Dresden 2026 – scientific programme

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TT: Fachverband Tiefe Temperaturen

TT 89: Cryotechnique: Refrigeration

TT 89.3: Talk

Thursday, March 12, 2026, 17:15–17:30, HSZ/0103

Cooling of electrons via superconducting tunnel junctions and their arrays exhibiting nodal lines — •Linus Aliani and Viktoriia Kornich — Institute for Theoretical Physics and Astrophysics, University of Würzburg, 97074 Würzburg, Germany

Condensed matter physics demands experimental control over a systems’ temperature. This is usually achieved by the use of commercial dilution refrigerators. However cooling to temperatures below mK is still an issue and usually phonons are cooled down instead of electrons. We therefore propose a setup, which cools electrons via electrons.

We consider theoretically a small current running from an electron bath through a setup based on superconducting tunneling junction(s). We employ tunneling junctions with a π phase difference in order to host nodal lines. These nodal lines and their surrounding spectrum depend on external parameters. Thus the setups’ entropy is adjustable via its’ dependence on their nodal lines. The high entropy of the setup forces electrons entering it to increase their entropy, thereby removing heat from the electron bath. We demonstrate the working principle of this approach by first studying the entropy of a simple superconductor-insulator-superconductor (SIS) junction and compare it to the free electron gas at chemical potential. Subsequently we modify the setup in various ways in order to introduce opportunities for fine tuning for possible experimental uses. For this we investigate superconducting tunnel junctions with a ferroelectric insulator and an array of such junctions with ferroelectrics in-between.

Keywords: electron cooling; tunneling junction; ferroelectrics; nodal lines