Quantum Dots Found to Blink
Have you ever been annoyed by a fluorescent light flickering on and off? I know I have and, when possible will try to fix the problem. Researchers at NIST and the Naval Research Laboratory have recently discovered that another kind of light source can blink on and off, but unlike ceiling lights, these quantum dot light sources could have a major impact on future technologies.
Quantum dots are specialized semiconductor crystals we are able to produce with whatever optical properties we desire. For this reason, many would like to integrate them into computer chips as photon sources, for use in and between quantum computers. Unfortunately the quantum dots that looked to be the best fit for these applications may not be suitable after all. For the dots to work, they must produce high quality, single photons reliably. The NIST researchers have found that indium arsenide and gallium arsenide quantum dots will blink on and off, over timescales of tens of nanoseconds to hundreds of milliseconds. This effectively cuts the efficiency of the dots from the requisite 100% to 50%-80%.
The reason this serious issue had never been noticed before was because the quantum dots were typically examined after being fabricated but before the surrounding devices were installed. Apparently the process of adding the materials creates defects, but the researchers hope to find ways to minimize them and the blinking in the future, to make them useable as originally hoped.