Ensemble de centres azote-lacune dans le diamant pour l'analyse de signaux radiofréquences
Simone Magaletti
The nitrogen-vacancy center (NV) is a diamond spin defect consisting of a nitrogen atom and a carbon vacancy in two adjacent positions of the diamond lattice. Its remarkable spin-dependent optical properties make it a promising platform for quantum sensing and quantum information applications.In the present manuscript, two applications involving an ensemble of NV centers in diamond are investigated: a radio frequency (RF) spectrum analyser and a widefield imaging technique of the RF radiation emitted in near field by microwave devices.In the first chapter, the NV centers in diamond, their properties and the motivations behind the two NV centers based applications proposed in this manuscript are presented. The available solutions and the state-of-the-art techniques for both RF spectral analysis and near field imaging of RF radiation are reviewed and the potential of alternative solutions using NV centres are discussed.In the second chapter, a set-up for the widefield optical detection of the NV centers spin resonances is presented and used to investigate the main properties of this diamond defect. The NV center electron spin resonances are detected over a large frequency range (more than 10 GHz) and different phenomena are investigated: the behaviour of an ensemble of NV centers under a static magnetic field, the polarization properties of the NV center photoluminescence (PL) and how they can be exploited to recognise the NV centers orientations, the NV’s nitrogen nuclear spin polarization over a large frequency range (more than 2 GHz).The third chapter is devoted to the implementation of a real-time RF spectrum analyser based on an ensemble of NV centers. The main physical features of NV centers considered as MW detectors are investigated and an experimental architecture which allows a real time RF spectral analysis over a tuneable frequency range (10 MHz to 25 GHz), 4 GHz bandwidth, a MHz frequency resolution and a ms time resolution is demonstrated. The implementation of this device required an interesting analysis on the behaviour of an ensemble of NV centers under strong magnetic field gradient (tens of Tesla per meter) which is detailed in the chapter.The fourth and last chapter deals with the widefield imaging of RF field based on an ensemble of NV centers. Two techniques are proposed. The first is based on the RF power broadening of the NV center spin resonances in the continuous regime domain while the second is based on the widefield detection of NV centers Rabi oscillations in a pulsed regime. Both techniques allowed reconstructing the magnetic near field RF field emitted by a loop antenna. However, while the first technique requires a calibration to retrieve the amplitude of the RF field, the second allows a direct measurement of it. The widefield detection of the NV centers Rabi oscillations has thus been investigated both by means of experiments and simulations. Since the NV centers Rabi oscillations detected using our widefield experimental set-up showed an asymmetric shape, a model has been realized to figure out the NV centers behaviour during the pulse sequence employed to drive the Rabi oscillation. The results of the simulations, in agreement with the experimental results, enable to have a better insight of the NV center spin optical polarization and readout during the widefield detection of the Rabi oscillations.
•Dec 15, 2021•0 citations