Investigation of coherent microscopic defects inside the tunneling barrier of a Josephson junction

In disordered solids, two-level atomic-tunneling systems are present in large quantity. Only recently, superconducting qubits opened a door for a detection and individual coherent manipulation of such microscopic quantum systems. We succeeded to tune the resonance frequencies of these systems by applying external strain on the qubit chip. Moreover, we observed and analyzed the interaction between two coupled tunneling systems.