Abstract
Multiparameter estimation is a general problem that aims at measuring unknown physical quantities, obtaining high precision in the process. In this context, the adoption of quantum resources promises a substantial boost in the achievable performances with respect to the classical case. However, several open problems remain to be addressed in the multiparameter scenario. A crucial requirement is the identification of suitable platforms to develop and experimentally test novel efficient methodologies that can be employed in this general framework. We report the experimental implementation of a reconfigurable integrated multimode interferometer designed for the simultaneous estimation of two optical phases. We verify the high-fidelity operation of the implemented device, and demonstrate quantum-enhanced performances in two-phase estimation with respect to the best classical case, post-selected to the number of detected coincidences. This device can be employed to test general adaptive multiphase protocols due to its high reconfigurability level, and represents a powerful platform to investigate the multiparameter estimation scenario.
Highlights
Quantum metrology aims at exploiting quantum resources to enhance the sensitivity in the estimation of unknown physical parameters with respect to what can be achieved with classical approaches [1, 2]
In the single parameter case, the estimation of an unknown physical quantity with classical resources is bounded by the standard quantum limit (SQL), stating that the achievable error on the unknown parameter scales as ν−1/2, being ν the number of particles
In this work we report on an integrated three-mode interferometer built through the femtosecond laser writing (FLW) technique [14, 60], to implement quantum multiphase estimation tasks
Summary
Quantum metrology aims at exploiting quantum resources to enhance the sensitivity in the estimation of unknown physical parameters with respect to what can be achieved with classical approaches [1, 2]. In the last few years, several theoretical investigations on multiparameter estimation have been reported [9, 31, 34,35,36,37,38,39], while experimental tests are surprisingly few These include the simultaneous estimation of phase and its diffusion noise [40,41,42], phase and quality of the probe state [43], the discrimination of an actual signal from parasitic interference [44], and quantum-enhanced tomography of an unknown unitary process by multiphoton states [21]. In this work we report on an integrated three-mode interferometer built through the femtosecond laser writing (FLW) technique [14, 60], to implement quantum multiphase estimation tasks Such device is composed by two cascaded tritters [61] and includes six reconfigurable thermo-optic phase shifters. The device reconfigurability can be exploited to implement general adaptive multiphase estimation protocols [62,63,64], providing a promising platform to develop appropriate methodologies for this task
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