论文标题
量化门误对量子化学变异量子本质体的影响
Quantifying the effect of gate errors on variational quantum eigensolvers for quantum chemistry
论文作者
论文摘要
变分量子本素（VQE）是候选者，以证明近期量子优势。在这里，我们对一系列分子进行了基于栅极的VQS的密度矩阵模拟。我们从数值上量化了它们的可耐受性去极化栅极的水平。我们发现：（i）表现最佳的VQE需要$ 10^{ - 6} $和$ 10^{ - 4} $（$ 10^{ - 4} $和$ 10^{ - 4} $和$ 10^{ - 2} $的$ 10^{ - 2} $使用错误缓解），以在化学准确性，地基于底层的小对象，与4-14 $ 4-14 $ 4-14 $ 4-14 $ 4-14 $ 4-14 $ 4-14 $ 4-14 $ 4-14。 （ii）构造Ansatz循环的Adapt-VQE迭代固定电路VQE。 （iii）适应性VQE的表现更好，其电路是由闸门效率而不是物理动机元素构成的。 （iv）任何VQE的最大允许的门概率，$ p_c $，以实现化学精度，随着数字$ \ ncx $ noisy dqubit的大门为$ \ ncx $，为$ p_c \ loctprop \ loctprop \ ncx^{ - 1} $。此外，$ p_c $随着系统大小而减小，即使有误差缓解，这意味着较大的分子甚至需要较低的栅极错误。因此，除非通过数量级降低栅极误差概率，否则不太可能通过基于门的VQE进行量子优势。
Variational quantum eigensolvers (VQEs) are leading candidates to demonstrate near-term quantum advantage. Here, we conduct density-matrix simulations of leading gate-based VQEs for a range of molecules. We numerically quantify their level of tolerable depolarizing gate-errors. We find that: (i) The best-performing VQEs require gate-error probabilities between $10^{-6}$ and $10^{-4}$ ( $10^{-4}$ and $10^{-2}$ with error mitigation) to predict, within chemical accuracy, ground-state energies of small molecules with $4-14$ orbitals. (ii) ADAPT-VQEs that construct ansatz circuits iteratively outperform fixed-circuit VQEs. (iii) ADAPT-VQEs perform better with circuits constructed from gate-efficient rather than physically-motivated elements. (iv) The maximally-allowed gate-error probability, $p_c$, for any VQE to achieve chemical accuracy decreases with the number $\ncx$ of noisy two-qubit gates as $p_c\approxprop\ncx^{-1}$. Additionally, $p_c$ decreases with system size, even with error mitigation, implying that larger molecules require even lower gate-errors. Thus, quantum advantage via gate-based VQEs is unlikely unless gate-error probabilities are decreased by orders of magnitude.
