Large array of low-frequency readout quantum capacitance detectors

Quantum capacitance detectors (QCDs) are photon shot noise-limited terahertz detectors based on a single Cooper-pair box superconducting qubit. The QCD has demonstrated photon shot noise-limited performance for 1.5 THz radiation under loading conditions between 10  −  20 and 10  −  18  W and single-photon detection and counting at that frequency. We report here fabrication and preliminary characterization of a 441 pixel array of QCDs with readout frequencies between 700 and 850 MHz.