Pseudo-digital quantum bits

Quantum computers are analog devices; thus they are highly susceptible to accumulative errors arising from classical control electronics. Fast operation-as necessitated by decoherence-makes gating errors very likely. In most current designs for scalable quantum computers, it is not possible to satisfy both the requirements of low decoherence errors and low gating errors. Here, we introduce a hardware-based technique for pseudo-digital gate operation. We perform self-consistent simulations of semiconductor quantum dots, finding that pseudo-digital techniques reduce operational error rates by more than two orders of magnitude, thus facilitating fast operation. (C) 2002 American Institute of Physics.