Title: Quantum Blockchain using entanglement in time,
Abstract: A conceptual design for a quantum blockchain is proposed. Our method involves
encoding the blockchain into a temporal GHZ (Greenberger-Horne-Zeilinger) state
of photons that do not simultaneously coexist. It is shown that the
entanglement in time, as opposed to an entanglement in space, provides the
crucial quantum advantage. All the subcomponents of this system have already
been shown to be experimentally realized. Perhaps more shockingly, our encoding
procedure can be interpreted as non-classically influencing the past; hence
this decentralized quantum blockchain can be viewed as a quantum networked time
machine.