Editing Quantum Weak Coin Flipping (section)

==Outline==

[https://arxiv.org/abs/quant-ph/0202118 The QWCF protocol by Spekkens and Rudolph] consists of the following steps:
# Alice and Bob agree on two orthogonal single-qubit states, ψ(0) and ψ(1), that have equal probability distribution in the computational basis. They also agree on an angle θ between ψ(0) and ψ(1), which determines the bias of the protocol.
# Alice and Bob each choose a secret bit, a and b, respectively, that represents their preferred outcome. They also choose a random bit, x and y, respectively, that will be used to encode their qubits.
# Alice and Bob each send two qubits to the other party, one in the state ψ(x) and the other in the state ψ(x⊕a). They also send a classical bit, z and w, respectively, that is the XOR of their secret bit and their random bit, i.e., z=x⊕a and w=y⊕b.
# Alice and Bob each return one of the qubits they received from the other party, depending on the value of the classical bit they received. If the classical bit is 0, they return the first qubit; if the classical bit is 1, they return the second qubit.
# Alice and Bob each measure the qubit they kept from the other party in the basis spanned by ψ(0) and ψ(1). They also measure the qubit they returned to the other party in the same basis. If any of the measurements fails, they abort the protocol.
# Alice and Bob each announce their secret bit, a and b, respectively. They also announce the result of their measurements, m and n, respectively. The outcome of the coin flip is the XOR of their secret bits and their measurements, i.e., c=a⊕m=b⊕n.