Print Email Facebook Twitter Simulating the Charge-Resonance Check in Nitrogen-Vacancy Centers using Python Title Simulating the Charge-Resonance Check in Nitrogen-Vacancy Centers using Python Author Ognjanović, U. (TU Delft Applied Sciences; TU Delft Electrical Engineering, Mathematics and Computer Science) Contributor Hanson, R. (mentor) Dubbeldam, J.L.A. (mentor) Budko, N.V. (graduation committee) van der Sar, T. (graduation committee) Degree granting institution Delft University of Technology Programme Applied Mathematics | Applied Physics Date 2020-07-22 Abstract In this report we present a model to simulate the performance and robustness of the Charge-Resonance Check (CR-Check) in the Nitrogen-Vacancy (NV) center. The CR-Check is a routine which verifies that the charge state of the NV center is NV$^-$ and that the lasers, addressing the NV center, are on resonance with the optical lines. This is done by shining a red (λ=637 nm) laser on the NV center and measuring the amount of fluorescence photons, since they are dependent on the resonance frequency being near the frequency of the laser. If these counts do not pass the threshold for success, then either a new measurement of the photons is done or the system is repumped with a green (λ=532 nm) high intensity laser if they are below the repump threshold. The most important parameters are the duration of the red laser (dt) and the spectral diffusion of the NV center (sigma), which is an intrinsic property of the NV center. The model was implemented in Python, where also Numba, a high-performance Python compiler was used. An algorithm for finding the optimal values is included, so that different implementations can be compared. Then parameter sweeps were performed to get insight on the effects of the parameters. The distribution of frequency spectrum was investigated, it follows the shape of the Generalized Normal distribution with a disturbance due to the memory parameter. We observed that the mean time till success goes up linearly with the sigma after it is higher than 80 MHz for dt. This effect can be explained by taking into account the Normal distribution which was used to determine the resonance frequency. It became clear that the N_thr_repump and N_thr_success often come as pairs, which have been shown to be linearly dependent on the rate. Also it has been observed that after a certain sigma amount the N_thr_repump and N_thr_success do not change anymore. We noticed that for fixed sigma there is a optimal value of dt. This optimal value of dt is dependent on sigma. Average number of photon counts was nearly independent of sigma and only linearly dependent on dt. This is a sign that the CR-Check can always bring the NV center sufficiently on resonance. It has been observed that when the NV center's spectral diffusion is below 40 MHz, it is significantly faster to use the CR-strategy with dt = 25 μs compared to the standard dt of 50 μs. Lastly new implementations, where p-values are used rather than the measured counts, were shown to be capable of performing a CR-Check procedure. These implementations have used either the cumulative density function (cdf) of the Poisson distribution or the t-test or the Wilcoxon signed-rank test. The test using the cdf performed very similar to the current implementation. The other two test were slower with regards to the mean time till success, as they seem to require a lower spectral diffusion than was mandated. Subject NV-centerNV-centreCR-CheckChargeResonancePythonSimulation To reference this document use: http://resolver.tudelft.nl/uuid:cc60a154-50ad-4cb2-aa86-988996d7c0b2 Part of collection Student theses Document type bachelor thesis Rights © 2020 U. Ognjanović Files PDF CR_Check_report.pdf 2.14 MB Close viewer /islandora/object/uuid:cc60a154-50ad-4cb2-aa86-988996d7c0b2/datastream/OBJ/view