Convex optimization of programmable quantum computers

@article{Banchi2020ConvexOO,
  title={Convex optimization of programmable quantum computers},
  author={Leonardo Banchi and Jason L. Pereira and Seth Lloyd and Stefano Pirandola},
  journal={npj Quantum Information},
  year={2020},
  volume={6},
  pages={1-10}
}
A fundamental model of quantum computation is the programmable quantum gate array. This is a quantum processor that is fed by a program state that induces a corresponding quantum operation on input states. While being programmable, any finite-dimensional design of this model is known to be nonuniversal, meaning that the processor cannot perfectly simulate an arbitrary quantum channel over the input. Characterizing how close the simulation is and finding the optimal program state have been open… 
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