Researchers at UT Arlington have created the first electronic device that can cool electrons to -228 degrees Celsius (-375F), without any kind of external cooling. The chip itself remains at room temperature, while a quantum well within the device cools the electrons down cryogenic temperatures. Why is this exciting? Because thermal excitation (heat) is by far the biggest problem when it comes to creating both high-performance and ultra-low-power computers. These cryogenic, quantum well-cooled electrons could allow for the creation of electronic devices that consume 10 times less energy than current devices, according to the researchers.
What, you may ask, is a quantum well? In essence, a quantum well is a very narrow gap between two semiconducting materials. Electrons are happily bouncing along the piece of semiconductor when they hit the gap (the well). Only electrons that have very specific characteristics can cross the boundary. In this case, only electrons with very low energy (i.e. cold electrons) are allowed to pass, while hot electrons are sent back from whence they came. (If you’re technically minded, the well is created by sandwiching a narrow-bandgap semiconductor between two semiconductors with a wider bandgap – it’s basically the quantum equivalent of the neck between the two bulbs of an hourglass).
A diagram illustrating the layout of UTA’s quantum well
Once you have a stream of cold electrons coming through the quantum well, you can tack other components onto the circuit — such as transistors. In this case, to prove that their quantum well was actually producing cold electrons, the UT Arlington researchers created some single-electron transistors (SETs) — very efficient transistors that are very sensitive to thermal excitation and thus usually have to be cryogenically cooled with liquid helium. Despite being at room temperature, the SETs worked just fine — all thanks to the 45 Kelvin (-228C) electrons. The chip pictured at the top of the story, created by the UTA researchers, contains a bunch of quantum wells and SETs.
That’s me, checking out one of IBM’s quantum computers
Moving forward, it now becomes a question of integrating these quantum wells with actual electronic devices. “When implemented in transistors, these research findings could potentially reduce energy consumption of electronic devices by more than 10 times compared to the present technology,” says Usha Varshney of the National Science Foundation, which funded UTA’s research. Because every facet of computing is interconnected by the laws of physics, a 10x reduction in power consumption could affect just about everything — from battery life, to device size and weight, to max performance. [Research paper: doi:10.1038/ncomms5745 – "Energy-filtered cold electron transport at room temperature"]
The researchers also note that further investigation into quantum well construction could result in a stream of electrons with zero temperature (i.e. zero kelvin). As we’ve discussed before, weird and wonderful things can happen when you get down towards absolute zero — not least of which, the construction of some wondrously powerful and energy efficient computers.
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