The macroscopic properties of quantum materials arise from microscopic quantum phenomena and cannot be understood solely through classical physics and chemistry. Sometimes, they behave entirely counter to intuition. In an article recently published in the journal Nature, a group of authors from Italy, the IJS (Jožef Stefan Institute), and Germany revealed an unusual quantum effect, where the properties of a quantum material change significantly when it is placed in a cavity with cooled mirrors. The experiment, seemingly straightforward, demonstrates a remarkably large shift in the transition temperature between insulator and metal in a crystal of 1T-TaS₂, a substance which is known for its very intriguing quantum properties. The observations are unusual because the material during the experiment is not in contact with its surroundings, and the influence of the mirrors implies a strong coupling between the motion of electrons in the crystal and quantum fluctuations of the electromagnetic field – or light- in vacuum, which almost magically alter the transition temperature. The effect is entirely of a fundamental nature but also holds potential applications, such as for specialized sensors. Importantly, the experiment paves the way for research into new quantum effects and highlights 1T-TaS₂ as a very quantum material. The material was synthesized by Petra Sutar at IJS, while Peter Prelovšek and Dragan Mihailović collaborated on the theoretical and experimental aspects.
You can read the article here: https://www.nature.com/articles/s41586-023-06596-2