Dynamical mean field theory for real materials on a quantum computer

Quantum computers hold promise for advancing materials simulations, especially at the atomistic scale involving strongly correlated fermionic systems, where accurately describing quantum many-body effects scales poorly with size. Although full-scale treatment of condensed matter systems with current noisy quantum computers is not yet feasible, quantum embedding schemes like dynamical mean-field theory (DMFT) can map an effective, reduced subspace Hamiltonian to currently available noisy quantum computers, enhancing the accuracy of ab initio calculations such as density functional theory (DFT). We present a hybrid quantum-classical DFT+DMFT simulation framework utilizing a quantum impurity solver based on the Lehmann representation of the impurity Green's function. Hardware experiments with up to 14 qubits on the IBM Quantum system are conducted, using advanced error mitigation methods and a novel calibration scheme for improved zero-noise extrapolation to reduce the impact of inherent noise on current quantum devices. We demonstrate the utility of our quantum DFT+DMFT workflow by evaluating the correlation effects on the electronic structure of Ca2CuO2Cl2, and by benchmarking our quantum results against exact reference solutions as well as experimental spectroscopy measurements.