Interaction-Assisted Reversal of Thermopower with Ultracold Atoms

Abstract

We study thermoelectric currents of neutral, fermionic atoms flowing through a mesoscopic channel connecting a hot and a cold reservoir across the superfluid transition. The thermoelectric response results from a competition between density-driven diffusion from the cold to the hot reservoir and the channel favoring transport of energetic particles from hot to cold. We control the relative strength of both contributions to the thermoelectric response using an external optical potential in a nearly non-interacting and a strongly-interacting system. Without interactions, the magnitude of the particle current can be tuned over a broad range but is restricted to flow from hot to cold in our parameter regime. Strikingly, strong interparticle interactions additionally reverse the direction of the current. We quantitatively model ab initio the non-interacting observations and qualitatively explain the interaction-assisted reversal by the reduction of entropy transport due to pairing correlations. Our work paves the way to studying the coupling of spin and heat in strongly correlated matter using spin-dependent optical techniques with cold atoms.

7 + 11 pages, 4 + 5 figures

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• Dynamics of thermalization of two tunnel-coupled one-dimensional quasicondensates
• Nonequilibrium noise as a probe of pair-tunneling transport in the BCS--BEC Crossover
• Irreversible entropy transport enhanced by fermionic superfluidity
• Giant rectification in strongly-interacting driven tilted systems
• Microscopic contributions to the entropy production at all times: From nonequilibrium steady states to global thermalization
• Particle and spin transports of spin-orbit coupled Fermi gas through a Quantum Point Contact
• Heat transport in an optical lattice via Markovian feedback control
• Universal relations between thermoelectrics and noise in mesoscopic transport across a tunnel junction
• Quantum emulation of topological magneto-optical effects using ultracold atoms
• Typical Positivity of Nonequilibrium Entropy Production for Pure States
• Elastic collision rates of spin-polarized fermions in two dimensions
• Thermoelectric effect on diffusion in the two-dimensional Hubbard model
• Generation of spin currents by a temperature gradient in a two-terminal device