Dark Trions in Tungsten Diselenide Could Revolutionize Information

Dark trions in an ultraclean single-layer tungsten diselenide (WSe2) semiconductor could increase the capacity and alter the form of information transmission, a feat that has been developed by a research team led by physicists at the University of California, Riverside.

In semiconductors such as WSe2, the trions are a quantum bound state of three charged particles. The negatively charged trions contain two electrons and one hole, and the positively charged trions contains two holes and one electron. A hole is a vacancy of electrons in a semiconductor and behaves like a positively charged particle. Because the trions contain three interacting particles, they can carry more information than a single electron. Besides, since trions carry a net charge, their motion can be controlled by an electric field, and thus can be used as an information carrier. It also has controllable spin, momentum values and a rich internal structure that can be used to encode information.

Trions can be divided into bright and dark depending on the different spin configurations. Bright trions contain an electron and a hole with an opposite spin, which are strongly coupled to light and illuminate. It means they decay rapidly. Dark trions contain an electron and a hole with the same spin, and they are weakly coupled to light, which means they decay more slowly. Also, its lifespan is more than 100 times longer than that of bright trions, so that information can travel longer distances.

Chunhong Lv, the research director and assistant professor of physics and astronomy, explained that most of the researches focus on bright trions because they emit more light and are easier to measure, but their research focuses on dark trions. The energy level of them inside the single-layer tungsten diselenide atom is lower than that of the bright trions, so that they can be aggregated and detected. In addition, through simply adjusting the external voltage, it can be continuously turned into electronegative from electropositive.

The team plans to demonstrate the actual transmission of information. Chunhong Lv said: "We intend to show the first working device that transmits information using dark trions. If such a prototype device can work, it can be used to transmit quantum information. We can use light to write and read Information and control how the information is encoded in it to revolutionize information transmission."

Although it sounds like a landmark study that dark trions in tungsten diselenide are expected to "change information transmission". It is still at the level of proof-of-concept research, and it is still far away from that step. Characterizing and controlling it, and this transmission method really out of the laboratory is probably a very long-time process.

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