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We study the electrical transport of vertically-stacked Josephson tunnel junctions using GdBa$_2$Cu$_3$O$_{7-d}$ electrodes and a BaTiO$_3$ barrier with thicknesses between 1 nm and 3 nm. The junctions with an area of 20 mm x 20 mm were…

Superconductivity · Physics 2020-09-23 H. Navarro , M. Sirena , Jeehoon Kim , N. Haberkorn

We have developed a combined photolithography and electron-beam lithography fabrication process for sub-\mum to \mum-size Nb/Al-AlOx/Nb Josephson junctions. In order to define the junction size and protect its top electrode during anodic…

Superconductivity · Physics 2011-02-14 Christoph Kaiser , J. M. Meckbach , K. Ilin , J. Lisenfeld , R. Schäfer , A. V. Ustinov , M. Siegel

The most commonly used physical realization of superconducting qubits for quantum circuits is a transmon. There are a number of superconducting quantum circuits applications, where Josephson junction critical current reproducibility over a…

Bi$_2$Se$_3$ nanoribbons, grown by catalyst-free Physical Vapour Deposition, have been used to fabricate high quality Josephson junctions with Al superconducting electrodes. The conductance spectra (dI/dV) of the junctions show clear…

Superconductivity · Physics 2020-01-08 Gunta Kunakova , Thilo Bauch , Edoardo Trabaldo , Jana Andzane , Donats Erts , Floriana Lombardi

Many nanoelectronic devices rely on thin dielectric barriers through which electrons tunnel. For instance, aluminium oxide barriers are used as Josephson junctions in superconducting electronics. The reproducibility and drift of circuit…

Mesoscale and Nanoscale Physics · Physics 2020-02-05 M. J. Cyster , J. S. Smith , J. A. Vaitkus , N. Vogt , S. P. Russo , J. H. Cole

Topological superconductors are appealing building blocks for robust and reliable quantum information processing. Most platforms for engineering topological superconductivity rely on a combination of superconductors, materials with…

Mesoscale and Nanoscale Physics · Physics 2025-08-06 Ignacio Sardinero , Rubén Seoane Souto , Pablo Burset

Tantalum (Ta) has emerged as a promising low-loss material, enabling record coherence times in superconducting qubits. This enhanced performance is largely attributed to its stable native oxide, which may host fewer two-level system (TLS)…

Tunneling defects in disordered materials form spurious two-level systems which are a major source of decoherence for micro-fabricated quantum devices. For superconducting qubits, defects in tunnel barriers of submicrometer-sized Josephson…

Quantum Physics · Physics 2022-03-09 Alexander Bilmes , Serhii Volosheniuk , Alexey V. Ustinov , Jürgen Lisenfeld

We have studied Josephson junctions with barriers prepared from the Heusler compound Cu$_2$MnAl. In the as-prepared state the Cu$_2$MnAl layers are non ferromagnetic and the critical Josephson current density $j_{c}$ decreases exponentially…

Superconductivity · Physics 2010-03-11 D. Sprungmann , K. Westerholt , H. Zabel , M. Weides , H. Kohlstedt

The most developed integrated receivers for THz radiation nowadays are based on Josephson junction SIS devices. In this kind of devices, the highest receivable frequency is determined by the energy gap of the superconducting electrodes and…

Superconductivity · Physics 2016-12-09 M. Merker , C. Bohn , M. Völlinger , K. Ilin , M. Siegel

We report low-temperature measurements of current-voltage characteristics for highly conductive Nb/Al-AlOx-Nb junctions with thicknesses of the Al interlayer ranging from 40 to 150 nm and ultra-thin barriers formed by diffusive oxidation of…

Mesoscale and Nanoscale Physics · Physics 2012-04-12 V. Lacquaniti , M. Belogolovskii , C. Cassiago , N. De Leo , M. Fretto , A. Sosso

Metal-Insulator-Metal tunnel junctions (MIMTJ) are common throughout the microelectronics industry. The industry standard AlOx tunnel barrier, formed through oxygen diffusion into an Al wetting layer, is plagued by internal defects and…

We characterize highly coherent transmon qubits fabricated with a direct-write photolithography system. Multi-layer evaporation and oxidation allows us to change the critical current density by reducing the effective tunneling area and…

Mesoscale and Nanoscale Physics · Physics 2021-08-11 J. T. Monroe , D. Kowsari , K. Zheng , C. Gaikwad , J. Brewster , D. S. Wisbey , K. W. Murch

Reproducible high-Tc Josephson junctions have been made in a rather simple two-step process using ion irradiation. A microbridge (1 to 5 ?m wide) is firstly designed by ion irradiating a c-axis-oriented YBa2Cu3O7-? film through a gold mask…

Superconductivity · Physics 2009-11-11 N. Bergeal , X. Grison , J. Lesueur , G. Faini , M. Aprili , J. P. Contour

We experimentally demonstrated the optical responses of the switching currents in two types of Josephson tunnel junctions: Al/AlOx/Al and Nb/AlOx/Nb. The radiation-induced switching current shifts were measured at ultra-low bath temperature…

Mesoscale and Nanoscale Physics · Physics 2017-02-28 Yiwen Wang , Pinjia Zhou , Lianfu Wei , Beihong Zhang , Qiang Wei , Jiquan Zhai , Weiwei Xu , Chunhai Cao

One of the practical limitations of solid-state superconducting quantum processors technology is frequency crowding due to low qubits fabrication reproducibility. Josephson junction 100 nm-scale nonlinear inductance of the qubits still…

We fabricated high quality $\Nb/\Al_2\O_3/\Ni_{0.6}\Cu_{0.4}/\Nb$ superconductor-insulator-ferromagnet-superconductor Josephson tunnel junctions. Depending on the thickness of the ferromagnetic $\Ni_{0.6}\Cu_{0.4}$ layer and on the ambient…

Superconductivity · Physics 2007-05-23 M. Weides , M. Kemmler , H. Kohlstedt , A. Buzdin , E. Goldobin , D. Koelle , R. Kleiner

Sandwich-type MgB2 Josephson tunnel junctions (MgB2/AlOx/MgB2) have been fabricated using as-grown MgB2 films formed by molecular beam epitaxy. The junctions exhibited substantial supercurrent and a well-defined superconducting gap…

Superconductivity · Physics 2007-05-23 K. Ueda , S. Saito , K. Semba , T. Makimoto , M. Naito

Josephson junctions translate quantum phase coherence into an electrical response and underpin superconducting sensors and quantum circuits. In conventional junctions, the barrier acts primarily as a passive weak link, however, when the…

Tantalum and aluminum on sapphire are widely used platforms for qubits of long coherent time. As quantum chips scale up, the number of Josephson junctions on Sapphire increases. Thus, both the uniformity and stability of the junctions are…

Superconductivity · Physics 2024-05-08 Yuzhen Zheng , Shuming Li , Zengqian Ding , Kanglin Xiong , Jiagui Feng , Hui Yang