The first topological quantum simulation device in the strong light-matter interaction mode, operating at room temperature

Researchers at Rensselaer Polytechnic Institute have created a device no wider than a human hair that will help physicists investigate the fundamental nature of matter and light. The results of their research were published in the journal Nanotechnology of natureit could also support the development of more efficient lasers, which are used in fields ranging from medicine to manufacturing.

The device is made of a special type of material called a photonic topological insulator. A photonic topological isolator can direct photons, the wave-like particles that make up light, to interfaces specially designed in a material while preventing these particles from being scattered by the material itself.

Due to this property, topological insulators can make multiple photons coherently behave as one photon. The devices can also be used as topological “quantum simulators” – miniature laboratories in which researchers can study quantum phenomena, i.e. the physical laws that govern matter on very small scales.

“The photonic topological isolator we have created is unique. Works at room temperature. This is big progress. Previously, this regime could only be studied using large, expensive equipment that supercools matter in a vacuum. Many research laboratories do not have access to this type of equipment, so our device could enable more people to conduct this type 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’s also a promising step forward in the development of lasers that require less energy to operate because our device’s room temperature threshold – the amount of energy needed to operate – is seven times lower than previously developed low-temperature devices,” Bao added.

RPI scientists created their novel device based on the same technology used in the semiconductor industry to produce microchips, which involves stacking layers of 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 wafers of halide perovskite, a crystal made of cesium, lead and chlorine, and etched a polymer pattern onto them. They sandwiched these crystal plates and polymer between sheets of different oxide materials, ultimately creating an object about 2 microns thick and 100 microns long and wide (an average human hair is 100 microns wide).

When the researchers illuminated the device with laser light, a glowing triangular pattern appeared on contacts engineered into the material. This formula, dictated by the design of the device, results from the topological characteristics of the lasers.

“The ability to study quantum phenomena at room temperature is an exciting prospect. Professor Bao’s innovative work shows how materials science and engineering can help us answer some of science’s most important questions,” said Shekhar Garde, dean of the RPI School of Engineering.