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Scientists Harness Twisted Light to Boost Quantum Communication Speeds

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  Published in Science and Technology on Tuesday, December 2nd 2025 at 20:49 GMT by Phys.org

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Scientists Advance Quantum Signaling with Twisted Light Technology

In a breakthrough that could reshape the future of secure communications, a team of physicists has demonstrated that quantum information can be transmitted more efficiently and securely using “twisted light.” The research, detailed in a recent article on MSN’s technology news portal, shows how photons that carry orbital angular momentum (OAM) can be harnessed to encode and send quantum states over free‑space links, opening new avenues for quantum networks and quantum key distribution (QKD).

What is Twisted Light?

Unlike ordinary light, which has a uniform phase front, twisted light carries a helical or “vortex” phase structure. This means that as the beam propagates, its phase twists around the axis of propagation, giving each photon a discrete amount of angular momentum. The amount of twist—quantified by an integer called the topological charge—provides a natural basis for encoding information in multiple dimensions. In the language of quantum information, such photons can be treated as “qudits” (quantum digits) rather than simple qubits, dramatically expanding the data that can be carried in a single photon.

The Experiment

The researchers generated entangled photon pairs using spontaneous parametric down‑conversion (SPDC) in a nonlinear crystal. One photon of each pair was kept locally, while the other was converted into a twisted state by passing it through a spatial light modulator (SLM). The SLM imprinted the desired OAM onto the beam, creating a superposition of several OAM modes. The twisted photons were then transmitted through a 1‑km free‑space channel—a challenging environment where atmospheric turbulence and scattering typically degrade quantum signals.

On the receiving end, a mode‑sorting interferometer dissected the incoming beam, projecting it onto a set of orthogonal OAM basis states. By measuring coincidences between the local and remote detectors, the team verified that the entanglement survived the transmission with a fidelity exceeding 95 %. This high fidelity is critical for any practical quantum communication system, as it guarantees that the transmitted quantum state remains intact and uncorrupted.

Why Twisted Light Matters

1. Higher Dimensionality

Traditional QKD protocols encode information in two polarization states, limiting the amount of data per photon. With twisted light, each photon can carry multiple bits by occupying a higher‑dimensional OAM space. The experiment demonstrated successful encoding in a four‑dimensional basis, effectively doubling the data throughput compared to conventional polarization‑based protocols.

2. Resilience to Turbulence

The helical phase fronts of twisted photons are less susceptible to atmospheric distortions. The researchers found that the turbulence‑induced crosstalk between adjacent OAM modes was significantly lower than that observed in polarization‑based systems. This robustness is essential for long‑distance free‑space links, especially in urban or outdoor environments.

3. Enhanced Security

Higher‑dimensional entanglement makes eavesdropping attempts more difficult. An interceptor would need to determine the exact OAM state of each photon, a task that becomes increasingly infeasible as the dimensionality rises. The team quantified this security advantage by estimating the quantum bit error rate (QBER) for potential eavesdroppers; the QBER exceeded 25 % in their high‑dimensional protocol, far above the acceptable threshold for secure key generation.

Practical Implications

The immediate application of this research lies in quantum key distribution, the cornerstone of quantum‑secure communications. By integrating twisted‑light encoding into existing QKD protocols, networks could achieve higher key rates and longer transmission distances without the need for complex active stabilization systems.

Beyond QKD, the same technology could enable quantum teleportation of high‑dimensional states. Teleportation is the process by which a quantum state is transmitted from one location to another, using entanglement and classical communication. Twisted photons, with their rich mode structure, can carry more complex quantum information, making teleportation more efficient.

The researchers also highlight the potential for satellite‑based quantum networks. Free‑space links from ground to orbit are susceptible to turbulence, but twisted light’s resilience could help maintain entanglement over the thousands of kilometers required for satellite links. A future quantum internet would likely rely on a hybrid architecture combining fiber‑based and free‑space links; twisted light offers a promising bridge between the two.

Future Directions

While the experiment showcased a clear advantage of twisted light, several challenges remain:

• Mode Crosstalk in Long‑Distance Links: Even with turbulence‑resistant OAM modes, longer propagation distances will introduce more scattering. The team plans to test the protocol over distances exceeding 10 km and to develop adaptive optics solutions to further mitigate crosstalk.

• Integration with Fiber: Conventional fibers scramble OAM modes, but special “few‑mode” or “mode‑multiplexed” fibers can preserve them. The researchers are collaborating with fiber‑manufacturing groups to develop low‑loss, OAM‑friendly fibers that could enable metropolitan‑scale quantum networks.

• Quantum Repeaters: For global coverage, quantum repeaters will be essential to overcome exponential photon loss. Integrating twisted‑light entanglement with quantum memories—devices that can store photonic states—is an active area of research.

Conclusion

The article from MSN’s technology section captures a pivotal moment in quantum communication research. By harnessing the unique properties of twisted light, scientists have taken a significant step toward more robust, high‑capacity, and secure quantum networks. As the quantum internet moves from laboratory demonstrations to real‑world deployment, technologies like OAM‑based quantum signaling will likely play a central role in delivering the next generation of secure communications.