Twisted graphene provides a tunable platform for studying superconductivity in two dimensions. In the presence of electric currents and magnetic fields, vortices determine the phenomenological properties of the material. Related studies usually address bulk properties averaging over ensembles of vortices. Here, we employ a gate-defined Josephson junction as a single-vortex sensor, enabling direct access to individual vortex dynamical events. Our measurements reveal that, at elevated temperatures (T > 100 mK), vortices enter the superconducting leads via classical thermal activation over energy barriers. At lower temperatures (T < 90 mK), we observe macroscopic quantum tunneling through these barriers. The data are consistent with a sharp, first-order type quantum-to-classical transition. From our measurements, we extract vortex entry and exit energy barriers on the order of a few Kelvin and estimate the barrier thickness to be approximately 100 nm, corresponding to about one tenth of the device width.
@article{arxiv.2601.21735,
title = {Pearl-Vortex Tunneling in Magic-Angle Twisted Graphene},
author = {Marta Perego and Peter Koopmann and Clara Galante Agero and Alexandra Mestre Tora' and Artem O. Denisov and Takashi Taniguchi and Kenji Watanabe and Vadim Geshkenbein and Gianni Blatter and Thomas Ihn and Klaus Ensslin},
journal= {arXiv preprint arXiv:2601.21735},
year = {2026}
}