Security Details for Bit Commitment by Transmitting Measurement Outcomes
Recently, a new quantum relativistic bit commitment protocol was introduced. Its security relies, essentially, on the impossibility of completing a nonlocal measurement on a distributed state outside the joint future light cone of its components. Its implementation requires minimal quantum resources: the receiver needs to send quantum states (which can be unentangled qubits) to the committer, who needs to carry out individual measurements on them as soon as they are received. No further quantum communication is required by either party; nor do they require any entanglement, collective measurements, or quantum state storage. The authors present the protocol here in an idealized form assuming perfect state preparations, transmissions and measurements.