Vlad S. Pribiag

University of Minnesota

Superconducting devices with unconventional geometries

Superconducting devices offer exciting opportunities for science and technology, including the realization of new states of matter or of quantum computing hardware.  A key role is played by the Josephson junction, which is typically a two-terminal device with a homogeneous link material: an insulator, conductor or semiconductor. Recently, there has been growing interest in going beyond this traditional Josephson paradigm.  A particularly interesting area of exploration are devices that couple more than two superconductors, forming multi-terminal Josephson junctions (MTJJs). Combining the multi-terminal concept with hybrid superconducting-semiconducting materials is particularly promising as it enables phenomena based on the interplay between superconductivity, quantum confinement, ballistic transport and gate-tuning of superconducting couplings [1,2]. This talk will describe recent evidence from our group on achieving quantum correlations between Cooper pairs across the terminals of MTJJs [3], as well as the ability of MTJJs to host non-reciprocal superconductivity (superconducting diode effect) and non-linear intermodulation of signals in ambient magnetic fields, with full electrostatic control [4]. The talk will also connect these recent developments with ongoing efforts to create topological Josephson matter [5] using Andreev bound states in MTJJs.

In addition to these multi-terminal effects, we are also interested in exploring superconducting structures buit on periodically-textured templates. A particularly promising avenue draws on recent advances in DNA-nanoasembly [6] to build 3D superlattices with nanoscale periodicity. The talk will present our current approach and results for building superconducting devices on this platform, and the possible implications of this approach for imparting unconventional superconducting properties to conventional materials.

References:

[1] G. Graziano et al., Transport studies in a gate-tunable three-terminal Josephson junction, Phys. Rev. B 101, 054510 (2020).

[2] G. Graziano, M. Gupta et al., Selective control of conductance modes in multi-terminal Josephson junctions, Nature Communications 13, 5933 (2022).

[3] M. Gupta et al., Evidence for π-shifted Cooper quartets in PbTe nanowire three-terminal Josephson junctions, Nano Letters 24, 13903 (2024).

[4] M. Gupta et al., Gate-tunable superconducting diode effect in a three-terminal Josephson device, Nature Communications 14, 3078 (2023).

[5] R. Riwar et al., Multi-terminal Josephson junctions as topological matter, Nature Communications 7, 11167 (2016).

[6] A. Michelson, L. Shani et al., Scalable fabrication of Chip-integrated 3D-nanostructured electronic devices via DNA- programmable assembly, Science Advances 11, eadt5620 (2025).