Niobium-stress influence on Nb/Al-oxide/Nb Josephson junctions

Kuroda, Kenichi; Yuda, M.

doi:10.1063/1.341051

Cited by 58 publications

(16 citation statements)

References 10 publications

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“…A bare intrinsic Si wafer is coated with a film of Nb (M1) after stripping the native SiO x with hydrofluoric (HF) acid. Here and below, sputter conditions are tuned to yield films with slight compressive stress [53]; the deposition rate is 45 nm/min. This layer is patterned with an i-line step-andrepeat (stepper) lithography tool and etched with a During the entirety of the fabrication process of the SFQ driver circuit, the area that will support the quantum circuit is left unpatterned and unetched and is protected by the first deposited layer of SiOx.…”

Section: Appendix a Fabrication Detailsmentioning

confidence: 99%

Digital Coherent Control of a Superconducting Qubit

et al. 2019

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High-fidelity gate operations are essential to the realization of a fault-tolerant quantum computer. In addition, the physical resources required to implement gates must scale efficiently with system size. A longstanding goal of the superconducting qubit community is the tight integration of a superconducting quantum circuit with a proximal classical cryogenic control system. Here we implement coherent control of a superconducting transmon qubit using a Single Flux Quantum (SFQ) pulse driver cofabricated on the qubit chip. The pulse driver delivers trains of quantized flux pulses to the qubit through a weak capacitive coupling; coherent rotations of the qubit state are realized when the pulse-to-pulse timing is matched to a multiple of the qubit oscillation period. We measure the fidelity of SFQ-based gates to be ∼95% using interleaved randomized benchmarking. Gate fidelities are limited by quasiparticle generation in the dissipative SFQ driver. We characterize the dissipative and dispersive contributions of the quasiparticle admittance and discuss mitigation strategies to suppress quasiparticle poisoning. These results open the door to integration of large-scale superconducting qubit arrays with SFQ control elements for low-latency feedback and stabilization.

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Section: Appendix a Fabrication Detailsmentioning

confidence: 99%

Digital Coherent Control of a Superconducting Qubit

et al. 2019

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“…The internal film stresses which result from sputter deposition on to a substrate are well known to affect the properties of devices made from those films 11 . While working pressure, deposition power, operation mode (constant power, voltage, or current bias) and even deposition rate must all be examined in order to obtain optimal conditions, the continual erosion of the magnetron sputtering target over its lifetime requires that these parameters be continually re-examined 12 .…”

Section: Thin Film Stress and Bilayer T Cmentioning

confidence: 99%

Frequency selective bolometer development at Argonne National Laboratory

et al. 2008

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We discuss the development, at Argonne National Laboratory, of a four-pixel camera suitable for photometry of distant dusty galaxies located by Spitzer and SCUBA, and for study of other millimeter-wave sources such as ultra-luminous infrared galaxies, the Sunyaev-Zeldovich (SZ) effect in clusters, and galactic dust. Utilizing Frequency Selective Bolometers (FSBs) with superconducting Transition-Edge Sensors (TESs), each of the camera's four pixels is sensitive to four colors, with frequency bands centered approximately at 150, 220, 270, and 360 GHz.The current generation of these devices utilizes proximity effect superconducting bilayers of Mo/Au or Ti/Au for TESs, along with frequency selective circuitry on membranes of silicon nitride 1 cm across and 1 micron thick. The operational properties of these devices are determined by this circuitry, along with thermal control structures etched into the membranes. These etched structures do not perforate the membrane, so that the device is both comparatively robust mechanically and carefully tailored in terms of its thermal transport properties.In this paper, we report on development of the superconducting bilayer TES technology and characterization of the FSB stacks. This includes the use of new materials, the design and testing of thermal control structures, the introduction of desirable thermal properties using buried layers of crystalline silicon underneath the membrane, detector stability control, and optical and thermal test results. The scientific motivation, FSB design, FSB fabrication, and measurement results are discussed. SCIENTIFIC MOTIVATIONMillimeter and sub-millimeter wavelength observations offer unique insights about the early universe. Recognizing this, and spurred on by the recent success of mm/sub-mm observations, the observational cosmology community is currently developing telescopes and receivers of unprecedented sensitivity and scale. Multi-frequency studies will be necessary in order to obtain spectra from sources of interest uncontaminated by background and foreground signals. Therefore, the new telescopes must possess high optical efficiencies over a wide range of wavelengths. A receiver technology which simultaneously utilizes a telescope's full light-gathering power at several distinct frequencies has a great sensitivity advantage over conventional multi-color observing schemes in which only some of the collected light or observing time is allocated to each frequency band. The Frequency Selective Bolometer (FSB) presently under prototype development at Argonne National Laboratory is just such a technology. _____________________________ Corresponding author information for A.D.: E-mail: datesman@anl.gov, Phone: 1 630 252 9154, Mail: 9700 S. Cass Ave., Argonne, IL 60439 U.S.A.

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“…11 With hexagonal Ti film, the c and a axes are not identical, and their lattice parameters change in opposite directions with varying Ar pressure. c-and a-axis lattice parameters determined from the resulting diffraction peaks of ͑002͒ and ͑114͒ planes in the 2 scans are plotted in Figs.…”

Section: ͓S0003-6951͑98͒04923-7͔mentioning

confidence: 99%

Fabrication and properties of all-refractory Nb/Al–AlOx–Ti junctions for microbolometers and microrefrigerators

Zhao

Chen

et al. 1998

Applied Physics Letters

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Fabrication of all-refractory Nb/Al–AlOx–Ti superconducting tunnel junctions using selective titanium etching process (STEP) is described. Results including anodization properties of Ti, and junction’s I–V characteristics and subgap currents measured in the temperature range of 0.4–9.2 K are presented. The junctions show fairly high quality with respect to their stability and reproducibility. Possible utilization of these junctions as superconductor–insulator–normal metal type devices operating around 100 mK and above for ultrasensitive microbolometer and electronic microrefrigerator applications is discussed.

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Niobium-stress influence on Nb/Al-oxide/Nb Josephson junctions

Cited by 58 publications

References 10 publications

Digital Coherent Control of a Superconducting Qubit

Digital Coherent Control of a Superconducting Qubit

Frequency selective bolometer development at Argonne National Laboratory

Fabrication and properties of all-refractory Nb/Al–AlOx–Ti junctions for microbolometers and microrefrigerators

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