Dark State Transport between Unitary Fermi Superfluids.

The formation of dark states is an important concept in quantum sciences, but its compatibility with strong interparticle interactions-for example, in a quantum degenerate gas-is hardly explored. Here, we realize a dark state in one of the spins of a two-component, resonantly interacting Fermi gas using a Λ system within the D_{2} transitions of ^{6}Li at high magnetic field. The dark state is created in a micrometer-sized region within a one-dimensional channel connecting two superfluid reservoirs.

Irreversible entropy transport enhanced by fermionic superfluidity.

The nature of particle and entropy flow between two superfluids is often understood in terms of reversible flow carried by an entropy-free, macroscopic wavefunction. While this wavefunction is responsible for many intriguing properties of superfluids and superconductors, its interplay with excitations in non-equilibrium situations is less understood. Here we observe large concurrent flows of both particles and entropy through a ballistic channel connecting two strongly interacting fermionic superfluids.

Superfluid Signatures in a Dissipative Quantum Point Contact.

We measure superfluid transport of strongly interacting fermionic lithium atoms through a quantum point contact with local, spin-dependent particle loss. We observe that the characteristic non-Ohmic superfluid transport enabled by high-order multiple Andreev reflections transitions into an excess Ohmic current as the dissipation strength exceeds the superfluid gap. We develop a model with mean-field reservoirs connected via tunneling to a dissipative site.