@article{viola_lloyd_1998, 
  title={Dynamical suppression of decoherence in two-state quantum systems}, 
  volume={58}, 
  DOI={10.1103/physreva.58.2733}, 
  publisher={American Physical Society (APS)}, 
  author={Viola and Lloyd}, 
  year={1998}, 
  month={Oct}
  }