Wednesday, March 7, 2007

Quantum 411

This is guest post from Ben, one of our good friends at the American Institute of Physics.

This year's meeting features a lot of new developments in quantum information and quantum computing. Ten years ago, quantum computing was mainly discussed at the DAMOP (Division of Atomic, Molecular, and Optical Physics) meetings. But now, condensed-matter researchers are getting into the game, making progress with quantum-computer designs based on superconductors and semiconductors, for example. In a Reese's peanut-butter-cup kind of development ("you put chocolate in my peanut butter!" "you put peanut butter in my chocolate!"), DAMOP physicists are coming to the March Meeting now, too. Helping to bridge these two communities further is a recently created APS unit devoted to quantum information (called GQI).

This morning's APS news conference on quantum information featured a "Murderer's Row" of some of the top researchers in the field. Paul Kwiat of the University of Illinois gave a nice introduction to the topic to science reporters from newspapers and magazines. He explained superposition by taking out a coin. "Tails" would represent 0, and "heads" would represent "1". To illustrate the superposition of the two states, he spun the coin, which he said was analogous to the coin being heads and tails at the same time. He liked the analogy because the coin eventually settles into heads or tails, just as a quantum superposition always collapses into a single state. Along this same theme, Kwiat discussed a new random-number generator that uses photons, or specifically the random timing intervals between photons hitting a detector, to generate random numbers.

Next up was David Wineland of NIST. His group traps ions with electric fields, then manipulates them with lasers. These ions can act as bits in a future quantum computer. Ion traps are the currently the most advanced quantum computation technology, but as Wineland modestly told me, it's like being two feet ahead at the start of the marathon. Ion traps were once big and clunky. Wineland showed miniature computer-chip like designs, from his lab and others around the world, that can potentially manipulate many ions for a more scaled-up and advanced quantum computing approach.

Jian-Wei Pan of the University of Heidelberg in Germany and Hefei National Laboratory in China unveiled a six-photon quantum computer. Pan is also a master of quantum teleportation (he's giving an invited talk on the topic on Thursday morning). After the news conference, he expressed the hope that quantum teleportation of ions, rather than just photons, would someday be possible over long distances. Star Trek is coming closer to reality all the time.

Batting cleanup was Anton Zeilinger of the University of Vienna in Austria. In a recent dramatic display, he and his collaborators transmitted a quantum-encrypted message between two Canary Islands at a distance of 144 km (about 90 miles). He showed future plans to transmit quantum keys via the International Space Station to ground-based receivers spaced thousands of kilometers apart. Quantum cryptographic systems, he pointed out, are already commercially available. He actually convinced a banker he knows that quantum cryptography was the best way to transmit sensitive information. But the banker, he says, is being a bit cautious. He's going to let one of his competitors adopt the technology first, and see if his customers will demand the same quantum service.

1 comment:

Anonymous said...

nice poster, Ben.
I was not able to attend the Marching meeting but your article gave me quite an impression.