  Clock synchronization for nonfaulty processes in multiprocess networks is
indispensable for a variety of technologies. A reliable system must be able to
resynchronize the nonfaulty processes upon some components failing causing the
distribution of incorrect or conflicting information in the network. The task
of synchronizing such networks is related to detectable Byzantine agreement
(DBA), which can classically be solved using recursive algorithms if and only
if less than one-third of the processes are faulty. Here we introduce a
nonrecursive quantum algorithm that solves the DBA and achieves clock
synchronization in the presence of arbitrary many faulty processes by using
only a single quantum system.
