Dresden 2011 – wissenschaftliches Programm

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TT: Fachverband Tiefe Temperaturen

TT 30: TR: Quantum Coherence and Quantum Information Systems 1 (jointly with MA and HL)

TT 30.9: Vortrag

Mittwoch, 16. März 2011, 12:45–13:00, HSZ 03

Qubit-oscillator system under ultrastrong coupling and extreme driving — •Johannes Hausinger and Milena Grifoni — Universität Regensburg, Germany

We present our recent study on the time-dependent qubit-oscillator Hamiltonian beyond the driven Jaynes-Cummings model [1]. We include counter-rotating terms for both the coupling of the two-level system to the quantized oscillator mode and to the external classical driving. Thus, the dynamics of the qubit can be examined analytically in the ultrastrong coupling regime, where the ratio g/Ω between coupling strength and oscillator frequency approaches unity or goes beyond, and simultaneously for driving strengths much bigger than the qubit energy splitting (extreme driving). Both qubit-oscillator coupling and external driving lead to a dressing of the qubit tunneling matrix element of different nature: the former can be used to suppress specifically certain oscillator modes in the spectrum [2], while the latter can yield coherent destruction of tunneling (CDT). We show that CDT is robust even in the case of ultrastrong coupling. Our findings are within the reach of present experimental superconducting setups for quantum information processing.
J. Hausinger, and M. Grifoni, arxiv:1009.1485
J. Hausinger, and M. Grifoni, arxiv:1007.5437, PRA (in press)