Overcoming Noise in Entanglement Distribution (1904.01552v2)

Abstract: Noise can be considered the natural enemy of quantum information. An often implied benefit of high-dimensional entanglement is its increased resilience to noise. However, manifesting this potential in an experimentally meaningful fashion is challenging and has never been done before. In infinite dimensional spaces, discretisation is inevitable and renders the effective dimension of quantum states a tunable parameter. Owing to advances in experimental techniques and theoretical tools, we demonstrate an increased resistance to noise by identifying two pathways to exploit high-dimensional entangled states. Our study is based on two separate experiments utilising canonical spatio-temporal properties of entangled photon pairs. Following these different pathways to noise resilience, we are able to certify entanglement in the photonic orbital-angular-momentum and energy-time degrees of freedom up to noise conditions corresponding to a noise fraction of 72 % and 92 % respectively. Our work paves the way towards practical quantum communication systems that are able to surpass current noise and distance limitations, while not compromising on potential device-independence.

Overcoming Noise in Entanglement Distribution

The paper "Overcoming Noise in Entanglement Distribution" by Sebastian Ecker et al. presents a significant paper on enhancing noise resilience in quantum entanglement distribution using high-dimensional quantum states. The research primarily demonstrates the potential pathways to improve the robustness of entangled photon pairs against environmental noise, which is a critical challenge in quantum information processing and quantum communication.

In quantum communication systems, noise is a significant adversary that deteriorates the coherence of entangled quantum states, consequently limiting the transmission distance and channel capacity. This research exploits high-dimensional entanglement to address noise in quantum channels, focusing on both theoretical and experimental advancements to achieve noise-resilient quantum communication.

Key Findings

The paper identifies two pathways for utilizing high-dimensional entanglement to overcome noise:

1. Fine-Graining High-Dimensional States: This pathway involves increasing the dimensionality of the entangled states to dilute the effect of noise, effectively spreading the noise over a larger state space. By discretizing the temporal properties of photon pairs, entanglement was certified under noise conditions with noise fractions up to 0.93.
2. Exploiting Multiple Measurement Bases: The second pathway leverages the multiplicity of mutually unbiased bases (MUBs) available in higher dimensions to provide additional information about the entangled states. Measurements of orbital-angular-momentum entangled states demonstrated noise tolerance up to a noise fraction of 0.72.

Both pathways revealed a pattern of increased noise thresholds corresponding to higher dimensions, which is pivotal for advancing practical quantum communication systems capable of operating in noisy environments.

Experimental Implications

From an experimental viewpoint, the findings offer promising implications for quantum communication technologies, particularly in scenarios involving long-distance or free-space transmission where ambient noise is prominent. The ability to certify entanglement via high-dimensional encodings under noisy conditions broadens the feasibility of deploying quantum systems beyond laboratory settings.

The paper also addresses the interplay between additional noise due to increased complexity in measurement setups and the resilience offered by high-dimensional states. The practical quantum communication protocols emerging from both identified pathways have the potential to surpass current noise limitations while maintaining device independence.

Theoretical Implications and Future Prospects

Theoretically, this research contributes to a deeper understanding of quantum information capacity in high-dimensional quantum systems. As high-dimensional entangled states display enhanced noise resistance, they challenge conventional paradigms in quantum communication, urging the development of high-dimensional protocols tailored to exploit this attribute.

Future investigations could focus on optimizing the trade-offs between dimensionality and noise resilience to identify the most effective practical implementations. Moreover, extending the search for MUBs in non-prime dimensions could significantly optimize communication protocols, paving the way for more robust quantum networks.

In conclusion, the paper lays a strong foundation for future work in quantum entanglement distribution, highlighting the transformative potential of high-dimensional quantum information. Researchers and practitioners in the field are poised on the brink of substantial advancements in overcoming noise-related challenges in quantum communication systems.