Modern information networks rely on optical fibres as their backbone. From long-distance Internet communication to high-speed data transfer within data centres and stock exchanges, optical fibre remains indispensable in our globalized society. However, fiber networks are not architecturally flawless, and information transit can be impeded if something goes wrong. To solve this issue, physicists from the University of Bath in the United Kingdom have invented a new type of fiber intended to increase the network’s resilience. In the upcoming era of quantum networks, this resiliency could prove to be very crucial.
Using the mathematics of topology, the team has created optical fibres (the flexible glass conduits through which data is transported) that can safeguard light (the medium through which data is transmitted). Moreover, these modified fibres are easily scalable, which means that the structure of each fibre may be maintained over thousands of kilometers. Optical fiber, which normally has a diameter of 125 m (equivalent to that of a thick hair), consists of a solid glass core surrounded by cladding. Light goes through the center, where it is reflected as though from a mirror. Turns, loops, and bends are the standard for an optical fiber’s journey as it traverses the landscape. As information travels from source to receiver, distortions in the fiber may impair the signal. “The difficulty was to construct a network that takes robustness into account,” said Nathan Roberts, a doctoral student in physics who conducted the study.
“When fabricating a fiber-optic cable, slight differences in the fibre’s physical structure are unavoidable. When the fiber is installed in a network, it can also become twisted and bent. To combat these variances and flaws, it is important that the fibre design process has a strong emphasis on robustness. This is where we discovered topological concepts to be valuable.” The Bath team employed topology, the mathematical study of quantities that remain unchanged despite continual alterations to the geometry, to design this novel fiber. Its concepts have already been implemented in numerous fields of physics study. By relating physical phenomena to constant numbers, it is possible to avoid the damaging effects of an unorganized environment. The fiber designed by the Bath team employs topological concepts by including many light-guiding cores spiraled within a single fiber. Light can bounce between these cores, but due to the topological architecture, it becomes stuck at the edge. These edge states are safeguarded from structural disorder.
Dr. Anton Souslov, a physicist at the University of Bath and the study’s theory lead, stated, “Using our fiber, light is less impacted by ambient disorder than it would be in a comparable system lacking topological design. By adopting optical fibers with a topological architecture, researchers will have the means to anticipate and prevent signal-degrading effects by constructing photonic systems that are fundamentally durable.” Dr. Peter Mosley, a physicist at the University of Bath and co-author of the study and experimental lead, stated, “Previously, scientists have applied the complex mathematics of topology to light, but here at the University of Bath we have a great deal of experience making optical fibres, so we combined the mathematics with our expertise to create topological fibre.” The team, which also consists of PhD student Guido Baardink and Dr. Josh Nunn from the Department of Physics, is currently seeking industrial partners to further develop their concept.
Dr. Souslov stated, “We are eager to assist people in constructing resilient communication networks and are prepared for the next step of this effort.” Mr. Roberts continued, “We have demonstrated that kilometers of topological fiber can be wound around a spool. We imagine a quantum internet in which data will be securely transferred across continents utilizing topological principles.” In addition, he mentioned that this study has consequences that extend beyond communications networks. “Fiber development is not only a technological problem, but also a fascinating scientific field in its own right,” he stated. Understanding how to construct optical fiber has led to the development of light sources ranging from a brilliant “supercontinuum” that spans the entire visible spectrum to quantum light sources that emit individual photons — single particles of light. In the coming decades, quantum networks are widely anticipated to play a significant technological role. Quantum technologies are capable of storing and processing information more effectively than ‘classical’ computers can today, as well as transmitting communications across global networks without the possibility of eavesdropping. However, the quantum states of light that transport information are quickly affected by their environment, and protecting them is a formidable challenge. Using topological design, this approach may be a step toward preserving quantum information in fiber optics.