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Nanoelectronics

Semiconductor-based technologies are evolving rapidly, with quantum effects playing an increasingly important role in data communication, processing, and storage. As interest in quantum computing, secure data transmission, and other quantum technologies grows, understanding and controlling quantum mechanical properties such as electron and spin transport, resonant tunneling, and coherent coupling of quantum states becomes essential. These effects hold the potential to enhance electronic functionalities and enable new device concepts.

The Nanoelectronics Core Research Area explores quantum effects and transport in artificial hetero- and nanostructures, which we typically fabricate by electron-beam lithography. We are interested in the fundamental electronic dynamics of quantum circuits, which we study by transport spectroscopy at low temperatures and in high magnetic fields. A present focus is thereby the interaction between electrons or holes and vibrational eigenstates of the crystal (phonons) as a means of coherent coupling between solid state quantum bits.

Our research contributes to the development of next-generation electronic and quantum technologies by fostering our fundamental understanding of the underlying physics. While many challenges remain, the exploration of quantum mechanical phenomena in nanoscale structures holds promise for future applications in emerging computational paradigms.

Scientific Highlights

Current distribution in the quantum Hall regime: moving from the edge to the center

The quantum Hall effect (QHE) is one of the most remarkable phenomena in condensed matter physics. Textbooks still describe it in terms of perfect one-dimensional edge channels that carry a dissipationless current around an insulating bulk. More recently, this picture has been challenged for neglecting Coulomb interactions between current-carrying electrons. In our experiment, we used an additional contact at the center of the Hall bar to detect the predicted bulk current — to our knowledge, the first direct measurement of its kind. More…

Controlling free electrons in quantum circuits

The progress of electronic devices is increasingly linked to the utilization of quantum effects. A future scenario are integrated quantum circuits containing coupled nanostructures. Interconnects, coupling distant on-chip components, could then be realized by the exchange of ballistic electrons. Our work aims at optimizing the coherent exchange of ballistic electrons between quantum point contacts, fundamental building blocks of quantum circuits. More…

Selected Publications

  1. Transition from edge- to bulk-currents in the quantum Hall regime
    Authors: Sirt, S. and Umansky, V. Y. and Siddiki, A. and Ludwig, S.
    Source: Appl. Phys. Lett., 126 (24): 243101, (2025)
    DOI: 10.1063/5.0275599
     
  2. Classical analogue to driven quantum bits based on macroscopic pendula
    Authors: H. Lorenz, S. Kohler, A. Parafilo, M. Kiselev, S. Ludwig
    Source: Sci. Rep., 13, 18386 (2023)
    DOI: 10.1038/s41598-023-45118-y
     
  3. Scanning X-Ray Diffraction Microscopy of a 6-GHz Surface Acoustic Wave
    Authors: M. Hanke, N. Ashurbekov, E. Zatterin, M.E. Msall, J. Hellemann, P.V. Santos, T.U. Schulli, and S. Ludwig
    Source: Phys. Rev. Applied 19, 024038, 1 – 10 (2023)
    DOI: https://doi.org/10.1103/PhysRevApplied.19.024038
     
  4. Coherent electron optics with ballistically coupled quantum point contacts
    Authors: J. Freudenfeld, M. Geier, V. Umansky, P. W. Brouwer, and S. Ludwig 
    Source: Phys. Rev. Lett. 125, 107701 (2020)
    DOI: 10.1103/PhysRevLett.125.107701

Contacts

Staff Publications