On-Chip Nonreciprocal Superconducting Frequency Multiplier for Cryogenic Millimeter-Wave Multiplexed Control

Abstract

Space-time-periodic modulation of superconducting circuits offers a compact, on-chip route to nonreciprocity, frequency conversion, and parametric gain, without the bulk of conventional ferrite-based components. This paper presents an on-chip nonreciprocal space-time-periodic Josephson frequency multiplier that up-converts a single low-frequency input tone into a comb of high-order harmonics while enforcing directional signal propagation along the bus. Full-wave time-domain simulations show that the harmonic content and bandwidth of the generated comb can be controlled through the applied DC and RF flux bias, and that individual output channels can be selectively addressed by tuning the bus operating point. We characterize the resulting nonreciprocal isolation between channels and discuss the associated design trade-offs, including the influence of modulation depth on harmonic-generation efficiency and back-reflection. Because the device delivers multiple mutually isolated frequency channels from a single low-frequency source, it is well suited to applications requiring multiplexed delivery of tones to spatially distributed, frequency-addressable loads; we discuss multiplexed control of superconducting qubits as one such potential application area. The proposed architecture offers a compact, integrated route toward on-chip frequency multiplexing and directional isolation for cryogenic microwave and millimeter-wave systems.