Solid-State Cooling Technology for Cryogenic Devices

Introduction

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.

Challenges in Current Technologies

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. This is due to the intrinsic need for circulating the rare 3He cryogen or the heavy magnets required for their refrigeration. These limitations have been an obstacle to the broad-scale deployment of sub-kelvin electronics and photonics.

Development of a New Refrigerator

Here we develop an extremely compact and fully electrical general-purpose solid-state refrigerator, able to continuously cool electronic and photonic devices from above 1 K to below 100 mK. This is achieved without any need for thermodynamic cycles based on 3He cryogenic fluid or magnetic fields.

Technological Discovery

Our approach is based on a recent technological discovery which showed that superconductive tunnel junctions can operate similarly to vacuum isolated thermionic coolers. This approach provides:

• Full scalability for the total cooling power
• Ability to create large temperature drops with cryogenic electrical coolers

These features were not available before.

Engineering the Cooler System

We follow this approach and engineer a 3D stacked multi-chip cooler system. We capitalize on several of our previous milestones and aim to demonstrate a complete cooler system that can reach performance comparable to dilution refrigeration, without the need for 3He and at a fraction of the mass and cost.

Vision and Applications

Our vision entails new application avenues in the fields of:

1. Quantum technology
2. Material analysis and surveying
3. Radiation detection
4. Cosmology
5. Astronomy

We expect significant impact for airborne or space-oriented applications, due to the breakthrough reduction in payload mass and complexity allowed by our cooling solution.