Fast Quantum Many Body State Synthesis

Abstract: Quantum Mechanical ground states of many-body systems can be important resources for various investigations: for quantum sensing, as the initial state for nonequilibrium quantum dynamics following quenches, and the simulation of quantum processes that start by coupling systems in ground states, eg, could be a process in quantum chemistry. However, to prepare ground states can be challenging; for example, requires adiabatic switching of Hamiltonian terms slower than an inverse gap, which can be time consuming and bring in decoherence. Here we investigate the possibility of preparing a many-body entangled ground state of a certain Hamiltonian, which can be called a quantum problem'' Hamiltonian, using the time evolution of an initial fiducial state by anothersolver'' Hamiltonian/s for a very short fixed (unit) time. The parameters of the solver Hamiltonian are optimised classically using energy minimisation as the cost function. We present a study of up to n=10 qubit many-body states prepared using this methodology.