Regensburg 2010 – scientific programme
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TT: Fachverband Tiefe Temperaturen
TT 36: TR: Poster Session
TT 36.29: Poster
Thursday, March 25, 2010, 14:00–18:00, Poster A
Back-action on the flux-qubit from a driven non-linear detector — •Vicente Ancelmo Leyton Ortega1, Vittorio Peano1, Michael Thorwart1, and John Henrry Reina2 — 1Freiburg Institute for Advanced Studies (FRIAS), Albert-Ludwigs Universität Freiburg, 79104 Freiburg — 2Universidad del Valle, Departamento de Física, A.A. 25360, Cali-Colombia.
We consider a superconducting flux qubit inductively coupled to a driven SQUID, acting as a detector, in presence of weak dissipation and close to the optimal working point. We study the nonlinear response of the detector to the drive and the population difference of the qubit state. By varying the external magnetic field piercing the SQUID, we access two different regimes: i) For vanishing external flux, the SQUID acts as a Josephson bifurcation amplifier, however, operated here with few energy quanta rather than in its classical regime. In this regime, we show that the back-action of the detector on the qubit is small, rendering the driven SQUID an ideal detector. ii) When the external flux is close to half a flux quantum, the combined qubit-oscillator system implements the two-photon Jaynes-Cummings model. We study multiphoton (anti-)resonances in the two-photon transition regime.