Quantifying entanglement preservability of experimental processes

TL;DR

This paper introduces experimentally feasible measures and benchmarks to quantify how well quantum processes preserve entanglement, crucial for quantum computing and communication, applicable across various physical systems.

Contribution

It develops new measures and a fidelity benchmark for quantifying entanglement preservability in quantum processes, extendable to all quantum operations.

Findings

Measures are experimentally feasible with local measurements.

Applicable to diverse physical systems like photonic and superconducting qubits.

Extends channel analysis tools to non-trace-preserving processes.

Abstract

Preserving entanglement is a crucial dynamical process for entanglement-based quantum computation and quantum-information processes, such as one-way quantum computing and quantum key distribution. However, the problem of quantifying the ability of an experimental process to preserve two-qubit entanglement in experimentally feasible ways is not well understood. Accordingly, herein, we consider the use of two measures, namely composition and robustness, for quantitatively characterizing the ability of a process to preserve entanglement, referred to henceforth as entanglement preservability. A fidelity benchmark is additionally derived to identify the ability of a process to preserve entanglement. We show that the measures and introduced benchmark are experimentally feasible and require only local measurements on single qubits and preparations of separable states. Moreover, they are applicable to all physical processes that can be described using the general theory of quantum operations, e.g., qubit dynamics in photonic and superconducting systems. Our method extends the existing tools for analyzing channels, e.g., channel resource theory, to quantify entanglement preservability for non-trace-preserving quantum processes. The results are of significant interest for applications in quantum-information processing in which entanglement preservation is required.