In 2007, a fourth group arrived on the scene: the topological insulators. These materials conduct electricity but only on their surface. Yet they conduct it extremely well. In their centre, however, they are insulators. Topological insulators belong to a growing family of new types of materials whose exotic properties are largely based on quantum physical effects. They are therefore referred to as quantum materials.

The newly approved Transregio-Collaborative Research Centre will advance the research and development of such materials in the coming years, which are considered the key to the development of ultra-fast quantum computers. Such computers make use of quantum mechanical effects to solve specific mathematical problems. Tasks for which today's computers need years could therefore be completed within a fraction of a second.

Quantum physical effects at room temperature

Quantum effects often only play a role in a world of very small things, as for example, at the molecular or atomic level. “The quantum computers available to date therefore require very elaborate techniques to manipulate individual atoms,” explains Augsburg physicist Prof. Dr István Kézsmárki, spokesperson for the new Transregio-Collaborative Research Centre.

The atoms usually have to be cooled down considerably. In this state, they can then be gripped with “tweezers” made of laser light and written with information. “The technologies required for this are highly complex,” says the physicist from the Institute of Experimental Physics at the University of Augsburg. “The systems are also susceptible to disruptive influences.” Even a very simple quantum computer therefore currently fills half a laboratory.

In comparison, quantum materials are much easier to handle. Here, certain quantum mechanical effects occur even when many atoms or molecules come together. “It is also conceivable that ma-terials could exhibit these phenomena at room temperature,” Kézsmárki emphasises. The Collabo-rative Research Centre is therefore searching for materials that could be suitable for use in future quantum computers.

Constraints simplify the search for new materials

Constraints play an important role in the search for new materials. They refer to cleverly implemented special rules imposed on a material. Although these rules initially act as strong limitations, they also rather interestingly lead to the generation of materials with new exotic properties, holding true to the principle that “less is more.” Only when the material satisfies the constraints does it exhibit the desired quantum phenomena. “By orienting ourselves to such constraints, we can more easily find materials with the relevant properties,” explains Kézsmárki. “Moreover, we hope that this will also allow us to produce new targeted quantum states.”

As part of their search, the physicists are focussing on materials that include topological insulators. As a further starting point, they are also looking at a second group of materials that form quantum spin liquids. “We also want to investigate how quantum materials behave when we bring them out of equilibrium by, for example, adding radiant energy,” says Kézsmárki. “We expect that they will then suddenly exhibit completely different and possibly also completely new properties.”

DFG funding underlines Augsburg’s scientific expertise

Prof. Dr Sabine Doering-Manteuffel, president of the University of Augsburg, views the funding grant as evidence of the university’s high scientific reputation in the promising field of quantum physics: “We are very proud that our Collaborative Research Centre proposal was approved,” she says. “The DFG's funding decision will lend even greater international visibility to the scientific expertise the University of Augsburg has to offer in this field.”

In the large-scale project entitled “Eingeschränkte Quantenmaterie” (Constrained Quantum Matter) scientists from a wide variety of different physical disciplines are cooperating together. Alongside with the University of Augsburg, TUM is a co-applicant, with Prof. Dr Frank Pollmann from TUM as deputy spokesperson.

In addition to the University of Augsburg and TUM, research groups from the University of Leipzig, the University of Tokyo, the Max Planck Institutes for Solid State Research (Stuttgart) and for Quantum Optics (Garching), the Walther-Meißner-Institute (Garching), and the Heinz Maier Leibnitz-Zentrum (Garching) are also involved.

Through the Collaborative Research Centres, the DFG funds particularly innovative, challenging, and long-term collaborative projects for a maximum of 12 years. A decision on further funding is made every four years. The University of Augsburg is coordinating the approved Transregio project and is also involved in three other Collaborative Research Centres.
The University of Augsburg is involved in three other Collaborative Research Centres:

The University of Augsburg is involved in three further Collaborative Research Centres/Transregio projects approved by the DFG:

• Collaborative Research Centre 1585 “Strukturierte Funktionsmaterialien für multiplen Transport in nanoskaligen räumlichen Einschränkungen” (University of Bayreuth, spokesperson: Professor Dr Jürgen Senker; representative at the University of Augsburg: Prof. Dr Fabian Pauly, Theoretical Physics)
• Collaborative Research Centre/Transregio 386 “HYP*MOL – Hyperpolarisation in molekularen Systemen” (Leipzig University, spokesperson: Professor Dr Jörg Matysik; also involved: TU Chemnitz; representative at the University of Augsburg: Dr. Christian Wiebeler, Computational Biology)

• Collaborative Research Centre 1389 “Überwindung der Therapieresistenz von Glioblastomen” (Heidelberg University, spokesperson: Professor Dr Wolfgang Wick; representative at the University of Augsburg: Prof. Dr Matthias Schlesner, Biomedical Informatics, Data Mining und Data Analytics)