Building nonlocal machines using GHZ states

A physical n-input/n-output nonlocal machine is proposed for optimal values of Bell operators in the Bell-type inequalities. It is required that all outputs are locally random. In our scheme, maximally entangled (n+1)-qubit GHZ states are employed for an n-input/n-output nonlocal machine. In addition, (n−1) bits of communication are necessary to avoid random correlation. We introduce how to perform quantum oblivious transfer using simulation of nonlocal machines. In addition, we also argue the security of quantum secret sharing using GHZ states are based on the nonlocal machines.