Berlin 2015 – wissenschaftliches Programm

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TT: Fachverband Tiefe Temperaturen

TT 7: Transport: Quantum Coherence and Quantum Information Systems – Theory (jointly with HL, MA)

TT 7.11: Vortrag

Montag, 16. März 2015, 12:15–12:30, H 3005

Quantum dynamics of a strongly driven Josephson Junction — •Jennifer Gosner, Björn Kubala, and Joachim Ankerhold — Institute for Complex Quantum Systems, University of Ulm, Germany

A Josephson Junction embedded in a dissipative circuit can be driven to exhibit non-linear oscillations.

Classically the non-linear oscillator shows under sufficient strong driving and weak damping dynamical bifurcations and a bistable region similar to the conventional Duffing-oscillator. These features depend sensitively on initial conditions and parameters. The sensitivity of this circuit, called Josephson Bifurcation Amplifier, can be used to amplify an incoming signal, to form a sensing device or even for measuring a quantum system.

The quantum dynamics can be described by a dissipative Lindblad master equation. Signatures of the classical bifurcation phenomena appear in the Wigner representation, used to characterize and visualize the resulting behaviour. In order to compare this quantum dynamics to that of the conventional Duffing-oscillator, the complete cosine-nonlinearity of the Josephson Junction is kept for the quantum description while going into a rotating frame.