  We propose a multi party quantum clock synchronization protocol that makes
optimal use of the maximal multipartite entanglement of GHZ-type states. To
realize the protocol, different versions of maximally entangled eigenstates of
collective energy are generated by local transformations that distinguish
between different groupings of the parties. The maximal sensitivity of the
entangled states to time differences between the local clocks can then be
accessed if all parties share the results of their local time dependent
measurements. The efficiency of the protocol is evaluated in terms of the
statistical errors in the estimation of time differences and the performance of
the protocol is compared to alternative protocols previously proposed.
