Macroscopic Quantum Tunneling and Resonant Activation of Current Biased Intrinsic Josephson Junctions in Bi-2212

The utilization of a high-Tc superconductor for implementing a superconducting qubit is to be expected. Recent researches on the quantum property of Josephson junctions in high-Tc superconductors indicate that the low energy quasiparticle excitation is weak enough to observe the macroscopic quantum tunneling. Therefore, a detailed study on the quantum property of high-Tc Josephson junctions becomes more important for applications. We show our experimental results of the macroscopic tunneling of current biased intrinsic Josephson junctions in Bi-2212 and its resonant activation in the presence of microwave radiation. key words: Josephson junction, macroscopic quantum tunneling, high-Tc superconductor, resonant activation, qubit