Proposed experiment for the quantum “Guess My Number” protocol
Adán Cabello, Antonio J. López-Tarrida · Physical Review A · 2005
An experimental realization of the entanglement-assisted ``Guess My Number'' protocol for the reduction of communication complexity, introduced by Steane and van Dam, would require producing and detecting three-qubit GHZ states with an efficiency $\ensuremath{\eta}>0.70$, which would require single photon detectors of efficiency $\ensuremath{\sigma}>0.89$. We propose a modification of the protocol which can be translated into a real experiment using present-day technology. In the proposed experiment, the quantum reduction of the multiparty communication complexity would require an efficiency $\ensuremath{\eta}>0.05$, achievable with detectors of $\ensuremath{\sigma}>0.47$, for four parties, and $\ensuremath{\eta}>0.17$ $(\ensuremath{\sigma}>0.55)$ for three parties.