论文标题
圆形摇动的光学晶格中的相互交织的时空对称性，轨道磁和动态浆果曲率
Intertwined Space-Time Symmetry, Orbital Magnetism and Dynamical Berry Curvature in a Circularly Shaken Optical Lattice
论文作者
论文摘要
我们研究了二维光学晶格的圆形摇动，该晶格本质上是（2+1）维时空晶格，在空间和时间尺寸中都显示出周期性。这里考虑的近谐振光学摇动动态地伴随着低洼的$ s $ band和第一个激动的$ p $ bands，通过传递摇动频率的光子。进一步发现了相互交织的时空对称性，以阐明用广义的Bloch-Floquet定理求解的光谱中的退化。设置循环摇动的手性明确打破了时间逆转对称性，并提高了$ p_ \ pm = p_x \ pm pm ip_y $ orbitals的退化，从而导致轨道磁性的局部循环，即$ p_ \ pm pm $ Orbitals中的不平衡职业。此外，浆果连接的动力学通过浆果曲率和极化的时间演化揭示，它们在实验中具有可观察到的物理作用。有趣的是，该动力学的特征是通用相移，该动力学由涉及时间的分数翻译的时螺钉旋转对称性控制。这些发现表明，当前的晶格震动方案为研究轨道物理学和对称性保护动力学提供了多功能平台。
We study the circular shaking of a two dimensional optical lattice, which is essentially a (2+1) dimensional space-time lattice exhibiting periodicities in both spatial and temporal dimensions. The near-resonant optical shaking considered here dynamically couples the low-lying $s$ band and the first excited $p$ bands by transferring a photon of shaking frequency. The intertwined space-time symmetries are further uncovered to elucidate the degeneracy in the spectrum solved with the generalized Bloch-Floquet theorem. Setting the chirality of circular shaking explicitly breaks time reversal symmetry and lifts the degeneracy of $p_\pm = p_x \pm ip_y$ orbitals, leading to the local circulation of orbital magnetism, i.e the imbalanced occupation in $p_\pm$ orbitals. Moreover, the dynamics of Berry connection is revealed by the time evolution of the Berry curvature and the polarization, which have physical observable effects in experiments. Interestingly, the dynamics is found characterized by a universal phase shift, governed by the time screw rotational symmetry involving a fractional translation of time. These findings suggest that the present lattice-shaking scheme provides a versatile platform for the investigation of the orbital physics and the symmetry-protected dynamics.
