Narrow Results

Communication complexity is an area of classical computer science which studies how much communication is necessary to solve various distributed computational problems. Quantum information processing can be used to reduce the amount of communication required to carry out some distributed problems. We speak of pseudo-telepathy when it is able to completely eliminate the need for communication. The matching game is the newest member of the family of pseudo-telepathy games. After introducing a general model for pseudo-telepathy games, we focus on the question what the smallest size of inputs is for which the matching game is a pseudo-telepathy game.

We briefly trace the progress in study of Bell–CH inequalities from two-level systems to its higher dimensional versions. We also present a Bell–CH and CHSH-like inequality for three-dimensional systems.

We consider a two-particle/two-setting Bell experiment to visualize the conflict between Bell–Żukowski inequality and Bell–Mermin inequality. The experiment is reproducible by local realistic theories which are not rotationally invariant. We find that the average value of Bell–Żukowski operator is evaluated by the two-particle/two-setting Bell experiment in question. Bell–Żukowski inequality reveals that the constructed local realistic theories for the experiment are not rotationally invariant. The two-particle Bell experiment in question reveals the conflict between Bell–Żukowski inequality and Bell–Mermin inequality. Our analysis finds the threshold visibility for the two-particle interference to reveal the conflict noted above. The threshold visibility agrees with the value to obtain a violation of Bell–Żukowski inequality.

Recently, it has been argued that all presently performed continuous variable quantum teleportation experiments could be explained using a local hidden variable theory. In this paper, we study a modification of the original protocol which requires a fully quantum mechanical explanation even when coherent states are teleported. Our calculations of the fidelity of teleportation using a pair-coherent state under ideal conditions suggest that fidelity above the required limit of 1/2 may be achievable in an experiment also.

In this paper we present some recent work performed at "Carlo Novero" lab on quantum information and foundations of quantum mechanics.

It is argued that local realism is a fundamental principle, which might be rejected only if experiments clearly show that it is untenable. Forty years after Bell's work no experiment has provided a valid, loophole-free, violation of local realism which, in my opinion, is thus reinforced. I study a simple, but wide, family of local realistic models and derive new inequalities almost insensitive to the detection loophole. I argue that quantum mechanics, with some change in the theory of measurement, might be compatible with local realism.