Average-Computation Benchmarking for Local Expectation Values in Digital Quantum Devices.

Abstract:
As quantum devices progress towards a quantum advantage regime, they become harder to benchmark. A particularly relevant challenge is to assess the quality of the whole computation, beyond testing the performance of each single operation. In this talk I will introduce a scheme for this task that combines the target computation with variants of it, which, when averaged, allow for classically solvable correlation functions. Importantly, the variants exactly preserve the circuit architecture and depth, without simplifying the gates into a classically-simulable set. The method is based on replacing each gate by an ensemble of similar gates, which when averaged together form space-time channels [P.Kos and G.Styliaris, Quantum 7, 1020 (2023)]. I will introduce explicit constructions for ensembles producing such channels, all applicable to arbitrary brickwork circuits.