Two teams have shown how quantum approaches can solve problems faster than classical computers, bringing physics and computer science closer together.
For Valeria Saggio to boot up the computer in her former Vienna lab, she needed a special crystal, only as big as her fingernail. Saggio would place it gently into a small copper box, a tiny electric oven, which would heat the crystal to 77 degrees Fahrenheit. Then she would switch on a laser to bombard the crystal with a beam of photons.
This crystal, at this precise temperature, would split some of those photons into two photons. One of these would go straight to a light detector, its journey finished; the other would travel into a tiny silicon chip — a quantum computing processor. Miniature instruments on the chip could drive the photon down different paths, but ultimately there were only two outcomes: the right way, and the many wrong ways. Based on the result, her processor could choose another path and try again.
The sequence feels more Rube Goldberg than Windows, but the goal was to have a quantum computer teach itself a task: Find the right way out.
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Physicists calculated that these mysterious particles will betray their location with heat. To prove it, they’ll need the most powerful telescopes in the cosmos.
WE’RE BATHING IN an uncertain universe. Astrophysicists generally accept that about 85 percent of all mass in the universe comes from exotic, still-hypothetical particles called dark matter. Our Milky Way galaxy, which appears as a bright flat disk, lives in a humongous sphere of the stuff—a halo, which gets especially dense toward the center. But dark matter’s very nature dictates that it’s elusive. It doesn’t interact with electromagnetic forces like light, and any potential clashes with matter are rare and hard to spot.
Physicists shrug off those odds. They’ve designed detectors on Earth made out of silicon chips, or liquid argon baths, to capture those interactions directly. They’ve looked at how dark matter may affect neutron stars. And they’re searching for it as it floats by other celestial bodies. “We know we have stars and planets, and they’re just peppered throughout the halo,” says Rebecca Leane, an astroparticle physicist with SLAC National Accelerator Laboratory. “Just moving through the halo, they can interact with the dark matter.”
For that reason, Leane is suggesting that we look for them in the Milky Way’s vast collection of exoplanets, or those outside our solar system.
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One day a “magic carpet” based on this light-induced flow technology could carry climate sensors high in the atmosphere—wind permitting.
IN THE BASEMENT of a University of Pennsylvania engineering building, Mohsen Azadi and his labmates huddled around a set of blinding LEDs set beneath an acrylic vacuum chamber. They stared at the lights, their cameras, and what they hoped would soon be some action from the two tiny plastic plates sitting inside the enclosure. “We didn’t know what we were expecting to see,” says Azadi, a mechanical engineering PhD candidate. “But we hoped to see something.”
Let’s put it this way: They wanted to see if those plates would levitate, lofted solely by the power of light.
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