  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.
