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RIVERSIDE, California – Spread, electrons; it is time to make way for the trion.
A research team led by physicists from the University of California, Riverside, observed, characterized and controlled dark trions in a semiconductor – ultra-pure monolayer diselenide tungsten (WSe)2) – an exploit that could increase the capacity and change the form of information transmission.
In a semiconductor, such as WSe2, a trion is a quantum bound state of three charged particles. A negative trion contains two electrons and a hole; a positive trion contains two holes and an electron. A hole is the vacancy of an electron in a semiconductor, which behaves like a positively charged particle. Because a trion contains three interacting particles, it can hold much more information than a single electron.
Today, most electronic products use individual electrons to conduct electricity and transmit information. As the trions carry a net electric charge, their movement can be controlled by an electric field. Trions can therefore also be used as an information medium. Compared to individual electrons, the trions have controllable spin and momentum indices, as well as a rich internal structure, which can be used to encode information.
The trions can be classified into bright and dark trions with distinct spin configurations. A bright trion contains an electron and a hole with opposite spins. A black trion contains an electron and a hole with the same spin. The bright trions are strongly coupled to light and emit light efficiently, which means they decay quickly. Dark trions, however, weakly couple to light, which means that they disintegrate much more slowly than bright trions.
The researchers measured the lifespan of the dark trions and found that they lasted more than 100 times longer than the more common bright trions. The long life allows trions to transmit information over a much longer distance.
"Our work allows us to write and read information about Trion in the light," said Chun Hung (Joshua) Lui, an assistant professor of physics and astronomy at UC Riverside, who led the research. "We can generate two types of trions – the dark trions and the clear trions – and control the coding mode of the information they contain."
The results of the research are published in the journal Letters of physical examination.
"Our findings could lead to new methods of transmitting information," said Erfu Liu, lead author of the research paper and postdoctoral researcher in Lui's lab. "The dark trions, with their long lifespan, can help us achieve the transmission of information through trions.As is increasing your home Wi-Fi bandwidth, trion transmission allows to convey more information than individual electrons. "
The researchers used a single layer of WSe2 atoms, resembling a graphene sheet because the energy level of the dark trion in WSe2 is below the level of luminous trion energy. Dark trions can therefore accumulate a large population, which allows their detection.
He explained that most trion research nowadays focuses on bright trions because they emit a lot of light and can be easily measured.
"But we focus on dark trions and their detailed behavior under different charge densities in single layer WSe2 "We were able to demonstrate a continuous agreement of the dark trion positive dark trions by simply adjusting an external voltage, and we were able to confirm the distinct spin configuration of the dark trions from the bright trions.
"If we can use trions to transmit information, our information technologies will be greatly enriched," he added. "The major hurdle to such development has been the short lifespan of bright trions.Now, long-lasting dark trions can help us overcome this hurdle."
His team then plans to demonstrate the actual transport of information by dark trions.
"We intend to demonstrate the first device in working order using dark trions to carry information," said Lui. "If such a prototype trion device works, then dark trions can be used to carry quantum information."
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The research was funded by UCR start-up funds.
He and Liu were joined in the study by Jeremiah van Baren and Mashael M. Altaiary of UCR; Zhengguang Lu and Dmitry Smirnov of the National High Magnetic Field Laboratory, Florida; and Takashi Taniguchi and Kenji Watanabe from the National Institute of Materials Science, Japan.
University of California, Riverside (http: // www.
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