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TT: Tiefe Temperaturen

TT 1: Superconductivity: Tunnelling, Josephson Junctions, SQUIDs

TT 1.2: Vortrag

Montag, 27. März 2006, 09:45–10:00, HSZ 02

Enhanced Macroscopic Quantum Tunneling in Bi₂Sr₂CaCu₂O_8+δ Intrinsic Josephson Junction Stacks — •X.Y. Jin, J. Lisenfeld, Y. Koval, A. Lukashenko, A.V. Ustinov, and P. Müller — Physikalisches Institut III, Universität Erlangen-Nürnberg, Germany

We have investigated macroscopic quantum tunneling (MQT) in Bi₂Sr₂CaCu₂O_8+δ intrinsic Josephson junctions (IJJs) and performed spectroscopic measurements. Classical-to-quantum crossover temperatures T* of up to  700mK were found. Plasma frequencies ω_p of up to 1.13 THz have been observed. We discovered that T* of IJJ stacks is significantly enhanced in comparison to a single intrinsic junction having a comparable plasma frequency. This enhancement of MQT is due to the unique stacking structure of IJJs. The quality factor of the IJJ stacks is Q∼50 and the spectroscopic coherence time is τ∼1.3ns. This will allow to observe Rabi oscillations at rather high temperatures.