Synergetic quantum error mitigation by randomized compiling and zero-noise extrapolation for the variational quantum eigensolver

Understand

We propose a quantum error mitigation strategy for the variational quantum eigensolver (VQE) algorithm.

• We find, via numerical simulation, that very small amounts of coherent noise in VQE can cause substantially large errors that are difficult to suppress by conventional mitigation methods, and yet our proposed mitigation strategy is able to significantly reduce these errors.
• The proposed strategy is a combination of previously reported techniques, namely randomized compiling (RC) and zero-noise extrapolation (ZNE).
• Intuitively, randomized compiling turns coherent errors in the circuit into stochastic Pauli errors, which facilitates extrapolation to the zero-noise limit when evaluating the cost function.