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arXiv · 1910.01830

Non-unitary operations for ground-state calculations in near term quantum computers

Guglielmo Mazzola·Pauline Ollitrault·Panagiotis Barkoutsos·Ivano Tavernelli
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Abstract

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 non-unitary 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 sub-optimal variational quantum heuristic ansatz. The accuracy of this approach is demonstrated numerically in finding energies of entangled ground-states of many-body lattice models. We demonstrate a practical implementation on IBM quantum hardwares up to an 8 qubits circuit.

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Guglielmo Mazzola, Pauline Ollitrault, Panagiotis Barkoutsos, Ivano Tavernelli. 2019-10-04. Non-unitary operations for ground-state calculations in near term quantum computers. https://doi.org/10.1103/physrevlett.123.130501

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