Overcoming resolution limits with quantum sensing

 Abstract: Quantum sensing and metrology exploit quantum aspects of individual and complex systems to measure a physical quantity. Quantum sensing targets a broad spectrum of physical quantities, of both static and time-dependent types. While the most important characteristic for static quantities is sensitivity, for time-dependent signals it is the resolution, i.e. the ability to resolve two different frequencies. In this talk I will present a study of spectral resolution problems with quantum sensors, and the development of new superresolution methods that rely on quantum features. We first formulate a general criterion for superresolution in quantum problems. Inspired by this, we show that quantum detectors can resolve two frequencies from incoherent segments of the signal, irrespective of their separation, in contrast to what is known about classical detection schemes. The main idea behind these methods is to overcome the vanishing distinguishability in resolution problems by nullifying the projection noise.