Broad Spectrum Quantum Frequency Conversion with Kinetic Inductance Superconducting Metastructures

Quantum frequency converters (QFCs) play a critical role in bridging the frequency gap between quantum information carriers. QFCs in the microwave band are particularly important for superconducting quantum processors, but their operating bandwidth is often strongly limited. Here, we present a multimode kinetic metastructure for parametric quantum frequency conversion between broadly spanning frequency modes. This device comprises a chain of asymmetric kinetic inductance grids designed to deliver efficient three-wave mixing nonlinearity. We demonstrate near-unity conversion efficiency among broadly distributed modes, and the mode frequency is continuously tunable by controlling the external magnetic field strength, making it ideally suited for quantum computing and communication applications requiring flexible and efficient frequency conversion.