Model-based framework for automated quantification of error sources in quantum state tomography

TL;DR

This paper introduces an automated, model-based framework that quantifies individual error sources in quantum state tomography, enhancing understanding and correction of errors in quantum state generation across various platforms.

Contribution

The authors develop a novel automated method combining simulation and optimization to identify and quantify specific error sources in quantum state tomography, applicable to multiple quantum platforms.

Findings

Optimization reduced trace distance from 0.177 to 0.024

Modeled error sources explain 86% of errors

Framework validated on time-bin entangled photon pairs

Abstract

High-quality quantum state generation is essential for advanced quantum information processing, including quantum communication, quantum sensing, and quantum computing. In practice, various error sources degrade the quality of quantum states, and quantum state tomography (QST) is a standard diagnostic tool. However, in QST, multiple error sources gather in a single density matrix, making it difficult to identify individual error sources. To address this problem, we propose an automated method for quantifying error sources by combining simulation and parameter optimization to reproduce the experimental density matrix. We focus on the experimental generation of time-bin entangled photon pairs, for which we model the relevant error sources and simulate the density matrix with adjustable model parameters, thereby optimizing the parameters and minimizing the trace distance to the experimental data. Optimization of the parameters reduced the trace distance from 0.177 to 0.024, indicating that our modeled error sources explain 86% of the errors. Reducing the predicted error sources improves the state quality, consistent with our predictions and thus validating the proposed method. In addition, the modular structure of this framework makes it applicable to other quantum platforms, such as superconducting qubits, atoms, and solid-state spins.