  Client-server models enable computations to be hosted remotely on quantum
servers. We present a novel protocol for realizing this task, with practical
advantages when using technology feasible in the near term. Client tasks are
realized as linear combinations of operations implemented by the server, where
the linear coefficients are hidden from the server. We report on an
experimental demonstration of our protocol using linear optics, which realizes
linear combination of two single-qubit operations by a remote single-qubit
control. In addition, we explain when our protocol can remain efficient for
larger computations, as well as some ways in which privacy can be maintained
using our protocol.
