Convergence acceleration of the contracted quantum eigensolver

Accelerated Convergence of Contracted Quantum Eigensolvers through a Quasi-Second-Order, Locally Parameterized Optimization

Contracted quantum eigensolvers (cqes) find a solution to the many-electron many-electron schr\"odinger equation by solving its integration (or contraction) to the 2-electron space on a quantumcomputer.In this work
, we accelerate the convergence of the cqes and its wavefunction ansatz via tools from classical optimization theory.The convergence acceleration is important because it can both minimize the accumulation of noise on near-term intermediate-scale quantum (near-term intermediate-scale quantum) computers and achieve highly accurate solutions on future fault-tolerant quantum devices.We demonstrate the algorithm, as well as some heuristicimplementations relevant for cost-reduction considerations, comparisons with other common methods such as variational quantum eigensolvers, and a fermionic-encoding-free form of the cqes.