Qubit unitary coupled cluster with generalized single and paired double excitations ansatz for variational quantum eigensolver

Xie, Qing-Xing1; Zhang, Wen-gang2; Xu, Xu-Sheng3; Liu, Sheng1; Zhao, Yan1

2022-08-01

10.1002/qua.27001

INTERNATIONAL JOURNAL OF QUANTUM CHEMISTRY   Impact Factor & Quartile

0020-7608

1097-461X

Variational quantum eigensolver (VQE) with a unitary coupled cluster (UCC) ansatz has been suggested as a promising method for electronic structure calculations on future quantum computers. However, the complexity of the excitation terms for UCC with the single and double excitations (UCCSD) ansatz is up-bounded to O oM ((NTHORNN2)-N-2) where N is the number of electrons and M is the number of spin orbitals. The gate complexity of quantum circuit for the UCCSD ansatz is up-bounded to O MoM (NTHORNN2)-N-2 using the Jordan-Wigner transformation. These complexities significantly limit the implementation of UCCSD on current Noisy Intermediate-Scale Quantum (NISQ) devices. Herein, we developed a k-QUpCCGSD ansatz which is based on the generalized paired double excitation operators and the particle preserving exchange gate. The former reduces the number of the excitation operators, the latter reduces the number of qubit gates for transforming excitation operators to quantum circuit. The gate complexity of the proposed k-QUpCCGSD ansatz is upbounded to OokM(2) THORN, which significantly reduce the complexity of the VQE algorithm on NISQ devices. The performance of the proposed ansatz on VQE is demonstrated by calculating ground-state dissociation energy curves of the H6, LiH, H2O, and BeH2 molecules with the STO-3G minimal basis set, and the accuracy is evaluated by comparing to the full configuration interaction (FCI) benchmarks. Moreover, we compare the number of quantum gates, especially the CNOT gates, and accuracies of various ansatzes. The assessments have shown that the accuracy of qubit unitary coupled cluster (QUCC) ansatzes is slightly worse than that of the UCC ones, but the circuit complexity of QUCC is much less than that of UCC. Among the tested QUCC ansatzes, k-QUpCCGSD achieves higher accuracy with fewer quantum gates than QUCCSD, and k-QUpCCGSD is a promising ansatz for VQE calculation on NISQ devices.

electronic structure ground state calculation quantum chemistry quantum computing variational quantum eigensolver (VQE)

SCI ; EI

English

Others

Key R&D Program of Hubei[2021BAA173]

Chemistry ; Mathematics ; Physics

Chemistry, Physical ; Mathematics, Interdisciplinary Applications ; Quantum Science & Technology ; Physics, Atomic, Molecular & Chemical

WOS:000842172200001

WILEY

20223612678987

Benchmarking ; Cluster computing ; Ground state ; Lithium compounds ; Logic gates ; Numerical methods ; Quantum chemistry ; Quantum electronics ; Qubits

Logic Elements:721.2 ; Digital Computers and Systems:722.4 ; Light, Optics and Optical Devices:741 ; Nanotechnology:761 ; Physical Chemistry:801.4 ; Numerical Methods:921.6 ; Quantum Theory; Quantum Mechanics:931.4

CHEMISTRY

Web of Science

1.Wuhan Univ, Inst Technol Sci, Wuhan 430072, Peoples R China
2.Southern Univ Sci & Technol, Dept Phys, Shenzhen, Peoples R China
3.Huawei Technol Q27, Beijing, Peoples R China

Xie, Qing-Xing,Zhang, Wen-gang,Xu, Xu-Sheng,et al. Qubit unitary coupled cluster with generalized single and paired double excitations ansatz for variational quantum eigensolver[J]. INTERNATIONAL JOURNAL OF QUANTUM CHEMISTRY,2022.

Xie, Qing-Xing,Zhang, Wen-gang,Xu, Xu-Sheng,Liu, Sheng,&Zhao, Yan.(2022).Qubit unitary coupled cluster with generalized single and paired double excitations ansatz for variational quantum eigensolver.INTERNATIONAL JOURNAL OF QUANTUM CHEMISTRY.

Xie, Qing-Xing,et al."Qubit unitary coupled cluster with generalized single and paired double excitations ansatz for variational quantum eigensolver".INTERNATIONAL JOURNAL OF QUANTUM CHEMISTRY (2022).