Bridging the Quantum Frequency Gap
Many quantum technologies require microwave signals to be transmitted between various components. But a given component can typically send and receive signals only in a specific, limited frequency range. Although this problem can be tackled by adding devices that convert microwave signals from one frequency to another, such devices are often limited in conversion bandwidth or efficiency. Now Yufeng Wu and his colleagues at Yale University have demonstrated a device that offers high conversion efficiency across a broad frequency range [1].
The device consists of a microscopic circuit patterned on a thin film of the superconducting material niobium nitride, which sits on a silicon substrate. The circuit features a series of precisely engineered hairpin-like loops. Within these loops, a microwave signal of a given frequency mixes with a strong microwave pulse to produce a signal of a different frequency. This frequency shift can be tuned by applying a magnetic field to the circuit and adjusting the field’s strength.
Wu and his colleagues report that their device can operate in the frequency range from 4.85 to 8.5 GHz with a conversion efficiency of between 80% and 100%. Crucially, the conversion process adds little noise to the microwave signal and preserves the signal’s fragile quantum properties. The researchers say that the device’s versatility could help scientists improve the efficiency and integration of a wide range of quantum networks and quantum information processors that operate at microwave frequencies.
–Ryan Wilkinson
Ryan Wilkinson is a Corresponding Editor for Physics Magazine based in Durham, UK.
References
- Y. Wu et al., “Broad-spectrum coherent frequency conversion with kinetic inductance superconducting metastructures,” Phys. Rev. Appl. 24, 024015 (2025).