Probe on frozen wafer determines the quality of qubit devices for quantum computing and quantum sensing

Germany’s first cryogenic setup for measuring the statistical quality of qubit devices across 200 and 300 mm wafers has commenced operations at the Fraunhofer IAF. The wafer detector can characterize devices based on semiconductor quantum dots and quantum wells as well as superconductors at measuring temperatures below 2 K.

Fully automated operation will allow researchers to build quantitatively relevant databases and accelerate industrial production of high-quality devices for quantum computing and quantum sensing in Europe. Europe.

With the newly established frozen wafer probe, researchers at the Fraunhofer Institute for Applied Solids Physics (IAF) aim to better understand the workings of quantum dot-based devices. semiconductors and quantum wells as well as superconductors. The device can characterize wafers at industrial size (200 mm and 300 mm) and bulk (up to 25 consecutive wafers) fully automatically at cryogenic temperatures below 2 K (271,15°C).

The resulting datasets significantly reduce the dependence on random hits, which is characteristic of single measurements. In this way, the strengthening of metrological capacity at the institute contributes to the development of reliable production of high-quality qubits that can be used in quantum computers and quantum sensors.

At the time of operation, the facility was the fifth worldwide, the second in Europe and the first in Germany. The German Federal Ministry of Education and Research (BMBF) funded the procurement and installation of wafer probes as part of the project “KryoproPlus—Supply and verification of probes on frozen wafers” .

Development of industrial qubit production know-how

Professor Dr. Rüdiger Quay, KryoproPlus project coordinator and acting director of the Fraunhofer IAF Institute emphasized: “With the detector on the wafer, we gain new and unique possibilities for cryogenic properties worldwide. nation”. “With this system, we will support our research and industry partners in establishing Europe’s supply chain for materials and solid-state qubit production. This allows us to contribute to our contribution. important to German and European technological sovereignty,” Quay added.

Nikola Komerički, who is overseeing the KryoproPlus project as part of his doctoral thesis on the characterization of quantum computing devices. Komerički has coordinated the installation and commissioning of the system and is taking the first measurements.

“We wanted to better understand how to get good, homogeneous qubits to enable scaling and industrial qubit production in Germany and Europe,” adds Komerički. “To do that, it is necessary to expand the qualitative perspective to include a statistical, quantitative view of device behavior.”

Better data through automatic measurement of all 200 mm and 300 mm semiconductor wafers at temperatures below 2 K

Qubits are based on semiconductor quantum dots and quantum wells as well as superconductors that operate at temperatures near absolute zero (-273.15°C). This minimizes ambient interference, activating superconductivity and thus allowing the formation and entanglement of qubits. Accordingly, it is essential for qubit testing, optimization, and scaling that they be characterized at operating temperature and collect a statistically evaluable set of measurement data.

Probes on frozen wafers will close this property gap. Automatic measurement of the entire 200 mm and 300 mm wafer at temperatures below 2 K with short changeover times increases the amount of data available. This data provides researchers and engineers with the foundation needed to make targeted improvements to qubit-forming devices and increase scalability.

Characterization of qubit devices in the MATQu, QUASAR and QLSI . projects

With the wafer detector fully operational, the KryoproPlus project is complete. The first measurements of this facility are under the projects “MATQu—Materials for Quantum Computing”, “QUASAR—Semiconductor Quantum Processors with Conversion-Based Scalable Architecture” and “QLSI—Large-scale Quantum Integration with Silicon.”

For MATQu, Komerički is describing and analyzing Josephson (niobium) junctions, which are devices for transmon qubits. For QUASAR and QLSI, the field-effect transistor (FET) characteristics for single-electron transistors (SET) are based on silicon quantum wells and subsequently SETs that serve as devices for qubits. rotation is being performed.