QUANTA

Friday, March 18, 2011


Diamond-based quantum cryptography and quantum computation

March 18, 2011 

A team of physicists led by J.P. Hadden at the University of Bristol has developed atomic-scale light sources of single photons, which could open the door to diamond-defect-center-based quantum cryptography and quantum computation.

Fluorescent “defect centers” in diamond are trapped in a transparent material that’s large enough to be picked up manually. Unlike quantum dots or trapped atoms, they don’t need to be kept at super cold cryogenic temperatures or trapped in large electromagnetic fields to be stable.

To fulfill the potential of diamond defect centers, light must be collected efficiently from the diamond material. Collection efficiency is dramatically reduced by reflection and refraction of light passing through the diamond-air interface, but Hadden and colleagues were able to reliably etch hemispherical “solid immersion lenses” over defect centers to improve brightness, at a precision of about 100 nanometers.

Their work appears in the journal Applied Physics Letters.


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