Ricerc@Sapienza

Quantum metrology represents one of the most promising applications of quantum theory. In this context, quantum resources are employed to improve the sensitivity in the estimation of one or more unknown physical parameters. The adoption of quantum probe state promises to disclose the capability of reaching the fundamental Heisenberg limit, thus achieving better performances than any classical strategy. While the theoretical framework in the single-parameter scenario is well established and several schemes have been tested experimentally, the multiparameter case still presents several open problems. These include for instance the identification of the ultimate bounds, as well as the capability of performing optimal measurements in the general scenario.
A crucial requirement is then to identify a suitable testbench to investigate and develop suitable methodologies for multiparameter estimation. This platform is provided by multiarm interferometers, where the parameters to be measured are a set of unknown optical phases. Recent development in quantum integrated photonics have opened new possibilities in this direction, including the capability of fabricating reconfigurable phase shifters in complex networks.
The aim of this project is to perform first multiphase estimation experiments in an integrated photonic platform. By adopting multiphoton input states, we will pursue the capability of reaching quantum-enhanced performances in this task. Throughout the project we will also study and develop suitable adaptive protocols for this scenario, and apply such protocols in the implemented platform. The obtained results will provide a first step towards developing general recipes for quantum-enhanced multiparameter estimation, with several applications such as imaging, gravitational wave detection, or measurement in biological systems. Indeed, integrated multiarm interferometers represent a promising platform to be employed as a paradigmatic system for this scenario.