Nonunitary Operations for Ground-State Calculations in Near-Term Quantum Computers.

@article{Mazzola2019NonunitaryOF,
  title={Nonunitary Operations for Ground-State Calculations in Near-Term Quantum Computers.},
  author={Guglielmo Mazzola and Pauline J Ollitrault and Panagiotis Kl. Barkoutsos and Ivano Tavernelli},
  journal={Physical review letters},
  year={2019},
  volume={123 13},
  pages={
          130501
        }
}
We introduce a quantum Monte Carlo inspired reweighting scheme to accurately compute energies from optimally short quantum circuits. This effectively hybrid quantum-classical approach features both entanglement provided by a short quantum circuit, and the presence of an effective nonunitary operator at the same time. The functional form of this projector is borrowed from classical computation and is able to filter out high-energy components generated by a suboptimal variational quantum… 

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