Is quantum physics possible

In the first third of the 20th century, physicists such as Max Planck, Albert Einstein, Erwin Schrödinger and Werner Heisenberg put our understanding of nature on a new basis. With quantum mechanics, a theory emerged that puts the human imagination to the test. Her masterminds were amazed and distraught at the same time. In thought experiments they tried to illustrate the paradoxical consequences of the new theory. In the most famous, Schrödinger describes a cat that - if one follows the laws of quantum physics - is alive and dead at the same time. As absurd as such considerations may seem, quantum theory is now regarded as a central achievement of modern natural sciences. It has revolutionized our worldview.

Quantum physics has been causing a second revolution for around twenty years. Scientists keep showing with new experiments: We can use the crazy world of quantum physics to do useful things with it that we were not able to do with classical physics. Today, highly sensitive quantum sensors make it possible to measure magnetic fields faster and more precisely than ever before. In the near future, quantum physics could make tap-proof communication channels possible. Medical diagnostic devices such as magnetic resonance tomography based on the laws of quantum physics had already been developed earlier.

A calculator for completely new questions

Quantum physics has breathtaking innovation potential. Against this background, physicists at the University of Basel are pursuing the vision of a computer that makes use of the laws of quantum mechanics.

A quantum computer can perform a large number of arithmetic operations in parallel; it is therefore unimaginably fast and within hours solves problems for which today's supercomputers would need billions of years. While current top computers contain a billion transistors, a quantum computer would have a billion quantum bits (qubits). While classic bits can only have the state 0 or 1, qubits can be used to define more than just two states. Their sheer computing power could in the future enable answers to questions that we previously did not even dare to ask. It is conceivable, for example, that we can create molecules and thus materials with previously unknown properties: for example, novel active pharmaceutical ingredients. Or superconductors for the loss-free transport of electricity at room temperature. Or chlorophyll-like substances that convert sunlight into usable energy. Up until now, innovative substances were discovered by chance. Thanks to quantum computers, scientists will be able to specifically design materials with desired properties in the future.

The quantum computer is a great promise. First-class research teams from Harvard to Tokyo are working on its implementation. One of the foundations of their work is an idea that the physicist Daniel Loss formulated twenty years ago: The angular momentum (spin) of individual electrons should be used as the smallest information carrier in a quantum computer. Such qubits are considered promising candidates for building a quantum computer in laboratories around the world.

The originator of the idea, Daniel Loss, works in Basel. Here he devotes himself to the development of a Basel qubit. This qubit made of a semiconductor material is extremely small and fast. Silicon is a well-tested material for computer chips, so silicon qubits have decisive advantages over other qubit concepts. The development of a qubit is the overriding objective of Basel physics. Twelve professors are working towards this common goal with the know-how of their research teams.

Basel researchers run in the top group

So that there is no misunderstanding: The Department of Physics at the University of Basel is not an industrial laboratory that will build a quantum computer over the next few months and years. We do basic research. Such research takes a lot of time, but it has the potential to produce real innovations.

As a reminder: after the transistor was discovered in 1947, half a century has passed before personal computers and mobile phones found their way into our everyday lives and plowed up our working world. The marathon with a view to the quantum computer has only just begun. Companies such as Microsoft, Google and Intel rely on the quantum computer today because they realize that the increasing miniaturization of the classic CMOS chip is reaching its limits. Basel has the ambition to run in the top group.

So far we are well on our way. Basel physicists have received eight of the renowned ERC grants from the European Research Council in recent years, the last two from our professors Jelena Klinovaja and Ilaria Zardo. The funding commitments attest that our research is of the highest quality.

The luminosity of quantum research in Basel attracts many young researchers. The “Quantum Computing and Quantum Technologies” doctoral school, which currently brings together 20 doctoral students, has existed since autumn 2016. Also thanks to the generous support of the Georg H. Endress Foundation, we will be able to set up a cross-border postdoc cluster with the University of Freiburg from January 2018. Ten additional scientists will use it to work in the field of quantum computing. This initiative is based on the model of US foundations that fund postdocs at top research locations.