Quasiprobability distributions with weak measurements
Year: 2025
Authors: Bizzarri G., Gherardini S., Manrique M., Bruni F., Gianani., Barbieri M.
Autors Affiliation: Univ Roma Tre, Dipartimento Sci, Via Vasca Navale 84, I-00146 Rome, Italy; CNR, Ist Nazl Ott, Largo E Fermi 6, I-50125 Florence, Italy; Univ Firenze, European Lab Nonlinear Spect, I-50019 Sesto Fiorentino, Italy.
Abstract: We discuss and experimentally demonstrate the role of quantum coherence in a sequence of two measurements collected at different times using weak measurements. For this purpose, we have realized a weak-sequential measurement protocol with photonic qubits, where the first measurement is carried out as a positive operator-valued measure, whereas the second one is a projective operation. We determine the quasiprobability distributions associated to this procedure using both the commensurate and the Margenau-Hill quasiprobabilities. By tuning the weak measurements, we obtain a quasidistribution that may or may not exhibit negative parts, depending on the suitability of a contextual model for describing the experiment. Our results show how quasidistributions may find application in inspecting quantum monitoring, when part of the initial quantum coherence needs to be preserved.
Journal/Review: QUANTUM SCIENCE AND TECHNOLOGY
Volume: 10 (4) Pages from: 45008-1 to: 45008-9
More Information: We thank R Grasland for support during data collection and J Sperling for valuable discussion. This work was supported by the PRIN Project PRIN22-RISQUE-2022T25TR3 of the Italian Ministry of University. S G acknowledges support from the PRIN Project 2022FEXLYB Quantum Reservoir Computing (QuReCo), and the PNRR MUR Project PE0000023-NQSTI funded by the European Union-Next Generation EU. G B is supported by Rome Technopole Innovation Ecosystem (PNRR Grant M4-C2-Inv). IG acknowledges the support from MUR Dipartimento di Eccellenza 2023-2027.KeyWords: quasi-probability distributions; weak measurements; quantum statesDOI: 10.1088/2058-9565/adf573
