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arXiv · 2311.01105

ADAPT-QSCI: Adaptive Construction of an Input State for Quantum-Selected Configuration Interaction

Yuya O. Nakagawa·Masahiko Kamoshita·Wataru Mizukami·Shotaro Sudo·Yu-ya Ohnishi
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Abstract

We present a quantum-classical hybrid algorithm for calculating the ground state and its energy of the quantum many-body Hamiltonian by proposing an adaptive construction of a quantum state for the quantum-selected configuration interaction (QSCI) method. QSCI allows us to select important electronic configurations in the system to perform CI calculation (subspace diagonalization of the Hamiltonian) by sampling measurement for a proper input quantum state on a quantum computer, but how we prepare a desirable input state has remained a challenge. We propose an adaptive construction of the input state for QSCI in which we run QSCI repeatedly to grow the input state iteratively. We numerically illustrate that our method, dubbed ADAPT-QSCI, can yield accurate ground-state energies for small molecules, including a noisy situation for eight qubits where error rates of two-qubit gates and the measurement are both as large as 1%. ADAPT-QSCI serves as a promising method to take advantage of current noisy quantum devices and pushes forward its application to quantum chemistry.

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Yuya O. Nakagawa, Masahiko Kamoshita, Wataru Mizukami, Shotaro Sudo, Yu-ya Ohnishi. 2023-11-02. ADAPT-QSCI: Adaptive Construction of an Input State for Quantum-Selected Configuration Interaction. https://doi.org/10.1021/acs.jctc.4c00846

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