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Chilly chip achieves important quantum computing advance

University of California Santa Barbara Physics professor John Martinis is looking to trap sunshine in a bottle; or photons in a cavity, more precisely.  His former postdoctoral fellow Yi Yin -- now a professor at Zhejiang University in the city of Hangzhou, China -- has just published a work in the journal Phys. Rev. Letters detailing how her team used tiny superconducting structures to selectively trap and release photons.

Ms. Yin comments, "As one crucial step of achieving controllable quantum devices, we have developed an unprecedented level of manipulating light on a superconducting chip.  In our experiment, we caught and released photons in and from a superconducting cavity by incorporating a superconducting switch.  By controlling the switch on and off, we were able to open and close a door between the confined cavity and the road where photons can transmit. The on/off speed should be fast enough with a tuning time much shorter than the photon lifetime of the cavity."

The study uses a two-atom construct for the "qubit" (quantum bit) that stores the photon state information in the Fabry-Perot cavity.  The team uses a switchable mirror to act like a shutter, controlling the waveform of the released photons.

UCSB quantum chip
The UCSB superconducting quantum chip was chilled to three-hundreths of a degree Kelvin.

There were some rather significant technical hurdles that are required to achieve the team's impressive results.  The approximately 1 sq. inch chip had to be chilled to -273.12 ºC -- or about two-hundredths of a degree Kelvin above absolute zero.

The next step is to tune the device to transfer controlled-state photons between two cavities.  That will be a critical step towards quantum memory or a cavity-based quantum computing device.

Sources: UCSB, Phys. Rev. Letters



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RE: Correct me if i a wrong
By MozeeToby on 3/5/2013 3:17:06 PM , Rating: 3
Perpetual motion, by itself, is fine, it's extracting energy from a system that is in perpetual motion that isn't. Two black holes orbiting around each other in empty space will be stable for the lifetime of the universe (though even there, some energy is extracted in the form of gravity waves... well, according to theory anyway).

Imagine a loop of fiber optics that was efficient enough and long enough that you could connect and disconnect the ends before a signal made it all the way around. You could trap the light inside making loops and if fiber were optically perfect you could store the light that way. What they've done is found a way to connect up the ends of a loop (actually a cavity, but same thing in principle) so fast that the loop can be microscopic.


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