Speaker
Description
Multi-terminal Josephson junctions emerge in theory and experiment as versatile devices compatible with current quantum computing devices. Apart from theoretical predictions of non-trivial topologies [1], their basic and readily available architectures already allow the construction of efficient supercurrent diodes [2]. While in most theoretical and experimental works the central scattering region is structureless, we argue in [3] that by inserting a single electronic level, the supercurrent diode effect can be significantly enhanced [3]. A great advantage of such an architecture is that the underlying BCS gauge symmetry can be exploited to simplify its description down to a certain two-terminal analog. The powerful mapping of Ref. [3] ensures that devices with the same total hybridization of the leads with the central electronic level represent the same family that can be treated using the same input in an analytic way.
Consequently, this reduces the numerical resources required to optimize such devices in terms of the efficacy of the supercurrent diode effect. In this talk, we present such a study and show simple guidelines for their optimization in terms of maximizing the diode effect. Finally, using the three-terminal single level set-up, we derive a simple universal relation for completely switching off such a device. The condition is analytical and requires only certain geometrical properties of the device to be fulfilled. Its universality is moreover manifestly temperature and correlation independent. The resulting switching characteristic therefore allows for the construction of a supercurrent transistor switch of nanoscopic dimensions. We provide a corresponding device design based on existing 2DEG fabrication technology.
[1] R. L. Klees et al., Microwave Spectroscopy Reveals the Quantum Geometric Tensor of Topological Josephson Matter, Phys. Rev. Lett. 124, 197002 (2020).
[2] M. Coraiola et al., Flux-Tunable Josephson Diode Effect in a Hybrid Four-Terminal Josephson Junction, ACS Nano, Vol 18, Issue 12 (2024)
[3] P. Zalom, M. Žonda, and T. Novotný, Hidden symmetry in interacting-quantum-dot-based multi-terminal Josephson junctions, Phys. Rev. Lett. 132, 126505 (2024).
