According to a study published in Applied Physics Letters Quantum, physicists from the University of Bath have designed a new generation of customized optical fibers to address data transfer difficulties likely to emerge in the future age of quantum computing.
Bright light guided through an optical fiber manufactured at the University of Bath. Image Credit: Cameron McGarry
Quantum technologies promise to deliver unprecedented computational power, allowing scientists to solve hard logical issues, create new drugs, and provide unbreakable cryptographic solutions for secure communication. However, due to the solid cores of their optical fibers, today’s cable networks for transmitting information worldwide are likely to be suboptimal for quantum communications.
Unlike regular optical fibers, Bath’s specialized fibers contain a microstructured core made up of a complicated network of air pockets that span the length of the fiber.
The conventional optical fibers that are the workhorse of our telecommunications networks of today transmit light at wavelengths that are entirely governed by the losses of silica glass. However, these wavelengths are not compatible with the operational wavelengths of the single-photon sources, qubits, and active optical components, that are required for light-based quantum technologies.
Dr. Kristina Rusimova, Study Lead Senior Author and Lecturer, Department of Physics, University of Bath
Dr. Rusimova and her colleagues detail the innovative fibers created at Bath and other recent and prospective breakthroughs in the growing field of quantum computing in the study.
Dr. Rusimova added, “Optical-fiber design and fabrication is at the forefront of the University of Bath Department of Physics research, and the optical fibers we are developing with quantum computers in mind are laying the foundations for the data transmission needs of tomorrow.”
Quantum Entanglement
Light is a viable medium for quantum computation. Individual light particles, known as photons, have unique quantum characteristics that quantum technologies can exploit.
One such instance is quantum entanglement, in which two photons separated by a significant distance can immediately affect one other’s properties and hold information about one another. Pairs of entangled photons could exist simultaneously as both a one and a zero, releasing vast amounts of computational power, in contrast to the binary bits of traditional computers, which can only be one or a zero.
A quantum internet is an essential ingredient in delivering on the vast promises of such emerging quantum technology. Much like the existing internet, a quantum internet will rely on optical fibers to deliver information from node to node. These optical fibers are likely to be very different to those that are used currently and will require different supporting technology to be useful.
Dr. Cameron McGarry, Study First Author and Postdoctoral Research Associate, University of Sydney
In their perspective, the researchers explore the inherent issues of the quantum internet from the standpoint of optical fiber technology and provide several viable solutions for the scalability of a robust, large-scale quantum network.
This includes the specialty fibers that will enable quantum repeaters to be directly incorporated into the network, extending the range over which this technology can function and the fibers that will be utilized for long-range communication.
Beyond Connecting Nodes
They also demonstrate how specialty fibers can perform quantum processing at network nodes by serving as sources of entangled single photons, quantum wavelength converters, low-loss switches, or vessels for quantum memory.
Dr. McGarry added, “Unlike the optical fibers that are standardly used for telecommunications, specialty fibers which are routinely fabricated at Bath have a micro-structured core, consisting of a complex pattern of air pockets running along the entire length of the fiber. The pattern of these air pockets is what allows researchers to manipulate the properties of the light inside the fiber and create entangled pairs of photons, change the color of photons, or even trap individual atoms inside the fibers.”
Dr. Kerrianne Harrington who is a Postdoctoral Researcher in the Department of Physics, added, “Researchers around the world are making rapid and exciting advancements in the capabilities of microstructured optical fibers in ways that are of interest to industry. Our perspective describes the exciting advances of these novel fibers and how they could be beneficial to future quantum technologies.”
Dr. Alex Davis, an EPSRC Quantum Career Acceleration Fellow at Bath, added, “It is the ability of fibers to tightly confine light and transport it over long distances that makes them useful. As well as generating entangled photons, this allows us to generate more exotic quantum states of light with applications in quantum computing, precision sensing, and impregnable message encryption.”
The quantum advantage, or a quantum device’s ability to accomplish a task more effectively than a traditional computer, has yet to be shown decisively. The technological challenges mentioned in the viewpoint are expected to open up new lines of quantum research, bringing us closer to reaching this significant milestone. The optical fibers are expected to help create the groundwork for future quantum computers.
Bath’s study team also featured senior lecturer Dr. Peter Mosely.
Journal Reference:
McGarry, C., et. al. (2024) Microstructured optical fibers for quantum applications: Perspective. Applied Physics Letters Quantum. doi:10.1063/5.0211055