Coherent Quantum Dynamics of a Superconducting Flux Qubit

作者：I. Chiorescu, Yasunobu Nakamura, C. J. P. M. Harmans, Johan E. Mooij · 发表于：Science · 年份：2003 · DOI：10.1126/science.1081045 · 被引用次数：1228 · 研究领域：Quantum Information and Cryptography、Quantum and electron transport phenomena、Quantum optics and atomic interactions

We have observed coherent time evolution between two quantum states of a superconducting flux qubit comprising three Josephson junctions in a loop. The superposition of the two states carrying opposite macroscopic persistent currents is manipulated by resonant microwave pulses. Readout by means of switching-event measurement with an attached superconducting quantum interference device revealed quantum-state oscillations with high fidelity. Under strong microwave driving, it was possible to induce hundreds of coherent oscillations. Pulsed operations on this first sample yielded a relaxation time of 900 nanoseconds and a free-induction dephasing time of 20 nanoseconds. These results are promising for future solid-state quantum computing.