An infinite array of parallel current-carrying wires is known, from the field of neutral particle optics, to produce an exponentially localized magnetic field when the current direction is antiparallel in adjacent wires. We show that a finite array of several tens of superconducting Nb nanowires can produce a peak magnetic field of 10mT that decays by a factor of 10^4 over a length scale of 500nm. Such an array is readily manufacturable with current technology, and is compatible with both semiconductor and superconducting quantum computer architectures. A series of such arrays can be used to individually address single single-spin or flux qubits spaced as little as 100nm apart, and can lead to quantum logic gate times of 5ns.
Cite
@article{arxiv.cond-mat/0310352,
title = {Exponentially Localized Magnetic Fields for Single-Spin Quantum Logic Gates},
author = {Daniel A. Lidar and Joseph H. Thywissen},
journal= {arXiv preprint arXiv:cond-mat/0310352},
year = {2009}
}