Quantum Superposition of Macroscopic Persistent-Current States

作者：Caspar H. van der Wal, A. C. J. ter Haar, Frank K. Wilhelm, Raymond N. Schouten, C. J. P. M. Harmans, Terry P. Orlando, Seth Lloyd, Johan E. Mooij · 发表于：Science · 年份：2000 · DOI：10.1126/science.290.5492.773 · 被引用次数：991 · 研究领域：Physics of Superconductivity and Magnetism、Quantum and electron transport phenomena、Quantum Information and Cryptography

Microwave spectroscopy experiments have been performed on two quantum levels of a macroscopic superconducting loop with three Josephson junctions. Level repulsion of the ground state and first excited state is found where two classical persistent-current states with opposite polarity are degenerate, indicating symmetric and antisymmetric quantum superpositions of macroscopic states. The two classical states have persistent currents of 0.5 microampere and correspond to the center-of-mass motion of millions of Cooper pairs.