Correlated Charge Noise and Bit Flip Errors in Superconducting Qubits

We have characterized fluctuations in offset charge and temporal variations in energy relaxation time in a circuit comprising four weakly charge-sensitive transmon qubits. We find that discrete jumps in offset charge are highly correlated on a length scale over 600 µm; moreover, these jumps are accompanied by a strong transient suppression of qubit energy relaxation time across the millimeter-scale chip. These results are compatible with the direct charging event and associated quasiparticle poisoning due to absorption of gamma rays or cosmic ray muons in the qubit substrate. These results have major implications for proposed schemes to correct quantum errors by monitoring multiqubit parity operators, which assume that errors in the qubit array are uncorrelated.