"Connecting the dots" for quantum networks

Researchers at the US Naval Research Laboratory (NRL) have developed a new technique that could enable future advances in quantum technology.

The technique consists of pressing quantum dots, tiny particles composed of thousands of atoms, to emit single photons (individual light particles) with exactly the same color and with positions that can be distant from one millionth meter.

"This breakthrough could accelerate the development of quantum information technologies and brain-based computing," said Allan Bracker, a NRL chemist and one of the project's researchers.

For quantum dots to "communicate" (interact), they must emit light at the same wavelength. The size of a quantum dot determines this wavelength of emission. However, just as there are not two identical snowflakes, there are not two quantum dots that have exactly the same size and shape, at least when they were created.

This natural variability prevents researchers from creating quantum dots that emit light at the same wavelength [color]said NRL physicist Joel Grim, the project's lead researcher.

"Instead of starting by creating perfectly identical quantum dots, we then change their wavelength by wrapping them with laser-crystallized hafnium oxide film," Grim said. "The shrink film tightens the quantum dots, which changes their wavelength in a very controllable way."

While other scientists have already demonstrated that they "regulate" the wavelengths of quantum dots, this is the first time researchers have come to this point accurately, both in terms of quantum dots and quantum dots. length and in position.

"This means that we can do it not only for two or three people, but also for many quantum dots in an integrated circuit, which could be used for optical computing rather than for electrical computing," said Bracker.

NRL's broad research capabilities and scientific strengths enabled the team to test various approaches to achieve this breakthrough in a relatively short time.

"NRL has in-house facilities for crystal growth, device fabrication and quantum optical measurements," said Grim. "That means we could immediately coordinate our efforts to focus on quickly improving the properties of the material."

According to Grim and Bracker, this decisive step in the manipulation of quantum dots could lay the groundwork for future advances in a number of areas.

"The new NRL method for adjusting the wavelength of quantum dots could allow new technologies that use the strange properties of quantum physics for computing, communication and detection," said Bracker. "It could also lead to" neuromorphic "or brain-based computing, based on a network of tiny lasers."

The researchers said applications in which space and energy efficiency are limiting factors could also benefit from this revolutionary approach.