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Résumé |
The physics of a single Josephson junction coupled to a resistive environment is a long-standing
fundamental problem at the center of an intense debate about the existence and properties of the
superconducting-to-insulating Schmid-Bulgadaev transition. To circumvent the potential subtleties in the
original derivation, we investigate the emergent criticality of a junction coupled to a multimode resonator
when the number of modes is increased [1]. By solving the system via exact diagonalization, we show that
at the transition point the spectrum displays universality (scale invariance) not only at low frequencies.
This reflects in finite-frequency spectral signatures of the phase transition, in agreement with recent
experiments. The spectrum at the critical point is successfully compared with analytical and numerical
results obtained in the past [2]. Finally, we prove a low-energy exact self-duality of the model, that
emerges from two different finite-size circuits with different conserved quantities [3]. This confirms and
generalizes the approximate self duality that is usually invoked, and proves the independence of the
transition point on the ratio of Josephson to charging energy.
[1] Giacomelli L., Ciuti C., Nature Communications, 15(1), 5455 (2024)
[2] Paris, Giacomelli, Daviet, Ciuti, Dupuis, Mora, Phys. Rev. B, 111(6), 064509 (2025)
[3] Giacomelli L., Devoret M. H., Ciuti C., Phys. Rev. Lett., 136(13), 130401 (2026) |
