The Byzantine agreement protocol is an essential part of this task.
The constant-time quantum version of the Byzantine protocol,[1] is described below.
The problem usually is equivalently restated in the form of a commanding General and loyal Lieutenants with the General being either loyal or a traitor and the same for the Lieutenants with the following properties.
Failures in an algorithm or protocol can be categorized into three main types: A Byzantine resilient or Byzantine fault tolerant protocol or algorithm is an algorithm that is robust to all the kinds of failures mentioned above.
The solution can be formulated as a Byzantine fault tolerant protocol.
We will sketch here the asynchronous algorithm [1] The algorithm works in two phases: There are two types of coin flipping protocols: To generate a random coin assign an integer in the range [0,n-1] to each player and each player is not allowed to choose its own random ID as each player
and distributes this using a verifiable secret sharing scheme.
is assigned the value This requires private information channels so we replace the random secrets by the superposition
In which the state is encoded using a quantum verifiable secret sharing protocol (QVSS).
To prevent bad players from doing so we encode the state using the Quantum verifiable secret sharing (QVSS) and send each player their share of the secret.
the verification stage of the QVSS protocol guarantees that for a good dealer the correct state will be encoded, and that for any, possibly faulty dealer, some particular state will be recovered during the recovery stage.
We note that for the purpose of our Byzantine quantum coin flip protocol the recovery stage is much simpler.
The verification stage guarantees, with high probability, that in the presence of up to
In 2007, a quantum protocol for Byzantine Agreement was demonstrated experimentally [8] using a four-photon polarization-entangled state.
This shows that the quantum implementation of classical Byzantine Agreement protocols is indeed feasible.