Micro- and Nanoelectronics for Quantum Technologies

Rarely did experts agree so much: quantum technologies have what it takes to be a major "game changer". Among other things, they enable high-precision and high-performance sensor technology that is capable of recording brain waves more precisely, expanding the spectrum of microscopy or establishing physically secure communication links and new forms of encryption. Quantum computers are expected to easily solve problems that today's supercomputers fail at. This would make it possible to tackle demanding challenges in a wide variety of application fields, such as financial services, materials development, logistics and chemistry, in ways never before imagined.

The first quantum computers are already able to handle simple tasks, but they still suffer from a number of "child diseases". For example, external influences such as vibrations can throw the high-tech computers off course. The possibility of reading out or even manipulating qubits with the help of electromagnetic waves has also been an open flank of quantum computing so far.

Most ubiquitous quantum computers currently work only under special conditions in the Lab. They require a temperature lower than in space, must be cooled down to almost absolute zero of about minus 273 degrees, operate only under vacuum conditions and must be electromagnetically shielded.

The first European quantum computer, IBM Q System One, is located at the IBM site in Ehningen, Baden-Württemberg. With its 27 qubits, it is not one of the most powerful systems in the world today. But it is stable enough for industrial operation, while systems with more qubits are more like test systems. The Fraunhofer-Gesellschaft has had exclusive access to the computer since January 2021. On June 15,  2021, Q System One was inducted in a festive virtual ceremony. 

There are still some challenges to operate a quantum computer – and this is where micro- and nanoelectronics comes in as an enabler: If the components can be made ready for use in larger markets and outside laboratory environments by scaling, miniaturizing, reducing vulnerability to interference and lowering costs, the door to the world really is open for quantum computing. 

Fraunhofer EMFT focuses on bridging the gap between quantum technologies and conventional micro- and nanoelectronics. The aim of the R&D work is to optimize the scalability, integrability and individual addressability of the qubits. In the long term, this should enable the development of up to 1000 qubit systems as the basis for quantum computers.

At Fraunhofer EMFT, micro- and nanotechnologies are available for the production of qubit chips and systems with a focus on scaling and manufacturing. With the help of production-compatible process technologies, for example for coating and structuring the qubit chips, superconducting quantum circuits can be manufactured in larger quantities. In perspective, this could enable next-generation quantum computers with up to 500 qubits.

State-of-the-art integration technologies such as heterogeneous 3D integration can be used to integrate and miniaturize the qubit chips at wafer level in order to realize the smallest possible, high-performance and energy-efficient quantum systems.

The wide range of testing and analysis possibilities at Fraunhofer EMFT enable analysis and testing of the quantum chips at room temperature as well as in the 4K and 100mK range in order to check the quality of the chips and thus reduce the vulnerability to faults in the finished system.

Low-noise, shielded interconnects are essential to minimize heat dissipation during transmission of the multitude of sensitive signals. At Fraunhofer EMFT, reel-to-reel fabricated flexible low-noise interconnects for quantum computers can be produced with superconducting materials using lithography to minimize signal losses between the highly integrated qubit chip systems. Of particular interest are low-noise interconnects for microwave transmission lines and superconducting interconnects for thermal emission reduction.

In addition, Fraunhofer EMFT has the expertise and capabilities to design and develop ASICs, e.g. for signal processing with integrated fault correction and to realize an on-chip architecture for integrated optical/electrical control and readout of the quantum systems.

Fraunhofer EMFT is part of the Munich Quantum Valley (MQV). The new center for quantum research and technologies is based on a cooperation of university and non-university research institutions in Bavaria.