Beyond the Goldenberg-Vaidman protocol : Secure and efficient quantum communication using arbitrary, orthogonal, multi-particle quantum states

Restricted Access. An open-access version is available at arXiv.org (one of the alternative locations)It is shown that maximally efficient protocols for secure direct quantum communications can be constructed using any arbitrary orthogonal basis. This establishes that no set of quantum states (e.g. GHZ states, W states, Brown states or Cluster states) has an advantage over the others, barring the relative difficulty in physical implementation. The work provides a wide choice of states for experimental realization of direct secure quantum communication protocols. We have also shown that this protocol can be generalized to a completely orthogonal-state-based protocol of Goldenberg–Vaidman (GV) type. The security of these protocols essentially arises from duality and monogamy of entanglement. This stands in contrast to protocols that employ nonorthogonal states, like Bennett–Brassard 1984 (BB84), where the security essentially comes from noncommutativity in the observable algebra