  Recently, a protocol for quantum state discrimination (QSD) in a multi-party
scenario has been introduced [Phys. Rev. Lett. 111, 100501 (2013)]. In this
protocol, Alice generates a quantum system in one of two pre-defined
non-orthogonal qubit states, and the goal is to send the generated state
information to different parties without classical communication exchanged
between them during the protocol's session. The interesting feature is that, by
resorting to sequential generalized measurements onto this single system, there
is a non-vanishing probability that all observers identify the state prepared
by Alice. Here, we present the experimental implementation of this protocol
based on polarization single-photon states. Our scheme works over an optical
network, and since QSD lies in the core of many protocols, it represents a step
towards experimental multi-party quantum information processing.
