By Rosa Nan Von Leunbach
About 100 years ago, Niels Bohr established his Institute for Theoretical Physics, turning Denmark into an international hotspot for the new quantum mechanics. At that time, the University of Copenhagen and DTU - or the Polytechnical Institute, as DTU was called back then - were closely connected and located in the same place. Science had played a central role in Denmark's development from an agricultural to an industrial country, and there were high expectations for new technologies even then. However, Bohr's Institute broke away from the close connection to DTU, and quantum mechanics was allowed to develop independently: a theoretical field far from technology and engineering. It was about understanding quantized energy and the peculiar phenomena that occur at subatomic levels.
The first quantum technologies
Quantum mechanics found its way back into technology, aided by the collaboration between military, industry, and universities that characterized the post-World War II era. With quantum mechanics as a solid theory, there was a basis for developing the first quantum technologies: both the semiconductor transistor, the microchip, and the laser are examples of technologies built on the understanding that energy is quantized.
Research in quantum technology was also set to take place at DTU's new campus in Lyngby, which, upon its construction in 1960, was the largest consolidated educational building in Denmark's history. The significant investment in engineering education made room for new disciplines, including cipher technology, which today would be called programming, and solid-state physics, which specifically deals with the quantum mechanical properties of materials. At the new campus, they aimed to be at the forefront of technological development, establishing modern laboratories to study the new semiconductor materials. The new research also demanded more computing power, and DTU acquired its first computer - one that filled an entire room.
However, the rapid development of the microchip made computers both smaller and cheaper. With the many transistors that could be either on or off, microchips could store more and more digital information in less and less space. However, a new information technology emerged: in 1975, DTU offered its first course in optical communication. Here, it was light, not transistors, that could be on or off and even communicate over long distances. DTU's researchers began developing optical fibers, giving rise to an industry and a lucrative export adventure that would extend to the bottom of the sea, where undersea cables transport phone calls and internet.
A new way of computation
Quantum mechanics had found significant application in technologies that process information in the form of on and off units - in the form of 0s and 1s. However, the great mysteries of quantum physics - how particles can exist in multiple places at once (superposition) and communicate without being in contact (entanglement) - did not seem to offer significant practical applications, neither at DTU nor in the international scientific community. That was until the famous physicist Richard Feynman presented a new idea in 1983 that had taken shape among a few visionary researchers: to use quantum states, which can be both on, off, and something in between, for information technology. However, it was pure speculation without any suggestion of how the technology would work since isolating a quantum system from its surroundings is notoriously difficult.
Classical bits takes center stage
In the 1980s, the focus was largely on classical information technology and the great potential within microelectronics and fiber communication. DTU heavily invested in both hardware, software, and numerous computer bits. The research landscape also began to change as the world opened up, and information technology itself presented new research opportunities. International collaboration became more and more prevalent, and DTU's traditional laboratory structure was reevaluated. For instance, the research center MIDIT (Models, Nonlinear Dynamics, and Irreversible Thermodynamics) was established, bringing together research across the fields of physics, chemistry, and mathematics to a.o. study quantum effects at very low temperatures, where isolating systems is easier. In fact, all the fundamental tools for developing a quantum computer were assembled in this interdisciplinary center. However, this was not known at the time, and perhaps the idea of a quantum computer was not as interesting at the time?
The race for quantum technology begins
In the 1990s, the newly digitized world was shaken by Shor's algorithm, which demonstrated that a quantum computer, in theory, could be so fast that it could break the encryption used to protect digital information throughout society. This sparked a race to gain control over quantum particles. The first research results were published just before the turn of the millennium: MIT researchers succeeded in performing calculations with two so-called quantum bits, which, however, remained isolated for only a few nanoseconds. New proposals for more scalable quantum hardware emerged, such as superconducting circuits and ion traps, and the very first Ph.D. project at DTU in quantum information technology investigated optical quantum systems, where light functioned as quantum bits.
By 2005, the international record stood at eight quantum bits, and quantum technology began to take shape as an actual field of technology. This was also evident at DTU, where a research section was established to bring together existing research in optics and superconductivity with a common focus on fundamental research in the new generation of quantum technology. Although it was still relatively small compared to more mature technologies like nanotechnology, supercomputers, and AI, there were advantages to having shared research infrastructure, such as cleanroom laboratories.
Quantum technology 2.0
In the past 10 years, industry, authorities, and universities have truly embraced quantum information technology. Tech giants like Microsoft, Google, and IBM are competing to have the fastest quantum computer with the greatest computational power and the best error correction. IBM has even launched an online platform where ordinary people can work with superconducting quantum bits. The Danish Parliament has included quantum technology in the national budget and is preparing a national quantum strategy. DTU has also strengthened its position by becoming part of the new Danish NATO Center for Quantum Technology. The center, Quantum DTU, has been established as a gateway for researchers at DTU who, in one way or another, work on the new generation of quantum technology from almost a third of the university's departments. Although the development of quantum computers is comparable to where classical computers were in the 1950s, quantum mechanics, with its nearly 100 years of history, is now a mature field, and many researchers experience that the technological development has suddenly accelerated in recent years.
