Periodic Reporting for period 1 - SoCool (Solid-State Cooling Technology for Cryogenic Devices)
Periodo di rendicontazione: 2023-06-01 al 2024-05-31
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.
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.
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.
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.