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Mesoscopic transport with ultracold atoms: particles, spin and heat" Laura Corman, ETH Zürich The quantum behavior of fermionic particles can be revealed when the structure through which they flow is smaller than their coherence length. For electrons, this principle is the foundation of the field mesoscopic physics which has emerged thanks to the tremendous progress in fabrication techniques. Another platform to study mesocopic transport has appeared in atomic physics using ultracold gases of fermionic lithium. Although they are orders of magnitude more massive, more dilute and colder than electron gases in materials, it is possible to access similar regimes in both systems. This was demonstrated by the measurement of quantized conductance for neutral matter at an atomic quantum point contact [1]. Ultracold atom transport experiments allow some advantages compared to their electronics counterpart. First, structures on the order of the Fermi wavelength can be optically imprinted, which is fast and flexible. Second, the interactions between particles can be varied in a broad range, from weakly interacting (attractive or repulsive) to the unitary limit which corresponds to saturated contact interactions. In this talk, I will present how we engineer such transport experiments with atoms as well as some recent results of transport through 1D systems. First, by engineering the structure in which the atoms flow, we were able to explore insulating behaviors from a band insulator to a correlated, Luther-Emery insulator [2]. Second, we extended these structures to control to the effective spin degree of freedom of the atoms, creating local effective magnetic fields with Zeeman shifts on the order the Fermi energy [3]. Last, we can also study the coupling between different transported quantities to understand the nature of a system's elementary excitations, as we did for the unitary Fermi gas by observing the breakdown of the Wiedemann-Franz law [4]. [1] Krinner et al., Nature 517, 64-67 (2015). [2] Lebrat et al., Physical Review X 8, 011053 (2018). [3] Lebrat et al., arXiv:1902.05516 (2019) [4] Husmann et al., PNAS 115, 8563-8568 (2018).

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Laura Corman, ETH Zurich
Seminar Room of the Institute of Physics II
Contact: Sebastian Diehl