A role for ion implantation in quantum computing

We propose to create arrays of phosphorus atoms in silicon for quantum comp uting using ion implantation. Since the implantation of the ions is essenti ally random, the yield of usefully spaced atoms is low and therefore some m ethod of registering the passage of a single ion is required. This can be a ccomplished by implantation of the ions through a thin surface layer consis ting of resist. Changes to the chemical and/or electrical properties of the resist will be used to mark the site of the buried ion. For chemical chang es, the latent damage will be developed and the atomic force microscope (AF M) used to image the changes in topography. Alternatively, changes in elect rical properties (which obviate the need for post-irradiation chemical etch ing) will be used to register the passage of the ion using scanning tunneli ng microscopy (STM), the surface current imaging mode of the AFM. We addres s the central issue of the contrast created by the passage of a single ion through resist layers of PMMA and C-60. (C) 2001 Elsevier Science B.V. All rights reserved.