Distributed implementation of standard oracle operators

摘要

The standard oracle operator corresponding to a function f is a unitary operator that computes this function coherently, i.e., it maintains superpositions. This operator acts on a bipartite system, where the subsystems are the input and output registers. In distributed quantum computation, these subsystems may be spatially separated,in which case we will be interested in its classical and entangling capacities. For an arbitrary function f,we show that the unidirectional classical and entangling capacities of this operator are log_2(n_f) bits (ebits) where n_f is the number of different values this function can take. An optimal procedure for bidirectional classical communication with a standard oracle operator corresponding to a permutation on Z_M isgiven. The bidirectional classical capacity of such an operator is found to be 2 log_2(M) bits. The proofs of these capacities are facilitated by an optimal distributed protocol for the implementation of an arbitrary standard oracle operator.