Optically detected magnetic resonance imaging

Abstract

Optically detected magnetic resonance (ODMR) provides ultrasensitive means to detect and image a small number of electron and nuclear spins, down to the single spin level with nanoscale resolution. Despite the significant recent progress in this field, it has never been combined with the power of pulsed magnetic resonance imaging (MRI) techniques.Here, we demonstrate for the first time how these two methodologies can be integrated using short pulsed magnetic field gradients to spatially-encode the sample. This results in what we denote as an "optically detected magnetic resonance imaging" (ODMRI) technique. It offers the advantage that the image is acquired in parallel from all parts of the sample, with well-defined three-dimensional point-spread function, and without any loss of spectroscopic information. In addition, this approach may be used in the future for parallel but yet spatially-selective efficient addressing and manipulation of the spins in the sample. Such capabilities are of fundamental importance in the field of quantum spin-based devices and sensors. 3The selective control and measurement of a small number of electron spins with high spatial resolution is an experimental capability of fundamental importance that is at the basis of many spin-based quantum information devices and sensor technologies. For example, many suggestions and approaches to spin-based quantum computations (QCs -those making use of various quantum phenomena to solve some challenging computation tasks) require such capabilities as a prerequisite for fabricating an actual useful device. 1,2 Furthermore, the manipulation and measurement of electron spins are not only central to many quantum-proposed devices, but can also be used to fabricate spin-based sensors, for example, for high-resolution mapping of magnetic and electric fields with extreme accuracy. 3,4 One possible approach that can potentially answer these requirements makes use of optically detected magnetic resonance (ODMR).ODMR is a very sensitive technique that can detect a small number of paramagnetic species -even single spins -in specific systems whose optical transitions are coupled to their magnetic levels. 1 In recent years this technique has picked up a significant momentum, due mainly to the many applications and interesting physics revealed through the ODMR of nitrogen vacancy (NV) centers in diamonds. 2 ODMR can be relatively easily employed in the imaging of heterogeneous samples by making use of well-established conventional optical imaging modalities, such as confocal fluorescence microscopy. However, these approaches still have resolution limitations regarding applications aiming at the nanoscale regime. 4Furthermore, optical microscopy cannot provide a solution in cases where selective excitation of some of the paramagnetic centers is required, or where some other "dark" spins (i.e., spins that do not produce luminescence signals) in the vicinity of the optical-active center need to be imaged. 5 The existing approaches to high resolution (nanosc...

Zero-Field Magnetometry Based on Nitrogen-Vacancy Ensembles in Diamond

“…Negatively charged nitrogen-vacancy (NV) centers in diamond have garnered wide interest as magnetometers [1][2][3][4][5][6], with diverse applications ranging from electron spin resonance (ESR) and biophysics to materials science [7][8][9][10][11][12][13]. However, typical operation of an NV magnetometer requires an applied bias magnetic field to nonambiguously resolve magnetically sensitive features in the level structure.…”

Direct Measurement of the Flip-Flop Rate of Electron Spins in the Solid State

“…The measurements of the diamond sample were carried out using our optically-detected magnetic resonance imaging (ODMRI) setup [49], but with a specially-designed dielectric resonator for ~6.7 GHz, which can accommodate both the diamond sample and the gradient coils (Fig. 4b), for enhanced gradient efficiency (vs. our setup in [49], where the gradient coils are outside rather than inside a ~10.6 GHz resonator). The sample was placed with its [111] orientation along B 0 to enable efficient optical pumping of the NV spins' levels.…”

Spectroscopy, imaging, and selective addressing of dark spins at the nanoscale with optically detected magnetic resonance

“…Very recently, our team and others have shown how the pulsed magnetic field gradient imaging method can be combined with a pulsed ODMR detection sequence when imaging the NV centers themselves . In this so‐called ODMR imaging (ODMRI) method, pulsed field gradients spatially encode the image by tagging different phases to different spins based on their location in the sample.…”

“…The phase of the NV signal is detected by repeating the last π/2 MW pulse twice with two different phases ( x and y ), and combining the results (see full details in Ref. ).…”

“…We start our analysis by first examining a simpler case, where we phase‐encode the signal from the NVs themselves, as described in Fig. . Clearly, a first requisite for acquiring an image is that the individual echo signals, detected for different phase‐encoding pulses, have a sufficient signal‐to‐noise ratio (SNR) after a reasonable averaging time.…”