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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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By drycrust3 on 3/5/2013 2:05:52 PM , Rating: 2
quote:
That will be a critical step towards quantum memory or a cavity-based quantum computing device.

The interesting thing about photons is they are what transfers energy from one atom to another, and are always present at temperatures above absolute zero. It will be interesting to see how long they can keep their "trained" photons separate from the "untrained" rabble.
Another interesting thought is since the wavelength of the photon is inversely proportional to the energy content, then maybe the treatment given to a photon can be changed depending on its energy content, e.g. the high energy content photons could be "refracted" along a different path to those of low energy content.




"Young lady, in this house we obey the laws of thermodynamics!" -- Homer Simpson














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