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Fabrication and characterization of ultra-low noise narrow and wide band Josephson parametric amplifiers 下载免费PDF全文
We have fabricated two types of lumped-element Josephson parameter amplifiers (JPAs) by using a multilayer micro-fabrication process involving wet etching of Al films. The first type is a narrow band JPA which shows typical gain above 14 dB in a bandwidth around 35 MHz. The second type is a wideband JPA which is coupled to an input 50 Ω transmission line via an impedance transformer that changes the impedance from about 15 Ω on the non-linear resonator side to 50 Ω on the input transmission line side. The wideband JPA could operate in a 200 MHz range with a gain higher than 14 dB. 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. 相似文献
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通过H_α/D_α及杂质辐射研究HL-1等离子体特性 总被引:2,自引:2,他引:0
利用石英光纤光导、WDS-3单色仪和光电倍增管等构成的8道光电系统,通过观察H_α/D_α及杂质的辐射,研究了在低混杂波电流驱动(LHCD)、电子回旋共振加热(ECRH)、氩弹丸注入、孔栏加偏压及补送氦气等不同放电条件下的HL-1托卡马克等离子体的特性,并得到了较好的结果。 相似文献
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本文介绍了光纤使用三年来的简单情况;叙述了用氦、氢换气实验的再循环效果;分析了边界层氢和轻、重杂质的时空分布及变化情况;得到了等离子体放电时产生DP和MARFE辐射的时空分布立体图。 相似文献
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Measurements of three-junction flux qubits, both single flux qubits and coupled flux qubits, using a coupled direct current superconducting quantum interference device (dc-SQUID) for readout are reported. The measurement procedure is described in detail. We performed spectroscopy measurements and coherent manipulations of the qubit states on a single flux qubit, demonstrating quantum energy levels and Rabi oscillations, with Rabi oscillation decay time TRabi =- 78 ns and energy relaxation time T~ = 315 ns. We found that the value of TRabi depends strongly on the mutual inductance between the qubit and the magnetic coil. We also performed spectroscopy measurements on inductively coupled flux qubits. 相似文献
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We present the design of a superconducting flux qubit with a large loop inductance. The large loop inductance is desirable for coupling between qubits. The loop is configured into a gradiometer form that could reduce the interference from environmental magnetic noise. A combined Josephson junction, i.e., a DC-SQUID is used to replace the small Josephson junction in the usual 3-JJ (Josephaon junction) flux qubit, leading to a tunable energy gap by using an independent external flux line. We perform numerical calculations to investigate the dependence of the energy gap on qubit parameters such as junction capacitance, critical current, loop inductance, and the ratio of junction energy between small and large junctions in the flux qubit. We suggest a range of values for the parameters. 相似文献
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Tuning the phase separation in La_(0.325)Pr_(0.3)Ca_(0.375)MnO_3 using the electric double-layer field effect 下载免费PDF全文
Electric double-layer field effect experiments were performed on ultrathin films of La0.325Pr0.3Ca0.375MnO3, which is noted for its micrometer-scale phase separation. A clear change of resistance up to 220% was observed and the characteristic metal–insulator transition temperature TPwas also shifted. The changes of both the resistance and TPsuggest that the electric field induced not only tuning of the carrier density but also rebalancing of the phase separation states. The change of the charge-ordered insulating phase fraction was estimated to be temperature dependent, and a maximum of 16% was achieved in the phase separation regime. This tuning effect was partially irreversible, which might be due to an oxygen vacancy migration that is driven by the huge applied electric field. 相似文献
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