Real-time error mitigation for variational optimization on quantum hardware

In this work we put forward the inclusion of error mitigation routines in the process of training Variational Quantum Circuit (VQC) models. In detail, we define a Real Time Quantum Error Mitigation (RTQEM) algorithm to coadiuvate the task of fitting functions on quantum chips with VQCs. Although QEM methods cannot help with the problem of exponential cost concentration induced by noise in current devices, we demonstrate that our RTQEM routine is able to improve VQCs' trainability by mitigating the corruption of the cost function. To test this, we both simulated and deployed on a superconducting single-qubit device the fit of a monodimensional u-Quark Parton Distribution Function (PDF), and we further analyzed the scalability of the proposed technique by simulating a multidimensional fit with 8 qubits.