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Magnetic resonance is a branch of science that aims to detect spins via their absorption and emission of electromagnetic radiation. Two areas can be distinguished: nuclear magnetic resonance (NMR) which aims at detecting the spins of nuclei, and electron spin resonance (ESR) that concerns the detection of the spin of unpaired electrons. In this thesis, we introduce a new method for ESR spectroscopy, consisting of the detection of the incoherent microwave fluorescence signal emitted by an ensemble of spins relaxing to their ground state after an excitation pulse. In order to demonstrate this method, we use the electronic spins belonging to bismuth donors in silicon. Emission of the fluorescence signal is favored by the Purcell effect, due to the coupling of the spin ensemble to a superconducting resonator with small mode volume and low losses. We connect the output port of the spin-resonator system to the input of a newly-developed frequency-tunable single microwave photon detector (SMPD), based on four-wave mixing with a superconducting qubit. After an excitation pulse, the spins relax to their ground state emitting a stream of incoherent photons which constitutes the fluorescence signal and is detected with the SMPD. We show that the fluorescence signal can be used to perform spectroscopy of the ensemble and measure relevant properties. We compare this technique to standard echo detection and discuss its increased sensitivity for small numbers of spins.
Jean-François ROCH, ENS Paris-Saclay, president
Yasunobu NAKAMURA, RCAST Tokyo, rapporteur & examinateur
Gunnar JESCHKE, ETH Zurich, rapporteur & examinateur
Audrey BIENFAIT, CNRS Lyon, examinatrice
Yuimaru KUBO, OIST Okinawa, examinateur
Anaïs DREAU, CNRS Montpellier, examinatrice