Numerical Simulations of Noisy Variational Quantum Eigensolver Ansatz Circuits

Conference · Fri Oct 01 04:00:00 EDT 2021

DOI:https://doi.org/10.1109/QCE52317.2021.00032· OSTI ID:1846536

Gowrishankar, Meenambika ^[1]; Wright, Jerimiah ^[1]; Chaves Claudino, Daniel ^[1]; Nguyen, Thien ^[1]; Mccaskey, Alex ^[1]; Humble, Travis ^[1]

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1. ORNL

This is a case study of the variational quantum eigensolver (VQE) method using numerical simulations to test the influence of noise on the accuracy of the underlying circuit ansatz. We investigate a computational chemistry application of VQE to calculate the electronic ground state and its energy for Sodium Hydride (NaH), a prototypical two-electron problem. Using a one-parameter ansatz derived from unitary coupled cluster (UCC) theory, we simulate the effects of noise on the energy expectation value and variance with respect to the ansatz parameter. These numerical simulations provide insights into the accuracy of the prepared quantum state and the efficiency of the classical optimizer that iteratively refines the ansatz. We conduct a comparative study between analytical results derived for the UCC ansatz in the absence of noise and the noisy numerical simulation results obtained using an isotropic depolarizing noise model for each gate. We also compare the relative increase in noise on logically equivalent UCC ansatz circuits generated by randomized compiling. Notably, we observe that the intrinsic variance in the energy due to the simplicity of the ansatz itself compares with the noise induced by the bare circuit.

• Research Organization: Oak Ridge National Laboratory (ORNL), Oak Ridge, TN (United States)
• Sponsoring Organization: USDOE; USDOE Office of Science (SC)
• DOE Contract Number: AC05-00OR22725
• OSTI ID: 1846536
• Country of Publication: United States
• Language: English