Never heard of it. A quick google turned up a breathless Wikipedia article where the experimenters promised:
"a quantum vacuum plasma thruster-powered spacecraft weighing 90 tonnes would be able to reach Proxima Centauri in ~29.9 years at 4 newtons per kilowatt."I'd definitely buy one of those!
Alas, famed mathematician John Baez put the boot in. Both theory and experiment are all over the place and they probably observed a heating effect.