Levitation is plenty cool in its own right. But the projected graphics steer the work toward some real world applications. In the clip accompanying the new paper, a quick shot of a storefront window suggests one place where a floating display might be put to good use. Other sites where spectacle is encouraged, like theme parks, could be another possibility. It's hard to imagine that Disney's Imagineers couldn't find some use for this sort of technology in the Haunted Mansion.
Pixie Dust, as the team is calling it, builds on their previous system, which used a four-speaker array to summon objects into the air and move them around in three-dimensional space. While acoustic levitation isn't entirely new, the Japanese researchers have taken what they call the "digital controllability of non-digital objects" to impressive new levels. They can tug a small screw to and fro, for instance, and let part of a floating grid of sand fall away until just a floating cross remains.