Variational Preparation of Quantum Hall States on a Lattice

Simulation of many-body quantum systems is one of the most promising applications of near-term quantum computers. The fractional quantum Hall states display fascinating many-body physics such as topological order and strong correlations and so are interesting candidates for quantum simulation experiments. We classically diagonalize for the low-energy spectrum of the Kapit-Mueller Hamiltonian for hardcore bosons on a lattice. The Laughlin state is an exact ground state of this long-range Hamiltonian for appropriate magnetic flux densities. In addition, we study the low-lying spectrum of a shorter-range proxy Hamiltonian and tune its hopping and interaction parameters in order to optimize the associated topological degeneracy and many-body gap. We then demonstrate a scheme for variational preparation of the Laughlin state on the lattice through a Trotterization of adiabatic state preparation with defect-pinned particles as the reference state. Such calculations suggest a way forward in the simulation of fractional quantum Hall states on quantum hardware.