Realization of entanglement-assisted qubit-covariant symmetric-informationally-complete positive-operator-valued measurements

Abstract

We realize NMR optimal tomography of a single qubit by coupling it to an ancilla, letting them interact, and measuring properties of the joint system. Among other advantages, this approach reduces the number of counting rates that are necessary for establishing tomography of the qubit, due to the fact that this number (equal to 4) is equal to the number of real parameters of the density matrix. Connections with the discrete Wigner distribution are emphasized and discussed.