Spectroscopy on two coupled flux qubits

J. B. Majer, F. G. Paauw, A. C. J. ter Haar, C. J. P. M. Harmans, J. E. Mooij

Published 2003-08-10Version 1

We have performed spectroscopy measurements on two coupled flux qubits. The qubits are coupled inductively, which results in a $\sigma_1^z\sigma_2^z$ interaction. By applying microwave radiation, we observe resonances due to transitions from the ground state to the first two excited states. From the position of these resonances as a function of the magnetic field applied we observe the coupling of the qubits. The coupling strength agrees well with calculations of the mutual inductance.