Source: http://gizmodo.com/5893768/new-bi+plane-design-promises-all-of-the-sonic-none-of-the-boom
The Concorde became the premiere transport across the Atlantic in part because it was precluded from flying over populated areas due to the sonic boom it created on takeoff. A new two-wing design, however, may hold the secret to silently breaking the sound barrier. Guile does not approve.
As a plane moves through the air, it stacks up air pressure in front of the plane and creates a vacuum in its wake. When the plane hits super sonic speeds—actually travelling faster that the sound wave it's creating—the plane will drag and compress the leading and trailing pressure waves together to form a single big shock wave moving at the speed of sound. The wave from this hits the ground is what's considered the sonic boom.
A team of researchers from MIT and Stanford University developed the bi-plane design based on a design devised in the 1950's by German engineer Adolf Busemann. He figured that a design using triangular wings connected at the tip would effectively cancel out the boom. His original design wasn't quite efficient—the inner channel prevented sufficient air flow— so the researchers had to tweak the design a bit.
And man what a tweak. The design they settled on—with a smooth finish on the inner edge of the triangle and small bumps on the outer—could reduce the plane's fuel consumption by 50 percent and allow speeds in excess of Mach 5. Not to mention they'd be able to fly over the country and not just the oceans. Get ready for two-hour jaunts across the continent if this design reaches the market. [Sonic Boom Wiki - LiveSciences]