Initial state preparation of spin and fermionic systems through approximate quantum imaginary time evolution

One of the key ingredients for most quantum algorithms that aim to approximate an eigenstate of a Hamiltonian is the preparation of an initial state with sufficient support on that eigenstate. In this work, we study a recent heuristic algorithm that approximates the imaginary time propagation by a unitary operation (“QITE”) that can be executed on a quantum computer. We perform exact full Hilbert space simulation of QITE and discuss the performance of the initial state preparation w.r.t. interacting spin and molecular quantum many-body systems relevant for industrial applications, and compare the results to results obtained from classical methods.