Researchers at NIST have developed a new method to measure the quality of single-photon sources, which is crucial for quantum information processing. The method examines the dynamic fluctuations in photon emission from quantum emitters, allowing scientists to determine the “purity” and indistinguishability of photons produced.
The team studied quantum dots embedded in a gallium arsenide matrix, exciting them with pulsed lasers. They discovered that the time interval between laser pulses affects the quality of photons produced, with certain wavelengths and pulse timings leading to better single-photon sources.
The new diagnostic test for indistinguishability is based on quantum coalescence, where identical photons exiting a beam splitter will always register on the same detector. The researchers found that photons produced later in the emission cycle are more likely to be indistinguishable, likely due to reduced carrier pairs in the quantum dot.
This research builds on over a decade of work by the team, demonstrating the potential for evaluating other single quantum emitters and expanding the research to higher temperatures. The findings could help improve quantum technologies by identifying optimal conditions for single-photon sources.
Source: https://www.nist.gov/news-events/news/2013/04/single-photon-quantum-emitter-its-matter-timing
Keywords: photon, indistinguishability, quantum dot, excitation, emission
