We live in an information age where digital communication has become a lifeline for our businesses. Optical fibres are the backbone of our modern information networks. Long-range communication over the internet and high-speed information transfer within data centres take place over optical fibres.
Fibre networks, due to their structure and form, are prone to vulnerabilities. Information transfer can be compromised when things go wrong. Physicists at the University of Bath in the UK have developed a new kind of fibre designed to enhance the robustness of networks. This robustness can be important in the coming age of quantum networks.
The new optical fibres are fabricated using the mathematics of topology. They are easily scalable; the structure of each fibre can be preserved over thousands of kilometres.
In ordinary networks, light travels through the core of the fibre. The path taken by an optical fibre as it criss-crosses the landscape isn’t straight and undisturbed; turns, loops, and bends are the norm. Distortions in the fibre cause information to degrade as it moves through the channel.
The fibre designed by the Bath team deploys topological ideas by including several light-guiding cores in a fibre, linked together in a spiral. Light can hop between these cores but becomes trapped within the edge due to the topological design. These edge states are protected against disorder in the structure.
Conventional light sources for fibre-optic telecommunications emit many photons at the same time. In existing telecommunication networks, information is transmitted by modulating the properties of light waves travelling in optical fibres. In quantum communication, however, information is encoded in the phase of a single photon, the photon’s position in the wave in which it travels. This makes it possible to connect quantum sensors in a network spanning great distances and to connect quantum computers. Single-photon sources with operating wavelengths compatible with existing fibre communication networks have been developed.
The new fibres make it possible to integrate quantum light sources made of two-dimensional materials into communication networks. In addition, the two-dimensional nature of the material makes it easy to construct devices layer by layer. It helps integrate these light sources into emerging quantum computers to construct larger, modular computing systems and achieve quantum advantage for practical applications.
Quantum networks are expected to play an important communication role in the future. Quantum technologies can store and process information in more powerful ways than 'classical' computers can today, as well as send messages securely across global networks without any chance of eavesdropping.
But the quantum states of light that transmit information are easily impacted by their environment and finding a way to protect them is a major challenge. The new fibre optic networks can be a step towards maintaining quantum information in fibre optics using topological design.
Exciting times are ahead for quantum networks!