  The development of small-scale sensors and actuators enables the construction
of smart matter in which physical properties of materials are controlled in a
distributed manner. In this paper, we describe how quantum computers could
provide an additional capability, programmable control over some quantum
behaviors of such materials. This emphasizes the need for spatial coherence, in
contrast to the more commonly discussed issue of temporal coherence for quantum
computing. We also discuss some possible applications and engineering issues
involved in exploiting this possibility.
