Non-Markovian Noise Characterization with the Transfer Tensor Method

TL;DR

This paper introduces a protocol using transfer tensor maps for quantum noise spectroscopy, enabling the characterization of non-Markovian effects, noise spectral density, and collective decoherence in quantum systems.

Contribution

It presents a systematic method to deduce the memory kernel of quantum processes via process tomography, extending noise analysis beyond simple models.

Findings

IBM Quantum Experience qubits show mild non-Markovian dissipation

The method can assess non-Markovianity in quantum processes

It enables reconstruction of noise spectral densities in complex systems

Abstract

We propose simple protocols for performing quantum noise spectroscopy based on the method of transfer tensor maps (TTM), [Phys. Rev. Lett. 112, 110401 (2014)]. The TTM approach is a systematic way to deduce the memory kernel of a time-nonlocal quantum master equation via quantum process tomography. With access to the memory kernel it is possible to (1) assess the non-Markovianity of a quantum process, (2) reconstruct the noise spectral density beyond pure dephasing models, and (3) investigate collective decoherence in multiqubit devices. We illustrate the usefulness of TTM spectroscopy on the IBM Quantum Experience platform, and demonstrate that the qubits in the IBM device are subject to mild non-Markovian dissipation with spatial correlations.