# Coherent control of macroscopic quantum states in a single-Cooper-pair box

@article{Nakamura1999CoherentCO, title={Coherent control of macroscopic quantum states in a single-Cooper-pair box}, author={Y. Nakamura and Yu. A. Pashkin and J. S. Tsai}, journal={Nature}, year={1999}, volume={398}, pages={786-788} }

A nanometre-scale superconducting electrode connected to a reservoir via a Josephson junction constitutes an artificial two-level electronic system: a single-Cooper-pair box. The two levels consist of charge states (differing by 2e, where e is the electronic charge) that are coupled by tunnelling of Cooper pairs through the junction. Although the two-level system is macroscopic, containing a large number of electrons, the two charge states can be coherently superposed. The Cooper-pair box has…

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