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Q: Fachverband Quantenoptik und Photonik

Q 25: Poster: Quantum Optics and Photonics I

Q 25.32: Poster

Tuesday, March 12, 2019, 16:30–18:30, S Atrium Informatik

Beyond particle transport through a quantum point contact using ultracold atoms — •Samuel Häusler, Dominik Husmann, Martin Lebrat, Philipp Fabritius, Jeffery Mohan, Jean-Philippe Brantut, Laura Corman, and Tilman Esslinger — ETH Zurich, 8093 Zürich, Switzerland

Transport measurements through a quantum system probes its excitations which, in the case of strongly correlated matter, are challenging to characterise. Particle transport, an essential observable in solid state physics, is measured in our cold atom system consisting of two reservoirs of fermionic lithium atoms connected by a quantum point contact. Here, we go beyond pure particle transport by combining it with either heat or spin transport.

First, we study the coupling between particle and heat currents at unitarity close to the superfluid transition. After heating one reservoir, we observe an extreme initial particle current from cold to hot that brings the system to a non-equilibrium steady state where currents vanish. The steady state reveals a finite particle and suppressed thermal conductance, thus violating the Wiedemann-Franz law.

Second, we recently implemented a spin filter by shining a near-resonant tweezer inside the channel. It blocks particles of one spin species while allowing the other to pass, thereby realising a strong, local effective Zeeman field on the order of the Fermi energy. We are thus able to create fully spin-polarized currents in the presence of conductance quantization. Furthermore, we increase dissipation induced by the tweezer and tune interactions.