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Photons Open the Gateway For Quantum Networks

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In an optical chip embedded with a quantum dot, if you send a single photon into the quantum dot (top), the gateway is closed. If you send two photons at the same time (bottom), the gateway opens.

A team from the Niels Bohr Institute has been conducting experiments on an optical chip embedded with a quantum dot.

Credit: Alisa Javadi/Niels Bohr Institute

Researchers at the Niels Bohr Institute (NBI) in Denmark, in collaboration with researchers from the Korea Institute of Science and Technology, have created a photon contact, a type of transistor that can control the transport of photons in a circuit.

A photon contact is a key development in the effort to develop quantum computer networks.

Light normally spreads in all directions and will have to be controlled down to the individual photons in order to develop quantum technology based on light. A team from NBI's Quantum Photonic research group conducted experiments using an optical chip embedded with a quantum dot. Embedded in the middle of the chip and comprised of a collection of atoms, the quantum dot can be used as a contact for the photons, notes NBI professor Peter Lodahl.

The researchers used a laser to produce photons, and boosting its intensity improves the chance that two or more would be released at the same time. "If we send a single photon into the quantum dot, it will be thrown back--the gateway is closed," says NBI's Alisa Javadi. "But if we send two photons, the situation changes fundamentally--the gateway is opened and the two photons become entangled and are sent onwards."

From University of Copenhagen
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