Characterization of Uniformity in Nb/Nb<sub>x</sub>Si<sub>1-x</sub>/Nb Josephson Junctions

Haygood, Ian W.; Edwards, Eric R. J.; Fox, Anna E.; Pufall, Matthew R.; Schneider, Michael L.; Rippard, William H.; Dresselhaus, Paul D.; Benz, Samuel P.

doi:10.1109/tasc.2019.2922225

Cited by 7 publications

(2 citation statements)

References 18 publications

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“…To investigate the coupling between the defined ferromagnets and the Nb resonators the Fe-Co sample was placed in a cryogenic probe station with base temperature of 3.2 K. 35 Electrical contact was made using a set of GSG probes whose position could be adjusted in situ (with approximately 10 μm resolution). This flexibility allowed for the interrogation of the hybrid system by capacitively coupling to the CPW, resulting in a resonant measurement, or by placing the probes in direct contact with the center conductor, resulting in a broadband measurement.…”

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confidence: 99%

Strong Coupling of an Fe - Co Alloy with Ultralow Damping to Superconducting Co-planar Waveguide Resonators

et al. 2021

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We report on the strong coupling between a metallic ferromagnetic Fe75Co25 thin film patterned element and a range of superconducting Nb half-wavelength co-planar waveguide (CPW) resonators. By varying the volume of the ferromagnet we demonstrate that the coupling rate scales linearly with the square root of the number of spins and achieve a coupling rate over 700 MHz, approaching the ultrastrong coupling regime. Experiments varying the center conductor width while maintaining constant magnetic volume verify that decreasing the center conductor width increases coupling and cooperativity. Our results show that the frequency dependence of the coupling rate is linear with the fundamental and higher order odd harmonics of the CPW, but with differing efficiencies. The results show promise for scaling planar superconducting resonator/magnetic hybrid systems to smaller dimensions.

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confidence: 99%

Strong Coupling of an Fe - Co Alloy with Ultralow Damping to Superconducting Co-planar Waveguide Resonators

et al. 2021

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“…Besides the uniformity of junction properties on the same chip, the distribution and yield on the entire wafer are also very important, related to the operating margin of the circuit [24]. Figure 5 shows the spatial distributions of J c and V c of NbN/TaN/NbN junctions across a 4 inch wafer.…”

Section: Yield and Uniformity Of Sns Josephson Junctionsmentioning

confidence: 99%

Intrinsically shunted NbN/TaN/NbN Josephson junctions on Si substrates for large-scale integrated circuits applications

Yan¹,

Zhang²,

Zhong³

et al. 2022

Supercond. Sci. Technol.

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Superconducting circuits based on Josephson junctions have the potential to achieve high speed and ultra-low power consumption, but their integration is limited by the low controllability of Nb-based tunnel junction and the existence of shunt resistors. In this work, we report the fabrication of superconductor/normal metal/superconductor (SNS) Josephson junctions with high reproducibility on oxidized Si substrates. The junctions based on NbN/TaN/NbN trilayers measured at 4.2 K show excellent Josephson properties with a wide range of critical current (I c) from 227 to 2000 μA. The variations of critical current density (J c) and characteristic voltage (V c) are respectively less than 7.1% and 7.5% in the 2 inch region. The standard deviation of I c is calculated to be less than 1.7% for Josephson arrays with the number of junctions up to 10 000 occupying an area of 0.34 mm2. The results provide a guarantee for the applications of NbN-SNS Josephson junctions in superconducting large-scale integrated circuits.

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Miniaturization of Josephson Junctions for Digital Superconducting Circuits

et al. 2021

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In this work, we briefly overview various options for Josephson junctions, which should be scalable down to nanometer range for utilization in nanoscale digital superconducting technology. Such junctions should possess high values of critical current, I c , and normal state resistance, R N . Another requirement is the high reproducibility of the junction parameters across a wafer in a fabrication process. We argue that superconductor-normal metal-superconductor (SN -N -NS) Josephson junction of "variable thickness bridge" geometry is a promising choice to meet these requirements. Theoretical analysis of the SN -N -NS junction is performed in the case where the distance between the S electrodes is comparable to the coherence length of the N material. The restriction on the junction geometrical parameters providing the existence of superconductivity in the S electrodes is derived for the current flowing through the junction of an order of I c . The junction heating, as well as available mechanisms for the heat removal, is analyzed. The obtained results show that a SN -N -NS junction with a high (submillivolt) value of I c R N product can be fabricated from a broadly utilized combination of materials like Nb/Cu using well-established technological processes. The junction area can be scaled down to that of semiconductor transistors fabricated in the frame of a 40-nm process.

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Characterization of Uniformity in Nb/Nb_xSi_1-x/Nb Josephson Junctions

Cited by 7 publications

References 18 publications

Strong Coupling of an Fe - Co Alloy with Ultralow Damping to Superconducting Co-planar Waveguide Resonators

Strong Coupling of an Fe - Co Alloy with Ultralow Damping to Superconducting Co-planar Waveguide Resonators

Intrinsically shunted NbN/TaN/NbN Josephson junctions on Si substrates for large-scale integrated circuits applications

Miniaturization of Josephson Junctions for Digital Superconducting Circuits

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Characterization of Uniformity in Nb/NbxSi1-x/Nb Josephson Junctions

Cited by 7 publications

References 18 publications

Strong Coupling of an Fe - Co Alloy with Ultralow Damping to Superconducting Co-planar Waveguide Resonators

Strong Coupling of an Fe - Co Alloy with Ultralow Damping to Superconducting Co-planar Waveguide Resonators

Intrinsically shunted NbN/TaN/NbN Josephson junctions on Si substrates for large-scale integrated circuits applications

Miniaturization of Josephson Junctions for Digital Superconducting Circuits

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Characterization of Uniformity in Nb/Nb_xSi_1-x/Nb Josephson Junctions