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A Photonic System for Generating Unconditional Polarization-Entangled Photons Based on Multiple Quantum Interference

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Published on: September 5, 2019

Open-system dynamics of graph-state entanglement.

Daniel Cavalcanti¹, Rafael Chaves, Leandro Aolita

¹ICFO-Institut de Ciencies Fotoniques, Mediterranean Technology Park, 08860 Castelldefels, Barcelona, Spain.

Physical Review Letters

|August 8, 2009

Summary

Researchers developed methods to bound entanglement in quantum graph states during decoherence. For Pauli channels, these bounds precisely determine entanglement evolution, offering insights into quantum information robustness.

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Area of Science:

Quantum Information Science
Quantum Many-Body Systems
Quantum Communication and Computation

Background:

Graph states are crucial multipartite entangled states for quantum information processing.
Decoherence, the interaction with the environment, degrades entanglement, posing a significant challenge.
Understanding entanglement dynamics under decoherence is vital for robust quantum technologies.

Purpose of the Study:

To develop methods for quantifying entanglement bounds in graph states subjected to generic decoherence.
To derive exact analytical expressions for entanglement evolution under specific noisy channels.
To assess the robustness of graph states against decoherence and size scaling.

Main Methods:

Formulation of lower and upper bounds for system entanglement based on smaller subsystems.
Application of these bounds to Pauli maps (a class of noisy channels) for exact entanglement evolution.
Extension of results to graph-diagonal and arbitrary states via local depolarization.

Main Results:

Precise analytical expressions for entanglement evolution were obtained for graph states under Pauli channels.
The methods provide a lower bound for entanglement decay in any arbitrary quantum state.
The study identifies the inherent robustness of graph states to decoherence based on their connectivity.

Conclusions:

The developed bounds offer a powerful tool for analyzing entanglement dynamics in multipartite quantum systems.
The findings are applicable to a broad range of quantum states and entanglement measures.
This work provides a pathway to designing more resilient quantum states and protocols.