Enhanced dynamic range in terahertz quantum capacitance detectors through engineered quasiparticle trapping

Abstract

Superconducting quantum capacitance detectors (QCDs) have emerged as among the most sensitive terahertz (THz) photon detectors, positioning them as promising detector components for next-generation cryogenic telescopes. However, their limited dynamic range (DR, ∼32 dB) and low saturation power (∼0.1 fW) have hindered their broader applications, such as in THz astronomy, high-resolution spectroscopy, and microscopic imaging. Here, we propose a mechanism that enables controllable adjustment of the sensitivity and DR of THz QCDs, supported by both theoretical modeling and experimental validation. We developed a QCD design that features a fork-shaped gate capacitor and a high-efficiency grid absorber. The resulting devices exhibit a noise equivalent power of 5.0 × 10−20 W/Hz1/2 and a DR of 40 dB, providing a favorable balance between sensitivity and DR and advancing the practical application of QCDs in future THz applications.