Using lasers to propel probes

Time has an article by Cubie King and Justin Worland about a novel way to travel in space:

Reaching another star with a human-built spacecraft has, for decades, seemed like a challenge as distant as, well, any far-off star humans might try to reach. But now new technology utilizing small unmanned spacecrafts directed by lasers could offer a path forward in the coming decades, scientists say.
Astrophysicist Philip Lubin is one of those scientists. He’s developing wafer-thin crafts that will be guided through space by lasers that push the device close to the speed of light. The total travel time to Mars could be just a few days, Lubin says.
The idea may sound like science fiction, but Lubin says recent advances make the project feasible. And he’s attracting the capital to test it. Russian billionaire Yuri Milner just committed a hundred million dollars in the hope that Lubin will be able to build a proof of concept.

Rico says it's nice to have a million bucks to throw at things...