Floquet topological insulators, which have an exotic topological order sustained by time-varying Hamiltonians, could be of use in a range of technologies, including wireless communications, radar and quantum information processing. However, demonstrations of photonic Floquet topological insulators have been limited to systems that emulate time with a spatial dimension, which preserves time-reversal symmetry and thus removes valuable features including non-reciprocal topological protection. Here we report photonic Floquet topological insulators based on quasi-electrostatic wave propagation in switched-capacitor networks. The approach provides non-reciprocal Floquet topological insulators for electromagnetic waves and opens a large topological bandgap that spans up to gigahertz frequencies. Our devices exploit time modulation to operate beyond the delay–bandwidth limit of conventional linear time-invariant electromagnetic structures and therefore offer large delays, despite the broad bandwidth. The Floquet topological insulator is integrated into a complementary metal–oxide–semiconductor (CMOS) chip, and we illustrate its potential for 5G wireless systems by showing that it can be used for multi-antenna full-duplex wireless operation and true-time-delay-based broadband beamforming.

Floquet 拓扑绝缘体具有由时变哈密顿量维持的奇异拓扑顺序，可用于一系列技术，包括无线通信、雷达和量子信息处理。然而，光子 Floquet 拓扑绝缘体的演示仅限于模拟具有空间维度的时间的系统，该系统保留了时间反转对称性，从而消除了包括非互易拓扑保护在内的有价值的特征。在这里，我们报告了基于开关电容器网络中准静电波传播的光子 Floquet 拓扑绝缘体。该方法为电磁波提供了非互易 Floquet 拓扑绝缘体，并打开了一个跨越千兆赫频率的大拓扑带隙。我们的设备利用时间调制来超越传统线性时不变电磁结构的延迟带宽限制，因此尽管带宽很宽，但仍提供大延迟。Floquet 拓扑绝缘体集成到互补金属氧化物半导体 (CMOS) 芯片中，我们通过展示它可用于多天线全双工无线操作和实时延迟来说明其在 5G 无线系统中的潜力- 基于宽带波束形成。