Engineering 101

Dark Trions Could Transmit Quantum Data Faster than Today’s Electrons

By Dawn Allcot

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The age of telepathic communication via brain-to-brain hook-ups may be on the horizon thanks to research out of the University of Washington. But meanwhile, University of California, Riverside, researchers are seeking faster, more efficient ways to transmit information within and between electronic devices.

A team of physicists has observed, characterized, and controlled dark trions in a semiconductor — ultraclean single-layer tungsten diselenide (WSe2), which could increase the capacity and alter 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 one hole; a positive trion contains two holes and one 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 carry much more information than a single electron.

Most electronics today use individual electrons to conduct electricity and transmit information. As trions carry a net electric charge, their motion can be controlled by an electric field. Trions can, therefore, also be used as information carriers. Compared to individual electrons, trions have controllable spin and momentum indices and a rich internal structure, which can be used to encode information.

Trions can be categorized into bright and dark trions with distinct spin configurations. A bright trion contains an electron and a hole with opposite spins. A dark trion contains an electron and a hole with the same spin. Bright trions couple strongly to light and emit light efficiently, meaning they decay quickly. Dark trions, however, couple weakly to light, meaning they decay much more slowly than bright trions.

The researchers measured the lifetime of dark trions and found they last more than 100 times longer than the more common bright trions. The long lifetime enables information transmission by trions over a much longer distance.

Next, the team plans to demonstrate the actual transport of information by dark trions.

“We intend to demonstrate the first working device that uses dark trions to transport information,” said Chun Hung (Joshua) Lui, an assistant professor of physics and astronomy at UC Riverside, who led the research. “If such a prototype trion device works, dark trions can then be used to transport quantum information.”

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