Recent FUndamental Results in Single Photon Experiments

by Eliyahu Cohen

at Physics Colloquium

Tue, 21 Nov 2017, 15:30
Nanotechnology institute building (#51) room 15

Abstract

Quantum optics experiments employing a single photon source as well as a single photon detector allow us to probe the foundations of quantum theory In the last few years I have designed a line of experiments based on weak measurements 1 for this purpose Two of them have already been performed: 1 Measuring incompatible observables by exploiting sequential weak values 2 We measured for the first time the polarization of single photons in two incompatible bases By performing a sequence of two weak measurements over a large ensemble of single photons we were thus able to infer the information regarding two noncommutative operators practically measured on the same state 2 Determining the quantum expectation value by measuring a single photon 3 Here we did not use an ensemble of photons but rather employed the quantum Zeno effect for inferring the polarization expectation value using a genuine single photon This was the first demonstration of protective measurement 4 similar in spirit to our proposal in 5 The protection mechanism allows to defy the statistical character of the expectation value which up to now was always evaluated using a large ensemble of similarly prepared particles I will discuss some theoretical and practical consequences of these experiments and if time allows me will outline our upcoming experiments e g those concerned with the study of entanglement and nonlocality 6 7 References 1 Y Aharonov D Z Albert L Vaidman How the result of a measurement of a component of the spin of a spin 1 2 particle can turn out to be 100 Phys Rev Lett 60 1351 1988 2 F Piacentini A Avella M P Levi M Gramegna G Brida I P Degiovanni E Cohen R Lussana F Villa A Tosi F Zappa M Genovese Measuring incompatible observables by exploiting sequential weak values Phys Rev Lett 117 170402 2016 3 F Piacentini A Avella E Rebufello R Lussana F Villa A Tosi M Gramegna G Brida E Cohen L Vaidman I P Degiovanni M Genovese Determining the quantum expectation value by measuring a single Photon forthcoming in Nat Phys doi:10 1038 nphys4223 2017 4 Y Aharonov L Vaidman Measurement of the Schr dinger wave of a single particle Phys Lett A 178 38 42 1993 5 Y Aharonov E Cohen A C Elitzur Foundations and applications of weak quantum measurements Phys Rev A 89 052105 2014 6 Y Aharonov E Cohen A C Elitzur Can a future choice affect a past measurement s outcome Ann Phys 355 258 268 2015 7 A Brodutch E Cohen Nonlocal Measurements via Quantum Erasure Phys Rev Lett 116 070404 2016

Created on 12-11-2017 by Bar Lev, Yevgeny (ybarlev)
Updaded on 12-11-2017 by Bar Lev, Yevgeny (ybarlev)