Anomalous Dissipation in Current Biased Josephson Systems
arXiv:2607.11647
The paper theoretically studies how embedding a current‑biased Josephson junction in a resistor‑capacitor circuit creates anomalous dissipation that dramatically alters phase‑diffusion and quantum escape dynamics, producing enhanced switching and re‑trapping that could be useful for microwave photon detection and dissipative quantum annealing.
Abstract
A new phase diffusive regime in a current biased Josephson junction is theoretically explored which originates from embedding the junction in a circuit environment with anomalous dissipation. This is realized by placing parallel to the junction a resistor in series with a capacitor such that electromagnetic fluctuations effectively couple also to the charge of the junction. This leads to rich Josephson dynamics, in particular for the switching of the junction out of a zero voltage state. Modelled as the escape process of a fictitious phase-particle out of a metastable well, a detailed study reveals that anomalous dissipation has a strong impact at low temperatures when quantum tunneling dominates against thermal activation. As a manifestation, a regime is found, where for realistic circuit parameters the quantum escape process is substantially enhanced, followed by a short voltage pulse and re-trapping with high probability. This class of circuits may be leveraged for detecting microwave photons or dissipative quantum annealing processes. In addition, the analysis provides a general framework for engineering dissipative dynamics in nonlinear systems using anomalous environments.