Mitigating algorithmic errors in quantum optimization through energy extrapolation

Understand

Quantum optimization algorithms offer a promising route to finding the ground states of target Hamiltonians on near-term quantum devices.

• None the less, it remains necessary to limit the evolution time and circuit depth as much as possible, since otherwise decoherence will degrade the computation.
• And even where this is done, there always exists a non-negligible error in estimates of the ground state energy.
• Here we present a scalable extrapolation approach to mitigating this error, which significantly improves estimates obtained using three of the most popular optimization algorithms: quantum annealing (QA), the variational quantum eigensolver (VQE), and quantum imaginary time evolution (QITE), at fixed evolution time or circuit depth.