With the Electron Shuttle Towards a Scalable Quantum Computer
One significant challenge in constructing a quantum computer is its scalability, meaning the ability to interconnect millions of qubits. Unlike semiconductor chips in classical computers, quantum chips cannot simply be enlarged. Researchers from the JARA cooperation of the Forschungszentrum Jülich and the RWTH Aachen University, along with the Polish Academy of Sciences, have made progress using the electron shuttle method compared to previous demonstrations. The results were published in Nature Communications. (Source: Forschungszentrum Jülich – Press Releases)
Scientific Result
Qubits on quantum chips are usually positioned very close to each other so they can be coupled. However, in a scalable architecture with a very high number of qubits, this is only possible to a limited extent. Additional space on the quantum chip must be created for wiring and control electronics. One way to achieve this is by using an electron shuttle, which allows for bridging greater distances between semiconductor qubits.
In semiconductor qubits, quantum information is encoded in the spin of electrons located in so-called quantum dots – special semiconductor structures in the nanometer range. The electron shuttle enables the capture and controlled transport of electrons on these quantum dots without losing the quantum information.
Previous demonstrations have already shown that individual electrons can be transported over short distances using an electron shuttle. The current study focuses on examining the spin entanglement of a pair of electron spins that are initially separated and later reconnected. This demonstrates how long the quantum states are preserved. The shuttle speed was improved by four orders of magnitude compared to previous demonstrations. At the same time, it was observed that, surprisingly, the coherence of the qubits is maintained longer when an electron is moved over longer distances. External disturbances, which would normally reduce coherence, can be averaged out over time. Thus, the negative effects are partially offset.
Societal and Scientific Relevance
In many areas of science, there are questions that even the fastest supercomputers cannot compute. Quantum computers have the potential to solve such problems in the future, as they promise significantly higher computing power. For quantum computers to be of actual practical use, architectures with thousands, if not millions of qubits, are necessary. The integration of an electron shuttle into scalable semiconductor architectures represents a promising approach for this, as the current study confirms. Another advantage is that both semiconductor qubits and the electron shuttle are compatible with the industrial gate fabrication of classical computer chips, which are also made of semiconductors. These findings can be used for the construction of a functional prototype with semiconductor qubits.
FZJ/I. Heese, 12.03.2024
Note: The article has been translated from German to English. It is based on a press release from the FZJ.
The original press release can be found at:
Mit dem Elektronen-Shuttle zum skalierbaren Quantencomputer (only in german)
The original publication can be found at (Open Access):
Struck, T., Volmer, M., Visser, L. et al. Spin-EPR-pair separation by conveyor-mode single electron shuttling in Si/SiGe. Nat Commun 15, 1325 (2024). https://doi.org/10.1038/s41467-024-45583-7
Localization in Helmholtz Information:
Helmholtz Information, Program 2: Natural, Artificial and Cognitive Information Processing, Topic 2: Quantum Computing
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Contact:
Dr. Lars Schreiber
Peter Grünberg Institut (PGI)
JARA-Institute Quantum Information (PGI-11)
Forschungszentrum Jülich
Phone: +49 241/80-24486
E-Mail: l.schreiber@fz-juelich.de
Contact for this Press Release:
Dr. Irina Heese
Communication and Outreach JUQCA (Jülich Quantum Computing Alliance)
Forschungszentrum Jülich
Phone: +49 2461 61-85847
E-Mail: i.heese@fz-juelich.de
