Quantum teleportation coexisting with classical communications in optical fiber (2404.10738v4)

Abstract: The ability for quantum and conventional networks to operate in the same optical fibers would aid the deployment of quantum network technology on a large scale. Quantum teleportation is a fundamental operation in quantum networking, but has yet to be demonstrated in fibers populated with high-power conventional optical signals. Here we report to the best of our knowledge the first demonstration of quantum teleportation over fibers carrying conventional telecommunications traffic. Quantum state transfer is achieved over a 30.2-km fiber carrying 400-Gbps C-band classical traffic with a Bell state measurement performed at the fiber's midpoint. To protect quantum fidelity from spontaneous Raman scattering noise, we use optimal O-band quantum channels, narrow spectro-temporal filtering, and multi-photon coincidence detection. Fidelity is shown to be well maintained with an elevated C-band launch power of 18.7 dBm for the single-channel 400-Gbps signal, which we project could support multiple classical channels totaling many terabits/s aggregate data rates. These results show the feasibility of advanced quantum and classical network applications operating within a unified fiber infrastructure.

• The paper demonstrates quantum teleportation on a 30.2‐km optical fiber co‐carrying 400-Gbps classical signals using a Bell state measurement protocol.
• It employs wavelength division multiplexing and narrow spectro-temporal filtering to mitigate spontaneous Raman scattering and maintain high quantum state fidelity.
• The findings pave the way for integrating quantum networks with existing telecom systems, enabling scalable quantum communication alongside terabit-scale data rates.

Quantum Teleportation Coexisting with Classical Communications in Optical Fiber

The paper "Quantum teleportation coexisting with classical communications in optical fiber" presents notable advancements in the integration of quantum and classical communication within shared optical fiber infrastructure, specifically by achieving quantum teleportation in a context that simultaneously handles conventional data traffic. This research marks a meaningful development in the practical application of quantum networks by demonstrating their operation over existing telecom infrastructure, an essential step for scalable quantum network deployment.

Summary of Key Contributions

Experimental Setup and Methodology

The authors detail a pioneering demonstration of quantum teleportation conducted over a 30.2-kilometer fiber that is simultaneously carrying high-power 400-Gbps classical signals. Quantum state transfer is realized through a quantum teleportation protocol involving a Bell state measurement (BSM) at the midpoint of the fiber. The paper employs wavelength division multiplexing (WDM) to facilitate the coexistence of quantum and classical channels within the same infrastructure. To alleviate issues surrounding spontaneous Raman scattering (SpRS), which poses significant noise challenges to quantum signal detection, the quantum signals utilize optimal O-band channels combined with narrow spectro-temporal filtering.

Results and Performance

Through this setup, the authors demonstrate that quantum teleportation can maintain a high fidelity of state transfer, even in the presence of classical traffic with launch powers up to 18.7 dBm. This empowerment could feasibly support classical data rates aggregating to several terabits per second, confirming the robustness of this approach for contemporary high-data-rate environments.

The reported quantum teleportation process entails usage of heralded single photons for polarization-encoded qubits and evinces high Hong-Ou-Mandel (HOM) interference visibility, signifying low decoherence and high indistinguishability of quantum states despite co-propagation with conventional signals. This testifies to the effectiveness of the experimental design in preserving quantum coherence amidst noise from classical signal crosstalk.

Implications and Future Directions

Practically, this work indicates a path forward for integrating advanced quantum networking techniques, such as quantum repeaters and distributed quantum computing, within existing telecommunications setups. The successful teleportation over classical-fiber-carrying C-band data traffic projects substantial promise for near-term exploitation of current infrastructure in rolling out quantum communication technologies without new and exclusive fiber deployments.

On a theoretical level, the interplay between managing noise introduced from high-power classical signals and the preservation of quantum state fidelity remains paramount. While current approaches leverage O-band separation, the potential transition to C-band quantum channels—due to their lower loss in silica fibers—still requires innovative noise-suppression techniques and further exploration of high-dimensional entanglement to mitigate increased SpRS noise.

This research frames a compelling case for continuing to deepen the investigation into coexistent quantum and classical communication systems, driving forward the notion that the modernization of telecommunications may well accommodate the burgeoning needs of emergent quantum network applications. Future studies could focus on refining this integration approach further, particularly analyzing the benefits of engaging quantum memories, exploring different photon encoding schemes, and addressing the challenges of long-distance teleportation within such a dual-purpose infrastructure.