Dry 3He/4He dilution refrigerator with integrated superconducting magnet

• Subject Area: Condensed Matter Physics
• Term: Funded in 2025
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 563384148

Superconducting quantum sensors are a disruptive technology that, by exploiting quantum mechanical effects, increases the performance of sensors and detectors far beyond the limits of their classical counterparts. This enables the realization of experiments and applications considered impossible to achieve just a few years ago. For this reason, research groups worldwide are working intensively on the further development and application of superconducting quantum sensors for research, society, and industry. In this context, the research activities at the Institute for Micro- and Nanoelectronic Systems (IMS) at the Karlsruhe Institute of Technology (KIT) focus on the development of highly sensitive superconducting microcalorimeters and SQUID-based single-channel and multi-channel readout systems. These systems are intended for use in experiments such as investigating the neutrino mass using a future tritium-based experiment, searching for light dark matter using superfluid helium, or high-resolution X-ray spectroscopy at synchrotron light sources. A dry 3He/4He dilution refrigerator with an integrated superconducting magnet is required to develop, characterize, and apply superconducting quantum sensors at IMS. This cryostat should provide the operating temperatures needed for various detector and sensor technologies, ranging from 10 mK to 10 K. Additionally, it should offer the ability to evaluate the performance of the sensors or entire detector systems in magnetic background fields with flux densities up to 1 T. This is particularly relevant for experiments where the sensors must be placed in a magnetic background field due to application requirements, and magnetic shielding cannot be implemented. To meet the infrastructural conditions at the institute, the cryostat must not rely on liquid helium or liquid nitrogen for precooling and continuous operation. Therefore, the dilution cryostat should have a high-performance pulse tube cooler and an internal cold trap for the mixture circulation. Furthermore, for applications at synchrotron light sources, it must offer the capability to decouple the so-called booster unit from the rest of the mixture circulation system. Lastly, it must provide the option to install a sidearm for detector applications or couple photons and massive particles from external sources into the cryostat.

• DFG Programme: Major Research Instrumentation
• Major Instrumentation: Trockener 3He/4He-Verdünnungskryostat mit integriertem supraleitendem Magnet
• Instrumentation Group: 8550 Spezielle Kryostaten (für tiefste Temperaturen)
• Applicant Institution: Karlsruher Institut für Technologie
• Leader: Professor Dr. Sebastian Kempf