TL; DR
Measuring incompatible observables of a single photon
-- One of the most intriguing aspects of Quantum Mechanics is the impossibility of measuring at
the same time observables corresponding to non-commuting operators. This impossibility can be
partially relaxed when considering joint or sequential weak values evaluation [1{5]. Indeed, weak
measurements have been a real breakthrough in the quantum measurement framework that is of
the utmost interest from both a fundamental [6{13] and an applicative point of view [14{21]. In
this paper, we show how we realized for the first time a sequential weak value evaluation of two
incompatible observables on a single photon.
F. Piacentini1, M. P. Levi1;2, A. Avella1, E. Cohen3, R. Lussana4, F. Villa4,
A. Tosi4, F. Zappa4, M. Gramegna1, G. Brida1, I. P. Degiovanni1, M. Genovese1;5
Bell measurements as a witness of a dualism in entanglement
-- We show how a property of dualism, which can exist in the entanglement of identical particles,
can be tested in the usual photonic Bell measurement apparatus with minor modifications. Two
different sets of coincidence measurements on the same experimental setup consisting of a Hong-
Ou-Mandel interferometer demonstrate how the same two-photon state can emerge entanglement
in the polarization or the momentum degree of freedom depending on the dynamical variables used
for labeling the particles. Our experiment demonstrates how the same source can be used as both
a polarization entangled state, as well as a dichotomic momentum entangled state shared between
distant users Alice and Bob in accordance to which sets of detectors they access. When the particles
become distinguishable by letting the information about one of the variables to be imprinted in yet
another (possibly inaccessible) system or degree of freedom, the feature of dualism is expected to
vanish. We verify this feature by polarization decoherence (polarization information in environment)
or arrival time difference, which both respectively destroy one of the dual forms of entanglement.
E. Moreva1,2, G. Brida1, M. Gramegna1, S. Bose3, D. Home4, M. Genovese1∗
Vielleicht interessiert es jemanden gerade mit dem nötigen Händchen
dafür!
Gruß
PS: 1 Punkt heute für mich!
