Excitons—electrically neutral quasiparticles—have remarkable properties. They exist just in semiconducting and insulating materials and can be effectively gotten to in two-dimensional (2D) materials only a couple of atoms thick, for example, carbon and molybdenite. At the point when these 2D materials are consolidated, they show quantum properties that neither one of the materials has individually.
A new Tel Aviv University examine investigates the generation and propagation of excitons in 2D materials inside an extraordinary little time allotment and at an exceptionally high spatial goals. The exploration was driven by Prof. Haim Suchowski and Dr. Michael Mrejen of TAU’s Raymond and Beverly Sackler Faculty of Exact Sciences and distributed in Science Advances on February 1.
Quantum mechanics is a fundamental theory in physics that portrays nature at the littlest sizes of vitality. “Our new imaging technology captures the movement of excitons in a short time frame and at nanometer scale,” Dr. Mrejen says. “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,” Prof. Suchowski explains. “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.”
The researchers built up an interesting spatiotemporal imaging method at the femtosecond-nanometric scale and watched exciton-polariton dynamics in tungsten diselenide, a semiconductor material, at room temperature.
The exciton-polariton is a quantum animal spawned by the coupling of light and matter. Because of the particular material studied, the speed of propagation measured was about 1% of the speed of light. As of time scale, light figures out how to travel just 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,” Dr. Mrejen says. “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.”
The specialists are currently investigating methods for controlling the speed of semiconductor waves by, for instance, consolidating numerous 2D materials in stacks.