Identity-based Non-interactive Common-key Generation

Hatsukazu Tanaka

Hatsukazu Tanaka

A. Hovhannisyan, S. Weigert, A. E. Allahverdyan

Violations of Bell's inequalities imply that joint probabilities generated by non-commutative measurements on two (non-identical) quantum particles do not have a single common cause. But joint probabilities generated for such non-identical particles via commutative measurements do have non-trivial common cause variables. We focus on commutative measurements and consider two identical quantum particles, whose density matrices and observables (hermitian operators) are necessarily permutation-symmetric. It is natural to demand that the common cause describing joint probabilities is also permutation symmetric, i.e., it acts symmetrically on both particles. Looking at various ways of defining joint probabilities from the same measurement data, we conclude that either symmetric common causes need not exist (i.e., that the particles can be hiddenly distinguishable), or that symmetric screening variables exist, but they are trivial, i.e., no single common cause can explain all single-measurement correlations.

Arshak Hovhannisyan, Stefan Weigert, ARMEN E. ALLAHVERDYAN

Abstract Violations of Bell's inequalities imply that joint probabilities generated by non-commuting measurements on two (non-identical) quantum particles do not have a single common cause. However, joint probabilities generated by commuting measurements performed on non-identical particles do have non-trivial common-cause variables. We focus on commuting measurements and consider two identical quantum particles described by density matrices and observables (Hermitian operators) that are necessarily permutation-symmetric. It is natural to demand that the common cause describing joint probabilities is also permutation symmetric, i.e. , it should act symmetrically on both particles. Investigating two different ways of defining joint probabilities based on the same measurement data, we conclude that either symmetric common causes need not exist ( i.e. , there is a way to distinguish the particles, at least in principle), or that symmetric screening variables exist, but they are trivial. Hence, no single common cause can explain all correlations generated by commutative measurements.

Colin Boyd, Anish Mathuria, Douglas Stebila

Dario Fiore, Rosario Gennaro