EFFICIENT UNIVERSAL QUANTUM CIRCUITS

Universal circuits can be viewed as general-purpose simulators for central classes of circuits and can be used to capture the computational power of the, circuit class being simulated. We define and construct quantum universal circuits which are efficient and have very little overhead in simulation. For depth we construct universal circuits whose depth is the same order as the circuits being simulated. For size, there is a log factor blow-up in the universal circuits constructed here which is nearly optimal.