  The engineering challenges involved in building large scale quantum
computers, and the associated infrastructure requirements, mean that when such
devices become available it is likely that this will be in limited numbers and
in limited geographic locations. It is likely that many users will need to rely
on remote access to delegate their computation to the available hardware. In
such a scenario, the privacy and reliability of the delegated computations are
important concerns. On the other hand, the distributed nature of modern
computations has led to a widespread class of applications in which a group of
parties attempt to perform a joint task over their inputs, e.g., in cloud
computing. In this paper, we study the multi-client delegated quantum
computation problem where we consider the global computation be made up of
local computations that are individually decided by the clients. Each client
part is kept secret from the server and the other clients. We construct a
composable secure multi-client delegated quantum computation scheme from any
composable secure single-client delegated quantum computation protocol and
quantum authentication codes.
