Joint Quantum Institute, NIST/University of Maryland, College Park, Maryland 20742, USA.
Department of Electrical and Computer Engineering, and IREAP, University of Maryland, College Park, Maryland 20742, USA.
Phys Rev Lett. 2019 Jul 26;123(4):043201. doi: 10.1103/PhysRevLett.123.043201.
We experimentally realize a photonic analogue of the anomalous quantum Hall insulator using a two-dimensional (2D) array of coupled ring resonators. Similar to the Haldane model, our 2D array is translation invariant, has a zero net gauge flux threading the lattice, and exploits next-nearest neighbor couplings to achieve a topologically nontrivial band gap. Using direct imaging and on-chip transmission measurements, we show that the band gap hosts topologically robust edge states. We demonstrate a topological phase transition to a conventional insulator by frequency detuning the ring resonators and thereby breaking the inversion symmetry of the lattice. Furthermore, the clockwise or the counterclockwise circulation of photons in the ring resonators constitutes a pseudospin degree of freedom. The two pseudospins acquire opposite hopping phases, and their respective edge states propagate in opposite directions. These results are promising for the development of robust reconfigurable integrated nanophotonic devices for applications in classical and quantum information processing.
我们使用二维（2D）耦合环形谐振器阵列实验实现了光子类比反常量子霍尔绝缘体。与哈达内模型类似，我们的 2D 阵列具有平移不变性，晶格中没有净规范通量，并且利用最近邻耦合实现了拓扑非平凡的带隙。通过直接成像和片上传输测量，我们表明带隙中存在拓扑稳定的边缘态。我们通过频率失谐环形谐振器来演示拓扑相变到常规绝缘体，从而破坏晶格的反转对称性。此外，光子在环形谐振器中的顺时针或逆时针循环构成了赝自旋自由度。两个赝自旋获得相反的跃迁相位，并且它们各自的边缘态沿相反方向传播。这些结果为发展用于经典和量子信息处理的稳健可重构集成纳米光子器件提供了希望。
