According to a study published in Applied Physics Letters Quantum, physicists at the University of Bath have designed a new generation of customized optical fibres to tackle the data transmission challenges that may emerge in the future era of quantum computing.
Bright light guided through optical fibres manufactured at the University of Bath. Image credit: Cameron McGarry
Quantum technology promises to provide unprecedented computing power, allowing scientists to solve difficult logical problems, develop new medicines, and provide unbreakable encryption solutions for secure communications. But the current cable networks that transmit information around the world may not be ideal for quantum communication, because optical fiber has a solid core.
Unlike ordinary optical fibers, Bath’s special optical fiber contains a microstructured core made up of a complex network of air pockets that run the entire length of the fiber.
Traditional optical fibers, the workhorse of today’s communications networks, transmit light at wavelengths that are dominated entirely by the losses in silica glass. However, these wavelengths are incompatible with the operating wavelengths of the single-photon sources, qubits, and active optical components required for light-based quantum technologies.
Dr. Kristina Rusimova, lead author of the study and lecturer in the Department of Physics at the University of Bath
In their study, Dr Roussimova and her colleagues detail the innovative fibre developed at Bath and recent and future breakthroughs in the growing field of quantum computing.
Dr Rusimova added: “The design and manufacture of optical fibres is at the forefront of research at the University of Bath’s School of Physics and the optical fibres we are developing with quantum computing in mind will lay the foundations for future data transmission needs.”
Quantum entanglement
Light is a suitable medium for quantum computing: individual particles of light, called photons, have unique quantum properties that quantum technologies can exploit.
One such example is quantum entanglement, in which two photons separated by a large distance can instantly affect each other’s properties and retain information about each other. An entangled pair of photons can exist as both a 1 and a 0 simultaneously, enabling enormous computational power, as opposed to the binary bits of a classical computer, which can only be 1 or 0.
The quantum internet is a vital component in realizing the vast potential of these emerging quantum technologies. Like the existing internet, the quantum internet will rely on optical fibres to transmit information from node to node. These optical fibres may be significantly different from those in use today and will require different supporting technologies to function effectively.
Dr Cameron McGarry, lead study author and postdoctoral researcher at the University of Sydney
The researchers consider the inherent problems of the quantum internet from the perspective of fiber optic technology and provide some viable solutions for the scalability of robust, large-scale quantum networks.
This includes specialised fibre that would allow quantum repeaters to be built directly into the network, expanding the range over which the technology can operate, as well as fibre used for long-distance communications.
Beyond connecting nodes
They also demonstrate how specialized fibers can perform quantum processing at network nodes by acting as sources of entangled single photons, quantum wavelength converters, low-loss switches, or quantum memory containers.
Dr McCurley added: “Unlike standard optical fibres used for communications, the specialised optical fibres routinely manufactured at Bath have a microstructured core made up of a complex pattern of air pockets that run along the entire length of the fibre. These patterns of air pockets allow researchers to manipulate the properties of the light in the fibre, creating entangled pairs of photons, changing the colour of photons or even trapping individual atoms within the fibre.”
Dr. Kerriann Harrington, a postdoctoral researcher in the Department of Physics, added: “Researchers around the world are making rapid and exciting advances in the capabilities of microstructured optical fibers in ways that are of interest to industry. Our perspective illustrates the exciting advances in these new fibers and how they may benefit future quantum technologies.”
Dr Alex Davies, EPSRC Quantum Careers Acceleration Fellow at the University of Bath, added: “Fibers are useful because they can tightly confine light and transport it over long distances, allowing us to not only generate entangled photons but also more exotic quantum states of light for applications such as quantum computing, precision sensing and even unassailable message encryption.”
Quantum supremacy – the ability of quantum devices to perform tasks more efficiently than classical computers – has yet to be conclusively proven. The technical challenges mentioned in this opinion are expected to open up new areas of quantum research and bring us closer to achieving this important milestone. Optical fibers are expected to help lay the foundation for future quantum computers.
Bath’s research team also included senior lecturer Dr Peter Moseley.
Journal References:
McGarry, C., et. al. (2024) Microstructured optical fibers for quantum applications: A perspective. Applied Physics Letters Quantum. doi:10.1063/5.0211055
