Quantum materials

Quantum materials such as semiconductors and superconductors, which were discovered in the last century, are already used today in lasers, smartphones, solar cells, and particle accelerators. Now, these materials are to be used to develop further technologies such as quantum computers and quantum sensors. To this end, Jülich researchers are optimizing existing materials and developing new ones.

Complex and sensitive

Jülich physicist Dr. Markus Jerger preparing to measure the quantum mechanical state of qubits. Copyright: Forschungszentrum Jülich/Ralf-Uwe Limbach

However, finding suitable quantum materials for these new technologies is anything but easy. The quantum phenomena that give materials their special physical properties are complex, and the underlying quantum states are extremely sensitive.

To complicate matters further, unlike established technologies, the quantum states must be controlled in a very targeted manner if they are to be used to store information, for example. For a limited number of qubits – the computing units of quantum computers – this has already been achieved with semiconductors and superconductors. But in order to realize quantum computers with millions of qubits in the future, either the materials used today must be further optimized or completely different ones must be developed.

Sights set on exotic particles

At Jülich, researchers are investigating and developing quantum materials that reveal their properties under extreme conditions such as ultra-low temperatures or strong magnetic fields. A well-known example for which low temperatures are necessary is the quantum phenomenon of superconductivity. In this case, current flows below a critical temperature without electrical resistance. Another class of materials that are still relatively new are topological insulators. On the surface of these insulators, electrons move depending on their electron spin, while the material in the interior behaves like an electrical insulator.

Chip with hybrid qubits. Made of two quantum materials, these hybrid qubits are considered to be significantly more stable than semiconducting or superconducting qubits, which are sensitive and therefore prone to errors.Copyright:— Forschungszentrum Jülich/Ralf-Uwe Limbach

As an example, Jülich researchers were the first to succeed in integrating a topological insulator into a conventional superconducting qubit. These results are an important step on the way to realizing what are known as Majorana qubits. This type of qubit is regarded as a particularly promising candidate. Made of two quantum materials, these hybrid qubits are considered to be significantly more stable than semiconducting or superconducting qubits, which are sensitive and therefore prone to errors.

Top-class facilities

Prof. Ruslan Temirov and his team developed the Jülich quantum microscope. Copyright: Forschungszentrum Jülich/Sascha Kreklau

In their targeted search, Jülich researchers rely on theoretical models and calculations as well as on experimental testing of the materials. To enable this, Jülich offers unique technology laboratories such as the Helmholtz Nano Facility (HNF), where scientists can produce quantum chips, for example. In addition, construction began two years ago on the Helmholtz Quantum Center (HQC), which covers the entire spectrum of quantum computing research – from the exploration of quantum materials to the development of prototypes.

Many other facilities are also available, from supercomputers to neutron sources and special electron microscopes. Jülich researchers are also developing new instruments such as the quantum microscope, a unique scanning tunnelling microscope for investigating quantum effects.

Last Modified: 18.08.2022