Spectroscopy of Energy-Level Splitting between Two Macroscopic Quantum States of Charge Coherently Superposed by Josephson Coupling

作者：Yasunobu Nakamura, C. D. Chen, J. S. Tsai · 发表于：Physical Review Letters · 年份：1997 · DOI：10.1103/physrevlett.79.2328 · 被引用次数：210 · 研究领域：Quantum and electron transport phenomena、Physics of Superconductivity and Magnetism、Semiconductor Quantum Structures and Devices

We study Cooper-pair tunneling in a voltage-biased superconducting single-electron transistor under microwave irradiation. By tracing the peak positions of a photon-assisted Josephson-quasiparticle current as a function of the microwave frequency, we observe an energy-dispersion curve in the quasicharge space. This shows that energy-level splitting occurs between two macroscopic quantum states of charge coherently superposed by Josephson coupling.