Microwave spectroscopy reveals the quantum geometric tensor of topological Josephson matter*

Quantization effects due to topological invariants such as Chern numbers have become very relevant in many systems, yet, key quantities as the quantum geometric tensor [1] providing local information about quantum states remain experimentally difficult to access. Recently, it has been shown that multiterminal Josephson junctions constitute an ideal platform to synthesize topological systems in a controlled manner [2]. We theoretically study properties of Andreev states in topological Josephson matter and demonstrate that the quantum geometric tensor of Andreev states can be extracted by synthetically polarized microwaves [3]. The oscillator strength of the absorption rates provides direct evidence of topological quantum properties of the Andreev states.

[1] M. Kolodrubetz et al., Phys. Rep. 697, 1 (2017).
[2] R.-P. Riwar et al., Nat. Commun. 7, 11167 (2016); J. S. Meyer and M. Houzet, Phys. Rev. Lett. 119, 136807 (2017); H.-Y. Xie et al., Phys. Rev. B 96, 161406 (2017); Phys. Rev. B 97, 035443 (2018).
[3] R. L. Klees et al., arXiv:1810.11277.