Dresden 2017 – wissenschaftliches Programm
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TT: Fachverband Tiefe Temperaturen
TT 14: Superconductivity: Tunnelling, Josephson Junctions, SQUIDs 1
TT 14.10: Vortrag
Montag, 20. März 2017, 17:45–18:00, HSZ 201
Theory of enhanced interlayer tunneling in optically driven high Tc superconductors — •Junichi Okamoto1,2, Andrea Cavalleri3,4, and Ludwig Mathey1,2 — 1Zentrum für Optische Quantentechnologien and Institut für Laserphysik, Universität Hamburg, 22761 Hamburg, Germany — 2The Hamburg Centre for Ultrafast Imaging, Luruper Chaussee 149, 22761 Hamburg, Germany — 3Max Planck Institute for the Structure and Dynamics of Matter, 22761 Hamburg, Germany — 4Department of Physics, Clarendon Laboratory, University of Oxford, Oxford OX1 3PU, United Kingdom
Motivated by recent pump-probe experiments indicating enhanced coherent c-axis transport in underdoped YBCO [1], we investigate Josephson junctions periodically driven by optical pulses [2]. We propose a mechanism for this observation by showing that a parametrically driven Josephson junction exhibits an enhanced imaginary part of the low-frequency conductivity when the driving frequency is blue-detuned to the plasma frequency, implying an effectively enhanced Josephson coupling. We show that the emergent driven steady state is a genuine, non-equilibrium superconducting state, in which equilibrium relations between the Josephson coupling, current fluctuations, and the critical current no longer hold. Transient response under a short pump pulse is also discussed to fully compare our theory with the experimental results.
[1] W. Hu et al., Nature Materials 13, 705 (2014)
[2] J. Okamoto, A. Cavalleri, L. Mathey, Phys. Rev. Lett. 117, 227001 (2016)