Abstract
As a valid tool for solving ground state problems,imaginary time evolution(ITE)is widely used in physical and chemical sim-ulations.Different ITE-based algorithms in their quantum counterpart have recently been proposed and applied to some real systems.We experimentally realize the variational-based quantum imaginary time evolution(QITE)algorithm to simulate the ground state energy of hydrogen(H2)and lithium hydride(LiH)molecules in a superconducting qubit system.The H2 molecule is directly simulated using the 3-qubit circuit with unitary-coupled clusters(UCC)ansatz.We also combine QITE with the cluster mean-field(CMF)method to obtain an effective Hamiltonian.The LiH molecule is correspondingly simulated using the 3-qubit circuit with hardware-efficient ansatz.For comparison,the LiH molecule is also directly simulated using the 4-qubit circuit with UCC ansatz at the equilibrium point.All the experimental results show a convergence within 4 iterations,with high-fidelity ground state energy obtained.For a more complex system in the future,the CMF may allow further grouping of interactions to obtain an effective Hamiltonian,then the hybrid QITE algorithm can possibly simulate a relatively large-scale system with fewer qubits.
基金项目
国家自然科学基金(12074336)
国家自然科学基金(11934010)
国家重点研发计划(2019YFA0308602)
中央高校基本科研业务费专项(2020XZZX002-01)
Tencent Corporation()
维普
万方数据