Determining the quantum expectation value by measuring a single photon

Fabrizio Piacentini; Alessio Avella; Enrico Rebufello; Rudi Lussana; Federica Villa; Alberto Tosi; Marco Gramegna; Giorgio Brida; Eliahu Cohen; Lev Vaidman; Ivo P. Degiovanni; Marco Genovese

doi:10.1038/nphys4223

Determining the quantum expectation value by measuring a single photon

Fabrizio Piacentini^*, Alessio Avella, Enrico Rebufello, Rudi Lussana, Federica Villa, Alberto Tosi, Marco Gramegna, Giorgio Brida, Eliahu Cohen, Lev Vaidman, Ivo P. Degiovanni, Marco Genovese

^*Corresponding author for this work

School of Physics and Astronomy

Research output: Contribution to journal › Article › peer-review

49 Scopus citations

Abstract

One description provides only probabilities for obtaining various eigenvalues of a quantum variable. The eigenvalues and the corresponding probabilities specify the expectation value of a physical observable, which is known to be a statistical property of an ensemble of quantum systems. In contrast to this paradigm, here we demonstrate a method for measuring the expectation value of a physical variable on a single particle, namely, the polarization of a single protected photon. This realization of quantum protective measurements could find applications in the foundations of quantum mechanics and quantum-enhanced measurements.

Original language	English
Pages (from-to)	1191-1194
Number of pages	4
Journal	Nature Physics
Volume	13
Issue number	12
DOIs	https://doi.org/10.1038/nphys4223
State	Published - 1 Dec 2017

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AU - Rebufello, Enrico

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AU - Villa, Federica

AU - Tosi, Alberto

AU - Gramegna, Marco

AU - Brida, Giorgio

AU - Cohen, Eliahu

AU - Vaidman, Lev

AU - Degiovanni, Ivo P.

AU - Genovese, Marco

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Determining the quantum expectation value by measuring a single photon

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