News Release

Qubits from beam electrons

Peer-Reviewed Publication

University of Konstanz

The laws of quantum physics are not only extraordinary – they also offer some far-reaching and unique possibilities for advanced information processing, quantum computing and cryptography. So far, the basic building blocks for such quantum operations are electric circuitry in form of superconducting resonators, light in form of photons or atoms in form of ion chains. However, all these quantum systems have their drawbacks, and scientists are therefore continuously searching for useful alternatives.

In their recent publication in Physical Review Research, scientists from the Department of Physics at the University of Konstanz have found a way to modulate a free electron in vacuum into a so-called qubit, a two-level quantum bit. Such qubits are the building blocks of information processing in quantum computers. To generate their free-electron qubits, the researchers use the electron beam of a transmission electron microscope and intersect it with the electric field of classical laser light. “The resulting matter-wave interferences create a periodic modulation of the electron energy into discrete, well-defined energy levels, which we use as a resource for the formation of qubits”, explains Professor Peter Baum, the leader of the research team.

Read more about how this works and about the additional value of the experiment’s results for high-resolution electron microscopy in our extended article in the online magazine

  Key facts:

  • Original study: Maxim V. Tsarev, Andrey Ryabov, Peter Baum (2021): Free-electron qubits and maximum-contrast attosecond pulses via temporal Talbot revivals. Physical Review Research. DOI:
  • Researchers from the University of Konstanz use laser light to modulate the free electron as an elementary particle into a system with qubit properties.
  • Also, attosecond electron pulses are created for electron microscopy of ultrafast light-matter interactions.
  • Use of continuous laser light and a continuous electron beam produces the qubits and attosecond electron pulses at unprecedented rate.
  • Funding: European Research Council (ERC), German Research Foundation (DFG), Dr. K. H. Eberle Stiftung and Vector Stiftung

Note to editors:
You can download a photo here:
Caption: Laser-modulation of the electron beam in a transmission electron microscope into qubits and attosecond electron pulses.

Copyright: Maxim Tsarev

University of Konstanz
Communications and Marketing
Phone: + 49 7531 88-3603


Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.