Seminarium Optyczne

In Quantum Mechanics (QM) not all properties can be simultaneously well> defined. An important question is whether a joint probability> distribution can describe the outcomes of all possible measurements,> allowing a quantum system to be mimicked by classical means. Klyachko et> al. [PRL 101, 020403 (2008)] derived an inequality which allowed us to> answer this question experimentally. The inequality involves only five> measurements and QM predicts its violation for single spin-1 particles.> This is the simplest system where such a contradiction is possible. It> is also indivisible and as such cannot contain entanglement. In our> experiment with single photons distributed among three modes (isomorphic> to stationary spin-1 particles) we obtained a value of -3.893(6), which> lies more than 120 standard deviations below the ‘classical’ bound of> -3.081(2).