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arXiv · 2007.08697

Evaluating energy differences on a quantum computer with robust phase estimation

A. E. Russo·K. M. Rudinger·B. C. A. Morrison·A. D. Baczewski
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Abstract

We adapt the robust phase estimation algorithm to the evaluation of energy differences between two eigenstates using a quantum computer. This approach does not require controlled unitaries between auxiliary and system registers or even a single auxiliary qubit. As a proof of concept, we calculate the energies of the ground state and low-lying electronic excitations of a hydrogen molecule in a minimal basis on a cloud quantum computer. The denominative robustness of our approach is then quantified in terms of a high tolerance to coherent errors in the state preparation and measurement. Conceptually, we note that all quantum phase estimation algorithms ultimately evaluate eigenvalue differences.

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A. E. Russo, K. M. Rudinger, B. C. A. Morrison, A. D. Baczewski. 2020-07-17. Evaluating energy differences on a quantum computer with robust phase estimation. https://doi.org/10.1103/physrevlett.126.210501

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