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arXiv · 2004.12024

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

Takashi Tsuchimochi·Yuto Mori·Seiichiro L. Ten-no
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Abstract

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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Takashi Tsuchimochi, Yuto Mori, Seiichiro L. Ten-no. 2020-04-25. Spin-projection for quantum computation: A low-depth approach to strong correlation. https://doi.org/10.1103/physrevresearch.2.043142

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