Variational Coherent Error Mitigation (VCEM) for graph states

Graph states are one of the key resources in many quantum information processing tasks. For instance, Measurement Based Quantum Computing (MBQC) requires the generation of high quality graph states. We present an error mitigation strategy to counteract the effects of coherent errors, i.e. small deviations from the ideal angles of the gates in the circuit generating a graph state. This technique is based on parameterizing the circuit generating the graph state and learning the optimal parameters by minimizing a cost function built with the mean values of the graph state stabilizers. We show how this technique is effective also in the presence of incoherent errors allowing for its combination with mitigation techniques for such kinds of errors.