A Single Electron Charge Qubit in the Strong Driving Limit*

The dynamics of strongly driven two-level systems in the presence of dissipation have been thoroughly studied using theoretical models.$[1]$ We use a model system, a GaAs double quantum dot (DQD) containing a single electron, to experimentally explore the strong-driving regime. We measured the transport through the DQD as a function of detuning and applied microwave power and compare with the Tien-Gordon model. In contrast with previous experiments, we directly access the occupation of the DQD using a quantum point contact charge sensor. In the high frequency regime ($\hbar \omega_{driving} \gg \Delta$, where $\Delta$ is the tunnel coupling) we observe up to 9-photon transitions and clear Bessel function behavior of the DQD occupation with applied microwave power. We also studied the intermediate frequency regime, observing 18-photon transitions. The data are modeled using the time-dependent Schrodinger equation.$[2]$ By comparing the data with the simulations, we estimate $T_1\sim 15$ ns and $T_2\sim3$ ns. \\ \noindent $[1]$ A. J. Leggett \textit{et al.}, Rev. Mod. Phys. \textbf {59}, 1 (1987).\\ \noindent $[2]$ S. N. Shevchenko, S. Ashhab, F. Nori, Phys. Rep. {\bf492}, 1 (2010).