SAMOP 2023 – scientific programme

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Q: Fachverband Quantenoptik und Photonik

Q 50: Quantum Gases: Fermions I

Q 50.2: Talk

Thursday, March 9, 2023, 11:15–11:30, F342

Anomalous thermoelectric transport between fermionic superfluids — Philipp Fabritius, Jeffrey Mohan, Mohsen Talebi, Simon Wili, •Meng-Zi Huang, and Tilman Esslinger — Department of Physics, ETH Zürich, 8093 Zürich, Switzerland

Thermoelectric effects in superfluid systems have been far less explored than other superfluid transport both theoretically and experimentally. Landau's two-fluid model works well in conventional superconductors, yet studies beyond the two-fluid model are scarce. Here we study the Peltier and Seebeck effects together in a superfluid system, namely transport induced by a chemical potential bias and by a temperature bias, respectively. Our system is a mesoscopic channel connecting two superfluids of ultracold fermionic atoms, where the particle current in both the Peltier and the Seebeck configurations exhibits a strong non-Ohmic character. While non-Ohmic transport is associated with superfluid features, we observe a large entropy current concomitant with the particle current, incompatible with a simple two-fluid model. On the other hand, we engineer a controlled particle loss inside the mesoscopic channel to study its influence on thermoelectric response. Surprisingly, local dissipation can enhance the particle current in a Seebeck configuration (analogous to the fountain effect). This would imply a change in the reservoir response despite the dissipation being in the channel. We present possible explanations to the observations, including non-hydrodynamic transport.