First topological quantum simulator device with a strong light-matter interaction regime operating at room temperature

Researchers at Rensselaer Polytechnic Institute have created a device no wider than a human hair that will help physicists probe the fundamental nature of matter and light. Their findings, published in the journal Nature Nanotechnologycould also support the development of more efficient lasers, used in areas ranging from medicine to manufacturing.

The device is made of a special type of material called a photonic topological insulator. A photonic topological insulator can direct photons, the wave-like particles that make up light, to interfaces specifically designed into the material, while also preventing these particles from spreading through the material itself.

Because of this property, topological insulators can cause many photons to behave coherently as one photon. The devices can also be used as topological “quantum simulators,” miniature laboratories where researchers can study quantum phenomena, the physical laws that govern matter on very small scales.

“The photonic topological insulator we have created is unique. It works at room temperature. This is a major advance. Previously, you could only investigate this regime using large, expensive equipment that supercools matter in a vacuum. Many research labs do not have access to this kind of equipment, so our device could enable more people to conduct this kind of basic physics research in the laboratory,” said Wei Bao, assistant professor in the Department of Materials Science and Engineering at RPI and senior author of the study.

“It is also a promising step forward in the development of lasers that require less energy to operate, because our room temperature device threshold – the amount of energy required to make it work – is seven times lower than previously developed devices at low temperature.’ Bao added.

The RPI researchers created their new device using the same technology used in the semiconductor industry to make microchips, layering different types of materials, atom by atom, molecule by molecule, to create a desired structure with specific properties.

To create their device, the researchers grew ultrathin sheets of halide perovskite, a crystal made of cesium, lead and chlorine, and etched a patterned polymer on top of them. They placed these crystal plates and the polymer between layers of different oxide materials, ultimately forming an object about 2 microns thick and 100 microns long and wide (the average human hair is 100 microns wide).

When the researchers shined a laser light on the device, a glowing triangular pattern appeared on the interfaces designed into the material. This pattern, dictated by the device design, is the result of topological characteristics of lasers.

“Being able to study quantum phenomena at room temperature is an exciting prospect. Professor Bao’s innovative work shows how materials science can help us answer some of science’s biggest questions,” said Shekhar Garde, Dean of the RPI School of Engineering .