'Solid Light' Made from Photons
Researchers have made light act like a solid -- bringing the lightsaber to life (sort of).
Photons, the particles that make up light, don't behave like particles of matter. They can pass right through each other, and they don't bind together to make bigger structures. This has always been a fundamental law learned in every first-year physics class.
Not anymore. A group of scientists group led by Harvard professor of physics Mikhail Lukin and MIT Professor of Physics Vladan Vuletic has made photons link up to form something like a molecule. It's a state of matter that was previously only theoretical. Such "solid" light has been a fixture in science fiction - Star Wars' lightsaber is the most famous example.
The work is outlined in a recent edition of the journal Nature.
Making lightsabers though, isn't what the scientists were after. The real use for photons that interact with each other is in quantum computing. One of the challenges to making a working, reliable quantum computer is that each bit is contained in a single photon. But because photons don't interact with each other, information can't be exchanged the way it is in a conventional computer that works using electrons.
To make the photon stick together, the researchers took atoms of rubidium and put them into a vacuum chamber. They then fired laser beams at the rubidium to cool it within a hair of absolute zero, or about -460 degrees Fahrenheit. After that they fired another, weaker laser into the cloud. The second laser was so weak that only a single photon at a time went in.
Those single photons slowed down as they went through the cloud of rubidium. So far that's perfectly normal; light always slows down as it enters a medium. This is why it bends as it goes through glass or water. As the photon passed through the cloud, it transfered a little bit of its energy so that when it exited, it was moving relatively slowly, for a photon.
It was when the scientists fired two photons into the cloud that things got interesting. When they did that, the photons exited together, acting like a single entity.
It happened because photons can't excite atoms near each other to the same degree. When the first photon hit a rubidium atom it excited it, giving it some energy. The second photon arrived, but it couldn't excite any nearby atoms until the first one went on its way. So as the two photons passed through the cloud, they were forced to stay near each other - one allowed the other through behind it.
It's probably just as well that they don't plan to make lightsabers, though – or this might happen.
When it comes to technology, "first," "better" and "stretchier," sets some innovations apart from others. This week, we have the world's first solar power plant (seen here), the most efficient solar cell, the first thought-controlled bionic leg and the first transparent, stretchable organic light-emitting diode, which could lead to stretchy phones. Have a look.
The Ivanpah Solar Electric Generating System in California’s Mojave Desert just came online. Once it's up and running fully, it will generate 392 Megawatts of renewable energy, enough to power 140,000 homes and reduce carbon emissions by 400,000 tons per year.
High school students from Indiana's Mater Dei High School in Evansville built a DIY eco-car called Elroy that gets 849 miles to the gallon. Although it's not as efficient as the one students from the Université Laval in Quebec, Canada tested earlier this year, which got 3,587 miles per gallon. That said, the Mater Dei High kids still won the grand prize for their competition, a Duralast 392-piece tool cabinet valued at $2,500. Way to go, kids!
Theoretically, the efficiency of a solar cell tops out at 33.7 percent. But now scientists from the Fraunhofer Institute for Solar Energy Systems, Soitec, CEA-Leti and the Helmholtz Center have announced that they built a solar cell that's able to convert 44.7 percent of the sunlight hitting it into electricity. The team is not stopping there. They say they want to reach 50 percent efficiency by 2015, and they just might do it.
A new kind of antenna could make it easier to navigate in cities where buildings frequently force GPS signals to bounce around. The VRay, developed by the US Air Force Institute of Technology and the Locata Corp., uses a beam-forming antenna with 64 receiving elements that identify and subtract the numerous paths a signal takes while bouncing around, as well as other forms of interference, and produces a clean signal.
Tiny cage-like structures could work like delivery trucks inside our bodies to deliver the precise dose of medicine to the exact location. The "vehicles" are coated nickel and steered wirelessly by electromagnetic fields.
The world's first inflatable concert hall is getting pumped up for a show in Japan in Matsushima, which was hit by the tsunami of 2011. The Ark Nova, designed by sculptor Anish Kapoor and architect Arata Isozaki for the Lucerne Festival 2013, is made from a translucent purple membrane reminiscent of a parachute. It can house up to 500 people. Tsunami-damaged trees will be used to build seating and for acoustic reflectors inside.
Microsoft has unveiled its Surface 2. Two pieces of magnesium sandwich electronics powered by a Tegra 4 chip. The company hopes that customers will respond favorably to the tablet's lighter and thinner design, its full HD screen and camera that's 5 times sharper than in the Surface Pro.
Researchers from UCLA led by Qibing Pei, a materials scientist, have developed a transparent, elastic organic light-emitting device, or OLED. A transparent display that bends could usher in smartphone screens that have adjustable sizes, displays that double as window shades and medical implants and flex with a person’s body.
Zac Vawter, who lost his leg below the knee after a motorcycle accident four years, is the first amputee with a thought-controlled bionic leg. The leg has a computer chip that decodes the electrical signals traveling through Vawter's leg muscle and translates it into motion. A motor in the knee and ankle helps him push himself up stairs.
For the first time, scientists have put a kind of tuning fork for light waves onto a computer chip. Just as a tuning fork produces a standardized pitch in sound, this spiral-shaped optical resonator produces a consistent light frequency, or wavelength. Wavelengths correspond to colors in the light spectrum. Miniaturizing a device that's able control the frequency of light could lead to computer chips that use light instead of electrons to process signals -- and that could usher in super-fast computers, precise navigation and futuristic applications that haven't even been imagined yet.