Collective macroscopic tunneling in intrinsic Josephson junctions

A theory for photon-assisted macroscopic quantum tunneling (MQT) in a stack of capacitively-coupled intrinsic Josephson junctions is proposed. The theory predicts how the quantized energy-levels in the N-junction stacked system distribute. Furthermore, the theory reveals that the MQT escape rate from the single-plasmon states to the uniform voltage ones under microwave irradiation is proportional to the square of the junction number (N2). This result is consistent with the recent observation in Bi-2212 intrinsic Josephson junctions.