Landau–Zener Interferometry in a Cooper-Pair Box

In a driven system, a sequence of Landau–Zener transitions occur, and they may interfere with each other. We present experimental evidence of quantum interference effects in a superconducting charge qubit, a Cooper-pair box, where the LZ tunneling occurs at the charge degeneracy. By employing weak capacitive monitoring, we observe interference between consecutive LZ tunneling events.