Researchers in China have taken a significant step closer to creating quantum chips by, for the first time in the world, using conventional semiconductors to generate quantum light sources.
Quantum chips have the potential to solve complex problems much faster than traditional electronic-based computing, but scientists have struggled to manufacture the necessary components for an integrated circuit.
A research team in China has announced that they have developed one of these components—a quantum light source—using gallium nitride (GaN), a material that has been utilized in blue light-emitting diodes for several decades.
Chinese researchers have illuminated the potential of GaN in quantum optics. (Photo: SCMP).
According to the research team from the University of Electronic Science and Technology of China (UESTC), Tsinghua University, and the Shanghai Institute of System and Information Technology, the quantum light source has “remarkable potential” for creating small, powerful quantum chips. It generates pairs of entangled quantum light particles that can carry information.
Compared to existing quantum light sources based on materials like 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. Research leader Zhou Qiang stated: “We demonstrate that gallium nitride is a good quantum material platform for quantum photonic information, where generating quantum light is crucial. The gallium nitride platform offers promising prospects for developing quantum photonic chips in the near future.”
Quantum optics expert Thomas Walther from Darmstadt University of Technology (Germany) remarked that the work of the Chinese team is “a significant advancement,” as it could reduce the cost of manufacturing devices while making them much more compact and robust compared to current models.
In their experiment, Zhou and his colleagues first created a thin GaN film on a sapphire layer. They then etched a ring in the film with a diameter of 120 micrometers, allowing light particles from a laser beam to circulate around the ring.
When the researchers introduced infrared laser light into the GaN film, some light particles were captured and became “resonant” in pairs. Due to an effect known as spontaneous four-wave mixing, some resonant pairs generated new pairs of light particles that were uniquely entangled.
Zhou noted that the degree of entanglement produced by the GaN ring “can be compared” to levels measured in other quantum light sources.
The output wavelength range also expanded from 25.6 nanometers with previous materials to 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 the Chinese Science & Technology Daily.
In addition to being a quantum light source, GaN is also a promising material for creating other components of quantum circuits, including pump lasers and light particle detectors, according to the research team.
The team stated: “Compared to existing platforms, GaN has significant potential for fabricating comprehensive quantum photonic integrated circuits on a chip.”
