Microwave sensing of topological states in realistic planar Josephson junctions

Microwave spectroscopy using circuit quantum electrodynamics has been widely employed to explore Josephson junctions (JJs) [1,2]. This method makes it possible to capture the features of Andreev levels with high sensitivity and provides access to fast dynamics [3]. We consider a planar JJ coupled inductively to a microwave resonator, where fluctuations in the inductance of the resonator perturb the superconducting phase across the junction. We utilized the Jaynes-Cummings model to describe the Andreev bound states-microwave interaction. A split gate voltage over the junction can affect the transparency and the number of supercurrent channels in the planar JJ [4]. For long confinement lengths, Majorana zero modes are supported at the ends of the junction, and topological properties can be explored [5].

[1] B. H. Elfeky et al. Phys. Rev. X Quantum 4, 030339 (2023).

[2] D. J. Van Woerkom et al. Nat. Phys. 13, 876 (2017).

[3] M. Hinderling et al. Phys. Rev. Appl. 19, 054026 (2023).

[4] B. H. Elfeky et al. Preprint arXiv:2408.08487v1 (2024)

[5] B. Pekerten, D. Brandão et al. Phys. Rev. B 110, L060513 (2024)

Funding Acknowledgment:

U.S. ONR Awards N000141712793 and MURI N000142212764.