16 Quantum Teleportation Leaps Toward Reality
Scientists have teleported information between light and atoms...
32 Invisibility Cloak Invented!
The "first practical realization" of a cloak of invisibility...
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16 Quantum Teleportation Leaps Toward Reality
It's not exactly "Beam me up, Scotty," but for the first time scientists have teleported information between light and atoms, hastening the long-awaited advent of ultrafast quantum computers and unbreakable encryption schemes. Quantum teleportation is the process of making a subatomic particle's physical state vanish from one place and appear in another, a little like Captain Kirk's transporter. What makes this possible is a bizarre phenomenon known as entanglement, in which a pair of particles have complementary characteristics, such as two electrons spinning in opposite directions. The irreducible uncertainty of quantum mechanics makes it impossible to predict the state of a given electron, but because the two particles are entangled, measuring the state of one automatically determines the state of the other, regardless of how far apart they are.
In order to teleport a state between light and atoms, Eugene Polzik and his colleagues at the Niels Bohr Institute in Copenhagen, in collaboration with Ignacio Cirac of the Max Planck Institute for Quantum Optics in Germany, entangled a light beam with a magnetized gas of cesium atoms. The researchers then encoded the state they wanted to teleport into the light beam with laser pulses. By separating the entangled quantum information from the light beam and uncovering the laser message, the team was able to teleport the complementary state to the atoms at a distance of half a yard. "For the first time," Polzik says, quantum teleportation "has been achieved between light—the carrier of information—and atoms." This was also the first time that it was done with a macroscopic atomic object acting as the target. Scientists had previously teleported states only between pairs of photons or pairs of atoms. But a practical quantum computer, Polzik notes, requires the transfer of information between a data stream, such as light, and a stored quantum state, such as the atoms in a hard drive.
Curt Suplee
32 Invisibility Cloak Invented!
When a tabloid best known for topless pinups breaks a Science journal embargo to publish news of a major physics finding, you know the world has gone a little gaga. "Boffin invents invisibility cloak," blared British newspaper The Sun on October 19, reporting that physicists from Duke University and Imperial College London had designed radical new materials that can bend microwaves around an object so that they are neither absorbed nor scattered. This achievement is the "first practical realization" of a cloak of invisibility, says lead scientist David Smith. The researchers succeeded in cloaking a two-inch-wide foam-filled copper cylinder from microwaves. If they could guide shorter-wavelength visible light waves around the same object, "it would appear as though they came through free space, as if nothing was there," Smith says. Despite the screaming headlines—and the entreaties of both government intelligence agencies and Harry Potter fans—Smith admits "it may be a while" before he makes anyone vanish.
Josie Glausiusz
The invisibilty device
