In this joint project, Germany's leading scientists in the field of superconducting quantum circuits have teamed up to develop innovative concepts for the construction of an improved quantum processor. They aim to realize a quantum processor with improved quality based on new materials and manufacturing methods by the Karlsruhe Institute of Technology (KIT), tailor-made theoretical concepts of the Friedrich-Alexander University Erlangen Nürnberg (FAU), optimized control methods of the Forschungszentrum Jülichs (FZJ) and concepts for new architectures with higher connectivity at the Walther-Meißner-Institute (WMI – Bavarian Academy of Sciences and Technical University of Munich). In order to achieve this goal, semiconductor manufacturer Infineon will develop scalable manufacturing processes, while the Fraunhofer Institute for Applied Solid State Physics (IAF) in Freiburg is promoting the development of optimized chip packages. The processor performance will eventually be demonstrated using a specifically developed quantum algorithm at the WMI.

Improved technology for more powerful quantum computers

Quantum computers hold the promise to efficiently solve problems that are intractable with conventional computers. This includes, for example, the calculation of the properties of complex molecules for the chemical and pharmaceutical industry as well as the solution of optimization tasks, e.g. for manufacturing processes in the automotive industry or for calculations in the financial world. Already today, quantum computers have demonstrated their basic functionality by mastering small, specific problems. The long-term goal of a quantum computer that calculates exponentially faster than a classic computer, however, is still in the future. A suitable architecture for calculating practical problems can only be realized through fundamental improvements in both the hardware and the software.

Within the GeQCoS project, a quantum processor prototype is to be developed that consists of a few superconducting qubits with fundamentally improved components. In this technology the basic building blocks of a quantum computer, the quantum bits or qubits, are implemented by means of currents flowing without resistance in superconducting circuits. These currents are relatively robust to external interference and can retain their quantum properties over relatively long time scales. Together with reliable and scalable manufacturing methods, this has resulted in one of the leading quantum technologies that is already successfully used to build the first quantum processors.

The planned improvements concern, on the one hand, the qubit connectivity, the number of connections between the individual qubits, and the quality of the qubits to enhance the capability to quickly and efficiently produce the desired quantum states. 'By using new types of materials, we expect better reproducibility and a higher quality of the qubits,' says Prof. Ioan Pop (KIT). “We will also improve the manufacturing methods in order to avoid imperfections that effect on the quality of the qubits,” adds Prof. Alexey Ustinov (KIT).

The researchers pay special attention to the interplay between hardware and software, in which they develop algorithms that are ideally matched to the hardware, i.e. the type of qubits and operations as well as the existing connections between the qubits. 'This is the only way to make optimal use of the hardware resources currently available and in the near future,' says Prof. Hartmann (FAU). 'In particular, we will also develop more efficient and precise methods for characterizing the qubits and modeling the overall system,' adds Prof. Wilhelm-Mauch, who recently moved to Forschungszentrum Jülich and is working there with Prof. DiVincenzo and Dr. Bushev on setting up a quantum computing center. Ultimately, however, it is also important to lay the foundations for rapid industrialization and commercialization of quantum technology. This includes a reproducible production of scalable quantum circuits according to industrial standards. 'With its many years of experience in the manufacture of special semiconductor chips, Infineon can make a significant contribution to improving superconducting circuits. To achieve this goal, we can draw also on our quantum technology expertise in the field of ion traps, a second very promising quantum computer platform,' says Sebastian Luber from Infineon. In order to be able to control the highly sensitive quantum circuits accurately and at the same time shield them from the environment, optimized processor housings are being developed in the project. , Scaling to a large number of qubits and operating them at low temperatures also poses great challenges to the packaging technology. Here, however, we can very well adapt the existing tools from traditional fields and apply them to the field of quantum technologies ‘, mentions Sébastien Chartier (IAF).

A nucleus for future quantum computer development

The technologies developed within GeQCoS will not only lead to new scientific knowledge, but also strengthen the quantum ecosystem in Germany and Europe through close links with companies. A specific goal is to make the quantum processor available to first-time users both on the hardware and on the software level as early as possible. Thanks to numerous companies with strong research and development departments, Germany is in an ideal starting position to become a leading center for users and beneficiaries of quantum computing. With access to the processor developed in the project, companies in the quantum technology sector should be strengthened and new start-ups should be promoted.

In addition, the project may serve as the nucleus of the current federal initiative to build a quantum computer 'made in Germany'. The close association between science and industry is a clear commitment to the promotion of technology transfer and to the establishment of a Germany-wide network based on superconducting qubits. The orientation of the project at the interface between engineering, computer science and physics takes into account the interdisciplinary nature of the field of quantum information processing and serves as an important component of the German technology landscape for the training and further education of highly qualified scientists.

Press release from the Walther-Meißner-Institute WMI (German): Mit supraleitenden Qubits auf dem Weg zum Quantencomputer

The use of the photos is permitted exclusively in connection with this press release and under indication of the copyright.

GeQCoS is supported by the German Federal Ministry of Education and Research BMBF (Grant agreement number: 13N15680).