Coherence at a distance...

Summary: 

Long distance coherent coupling in a quantum dot array

The group led by Lieven Vandersypen at TU-Delft recently published a paper in Nature Nanotechnology in which they show that two distant sites in an electrostatically defined quantum dot array 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–Stückelberg interference. The long-distance 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.