Adaptive basis sets for practical quantum computing
Adaptive basis sets for practical quantum computing
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DOI：
10.1002/qua.27123
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发表时间：
2022-11
影响因子：
2.2
通讯作者：
Hyukgun Kwon;Gregory M. Curtin;Zack Morrow;C. T. Kelley;E. Jakubikova
中科院分区：
文献类型：
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作者：
Hyukgun Kwon;Gregory M. Curtin;Zack Morrow;C. T. Kelley;E. Jakubikova
对H$2$、H$2$O、LiH和BEH$2$等小系统进行化学精确的电子结构计算仍然是当代噪声中尺度量子(NISQ)器件面临的一个挑战。其中一个原因是由于设备的限制，在量子化学计算中通常只应用最小的基组，这使得人们可以将计算中使用的量子比特的数量保持在最小。然而，使用最小基组会导致计算的分子能量和势能面形状产生很大的误差。提高电子结构计算精度的一种方法是开发更适合量子计算的小基组。在这项工作中，我们证明了自适应基集的使用，其中指数和收缩系数取决于分子结构，提供了一种简单的方法来显著提高量子化学计算的精度，而不需要增加基集的大小，从而增加量子电路中使用的量子比特的数量。作为原理的证明，我们优化了一个用于H$2分子量子计算的自适应极小基集，其中指数和收缩系数依赖于H-H距离，并将其应用于IBM-Q量子器件上H$2$势能面的生成。自适应最小基集达到了双Zeta基集的精度，从而允许人们在不需要在模拟中使用两倍的量子比特的情况下对量子器件进行双Zeta质量计算。这种方法可以简单地推广到其他分子体系和更大的基组。
Electronic structure calculations on small systems such as H$_2$, H$_2$O, LiH, and BeH$_2$ with chemical accuracy are still a challenge for the current generation of the noisy intermediate-scale quantum (NISQ) devices. One of the reasons is that due to the device limitations, only minimal basis sets are commonly applied in quantum chemical calculations, which allow one to keep the number of qubits employed in the calculations at minimum. However, the use of minimal basis sets leads to very large errors in the computed molecular energies as well as potential energy surface shapes. One way to increase the accuracy of electronic structure calculations is through the development of small basis sets better suited for quantum computing. In this work, we show that the use of adaptive basis sets, in which exponents and contraction coefficients depend on molecular structure, provide an easy way to dramatically improve the accuracy of quantum chemical calculations without the need to increase the basis set size and thus the number of qubits utilized in quantum circuits. As a proof of principle, we optimize an adaptive minimal basis set for quantum computing calculations on an H$_2$ molecule, in which exponents and contraction coefficients depend on the H-H distance, and apply it to the generation of H$_2$ potential energy surface on IBM-Q quantum devices. The adaptive minimal basis set reaches the accuracy of the double-zeta basis sets, thus allowing one to perform double-zeta quality calculations on quantum devices without the need to utilize twice as many qubits in simulations. This approach can be extended to other molecular systems and larger basis sets in a straightforward manner.