China moves closer to quantum chips by creating a new light source

Researchers in China have moved a step closer to making quantum chips with the world's first use of conventional semiconductors to create a quantum light source.

Quantum chips are capable of solving complex problems many times faster than conventional computing based on electronics, but scientists have struggled to fabricate the components needed for an integrated circuit.

A research team in China now says it has created one of those components - a quantum light source - using the semiconductor gallium nitride (GaN) , a material used in light-emitting diodes. blue for decades.

Researchers in China have shed light on the potential of HaN in quantum optics. (Photo: SCMP).

According to the research team from the University of Electronic Science and Technology of China (UETC), Tsinghua University and Shanghai Institute of Microsystems and Information Technology, quantum light sources have 'remarkable potential' to making small, powerful quantum chips. It creates quantum mechanically entangled pairs of light particles that can be used to carry information.

Compared with existing quantum light sources based on materials such as silicon nitride and indium phosphide, GaN has a much wider wavelength range and can be used to fabricate other key components of quantum circuits.

The research was published in the journal Physical Review Letters last month. "We demonstrate that gallium nitride is a good quantum material platform for quantum photonic information , where the generation of quantum light is important," said lead researcher Zhou Qiang. gallium nitride offers promising prospects for the development of quantum photonic chips in the near future."

Quantum photonics expert Thomas Walther from the Technical University of Darmstadt (Germany) said that the work of the Chinese research team is 'a big step forward', because it can cut the cost of manufacturing devices, while at the same time improving the quality of the device. making them much more compact and sturdy than today.

In their experiment, Zhou and his colleagues first created a thin film of GaN on top of a sapphire layer. They then etched a ring in the membrane 120 micrometers in diameter, allowing light particles from the laser beam to move around the ring.

When researchers applied infrared laser light to the GaN film, some of the light particles were trapped and became 'resonant' in pairs. Due to an effect called spontaneous four-wave mixing , some resonant pairs create new pairs of light particles that are uniquely bound together.

Mr Zhou said the level of coupling produced by the GaN ring was 'comparable' to that measured in other quantum light sources.

The output wavelength range also extends from 25.6 nanometers compared to previous materials up to 100 nanometers with the new device.

"By providing more wavelength resources, we will be able to meet the needs of more users who wish to access quantum networks through different wavelengths," Zhou told Khoa . Chinese Science & Technology.

Besides quantum light sources, GaN is also a promising material for making other components of quantum circuits, including pump lasers and light particle detectors, according to the team.

"Compared with current platforms, GaN has significant promise for the fabrication of comprehensive on-chip quantum photonic integrated circuits," the team said .