Controlling long-range quantum correlations is central to quantum computation and simulation. In quantum dot arrays, experiments so far rely on nearest-neighbour couplings only, and inducing long-range correlations requires sequential local operations. Here we show that two distant sites can be tunnel coupled directly. The coupling is mediated by virtual occupation of an intermediate site, with a strength that is controlled via the energy detuning of this site. It permits a single charge to oscillate coherently between the outer sites of a triple dot array without passing through the middle, as demonstrated through the observation of Landau-Zener-St\"uckelberg interference. The long-range coupling significantly improves the prospects of fault-tolerant quantum computation using quantum dot arrays and opens up new avenues for performing quantum simulations in nanoscale devices.
@article{arxiv.1303.1034,
title = {Long-range coherent coupling in a quantum dot array},
author = {Floris R. Braakman and Pierre Barthelemy and Christian Reichl and Werner Wegscheider and Lieven M. K. Vandersypen},
journal= {arXiv preprint arXiv:1303.1034},
year = {2016}
}