Called the QDrive, it's a resonating cavity with design features that redirect the radiation pressure exerted in the cavity to create a radiation pressure imbalance on the cavity. This differential in radiation pressure generates an unbalanced force that creates thrust. This cavity produces — wait for it — thrust without use of propellant. Skeptical? They've posted the theory. Or check out the numerical models for yourself. And of course, they wouldn't go public without some experimental results."
Link to Original Source