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Register a new userProbing local pressure environment in anvil cells with nitrogen vacancy (NV-) centers in diamond
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Important discoveries have frequently been made through the studies of matter under high pressure. The conditions of the pressure environment are important for the interpretation of the experimental results. Due to various restrictions inside the pressure cell, detailed information relevant to the pressure environment, such as the pressure distribution, can be hard to obtain experimentally. Here we present the study of pressure distributions inside the pressure medium under different experimental conditions with NV centers in diamond particles as the sensor. These studies not only show a good spatial resolution, wide temperature and pressure working ranges, compatibility of the existing pressure cell design with the new method, but also demonstrate the usefulness to measure with these sensors as the pressure distribution is sensitive to various factors. The method and the results will benefit many disciplines such as material research and phase transitions in fluid dynamics.
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A study of the photophysical properties of nitrogen-vacancy (NV) color centers in diamond nanocrystals of size of 50~nm or below is carried out by means of second-order time-intensity photon correlation and cross-correlation measurements as a function of the excitation power for both pure charge states, neutral and negatively charged, as well as for the photochromic state, where the center switches between both states at any power. A dedicated three-level model implying a shelving level is developed to extract the relevant photophysical parameters coupling all three levels. Our analysis confirms the very existence of the shelving level for the neutral NV center. It is found that it plays a negligible role on the photophysics of this center, whereas it is responsible for an increasing photon bunching behavior of the negative NV center with increasing power. From the photophysical parameters, we infer a quantum efficiency for both centers, showing that it remains close to unity for the neutral center over the entire power range, whereas it drops with increasing power from near unity to approximately 0.5 for the negative center. The photophysics of the photochromic center reveals a rich phenomenology that is to a large extent dominated by that of the negative state, in agreement with the excess charge release of the negative center being much slower than the photon emission process.
Characterizing the local internal environment surrounding solid-state spin defects is crucial to harnessing them as nanoscale sensors of external fields. This is especially germane to the case of defect ensembles which can exhibit a complex interplay between interactions, internal fields and lattice strain. Working with the nitrogen-vacancy (NV) center in diamond, we demonstrate that local electric fields dominate the magnetic resonance behavior of NV ensembles at low magnetic field. We introduce a simple microscopic model that quantitatively captures the observed spectra for samples with NV concentrations spanning over two orders of magnitude. Motivated by this understanding, we propose and implement a novel method for the nanoscale localization of individual charges within the diamond lattice; our approach relies upon the fact that the charge induces an NV dark state which depends on the electric field orientation.
Currently, thermally excited magnons are being intensively investigated owing to their potential in computing devices and thermoelectric conversion technologies. We report the detection of thermal magnon current propagating in a magnetic insulator yttrium iron garnet under a temperature gradient using a quantum sensor: electron spins associated with nitrogen-vacancy (NV) centers in diamond. Thermal magnon current was observed as modified Rabi oscillation frequencies of NV spins hosted in a beam-shaped bulk diamond that resonantly coupled with coherent magnon propagating over a long distance. Additionally, using a nanodiamond, alteration in NV spin relaxation rates depending on the applied temperature gradient were observed under a non-resonant NV excitation condition. The demonstration of probing thermal magnon current mediated by coherent magnon via NV spin states serves as a basis for creating a new device platform hybridizing spin caloritronics and spin qubits.
We show that nitrogen-vacancy (NV) centers in diamond can produce a novel quantum hyperbolic metamaterial. We demonstrate that a hyperbolic dispersion relation in diamond with NV centers can be engineered and dynamically tuned by applying a magnetic field. This quantum hyperbolic metamaterial with a tunable window for the negative refraction allows for the construction of a superlens beyond the diffraction limit. In addition to subwavelength imaging, this NV-metamaterial can be used in spontaneous emission enhancement, heat transport and acoustics, analogue cosmology, and lifetime engineering. Therefore, our proposal interlinks the two hotspot fields, i.e., NV centers and metamaterials.
Pressure calibration for most diamond-anvil cell (DAC) experiments is mainly based on the ruby scale, which is key to implement this powerful tool for high-pressure study. However, the ruby scale can often hardly be used for programmably-controlled DAC devices, especially the piezoelectric-driving cells, where a continuous pressure calibration is required. In this work, we present an effective pressure gauge for DACs made of manganin metal, based on the four-probe resistivity measurements. Pressure dependence of its resistivity is well established and shows excellent linear relations in the 0 - 30 GPa pressure range with a slope of 23.4 (9) GPa for the first-cycle compression, in contrast to that of multiple-cycle compression and decompression having a nearly identical slope of 33.7 (4) GPa likely due to the strain effect. In addition, such-established manganin scale can be used for continuously monitoring the cell pressure of piezoelectric-driving DACs, and the reliability of this method is also verified by the fixed-point method with a Bi pressure standard. Realization of continuous pressure calibration for programmably-controlled DACs would offer many opportunities for study of dynamics, kinetics, and critical behaviors of pressure-induced phase transitions.
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