Single-Photon Emission at Room Temperature Now A Reality

Dec 06

Single-Photon Emission at Room Temperature Now A Reality

Photonic quantum information calls for highly pure, easily accessible, and scalable single-photon sources. Dr. FANG Wei from ZJU’s College of Optical Science and Engineering teamed up with JIN Yizheng and PENG Xiaogang from the Department of Chemistry and generated electrically-driven single-photon sources based on colloidal quantum dots with near-optimal antibunching at room temperature.

This has opened up a new approach to research into practical and integrated single-photon sources. Relevant findings were published in the October 26 issue of Nature Communications.

Single-photon sources are substantially differentiated from classical light ones. Photons emitted from coherent or thermal emission sources inevitably arrive in bunches whereas a single-photon source is a non-classical light source with sub-Poisson statistics, which ensures photons are emitted one by one (i.e., photons are “antibunched”). Single-photon sources are indispensable for photonic quantum information technologies.

Scientists have long been committed to developing integrated and convenient optimal single-photon sources. Single-photon emission has been demonstrated in various systems. For practical applications, compact as well as scalable single-photon sources, which can operate at room temperature and be electrically excited and controlled, are highly desirable. In this regard, great efforts have been devoted to developing room-temperature and electrically driven single-photon sources using different material platforms, including defects in wide-bandgap inorganic semiconductors and organic molecules in organic host matrices. However, these devices are far from being ideal.

"The sun displays a colorful world with its continuous spectrum. We explore the magical quantum world with one or two photons." - Dr. FANG Wei 

Colloidal quantum dots are solution-grown semiconductor nanocrystals with sizes in the quantum-confinement regime. Since 2014, FANG, JIN and PENG have attempted to use them to generate single-photon sources. They explored a single-colloidal quantum dot as a quantum emitter in electrically driven single-photon source. Combined with an isolating layer in the device, they realized near-optimal antibunching single-photon generation at room temperature with vanishing background emission. In addition, their quantitative model reveals that carrier injection/recombination dynamics suppress the multi-photon-emission probability.

The new findings highlight a pathway to the development of novel room-temperature quantum light sources for practical quantum information applications

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