Resonant second-order optical resonances in quantum magnets

John L. Remo

G. Caimi

D. S. Filimonenko, Valery M. Yasinskii, Alexander P. Nizovtsev +1 more

Abstract The photoluminescence intensity of the ensemble of NV centers in diamond at weak magnetic field was studied. Two resonances were revealed in the region of weak magnetic fields: the first resonance with a width of the order of 20 G, and the second resonance with a width of the order of 180 G. The presence of these optical resonances makes it possible to propose a new concept for creating magnetic field sensors based on a diamond with an ensemble of NV centers without the use of a microwave field.

Dylan G. Stone

With wide applications ranging from quantum communication and metrology to biomedicine, single photon sources in solid-state hosts have become a major area of study. Here, we focus on three applications: nanothermometry, optically detected magnetic resonance (ODMR), and second order autocorrelation. We present novel statistical and machine learning (ML) approaches to extract information from experimental and simulated data and benchmark these methods against traditional inference-based statistical approaches. We found that compared to traditional inference-based methods ML algorithms can: i) predict temperatures at the nanoscale with greater accuracy and with less calibration points than traditional fitting methods; ii) identify the resonance peaks in ODMR spectra with factors ~1.3x and ~4.7x better accuracy and resolution and achieved equal or better performance with ~5x less data; and iii) have the potential to parse second order autocorrelation data more efficiently. ML algorithms are thus powerful tools for quantum sensing techniques. Author Keywords: colour centers, machine learning, nanosensing, nanothermometry, optically detected magnetic resonance, second order autocorrelation

Brian DeMarco

François Beato, Agustin Palacios-Laloy

Abstract Optically-pumped magnetometers (OPM) based on parametric resonance allow real-time tri-axial measurement of very small magnetic fields with a single optical access to the gas cell. Most of these magnetometers rely on circularly polarized pumping light. We focus here on the ones relying on linearly polarized light, yielding atomic alignment. For these magnetometers we investigate three second order effects which appear in the usual regimes of operation, so to clarify if they translate to metrological problems like systematic errors or increased noise. The first of these effects is the breakdown of the three-step approach when the optical beam has a large intensity. The second one is the breakdown of the rotating wave approximation when the frequencies of the RF fields are not much larger than the rates of other atomic processes. The third one is the tensor light-shift which appears when the light is slightly detuned from resonance. This work should help to clarify the accuracy reachable with OPM, which is an important question notably for medical imaging applications.