University of Iowa researchers have found that using quantum dots could yield more efficient telecommunications and may advance uses for quantum communications, the military, and in medicine, according to a new study.
Ravitej Uppu, assistant professor in the Department of Physics and Astronomy, studied quantum dots, which are compound, nano-sized semiconductor composites that can emit one particle of light at a time.
Uppu’s team created quantum dots that emit single particles of light, called photons, in the telecommunications band — a wavelength best suited for secure quantum communications because it minimizes information loss.
The researchers created quantum dots using a method called nanohole etching, where tiny droplets of aluminum metal deposited on the surface of a semiconductor crystal form nanoholes in the surface. The researchers filled the nanoholes with gallium antimonide, a specialized compound semiconductor used in devices such as lasers and LEDs, creating quantum dots.
The researchers report that the nanoholes’ shape and depth improve the quantum dots’ performance. Deeper nanoholes, for example, produced a more stable and cleaner emission, while shallower nanoholes reduced photon quality, a key metric for quantum communication networks.
Current quantum dots typically emit shorter wavelengths, which often are converted to the telecommunications band, causing significant information loss. With the quantum dots created by Uppu’s team, the photons are created directly in the telecommunications band and thus don’t need to be converted from other wavelengths.
“In our vision of a quantum computing system or the quantum internet, emitters like these would form one of the core building blocks because it’s doing the hard work of generating the photon, which carries information and transmits information from point A to point B,” Uppu says.
The quantum dots also could underpin low-power lasers that require less energy and produce less heat, which would benefit technologies such as fiber-optic communication networks or photonic chips, where managing heat and efficiency are essential. Quantum dots also may have specialized infrared imaging applications for the military and could improve medical imaging that uses infrared light.
Uppu’s group carried out the research at the university’s Molecular Beam Epitaxy facility, led by John Prineas, professor and director of the Applied Physics Program at Iowa.
“This specialized facility was so important for us to achieve the precise nanoscale structures,” Uppu says. “It enabled us to control the semiconductor crystal process with atomic layer precision.”
Study authors include Aden Hageman, Ian Masson, David Montealegre, and John Prineas from Iowa; and Caleb Whittier, Bhaveshkumar Kamaliya, and Nabil Bassim from McMaster University, in Ontario, Canada.
The study, “Engineering Nanohole-Etched Quantum Dots for Telecom-Band Single-Photon Generation,” was published online in ACS Nano, a journal of the American Chemical Society.
The research was funded by the National Science Foundation, the University of Iowa’s Office of the Vice President for Research through the P3 Jumpstarting Tomorrow program, and the Natural Sciences and Engineering Research Council of Canada.