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

  title={Coherent control of macroscopic quantum states in a single-Cooper-pair box},
  author={Y. Nakamura and Yu. A. Pashkin and J. S. Tsai},
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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