Compact self-matched gyrators using edge magnetoplasmons

Edge magnetoplasmons provide a natural platform for chiral electrodynamics, where broken time-reversal symmetry enforces unidirectional propagation. When probed at microwave frequencies, they offer a route to compact non-reciprocal devices. So far, implementations have suffered from large losses or required complicated matching networks. Here we show that the circulating modes coupled to capacitive gates give rise to a gyrator response, characterized by directional {\pi} phase difference between forward and reverse transmission. By engineering a three-terminal capacitive geometry, we realize a self-impedance matched gyrator in which the gyration points coincide with transmission maxima, enabling nearly lossless gyration without external matching networks. Our devices are implemented on a GaAs 2D gas, operate from 0.2 to 2 GHz, tuned by magnetic field, with sub-millimeter footprints and insertion loss as low as 2 dB. This is a factor of 100 smaller and less lossy than commercial and plasmon units, respectively. A dissipative model, in agreement with experiment, provides the fundamental physics and delivers the key materials parameters, leading the way to even less lossy devices approaching ideal operation by materials improvement. The self-impedance matched concept is broadly applicable to a variety of devices, thus providing a foundation for a new generation of high-quality microwave plasmon technology.