Quickly detecting a lone electron is a difficult task
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We can now detect single electrons with the resolution of a few trillionths of a second, and this could prove essential for building a new generation of quantum electronic devices.
Traditional electronic circuits are filled with many electrons, but interactions between these particles often diminish their efficiency and effectiveness. Could we control single electrons well enough to make fast and efficient circuits that use just one electron at a time? Masaya Kataoka at the National Physical Laboratory (NPL) in the UK and his colleagues have moved one step closer to this goal by developing an extremely precise method for detecting electrons.
They injected two electrons into a thin piece of the semiconductor material gallium arsenide at two different points. The charged particles moved towards each other extremely quickly. When their paths got very close, an electric force between the electrons pushed them apart, bending their respective trajectories. The researchers kept track of one of the electrons and used this deflection to detect the presence of the other electron. They were able to find it within 6 trillionths of a second of the interaction, about 100 times faster than previous electron detections.
“Our experiment could be viewed as the world’s smallest sensor – an electron – detecting the world’s smallest object – an electron,” says Kataoka.
Team member Jon Fletcher, also at NPL, says interactions between electrons can be over in a few trillionths of a second. Now that they can access this timescale, researchers can start answering questions about exactly what two electrons do within a device – and use that knowledge to design new types of electronics.
Vyacheslavs Kashcheyevs at the University of Latvia says this work may be a milestone in the development of a new generation of electronics based on single fast electrons. Notably, a single electron is a fundamentally quantum particle. This means future devices could directly harness its quantum properties, like those already leveraged in quantum computing and communication, he says.
Researchers think devices based on a single electron could perform some of the same tasks as quantum devices based on a single particle of light – while also being a lot smaller. Such electron-based devices could even be integrated onto chips for ease of use, says Christian Flindt at Aalto University in Finland. He says a detection scheme such as this will be a necessary building block for all of these potential applications.
The findings could also contribute to our understanding of electric currents, says Rolf Haug at Leibniz University Hannover in Germany. The standard we use now for determining a unit of electrical current could be improved by perfecting the “electron pumps” the team used to inject electrons into their experiment, he says.
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