90007797

open access

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Spin-projection for quantum computation: A low-depth approach to strong correlation

English (英語)

Physical Review Research

2(4)

043142-043142

American Physical Society (APS)

2020-10-27

2021-01-27

Although spin is a core property in fermionic systems, its symmetry can be easily violated in a variational simulation, especially when strong correlation plays a vital role therein. In this study, we will demonstrate that the broken spin symmetry can be restored exactly in a quantum computer, with little overhead in circuits, while delivering additional strong correlation energy with the desired spin quantum number. The proposed scheme permits drastic reduction of a potentially large number of measurements required to ensure spin symmetry by employing a superposition of only a few rotated quantum states. Our implementation is universal, simple, and, most importantly, straightforwardly applicable to any Ansatz proposed to date.

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