Ancilla Assisted Quantum Process Tomography using Bound entangled states

TL;DR

This paper demonstrates that certain bound entangled states can be effectively used for ancilla-assisted quantum process tomography, expanding their practical applications in quantum information processing.

Contribution

The work explicitly shows bound entangled states' utility in AAQPT and compares their efficiency with other entangled states, providing new insights into their practical use.

Findings

Bound entangled states can be used for AAQPT.

Local filtering operations are ineffective for AAQPT.

Quantitative bounds on the efficiency of bound entangled states are established.

Abstract

Lu \textit{et al.} [Ann. Phys. (Berlin) \textbf{534}, 2100550 (2022)] posed the question of whether bound entangled states can be used for ancilla-assisted quantum process tomography (AAQPT). In this work, we answer this question in the affirmative by explicitly demonstrating that certain bound entangled states can be used for AAQPT. We further show that, although local filtering operations may improve the trace norm of the realignment criterion, they are essentially ineffective for AAQPT, as they render the resulting states \emph{unfaithful} and therefore unsuitable for reliable process reconstruction. Further, we investigate the efficiency of bound entangled states for AAQPT and establish quantitative bounds by comparing their performance with Werner and isotropic states. Our results therefore provide a new application of bound entangled states in the context of ancilla-assisted quantum process tomography.