Korea University: Electrically driven single-photon sources developed for commercialization of quantum communication
A research team led by Park Hong-gyu, a professor in the Department of Physics under the College of Science, became the first to develop electrically driven single-photon sources with deterministically controlled emission sites using an atomically thin 2D heterostructure.
Supported by the Samsung Research Funding and Incubation Center of Samsung Electronics, the study has been acknowledged as contributing to the commercialization of next-generation quantum communication technologies. The results were published in Science Advances, a sister journal of Science, on October 20.
New single-photon sources developed using artificial quantum dots are expected to boost next-generation quantum cryptography
Quantum cryptography, which uses the principles of quantum mechanics, is seen as a possible solution to eavesdropping in classical cryptography. The proposed single-photon sources are essential for quantum cryptography and quantum information processing.
Unlike conventional light sources, single-photon light sources emit light as single photons one at a time. While conventional communication relies on the wavelength or amplitude of light, quantum cryptography carries signals in the unit of a photon. The use of single-photon sources means that eavesdropping by intercepting a part of photons is, in principle, impossible.
Quantum cryptography with single-photon light sources offers outstanding security and is being increasingly used for military and industrial purposes.
However, existing single-photon emitters operate by optical pumping, and emitting single photons from desired sites is extremely difficult. These issue must be addressed in order to commercialize single-photon emitters. Using an atomically thin 2D heterostructure, the team led by Professor Park Hong-gyu succeeded in developing electrically driven single-photon sources with deterministically controlled emission sites.
First, an atomically thin 2D heterostructure was fabricated from conductive graphene, nonconductive boron nitride and semiconductive chalcogenide. Next, the thin heterostructure was transferred to a deformable polymer substrate, to which a force was applied using an atomic force microscope tip.
The band gap of 2D materials decreases at the indentation site, having the same effect as the creation of quantum dots. When electricity is passed through the artificial quantum dots, electrons are collected in the artificial quantum dot domain, and the quantum confinement effect leads to the emission of single photons.
Professor Park Hong-gyu said, “The significance of this study lies in the development of electrically driven single-photon sources, thus paving the way for the commercialization of quantum cryptography. By using on-chip quantum light sources, we expect to simplify functional quantum systems, such as quantum sensors and quantum computers.”