sINGle microwave photon dEtection for hybrid quaNtum Information prOcessing and quantUm enhanced Sensing

The wave/particle duality is one of the counter-intuitive traits of quantum mechanics. The fundamental constituents of matter and light can be either apprehended as corpuscules or waves depending on the choice of the measurement apparatus. In the case of light, one can either decide to measure the quadrature of the electromagnetic field or count the photons impacting the detector. These two modalities come with pros and cons, the first one is sensitive to both the phase and the amplitude of the field but at the cost of a fundamental noise associated to vacuum fluctuations while the latter is only sensitive to the energy of the field but at the Photons lie at the heart of the human experience; they are the most direct way to sense our immediate material environment. A light source irradiates material objects in its surroundings and depending on their composition, materials will re-emit the incident light with slight variations in intensity and color. In the course of the last century, the meaning of imaging has been considerably broadened, scientific and technological advances have enabled the detection of single quanta of light from further away, at smaller scales, and on a considerable enlarge portion of the electromagnetic spectrum. At one extremity of the spectrum, the field of microwave quantum optics (1-10 GHz) has emerged as a powerful tool to probe quantum systems. We have recently demonstrated high-performance single microwave photon detection based on elementary superconducting circuits. Based on this novel method, a new window on new material systems is opened at unprecedented sensitivities. This proposal aims at the improvement of the newly developed single microwave photon detector for the exploration of new luminescent systems in the microwave domain. In particular, the detection of individual paramagnetic electron spins for quantum computing and quantum-enhanced sensing applications; and the search of one of the leading dark-matter candidates, axions.