Dynamics of the Josephson flux qubit under strong harmonic driving

ALEJANDRO FERRÓN; DANIEL DOMINGUEZ

Brasilia DF, Brasil

Workshop; Quantum Nonstationary Systems; 2009

International Center for Condensed Matter Physics- ICCMP/UnB

We study the dynamics of the Josephson flux qubit, which consists on a SQUID loop with three Josephson junctions. We perform simulations of the time dependent Schroedinger equation when the system is started in the ground state. In this workwe drive the persistent-current qubit with a harmonic driving field. First we studied leakage from the two lowest energy levels of the qubit computational subspace to higher energy levels when the system is operated near a magnetic flux of half quantum. We obtain, as expected, that rf field pulses at theresonant frequency have a lower leakage than constant pulses, studied in a previouswork. In adition we present some perturbative results in the case of small values of the driving field amplitude.Finally we analyze the response of the system to different values of the driving amplitude at a fixed frequency. Using the simulations of the time dependent Schroedinger equation we study how the qubit state is driven through the constituent energy-level avoided crossings as the driving amplitude is increased.