Quantum System Identification by Bayesian Analysis of Noisy Data: Beyond Hamiltonian Tomography

TL;DR

This paper extends Bayesian methods for quantum system identification to include systems with dephasing, demonstrating high accuracy in estimating frequencies and dephasing rates in three-level quantum systems.

Contribution

It generalizes Bayesian quantum system identification to systems with dephasing, beyond pure Hamiltonian tomography, for more realistic noisy quantum systems.

Findings

Bayesian estimation accurately recovers frequencies and dephasing rates.

Errors mainly stem from inaccuracies in the reconstructed Hamiltonian basis.

Method is effective for three-level quantum systems with moderate dephasing.

Abstract

We consider how to characterize the dynamics of a quantum system from a restricted set of initial states and measurements using Bayesian analysis. Previous work has shown that Hamiltonian systems can be well estimated from analysis of noisy data. Here we show how to generalize this approach to systems with moderate dephasing in the eigenbasis of the Hamiltonian. We illustrate the process for a range of three-level quantum systems. The results suggest that the Bayesian estimation of the frequencies and dephasing rates is generally highly accurate and the main source of errors are errors in the reconstructed Hamiltonian basis.