For several years, the electron spin of individual electrons in a quantum dot has been identified as an ideal candidate for the smallest information unit in a quantum computer, otherwise known as a qubit.
Controlled via applied voltages
In quantum dots made of layered semiconductor materials, individual electrons are caught in a trap, so to speak. Their spins can be determined reliably and switched quickly, with researchers keeping the electrons under control by applying voltages to the various nanostructures within the trap.
Among other things, this allows them to control how many electrons enter the quantum dot from a reservoir via tunneling effects. Here, even small changes in voltage have a considerable influence on the electrons.
For each quantum dot, the applied voltages must therefore be tuned carefully in order to achieve the optimum conditions. When several quantum dots are combined to scale the device up to a large number of qubits, this tuning process becomes enormously time-consuming because the semiconductor quantum dots are not completely identical and must each be characterized individually.
Automation thanks to machine learning
Now, scientists from the Universities of Oxford, Basel, and Lancaster have developed an algorithm that can help to automate this process. Their machine-learning approach reduces the measuring time and the number of measurements by a factor of approximately four in comparison with conventional data acquisition.
First, the scientists train the machine with data on the current flowing through the quantum dot at different voltages. Like facial recognition technology, the software gradually learns where further measurements are needed with a view to achieving the maximum information gain.
The system then performs these measurements and repeats the process until effective characterization is achieved according to predefined criteria and the quantum dot can be used as a qubit.
"For the first time, we've applied machine learning to perform efficient measurements in gallium arsenide quantum dots, thereby allowing for the characterization of large arrays of quantum devices," says Dr. Natalia Ares from the University of Oxford.
"The next step at our laboratory is now to apply the software to semiconductor quantum dots made of other materials that are better suited to the development of a quantum computer," adds Professor Dr. Dominik Zumbühl from the Department of Physics and the Swiss Nanoscience Institute at the University of Basel. "With this work, we've made a key contribution that will pave the way for large-scale qubit architectures."
Efficiently measuring a quantum device using machine learning
D.T. Lennon, H. Moony, L.C. Camenzind, Liuqi Yu, D.M. Zumbuhl, G.A.D. Briggs, M.A. Osborne, E.A. Laird, and N. Ares
npj Quantum Information, doi: 10.1038/s41534-019-0193-4
Dr. Edward Laird
Department of Physics, Lancaster University
Office: A051, A - Floor, Physics Building
Lancaster LA1 4YB, UK
Tel: +44 (0)1524 510831
Dr. Dominik M. Zumbühl | EurekAlert!
Multifunctional e-glasses monitor health, protect eyes, control video game
28.05.2020 | American Chemical Society
Researchers incorporate computer vision and uncertainty into AI for robotic prosthetics
28.05.2020 | North Carolina State University
Humans rely dominantly on their eyesight. Losing vision means not being able to read, recognize faces or find objects. Macular degeneration is one of the major...
In meningococci, the RNA-binding protein ProQ plays a major role. Together with RNA molecules, it regulates processes that are important for pathogenic properties of the bacteria.
Meningococci are bacteria that can cause life-threatening meningitis and sepsis. These pathogens use a small protein with a large impact: The RNA-binding...
An analysis of more than 200,000 spiral galaxies has revealed unexpected links between spin directions of galaxies, and the structure formed by these links...
Two prominent X-ray emission lines of highly charged iron have puzzled astrophysicists for decades: their measured and calculated brightness ratios always disagree. This hinders good determinations of plasma temperatures and densities. New, careful high-precision measurements, together with top-level calculations now exclude all hitherto proposed explanations for this discrepancy, and thus deepen the problem.
Hot astrophysical plasmas fill the intergalactic space, and brightly shine in stellar coronae, active galactic nuclei, and supernova remnants. They contain...
In living cells, enzymes drive biochemical metabolic processes enabling reactions to take place efficiently. It is this very ability which allows them to be used as catalysts in biotechnology, for example to create chemical products such as pharmaceutics. Researchers now identified an enzyme that, when illuminated with blue light, becomes catalytically active and initiates a reaction that was previously unknown in enzymatics. The study was published in "Nature Communications".
Enzymes: they are the central drivers for biochemical metabolic processes in every living cell, enabling reactions to take place efficiently. It is this very...
19.05.2020 | Event News
07.04.2020 | Event News
06.04.2020 | Event News
05.06.2020 | Life Sciences
05.06.2020 | Physics and Astronomy
05.06.2020 | Life Sciences