Renyi Entropy Benchmarking of Superconducting Qubits

The ever-growing size of superconducting processors in recent years has significantly elevated the demand to efficiently benchmark the performance of large quantum circuits. Traditional methods such as state or process tomography suffer from a measurement overhead that scales double-exponentially with the number of qubits. Motivated by recent progress in trapped ion systems [1], we use sets of random gate unitaries to scramble many-body quantum states and infer their Renyi entropies, which reveal the rate of purity loss of the quantum system. The protocol is applied to benchmark the coherence of large quantum circuits run on the Google quantum processor. The scaling behavior of the randomized measurement protocol over system size is investigated in detail.

[1] T. Brydges et al., Science 364, 260 (2019)