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We consider a two-component pancake-shaped, i.e., effectively two-dimensional (2D), Bose-Einstein condensate coupled by the spin-orbit (SO) and Rabi terms. The SO coupling adopted here is of the mixed Rashba-Dresselhaus type. For this configuration, we derive a system of two 2D nonpolynomial Schrödinger equations (NPSEs), for both attractive and repulsive interatomic interactions. In the low- and high-density limits, the system amounts to previously known models, namely, the usual 2D Gross-Pitaevskii equation, or the Schrödinger equation with the nonlinearity of power 7/3. We present simple approximate localized solutions, obtained by treating the SO and Rabi terms as perturbations. Localized solutions of the full NPSE system are obtained in a numerical form. Remarkably, in the case of the attractive nonlinearity acting in free space (i.e., without any 2D trapping potential), we find parameter regions where the SO and Rabi couplings make 2D fundamental solitons dynamically stable. Read more here.

In this article, published online in Foundations of Physics, the authors describe a new class of experiments designed to probe the foundations of quantum mechanics. Using quantum controlling devices, it was shown how to attain a freedom in temporal ordering of the control and detection of various phenomena. Considering the wave-particle duality in the context of quantum-controlled and the entanglement-assisted delayed-choice experiments, a new interpretation of Bohr's complementarity principle raised. The discussion is then extended to the quantum-controlled CHSH experiment and to the measurement of a photon’s transversal position and momentum in a single experimental setup. Read more here.