A multinational team of researchers led by University of Cambridge scientist Dr. Alessandro Rossi and University of Adelaide’s Dr. Giuseppe Tettamanzi has developed a ground-breaking single-electron ‘pump.’ Their work was published on June 19, 2018 in the journal Nano Letters.
Rossi et al operate a hybrid electron pump in silicon obtained by coupling a quantum dot to multiple parasitic states and achieve robust current quantization up to a few gigahertz. Image credit: Rossi et al, doi: 10.1021/acs.nanolett.8b00874.
“In quantum metrology, semiconductor single-electron pumps are used to generate accurate electric currents with the goal of implementing the emerging quantum standard of the ampere,” said Dr. Rossi, Dr. Tettamanzi and their colleagues from Aalto University and the Universities of New South Wales and Latvia.
“Pumps based on electrostatically defined tunable quantum dots have thus far shown the most promising performance in combining fast and accurate charge transfer.”
“However, at frequencies exceeding approximately 1 GHz the accuracy typically decreases.”
The single-electron pump developed by the team can produce one billion electrons per second and uses quantum mechanics to control them one-by-one.
It’s so precise the scientists have been able to use their device to measure the limitations of current electronics equipment.
“Achieving full control of electrons in these nano-systems will be highly beneficial for realistic implementation of a scalable quantum computer,” Dr. Tettamanzi said.
“We, of course, have been controlling electrons for the past 150 years, ever since electricity was discovered. But, at this small scale, the old physics rules can be thrown out.”
In the Nano Letters paper, the scientists also report observations of electron behavior that’s never been seen before — a key finding for those around the world working on quantum computing.
“Quantum computing, or more broadly quantum information processing, will allow us to solve problems that just won’t be possible under classical computing systems,” Dr. Tettamanzi said.
“It operates at a scale that’s close to an atom and, at this scale, normal physics goes out the window and quantum mechanics comes into play.”
“To indicate its potential computational power, conventional computing works on instructions and data written in a series of 1s and 0s — think about it as a series of on and off switches; in quantum computing every possible value between 0 and 1 is available.”
“We can then increase exponentially the number of calculations that can be done simultaneously.”
“This research puts us one step closer to the holy grail — reliable, high-performance quantum computing,” he said.
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Alessandro Rossi et al. 2018. Gigahertz Single-Electron Pumping Mediated by Parasitic States. Nano Lett 18 (7): 4141-4147; doi: 10.1021/acs.nanolett.8b00874
