Two-qubit decoherence mechanisms revealed via quantum process tomography

TL;DR

This paper investigates how different local and non-local decoherence mechanisms affect quantum process tomography results for two-qubit systems, especially in superconducting qubits, enabling faster identification of dominant decoherence sources.

Contribution

It introduces a method to distinguish local and non-local decoherence mechanisms from QPT data, with specific patterns for rapid identification in two-qubit systems.

Findings

Identifies patterns in the QPT matrix for different decoherence types

Applies analysis to superconducting phase qubits with the $ m iSWAP$ gate

Provides a framework for quick decoherence mechanism identification

Abstract

We analyze the quantum process tomography (QPT) in the presence of decoherence, focusing on distinguishing local and non-local decoherence mechanisms for a two-partite system from experimental QPT data. In particular, we consider the $\sqrt{\rm iSWAP}$ gate realized with superconducting phase qubits and calculate the QPT matrix $\chi$ in the presence of several local and non-local decoherence processes. We determine specific patterns of these decoherence processes, which can be used for a fast identification of the main decoherence mechanisms from an experimental $\chi$-matrix.