Determining the Quantum Expectation Value by Measuring a Single Photon
Abstract
Quantum mechanics, one of the keystones of modern physics, exhibits several peculiar properties, differentiating it from classical mechanics. One of the most intriguing is that variables might not have definite values. A complete quantum description provides only probabilities for obtaining various eigenvalues of a quantum variable. These and 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, we demonstrate a unique method allowing to measure the expectation value of a physical variable on a single particle, namely, the polarisation of a single protected photon. This is the first realisation of quantum protective measurements.
Cite
@article{arxiv.1706.08918,
title = {Determining the Quantum Expectation Value by Measuring a Single Photon},
author = {F. Piacentini and A. Avella and E. Rebufello and R. Lussana and F. Villa and A. Tosi and M. Gramegna and G. Brida and E. Cohen and L. Vaidman and I. P. Degiovanni and M. Genovese},
journal= {arXiv preprint arXiv:1706.08918},
year = {2018}
}
Comments
Nature Physics, in press (this version corresponds to the one initially submitted to Nature Physics)