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Advancing Secure Communications: A Better Single-Photon Emitter For Quantum Cryptography

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A nanowire single photon emitter.

An atomic force microscope image of a nanowire single photon emitter.

Credit: Pallab Bhattacharya

University of Michigan researchers say they have developed a more efficient single-photon emitter that can be made using traditional semiconductor processing techniques, a development that could make quantum cryptography more practical.

The emitter is a single nanowire made of gallium nitride with a very small region of indium gallium nitride that behaves as a quantum dot. The researchers note the emitter is made of semiconducting materials that are commonly used in light-emitting diodes and solar cells.

"By making the diameter of the nanowire very small and by altering the composition over a very small section of it, a quantum dot is realized," says Michigan professor Pallab Bhattacharya.

The emitter is fueled by electricity rather than light, which makes it more practical than conventional designs. In addition, each photon it emits possesses the same degree of linear polarization.

"So in cryptic message, if you want to code them, you would only be able to use 50 percent of the photons," Bhattacharya says. "With our device, you could use almost all of them."

From University of Michigan News Service
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