http://arxiv.org/abs/2007.00638
We present a theoretical model and experimental characterization of a microwave kinetic inductance traveling-wave amplifier (KIT), whose noise performance, measured by a shot noise thermometer, approaches the quantum limit. Biased with a dc current, the KIT operates in a three-wave mixing fashion, thereby reducing by several orders of magnitude the power of the microwave pump tone compared to conventional four-wave mixing KIT devices. It is built in an artificial transmission line intrinsically matched to 50 Ohms, whose dispersion allows for a controlled amplification bandwidth. We experimentally measure $17.6^{+1.1}_{-1.4}$ dB of gain across a 2 GHz bandwidth, with an input 1 dB compression power of -63 dBm within that bandwidth, in qualitative agreement with theory. Using the KIT as the first amplifier in an amplification chain, we measure a system-added noise of $0.61\pm0.08$ K between 3.5 and 5.5 GHz, about one eighth the noise obtained when using only a representative classical amplifier. The KIT contribution to this added noise is estimated to be $0.2\pm0.1$ K, consistent with the quantum limit on amplifier added noise. This device is therefore suitable to read large arrays of microwave kinetic inductance detectors or thousands of superconducting qubits.
M. Malnou, M. Vissers, J. Wheeler, et. al.
Thu, 2 Jul 20
56/64
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