Upon combining these 2D materials, they demonstrate quantum properties that are possessed by neither material on its own.
Quantum mechanics—a fundamental physics theory—describes nature at the tiniest energy scales. “Our new imaging technology captures the movement of excitons in a short time frame and at nanometer scale,” stated Dr Mrejen. “This tool can be extremely useful for peeking into a material’s response at the very first moments light has affected it.”
Such materials can be used to significantly slow down light to manipulate it or even store it, which are highly sought-after capabilities for communications and for photonics-based quantum computers. From the instrument capability point of view, this tour de force opens up new opportunities to visualize and manipulate the ultrafast response of many other material systems in other spectrum regimes, such as the mid-infrared range in which many molecules are found to vibrate.
Haim Suchowski, Professor, Raymond & Beverly Sackler Faculty of Exact Sciences, Tel Aviv University.
The researchers created a specialized spatiotemporal imaging method at the femtosecond-nanometric scale and witnessed the exciton-polariton dynamics in tungsten diselenide, a semiconductor material, at ambient temperature.
The exciton-polariton is a quantum entity produced as a result of the coupling of light and matter. As the material under study was specific, the measured propagation speed was nearly 1% of the speed of light. At such a time scale, light can travel only a few hundred nanometers.
We knew we had a unique characterization tool and that these 2D materials were good candidates to explore interesting behavior at the ultrafast-ultrasmall intersection. I should add that the material, tungsten diselenide, is extremely interesting from an applications point of view. It sustains such light-matter coupled states in very confined dimensions, down to single atom thickness, at room temperature and in the visible spectral range.
Dr Michael Mrejen, Raymond & Beverly Sackler Faculty of Exact Sciences, Tel Aviv University.
Currently, the researchers are looking for means to control the velocity of semiconductor waves by, for instance, combining several 2D materials in stacks.