Apr 15 2005

ArticlePhy­sOrg: Opti­cal com­pu­ter made from fro­zen light
Scien­tists at Har­vard Uni­ver­sity have shown how ultra-cold atoms can be used to freeze and con­trol light to form the “core” — or cen­tral pro­ces­sing unit — of an opti­cal com­pu­ter. Opti­cal com­pu­ters would trans­port infor­ma­tion ten times fas­ter than tra­di­tio­nal elec­tro­nic devi­ces, smashing the intrin­sic speed limit of sili­con technology.

This new research could be a major breakth­rough in the quest to create super-fast com­pu­ters that use light ins­tead of elec­trons to pro­cess infor­ma­tion. Pro­fes­sor Lene Hau is one of the world’s fore­most autho­ri­ties on “slow light”. Her research group became famous for slo­wing down light, which nor­mally tra­vels at 186,000 miles per second, to less than the speed of a bicycle.

Using the same appa­ra­tus, which con­tains a cloud of ultra-cold sodium atoms, they have even mana­ged to freeze light alto­gether. Pro­fes­sor Hau says this could have appli­ca­tions in memory sto­rage for a future gene­ra­tion of opti­cal computers.

But Pro­fes­sor Hau’s most recent research addres­ses the issue of opti­cal com­pu­ters head-on. She has cal­cu­la­ted that ultra-cold atoms known as Bose-Einstein con­den­sa­tes (BECs) can be used to per­form “con­tro­lled cohe­rent pro­ces­sing” with light. In ordi­nary mat­ter, the ampli­tude and phase of a light pulse would be smea­red out, and any infor­ma­tion con­tent would be des­tro­yed. Hau’s work on slow light, howe­ver, has pro­ved expe­ri­men­tally that these attri­bu­tes can be pre­ser­ved in a BEC. Such a device might one day become the CPU of an opti­cal computer.

Tra­di­tio­nal elec­tro­nic com­pu­ters are advan­cing ever clo­ser to their theo­re­ti­cal limits for size and speed. Some scien­tists believe that opti­cal com­pu­ting will one day unleash a new revo­lu­tion in sma­ller and fas­ter computers.

Pro­fes­sor Lene Hau is Gor­don McKay Pro­fes­sor of Applied Phy­sics & Pro­fes­sor of Phy­sics at Har­vard University.

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