Unsupervised Classification of Quantum Data

@article{Sentis2019UnsupervisedCO,
  title={Unsupervised Classification of Quantum Data},
  author={Gael Sent'is and Alex Monras and Ramon Mu{\~n}oz-Tapia and John Calsamiglia and Emilio Bagan},
  journal={Physical Review X},
  year={2019}
}
We introduce the problem of unsupervised classification of quantum data, namely, of systems whose quantum states are unknown. We derive the optimal single-shot protocol for the binary case, where the states in a disordered input array are of two types. Our protocol is universal and able to automatically sort the input under minimal assumptions, yet partially preserves information contained in the states. We quantify analytically its performance for an arbitrary size and dimension of the data… 

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