Bristol physicists move closer to efficient single-photon sources

March 18, 2011 by
Filed under: News 

A team from Bristol has taken a big step toward efficient single-photon sources that could be used for completely secure optical communications.

Fluorescent “defect centres” in diamond act like atomic-scale light sources at toom temperature but need to be etched to generate the best source, and this is a huge challenge.  them strong contenders for use as sources of single photons (the quantum light particle) in secure quantum cryptography schemes, says J. P. Hadden, a Ph.D. candidate in the Centre for Quantum Photonics at the Department of Electrical and Electronic Engineering at the University of Bristol.

“Defect centres could also be used as building blocks for ‘solid-state quantum computers,’ which would use quantum effects to solve problems that are not efficiently solvable with current computer technology,” Hadden says.

“We managed to show an improvement in the brightness of these defect centres of up to ten times by etching hemispherical ‘solid immersion lenses’ into the diamond,” he said. “This is an important result, showing how nanofabrication techniques can complement and enhance quantum technologies, and opens the door to diamond-defect-center-based implementations of quantum cryptography and quantum computation.”

More recently, Hadden and colleagues developed a technique that allows them to reliably etch these structures over previously characterized defect centres to a precision of about 100 nanometers — another significant step toward a practical and repeatable combination of nanotechnology and quantum optics.

The team presented its findings in Applied Physics Letters, a journal published by the American Institute of Physics.

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