Quantum computed moments correction to variational estimates

Abstract

The variational principle of quantum mechanics is the backbone of hybrid quantum computing for a range of applications. However, as the problem size grows, quantum logic errors and the effect of barren plateaus overwhelm the quality of the results. There is now a clear focus on strategies that require fewer quantum circuit steps and are robust to device errors. Here we present an approach in which problem complexity is transferred to dynamic quantities computed on the quantum processor – Hamiltonian moments, hHni. From these quantum computed moments, an estimate of the ground-state energy can be obtained using the “infimum” theorem from Lanczos cumulant expansions which manifestly corrects t..