Regensburg 2025 – scientific programme

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TT: Fachverband Tiefe Temperaturen

TT 42: Superconductivity: Tunneling and Josephson Junctions

TT 42.5: Talk

Thursday, March 20, 2025, 10:30–10:45, H32

Optimal Parametric Control of Transport Across a Josephson Junction — •Hannah Victoria Kleine-Pollmann, Guido Homann, and Ludwig Mathey — Zentrum für Optische Quantentechnologien and Institut für Quantenphysik, *Universität Hamburg, 22761 Hamburg, Germany

We present optimal control strategies for the DC transport across a Josephson junction. Specifically, we consider a junction in which the Josephson coupling is driven parametrically, with either a bichromatic or a trichromatic driving protocol, and optimize the prefactor of the 1/ω divergence of the imaginary part of the conductivity. We demonstrate that for an optimal bichromatic protocol an enhancement of 70 can be reached, and for an optimal trichromatic protocol an enhancement of 135. This is motivated by pump-probe experiments that have demonstrated light-enhanced superconductivity along the c-axis of underdoped YBCO, where the junction serves as a minimal model for the c-axis coupling of superconducting layers. Therefore, the significant enhancement of superconductivity that we show for multi-frequency protocols demonstrates that the advancement of pump-probe technology towards these strategies is highly desirable.

Keywords: Josephson Junction; Optimal control; effective Josephson coupling