On the Speed of Quantum Computers with Finite Size Clocks

In previous work, the speed of locally coupled quantum computers with infinite size clocks has been investigated in detail. One of the results is that the Feynman quantum computer and the Margolus cellular automaton compute at a constant rate. We show that this is no longer true for computers with finite size clocks and we will argue that finite size clocks are more appropriate for the computers under consideration. Furthermore, we give alternative definitions for computational speed that seem to be appropriate for finite size computers.