Quantum Computing offers the potential to efficiently solve problems for which there are no known, efficient classical solutions such as factoring of semi-prime numbers and simulation of quantum- mechanical systems. This work considers a novel moments-based adaptation of the Variational Quantum Eigensolver (VQE), one of the leading candidates for demonstrating quantum supremacy.
The method for improving the estimated ground state energy of a quantum system, obtained using the Variational Quantum Eigensolver, is presented and tested for Heisenberg model systems using IBM’s superconducting quantum devices. The method is based on the application of a Lanczos expansion technique based on the computation of Hamiltonian moments and is found to offer better accuracy than conventional VQE for most cases considered, allowing for a simpler trial state and offsetting the effects of noise.