Abstract

Phase estimation represents one of the most notable examples in the context of the quantum metrology. The aim is to improve the capabilities to measure an unknown phase shift between the arms of an interferometer with respect to classical strategies by adopting quantum resources. Applications of the phase estimation task can be found in different contexts, such as imaging, measurements on biological systems, or gravitational wave detection [1]. While the theoretical and experimental frameworks for the single parameter case are well established, several open questions arise when extending the scenario to multiparameter estimation. Indeed, when the number of parameters to be estimated is larger than one, it is not trivial to saturate the ultimate bounds for all parameters simultaneously [2].

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