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 noninteracting 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 noninteracting 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.

中文翻译：

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超冷原子相互作用辅助的热电逆转

我们研究流过介观通道的中性，费米子原子的热电流，介观通道跨过超流体过渡连接热库和冷库。热电响应是由密度驱动的从冷到热储层的扩散与有利于高能粒子从热到冷的传输的通道之间的竞争产生的。我们在几乎不相互作用且相互作用强烈的系统中使用外部光势来控制对热电响应的两种贡献的相对强度。没有相互作用，粒子电流的大小可以在很宽的范围内调整，但在我们的参数范围内只能从热流向冷流流动。引人注目的是，强烈的粒子间相互作用还使电流方向反向。我们定量建模从头开始进行非交互观察，并定性地解释了由于配对相关而导致的熵传递减少，从而辅助了交互作用的逆转。我们的工作为使用自旋相关的光学技术和冷原子研究强相关物质中的自旋与热的耦合铺平了道路。