Researchers from Spain's Institute of Photonic Sciences (ICFO) were able to show how light can be used to "see" the quantum nature of an electronic materials. This was done by capturing the light in a net of carbon atoms and slowing it down so that it moves as slow as the electrons in graphene. The electrons and light then start to move in concert, revealing their quantum nature at a large scale.

The experiments were performed with ultra-high quality graphene. To see and capture the ultra-slow ripples of light in the graphene (also called plasmons), the researchers used a special antenna for light that scans over the surface at a distance of a few nanometres. Using this near field nanoscope, they saw that the light ripples on the graphene moved more than 300 times slower than light, dramatically different from what is expected from classical physics laws.

The study has been published in Science by ICFO researchers Dr. Mark Lundeberg, Dr. Achim Woessner, led by ICREA Prof. at ICFO Frank Koppens and in collaboration with Prof. Hillenbrand from Nanogune, Prof. Polini from IIT and Prof. Hone from Columbia University.

“Usually it is very difficult to probe the quantum world, and to do so it requires ultra-low temperatures; here we could just “see” it with light and even at room temperature," said Koppens.

The technique paves the way for exploring new types quantum materials, including superconductors or topological materials that allow for quantum information processing with topological qubits. “This could just be the beginning of a new era of near field nanoscopy," Prof. Hillenbrand noted.

“This discovery may eventually lead to understanding in a truly microscopic fashion complex quantum phenomena that occur when matter is subject to ultra-low temperatures and very high magnetic fields, like the fractional quantum Hall effect,” Prof. Polini said.

This research was partially supported by the European Research Council, the European Graphene Flagship, the Government of Catalonia, Fundació Cellex, and the Severo Ochoa Excellence program of the Government of Spain.