Suppression of Bloch Oscillations and Nonreciprocal Landau-Zener Tunneling in Bose-Einstein Quantum Droplets
We investigate the nonlinear Bloch dynamics and Landau-Zener (LZ) tunneling of quantum droplets in optical lattices. We show that the Lee-Huang-Yang (LHY) correction not only stabilizes the self-bound droplet, but also introduces nonlinear phase feedback that competes with the lattice-induced coherent motion. In the deep-lattice regime, applying a generalized super-Gaussian ansatz within the tight-binding model demonstrates that chirp accumulation modifies the internal phase profile and renormalizes mobility. The coherent Bloch oscillations (BO) are progressively arrested in the presence of the LHY interaction without dissipative damping. In the shallow-lattice regime, the system is mapped onto a nonlinear two-level Josephson-analog model in which the mean-field and LHY contributions enter through an effective nonlinear detuning, deforming the adiabatic spectrum and generating looped bands. Using the classical action-angle formulation, we demonstrate that the nonlinear LZ tunneling is governed by the underlying phase-space structure. In particular, the LHY correction suppresses the tunneling probability by modifying the separatrix action and renormalizing the exponential sweep-rate scaling through a nonlinear weighting factor. We further identify pronounced nonreciprocal LZ tunneling arising from branch-dependent population imbalance and the nonlinearly induced inertia. These results establish a unified mechanism in which the LHY interaction suppresses both coherent Bloch dynamics and interband tunneling by reorganizing the dynamical exchange among lattice motion, population imbalance, and internal phase modulation.