Solid-State Cooling Technology for Cryogenic Devices

Project Information

SoCool

Grant agreement ID: 101113086

DOI

10.3030/101113086

EC signature date 20 March 2023

Start date 1 June 2023

End date 31 August 2026

Funded under

• The European Innovation Council (EIC)

Total cost

€ 1 298 411,00

EU contribution

€ 1 298 411,00

Coordinated by

TEKNOLOGIAN TUTKIMUSKESKUS VTT OY
Finland

Periodic Reporting for period 1 - SoCool (Solid-State Cooling Technology for Cryogenic Devices)

Reporting period: 2023-06-01 to 2024-05-31

Summary of the context and overall objectives of the project

Temperatures below 1 kelvin are highly beneficial, if not prerequisite, to several important technologies that are key to development in present and upcoming decades. Examples include superconducting electronics such as x-ray calorimeters, qubits, single-photon detectors and RF amplifiers. In spite of the typically small size of the elements to be refrigerated, the techniques commonly used to access sub-kelvin temperatures are expensive and cumbersome, due to intrinsic need of circulating the rare 3He cryogen or the heavy magnets required for their refrigeration. These limitations have been an obstacle to broad-scale deployment of sub-kelvin electronics and photonics.

We aim to develop a cooler system that can reach performance comparable with dilution refrigeration, without need of 3He and at a fraction of the mass and cost. Our vision entails new application avenues in the fields of quantum technology, material analysis and surveying, radiation detection, cosmology, and astronomy. We expect significant impact for airborne or space-oriented applications, because of the breakthrough reduction in payload mass and complexity allowed by our cooling solution. The pursued electronic cooling solution resembles cascaded Peltier (thermoelectric) coolers, which are off-the-shelf components for room temperature operation. However, it has turned out extremely difficult to come up with scalable electronic cooling solutions for cryogenic temperatures.

Work performed from the beginning of the project to the end of the period covered by the report and main results achieved so far

Key activities of SoCool during the first year include developing technology building blocks for the project demonstrator and building understanding on the commercial landscape of the cooler solution. For the former the key milestones are 3D assembly and thermal resistance with-in and efficient Nb-based on-chip refrigetation above 2 K, which bridges the gap between electronic and pulse tube refrigerators.

Progress beyond the state of the art and expected potential impact (including the socio-economic impact and the wider societal implications of the project so far)

During the first year we have investigated chip-to-chip thermal resistance in a 3D assemblies at cryogenic temperatures for the first time. This quantitative work is important not only for micro-refrigerators but, in general, for thermal management of different cryogenic electronics and phonics from classical to quantum applications. We also have developed a scalable Al–AlOx–Nb superconducting tunnel junction cooler technology that can deliver electronic cooling power of ∼mW/mm2, which was enough to demonstrate significant electron temperature reduction of 0.82 K against the phonon bath at 2.4 K (34% relative cooling). Our work shows that the key material of integrated superconducting circuits–niobium–enables powerful cryogenic refrigerator technology.

a) Typical current dry dilution refrigerator and small ~1 cm system/circuit it is used for.