Dresden 2011 – wissenschaftliches Programm
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TT: Fachverband Tiefe Temperaturen
TT 34: TR: Quantum Coherence and Quantum Information Systems 2 (jointly with MA and HL)
TT 34.8: Vortrag
Mittwoch, 16. März 2011, 16:15–16:30, HSZ 03
Dynamical switching of a driven nonlinear resonator caused by a two-level fluctuator — •Stephan André1,2, Michael Marthaler1,2, and Gerd Schön1,2 — 1Institut für Theoretische Festkörperphysik, Karlsruhe Institute of Technology, 76128 Karlsruhe, Germany — 2DFG Center for Functional Nanostructures (CFN), Karlsruhe Institute of Technology, 76128 Karlsruhe, Germany
In recent “circuit QED” experiments, a nonlinear resonator was used to perform a quantum non-demolition readout of a superconducting qubit with a high contrast [1,2]. A driven nonlinear resonator can show bistability; increasing the driving strength will lead to switching from a state of low amplitude to a state of high amplitude oscillations. As the switching of the resonator occurs at a driving strength which depends on the state of the qubit, the resonator can be operated at a working point where, depending on the qubit state, it will switch to high amplitude oscillations or not, which provides a digital readout of the qubit.
We theoretically study the influence of a two-level fluctuator (TLF) coupled to a driven nonlinear resonator. TLFs have frequently been observed in superconducting circuits and generally affect the dynamics of the system. We investigate how the presence of a TLF influences the switching of the driven resonator between the two dynamical states. This will lead to a change in the readout contrast when the resonator is used to measure a qubit.
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