confinement of NV centers in the vicinity of a surface 11 and their atomic alignment on (100), (110), (113), and (111) substrates for the formation of thick diamond films 14,15,16,17,18,19,20 . Nearly all previous studies have focused on either low density NV centers (<10 13 cm -3 3 ) in the vicinity of a surface with no alignment 21,22,23 or the formation of NV ensembles with alignment in bulk.…”

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confidence: 99%

“…More than 6.1×10 15 cm -3 -3.1×10 16 cm -3 NV centers are detected from confocal scan. The results demonstrate highest NV density in the vicinity of the surface with perfect alignment of more than 99 %.…”

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confidence: 99%

Perfectly aligned shallow ensemble nitrogen-vacancy centers in (111) diamond

Ishiwata

Nakajima

Tahara

et al. 2017

We report the formation of perfectly aligned, high-density, shallow nitrogen vacancy (NV) centers on the Perfectly aligned shallow ensemble NV centers indicated a high Rabi contrast of approximately 30 % which is comparable to the values reported for a single NV center. Nanoscale NMR demonstrated surfacesensitive nuclear spin detection and provided a confirmation of the NV centers depth. Single NV center approximation indicated that the depth of the NV centers was approximately 9-10.7 nm from the surface with error of less than ±0.8 nm. Thus, a route for material control of shallow NV centers has been developed by step-flow growth using a CVD system. Our finding pioneers on the atomic level control of NV center alignment for large area quantum magnetometry. 6,7 . A fundamental limitation of an NV center based magnetometer is the material control required to confine the NV center in the vicinity (<10 nm) of the substrate surface with a high magnetic sensitivity.Previous studies that examined shallow NV centers focused on either a high-density ensemble for twodimensional large area imaging or a single NV center for high contrast and high coherent time to obtain a minimal detection volume using nanoscale NMR. However, it was found necessary to combine spatial localization of a NV centers with alignment, high density, and a long spin coherence time (T2) to obtain high magnetic sensitivity. The alignment of NV centers in an ensemble is the key to accomplish high contrast while maintaining high signal to noise ratio for high magnetic sensitivity with low accumulation time. In this regard, low energy ion implantation is the most common technique utilized for the production of NV centers in the vicinity of a surface 8 . However, this methodology suffers from large depth dispersion (>10 nm) of the NV centers due to ion straggling and channeling effects 9,10 . Additionally, high-density surface defects formed during implantation affect the spin coherence time and the ensembles show a random orientation with this technique 12,13,14 . Existing studies include reports of CVD growth that demonstrated a narrow distribution in the confinement of NV centers in the vicinity of a surface 11 and their atomic alignment on (100), (110), (113), and (111) substrates for the formation of thick diamond films 14,15,16,17,18,19,20 . Nearly all previous studies have focused on either low density NV centers (<10 13 cm -3 3 ) in the vicinity of a surface with no alignment 21,22,23 or the formation of NV ensembles with alignment in bulk.In this paper, the formation of a perfectly aligned high-density shallow NV center film for surfacesensitive detection of nuclear spin has been demonstrated. Results obtained from SIMS measurement combined with an effective depth obtained from nanoscale NMR measurement confirms presence of shallow NV center approximately 9-10.7 nm from surface with error of less than ±0.8 nm. The results of this study offer a path toward controlling the alignment of shallow NV center ensembles.In this study, NV-containing d...