Better 'Photon Loops' May Be Key to Computer and Physics Advances

From NIST Tech Beat: August 22, 2011
Contact: Chad Boutin
301-975-4261

Surprisingly, transmitting information-rich photons thousands of miles through fiber-optic cable is far easier than reliably sending them just a few nanometers through a computer circuit. However, it may soon be possible to steer these particles of light accurately through microchips because of research* performed at the Joint Quantum Institute of the National Institute of Standards and Technology (NIST) and the University of Maryland, together with Harvard University.

Artist's rendering of the proposed JQI fault-tolerant photon delay device for a future photon-based microchip. The devices ordinarily have a single row of resonators; using multiple rows like this provides alternative pathways for the photons to travel around any physical defects. Credit: JQI View hi-resolution image

The scientists behind the effort say the work not only may lead to more efficient information processors on our desktops, but also could offer a way to explore a particularly strange effect of the quantum world known as the quantum Hall effect in which electrons can interfere with themselves as they travel in a magnetic field. The corresponding physics is rich enough that its investigation has already resulted in three Nobel Prizes, but many intriguing theoretical predictions about it have yet to be observed.
The advent of optical fibers a few decades ago made it possible for dozens of independent phone conversations to travel long distances along a single glass cable by, essentially, assigning each conversation to a different color—each narrow strand of glass carrying dramatic amounts of information with little interference. 
Ironically, while it is easy to send photons far across a town or across the ocean, scientists have a harder time directing them to precise locations across short distances—say, a few hundred nanometers—and this makes it difficult to employ photons as information carriers inside computer chips.

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