Bosonic superfluid transport in a quantum point contact
arXiv:1906.09191 · doi:10.1103/PhysRevResearch.2.023284
Abstract
We present a microscopic theory of heat and particle transport of an interacting, low temperature Bose-Einstein condensate in a quantum point contact. We show that, in contrast to charged, fermionic superconductors, bosonic systems feature tunneling processes of condensate elements, leading to the presence of odd-order harmonics in the AC Josephson current. A crucial role is played by an anomalous tunneling process where condensate elements are coherently converted into phonon excitations, leading to even-order harmonics in the AC currents as well as a DC contribution. At low bias, we find dissipative components obeying Ohm's law, and bias-independent nondissipative components, in sharp contrast to fermionic superconductors. Analyzing the DC contribution, we find zero thermopower and Lorenz number at zero temperature, a breakdown of the bosonic Wiedemann-Franz law. These results highlight importance of the anomalous tunneling process inherent to charge neutral superfluids. The consequences could readily be observed in existing cold-atom transport setups.
11 pages, 5 figures
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- Superfluid signatures in a dissipative quantum point contact
- Perspective on new implementations of atomtronic circuits
- Comparative study for two-terminal transport through a lossy one-dimensional quantum wire
- Interaction-Assisted Reversal of Thermopower with Ultracold Atoms
- Role of Nambu-Goldstone modes in the fermionic superfluid point contact
- Multi-Particle Tunneling Transport at Strongly-Correlated Interfaces
- Dissipation in a Finite Temperature Atomic Josephson Junction
- Thermomagnetic anomalies in quantum magnon transport caused by tunable junction geometries in cold atomic systems
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