We study the fate of an impurity in an ultracold heteronuclear Bose mixture, focusing on the experimentally relevant case of a $^{41}$K-$^{87}$Rb mixture, with the impurity in a $^{41}$K hyperfine state. Our work provides a comprehensive description of an impurity in a BEC mixture with contact interactions across its phase diagram. We present results for the miscible and immiscible regimes, as well as for the impurity in a self-bound quantum droplet. Here, varying the interactions, we find novel, exotic states where the impurity localizes either at the center or at the surface of the droplet.
We propose to use ultracold fermionic atoms in one-dimensional optical lattices to quantum simulate the electronic transport in quantum cascade laser (QCL) structures. The competition between the coherent tunneling among (and within) the wells and the dissipative decay at the basis of lasing is discussed. In order to validate the proposed simulation scheme, we quantitatively address such competition in a simplified one-dimensional model. We show the existence of optimal relationships between the model parameters, maximizing the particle current, the population inversion (or their product), and the stimulated emission rate. This substantiates the concept of emulating the QCL operation mechanisms in cold-atom optical lattice simulators, laying the groundwork for addressing open questions, such as the impact of electron-electron scattering and the origin of transport-induced noise, in the design of new-generation QCLs.
A novel mm-scale Ioffe-Pritchard trap is used to achieve Bose-Einstein condensation in 7Li. The trap employs free-standing copper coils integrated onto a direct-bond copper surface electrode structure. The trap achieves a radial magnetic gradient of 420 G/cm, an axial oscillation frequency of 50 Hz and a trap depth of 66 G with a 100 A drive current and 7 W total power dissipation.
