Dresden 2003 – wissenschaftliches Programm

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SYQI: Quantum information processing in condensed media

SYQI 2: Quantum information processing in condensed media II

SYQI 2.5: Vortrag

Montag, 24. März 2003, 17:00–17:15, HSZ/01

Time-resolved observation of macroscopic quantum tunneling in a Josephson junction — •Jürgen Lisenfeld¹, Alexandr Lukashenko¹, Christian Coqui¹, Alexander Kemp¹, Fistul Misha¹, Andreas Wallraff², and Alexey Ustinov¹ — ¹Physikalisches Institut III / Universität Erlangen — ²Department of Applied Physics / University of Yale, New Haven

We present experimental results on direct life time measurements of a metastable state in a Josephson junction. The technique that we use allows to monitor in the time domain the switching probability of the junction to a resistive state. At milikelvin temperatures this process occurs by macroscopic quantum tunneling through a potential barrier and follows an exponential decay law, as observed in our experiment. The setup used in these measurements allows both coherent manipulating and reading out the quantum state of the junction. A single Josephson junction can be operated as a qubit by applying sequences of microwave and dc pulses.