Classical, semiclassical and quantum signatures of quantum phase transitions in a (pseudo) relativistic many-body system

Semiclassical excited-state signatures of quantum phase transitions in spin chains with variable-range interactions

We study the excitation spectrum of a family of transverse-field spin chain models with variable interaction range and arbitrary spin $S$, which in the case of $S=1/2$ interpolates between the Lipkin-Meshkov-Glick and the Ising model. For any finite number $N$ of spins, a semiclassical energy manifold is derived in the large-$S$ limit employing bosonization methods, and its geometry is shown to determine not only the leading-order term but also the higher-order quantum fluctuations. Based on a multi-configurational mean-field ansatz, we obtain the semiclassical backbone of the quantum spectrum…

Semiclassical Dynamics, Berry Curvature and Spiral Holonomy in Optical Quasicrystals

We describe the theory of the dynamics of atoms in two-dimensional quasicrystalline optical lattices. We focus on a regime of shallow lattice depths under which the applied force can cause Landau-Zener tunneling past a dense hierarchy of gaps in the quasiperiodic energy spectrum. We derive conditions on the external force that allow for a "semiadiabatic" regime in which semiclassical equations of motion can apply, leading to Bloch oscillations between the edges of a pseudo-Brillouin-zone. We verify this semiclassical theory by comparing to the results of an exact numerical solution. Interestin…

Quantum signatures of self-trapping transition in attractive lattice bosons

We consider the Bose-Hubbard model describing attractive bosonic particles hopping across the sites of a translation-invariant lattice, and compare the relevant ground-state properties with those of the corresponding symmetry-breaking semiclassical nonlinear theory. The introduction of a suitable measure allows us to highlight many correspondences between the nonlinear theory and the inherently linear quantum theory, characterized by the well-known self-trapping phenomenon. In particular we demonstrate that the localization properties and bifurcation pattern of the semiclassical ground-state c…

通过量子和半经典分析表征自旋玻色-爱因斯坦凝聚体中的动力学相变

Characterizing dynamical phase transitions in a spinor Bose-Einstein condensate via quantum and semiclassical analyses

本研究通过量子和半经典分析，在自旋玻色-爱因斯坦凝聚体中表征了两种动力学相变，揭示了其与经典系统分界线的关联，并验证了半经典方法的有效性。

Quantum signatures of Chimera states

Chimera states are complex spatiotemporal patterns in networks of identical oscillators, characterized by the coexistence of synchronized and desynchronized dynamics. Here we propose to extend the phenomenon of chimera states to the quantum regime, and uncover intriguing quantum signatures of these states. We calculate the quantum fluctuations about semiclassical trajectories and demonstrate that chimera states in the quantum regime can be characterized by bosonic squeezing, weighted quantum correlations, and measures of mutual information. Our findings reveal the relation of chimera states to…

Rydberg链中抑制量子混沌的半经典起源

Semiclassical origin of suppressed quantum chaos in Rydberg chains

本文将Rydberg链推广到任意自旋S，发现其经典极限中的稳定周期轨道可解释量子混沌被参数化抑制及相干时间按√S发散的现象。