Our recent study considers the dynamics of classical and quantum models, in particular ring geometry: (a) with classical particles that perform random walk in disordered environment; (b) with quantum Bose particles whose dynamics is coherent.

Details on (a): it is possible to induce non-equilibrium steady state current, which requires e.g. a radiation source. One question that has been addressed concerns the relaxation of such current, and how it depends on percolation and localization properties of the model.

Details on (b): there is a possibility to have a super-current that does not decay even in the absence of an external driving source. This is known as super-fluidity. The study provides a theory for the meta-stability of such flow-states. A central observation is that the analysis should take into account the chaos that prevails in the classical limit of the model. It is the first time that the theory of "chaos" meets the theory of super-fluidity.

Background: Circuits with condensed bosons are the building blocks for quantum Atomtronics. Such circuits will be used as QUBITs (for quantum computation) or as SQUIDs (for sensing of acceleration or gravitation). We study the feasibility and the design considerations for devices where the atoms are confined to move in a several-site geometry (so called Bose-Hubbard system). For SQUID-geometry the sites form a ring with a weak link. Such ring can support super-flow (non-decaying persistent currents). If used as a QUBIT, the anti/clockwise flow-states can represent the digits "0/1". It is essential to realize that the full theory for the meta-stability of such flow-states, and for the feasibility of coherent operation, involves novel "Quantum chaos" considerations.

To read more on works related to (a) click hereTo read more on works related to (b) click here