“…The core idea is exploiting PQCs to delegate classically difficult computation and variationally updating the parameters in PQCs with a powerful classical optimizer [28,29,30,31,32]. With error mitigation techniques [33,34,35,36,37,38,39,40], VQAs have been applied to various fields and the corresponding specific algorithms have been developed, including variational quantum eigensolver (VQE) [41,42,43,44,45], quantum approximate optimization algorithm [46,47,48,15,49], variational quantum simulator [50,51,52,53], quantum neural network (QNN) [54,55,56,57,58,59,60,61,62,63], and others [64,65,66,67,68,69,70,71,72,...…”