You know that sinking feeling when your phone is down to 3 percent power and about to shut itself off? What if you could aim a laser at it and have it back to 100 percent in no time?
Because it already is the future, scientists from the University of Maryland and Wesleyan University in Connecticut have created a gizmo that can power up your phone as if you were playing a video game. It can literally zap a device from across a room. This tech is an upgrade of an anti-laser, which works the opposite way a laser does. Lasers shoot out streams of photons in the same color. Photons fly through the air, one behind the other. Anti-lasers seem to press the rewind button on time by absorbing those photons.
The problem was that that the only way this could really be pulled off was with a narrow, focused beam in an empty space, because otherwise, photons would scatter chaotically and never make it to the absorber. Not anymore.
“The anti-laser concept was the initial concept for Coherent Perfect Absorption (CPA),” physicist Steven Anlange, who led the electrifying new work and co-authored a paper recently published in Nature Communications, told SYFY WIRE. “Among other things, our work has shown that this is not the most general way to think about it. We have identified ways to achieve CPA that are more flexible and practical, bringing it closer to real applications.”
CPA happens when all incoming radiation is absorbed by something on the other end. This has the potential to do more than just charge your phone or any other gadget from across a room. It could go from leveling up telecommunications to fueling electromagnetic warfare, though space battles probably won’t be like anything you see on Star Wars. Anglange and his team have done what was previously thought impossible by designing an absorber that can capture nearly all radiation over a long distance, even in a cluttered room.
Anglange actually believes that using a cluttered room for his version of an anti-laser is more efficient than an empty room. He actually wanted to see photons scattering in an environment full of obstacles, so that way the team could figure out how to achieve nearly perfect absorption so potential users of this technology won’t have to get a headache from reordering everything in the room a certain way just so their smartphones or tablets can absorb the neregy needed to recharge.
“A cool thing about CPA is that the waves naturally find their way to the target absorber, without any calculation or direction from humans, other than creating the CPA condition,” he said. “Our approach uses a simple characterization method to identify when CPA happens naturally. We have also developed a method to ‘nudge’ a complex scattering system into CPA through subtle manipulations of the scattering environment.”
The conditions under which CPA happens on its own have to be identified in order to program something like this. Instead of creating a scheme within which the photons would travel to the absorber in a straight line, Anglange and his team allowed the phenomenon to happen so they could find which paths were ideal for photons trying to get to the opposite end. Their approach makes it possible for energy from a more diffuse source to get absorbed. They set up a tangle of wires and boxes through which electromagnetic waves were supposed to travel, and made sure it was horribly disordered. Somewhere in the chaos of wires was an absorber. Firing different types of microwaves through the wires showed which ones would be able to transfer to the absorber (almost) perfectly.
The microwaves that were identified to be the most efficient had an unreal and unprecedented 99.999% of their photons caught by the absorber. Running this experiment again in a wireless environment proved almost as effective. The team fired photons through an empty space with an uneven hole in the middle and brass plates everywhere, a setup was intended to throw off the microwaves so they would get lost and bounce off everything. It still had an amazing 99.996% absorption rate. This would have been a massive fail if tested with a regular laser and anti-laser.
So much for having to turn back time, but the era of having to rewind cassetes and VHS tapes has been over for a while. “We can break time-reversal invariance (which is time-reversal symmetry) by a number of different methods,” explained Anlange. “For charged particle motion we simply change the direction of an applied magnetic field. For microwaves, we add a magnetized ferrite material to the propagation path for the microwave signals.”
This is where things can get complicated, which is why there won’t be lines of people eager to get their hands on one of these things anytime soon, and definitely not by Black Friday. Still, Anlange continues to take this technology further. He has already managed to earn patents an disclosures on several types of tech that use CPA, and is pushing for the commercialization of something that really might draw epic Black Friday lines someday.
“We showed for the first time that a disordered environment with broken time-reversal symmetry can also show CPA,” he said. “his goes beyond anti-lasers. It illustrates the power and generality of our ideas.”