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تسجيل مستخدم جديدA measurement method for responsivity of microwave kinetic inductance detector by changing power of readout microwaves
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Superconducting detectors are a modern technology applied in various fields. The microwave kinetic inductance detector (MKID) is one of cutting-edge superconducting detector. It is based on the principle of a superconducting resonator circuit. A radiation entering the MKID breaks the Cooper pairs in the superconducting resonator, and the intensity of the radiation is detected as a variation of the resonant condition. Therefore, calibration of the detector responsivity, i.e., the variation of the resonant phase with respect to the number of Cooper-pair breaks (quasiparticles), is important. We propose a method for responsivity calibration. Microwaves used for the detector readout locally raise the temperature in each resonator, which increases the number of quasiparticles. Since the magnitude of the temperature rise depends on the power of readout microwaves, the number of quasiparticles also depends on the power of microwaves. By changing the power of the readout microwaves, we simultaneously measure the phase difference and lifetime of quasiparticles. We calculate the number of quasiparticles from the measured lifetime and by using a theoretical formula. This measurement yields a relation between the phase response as a function of the number of quasiparticles. We demonstrate this responsivity calibration using the MKID maintained at 285mK. We also confirm consistency between the results obtained using this method and conventional calibration methods in terms of the accuracy.
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A microwave kinetic inductance detector (MKID) is a cutting-edge superconducting detector, and its principle is based on a superconducting resonator circuit. The superconducting transition temperature (Tc) of the MKID is an important parameter becaus
e various MKID characterization parameters depend on it. In this paper, we propose a method to measure the Tc of the MKID by changing the applied power of the readout microwaves. A small fraction of the readout power is deposited in the MKID, and the number of quasiparticles in the MKID increases with this power. Furthermore, the quasiparticle lifetime decreases with the number of quasiparticles. Therefore, we can measure the relation between the quasiparticle lifetime and the detector response by rapidly varying the readout power. From this relation, we estimate the intrinsic quasiparticle lifetime. This lifetime is theoretically modeled by Tc, the physical temperature of the MKID device, and other known parameters. We obtain Tc by comparing the measured lifetime with that acquired using the theoretical model. Using an MKID fabricated with aluminum, we demonstrate this method at a 0.3 K operation. The results are consistent with those obtained by Tc measured by monitoring the transmittance of the readout microwaves with the variation in the device temperature. The method proposed in this paper is applicable to other types, such as a hybrid-type MKID.
We present the development of a second generation digital readout system for photon counting microwave kinetic inductance detector (MKID) arrays operating in the optical and near-IR wavelength bands. Our system retains much of the core signal process
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