Multiqubit Spatially Correlated Noise Characterization

Spatiotemporally correlated noise and its impact on error correcting schemes such as the surface code are of critical interest for quantum information processing research. We propose and validate a quantum noise spectroscopy protocol to measure spatially correlated noise on two qubits. Our scheme reconstructs the real and imaginary part of the power spectrum using two fixed total time pulse sequences and performing single qubit and joint two-qubit measurements to separately resolve spatially correlated noise processes from the individual noise spectra of the participating qubits. We inject noise by using a technique known as Schrodinger Wave Autoregressive Moving Average, developed by our group [1], to generate phase error on the qubit control line. Our results demonstrate that our protocol is a way to characterize spatially correlated noise in a quantum device and inform error correction algorithms.

[1] Murphy, Andrew, et al. "Universal Dephasing Noise Injection via Schrodinger Wave Autoregressive Moving Average Models." arXiv preprint arXiv:2102.03370 (2021).