Quantum research at Paderborn University: From fundamentals to practical application
Quantum technologies are changing our lives. Research into the smallest energy particles (known as quanta) puts us tantalisingly close to opportunities that were long considered to be out of reach. New concepts are providing solutions to the key challenges of our time: for complex interactions relating to resource efficiency as part of the energy revolution, improved traffic flows thanks to real-time data, or eavesdropper-proof communications via quantum encoding.
Quantum physics appears to turn the laws of nature on their head. Although it is one of the fundamental pillars of modern physics, it can often seem mystifying: take entangled particles that have a form of long-distance relationship, the difficulty of measuring them, or the fact that they can be in several states at once. Nevertheless, quantum physics is already playing a key role in everyday life, from atomic clocks to lasers to magnetic resonance imaging (MRI) – all inventions that would have been impossible without it.
Small Particles, Big Impact
To understand the bigger picture, we enter the world of the very smallest particles – photons. These are particles of light that make up electromagnetic radiation. They form the basis for a range of quantum technologies and, thanks to their special properties, are considered key drivers of a revolution in data transmission and processing.
At Paderborn University, researchers have been studying these tiny packets of energy for many years. As part of the Collaborative Research Centre (CRC) Tailored Nonlinear Photonics, funded by the German Research Foundation (DFG), they are working on opening up new pathways in information and communication technology through the manipulation of light. The aim of this collaborative project with TU Dortmund University is to make data transmission safer and more efficient through photonics.
Custom photons
Working with photons has its challenges. The common sources used to produce these tiny particles are still relatively imprecise. However, as their targeted manipulation is one of the most important key elements of quantum technologies, (further) fundamental research in the field is vital. Physicists at Paderborn University have been continually working to develop innovative concepts for individual photons with tailored properties. This enables them to manipulate the shape of photons, their energy content and the information they transmit. Specifically, the technology is used in areas such as quantum cryptography.
Quantum research in Paderborn
Paderborn plays host to quantum research at the highest level. Thanks to proven experts in different subject areas (with physicists joined by computer scientists, engineers and mathematicians in particular), all of the necessary resources are joining up to undertake fundamental research and put its findings into practice – projects decisively shaping and accelerating quantum research in Germany and beyond. At the university and in particular its Institute for Photonic Quantum Systems (PhoQS), researchers in the fields of physics, mathematics, electrical engineering and computer science are seeking to establish a nationally and internationally leading centre for photonic quantum technologies. For example, in the ‘Photonic Quantum Computing (PhoQC)’ potential area, researchers are striving to develop an interdisciplinary approach to creating a photonic quantum computer.
Controlling light with light
Quantum computing: looking forward
Paderborn’s researchers are also working to develop scalable methods for quantum system control.. These enable the sources of individual photons to be precisely controlled using ultrafast electronics. However, these are also particularly interesting to explore as they are a prerequisite for something being worked on by big players in the technology and IT sectors: they form the basis for ‘quantum computers’. These are special computers that differ from traditional computers in that instead of using bits, they work on the basis of quantum mechanical states.
Quantum computers are one of the key future technologies of the 21st century, with their potential exceeding even that of the best supercomputers. As high-performance tools, they can solve even the most complex of computational problems – tasks that push traditional hardware and software to their limits and beyond.
In the future, Paderborn will play host to every step in this process, from fundamental research into new quantum algorithms to large, complex quantum systems to real photonic quantum networks for relevant computing applications. Together with partners from science and industry (in Germany and worldwide), the researchers are working on projects such as chips for photonic quantum computers. Areas of potential application include the chemical industry, drug discovery and materials science.
Photon entanglement: a special kind of long-distance relationship
Researchers at Paderborn University have recently developed the first programmable optical quantum memory based on so-called entangled pairs. In doing so, they have taken a significant step towards useful quantum technologies. In the experiments, the physicists stored a quantum state until the next one was generated - until now, this was an almost insurmountable hurdle. The work could therefore lay the foundation for ever larger entangled quantum states.
Entangled systems consisting of several quantum particles offer decisive advantages for realising quantum algorithms. Instead of a single state resulting from the conditions of a photon, an overall system of several states is created. A state corresponds to information that is transmitted or further processed. Such systems are used in communication, data security and quantum computing.
Albert Einstein called it a "spooky action at a distance": tiny particles that are connected to each other even though they are sometimes separated by thousands of kilometres. In the phenomenon of entanglement, certain properties of photons are coupled together. In concrete terms, this means, for example, that two photons, each with half the original energy, are created from one photon with a high energy content. These two particles, also known as a photon pair, are entangled with each other and have the same properties. They become twins, so to speak. This makes them particularly suitable candidates for further experiments and applications.
Researchers for tomorrow’s world
The race for technological leadership in the quantum sector has long been under way. It is therefore vital to train specialists in this future-oriented field and open up applications for business and large-scale industry. Given this, Paderborn University is working to train a new generation of exceptional researchers in the field of quantum computing. Corresponding study programmes are already available in various departments. The targeted combination of various different core competencies will enable Paderborn researchers to systematically develop the research field of photonic quantum computing and create new interactions that go far beyond the capacities of the individual disciplines. The establishment of new structures transferring topics from fundamental physics research into computer science and engineering research activities is unique in Germany’s research landscape.
Despite all the progress that has been made, there is still a long way to go before an application-specific quantum computer is actually produced. Key questions remain open and solutions are often only just beginning to emerge. Paderborn’s researchers are working hard to change this.