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We have fabricated two types of lumped-element Josephson parameter amplifiers(JPAs) by using a multilayer microfabrication process involving wet etching of Al films. The first type is a narrow band JPA which shows typical gain above14 d B in a bandwidth around 35 MHz. The second type is a wideband JPA which is coupled to an input 50 ? transmission line via an impedance transformer that changes the impedance from about 15 ? on the non-linear resonator side to 50 ?on the input transmission line side. The wideband JPA could operate in a 200 MHz range with a gain higher than 14 d B.The amplifiers were used for superconducting qubit readout. The results showed that the signal to noise ratio and hence the readout fidelity were improved significantly.
We have fabricated two types of lumped-element Josephson parameter amplifiers (JPAs) by using a multilayer microfabrication process involving wet etching of Al films. The first type is a narrow band JPA which shows typical gain above 14 d B in a bandwidth around 35 MHz. The second type is a wideband JPA which is coupled to an input 50? Transmission line via an impedance transformer that changes the impedance from about 15? On the non-linear resonator side to 50? On the input transmission line side. The wideband JPA could operate in a 200 MHz range with a gain higher than 14 d B. The amplifiers were used for superconducting qubit readout. The results showed that the signal to noise ratio and therefore the readout fidelity were significantly significantly.