New technique stabilises photon emission from quantum dots
Researchers say the method, which involves adding crystallised molecular layers to perovskite quantum dots, could pave the way for cheaper, room-temperature, chip-scale quantum light sources
Recently published research from the University of Oklahoma reports that adding a covering to a colloidal quantum dot (QD) light source can cause it to shine without faltering, opening the door to new, affordable quantum possibilities.
QDs are used in a variety of products, from computer monitors and LEDs to solar cells and biomedical engineering devices. They are also among the prime candidates for light sources in quantum computing and communication. However, QDs have historically had several problems, including that their surfaces can easily develop defects, which can cause them to fail, often after only 10-20 minutes of use.
Now, researchers led by Yitong Dong, assistant professor at the University of Oklahoma, have reported that adding a crystallised molecular layer to QDs made of perovskite neutralises surface defects and stabilises the surface lattices. According to the scientists, these coverings extend the continuous photon emission of QDs to more than 12 hours without any decay, and virtually no blinking.
“In quantum computing, you must be able to control how many photons are emitted at any given time,” said Dong. “QDs are notoriously unstable, so we worked to create a crystal covering that could stabilise their quantum emissions. This material is ideal because it is inexpensive to use and scale and is efficient at room temperature.”
This relates to another challenge associated with single-photon emitters: they have traditionally operated at extremely low cryogenic temperatures. In fact, they typically require liquid helium at -269 degrees Celsius, making them impractical for most real-world applications. However, the team say their research demonstrates that perovskite QDs achieve nearly 100 percent efficiency at room temperature, making them significantly easier, cheaper, and more appealing to use.
“Although there has been real interest in the exotic optical properties of this material, the sophistication needed to fabricate a single-photon emitter was cost-prohibitive,” Dong said. “But since perovskite QDs can be used at normal temperatures and synthesised for very little cost, we believe they could become the photonic chip light source for future quantum computing and quantum communication devices.”
According to Dong, these findings pave the way for future quantum emitter designs that extend beyond this specific material or molecular structure.
“In my opinion, our research has profound implications for the quantum field,” he said. “We’ve found a way to stabilise these QDs using organic and inorganic molecular crystals, opening the door for others to explore the fundamental optical properties and fundamental physics of these materials. It’s really exciting.”
Image credit: Jonathan Kyncl
