A new component of the “quantum internet” is taking shape in the laboratory of Nathalie de Leon in the Department of Electrical Engineering.
Such a global quantum network could transmit information far more securely than today’s networks, but one key challenge stems from the difficulty of transmitting quantum signals over long distances. The signals are fragile and can lose their quantum nature as they travel along optical fibers.
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De Leon and her team have created a “quantum repeater” that can be placed at nodes throughout a network to store signals before sending them on the next leg of their journey. But until now it has been difficult to find a material that can store quantum signals long enough to be useful.
To overcome this challenge, the team synthesized a diamond with specific impurities, replacing some of the carbon atoms with silicon. With careful materials processing, the team was able to make these defects, known as silicon vacancies, with a neutral charge. The resulting neutral silicon vacancies have just the right properties for handling quantum signals both as pulses of light for transmission in optical fibers and as electron spins for storage in the repeater.
The eventual goal is to integrate these neutral silicon vacancies with nanophotonic structures to build the components of long-distance quantum information networks.
“We’ve made a structure that can hold quantum information for a long time but can also ‘talk’ to light.”
-Nathalie de Leon, Assistant Professor of Electrical Engineering
Team members: Postdoctoral research associates Brendon Rose, Sorawis Sangtawesin and Paul Stevenson; Srikanth Srinivasan, former postdoctoral researcher; graduate students Ding Huang and Zihuai Zhang
Collaborators: Stephen Lyon, professor of electrical engineering; Alexei Tyryshkin, former staff researcher; Lorne Loudin at the Gemological Institute of America; Matthew Markham, Andrew Edmonds and Daniel Twitchen at Element Six
Development status: Patent protection is pending.
Funding: National Science Foundation, Air Force Office of Scientific Research