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Superconductor-Ferromagnetic-Superconductor (SFS) Josephson junctions are known to exhibit a transition between $\pi$ and 0 states. In this note we find the $\pi-0$ phase diagram of an SFS junction depending on the transparency of an…

Mesoscale and Nanoscale Physics · Physics 2009-11-07 N. M. Chtchelkatchev , W. Belzig , Yu. V. Nazarov , C. Bruder

The fundamental noise limit of a phase-preserving amplifier at frequency $\omega /2\pi $ is the standard quantum limit $T_{q}=\hbar \omega /2k_{B}$. In the microwave range, the best candidates have been amplifiers based on superconducting…

Mesoscale and Nanoscale Physics · Physics 2014-06-03 Pasi Lähteenmäki , Visa Vesterinen , Juha Hassel , Heikki Seppä , Pertti Hakonen

We develop a microscopic model to describe the Josephson dynamics between two superfluid reservoirs of ultracold fermionic atoms which accounts for the dependence of the critical current on both the barrier height and the interaction…

Quantum Gases · Physics 2019-12-04 Matteo Zaccanti , Wilhelm Zwerger

The origin of AC resistivity in the high Tc superconductors is not addressed adequately in literature. We found out, Josephson Junction (JJ) decoupling is the main origin of the AC resistivity in high Tc superconductors. We have measured…

Superconductivity · Physics 2007-05-23 S. Sarangi , S. P. Chockalingam , S. V. Bhat

We investigate Josephson junctions among conventional superconducting wires, in the presence of externally applied Zeeman fields and supercurrents. We demonstrate that the critical Josephson current and the current-phase relation of the…

Superconductivity · Physics 2022-08-02 Giorgos Livanas

Low-noise amplification atmicrowave frequencies has become increasingly important for the research related to superconducting qubits and nanoelectromechanical systems. The fundamental limit of added noise by a phase-preserving amplifier is…

Mesoscale and Nanoscale Physics · Physics 2014-05-21 Pasi Lähteenmäki , Visa Vesterinen , Juha Hassel , G. S. Paraoanu , Heikki Seppä , Pertti Hakonen

We consider a $SBS$ Josephson junction the superconducting electrodes $S$ of which are in contact with normal metal reservoirs ($B$ means a barrier). For temperatures near $T_{c}$ we calculate an effective critical current $% I_{c}^{\ast}$…

Superconductivity · Physics 2009-11-13 A. F. Volkov

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

We calculate the Josephson current in a diffusive superconductor/ferromagnet/superconductor junction, where the ferromagnetic region contains multiple layers (or domains). In particular, we study a configuration where there are two layers…

Superconductivity · Physics 2009-11-13 Iver B. Sperstad , Jacob Linder , Asle Sudbø

Josephson junction parametric amplifiers are playing a crucial role in the readout chain in superconducting quantum information experiments. However, their integration with current 3D cavity implementations poses the problem of…

Quantum Physics · Physics 2014-07-23 A. Narla , K. M. Sliwa , M. Hatridge , S. Shankar , L. Frunzio , R. J. Schoelkopf , M. H. Devoret

We have measured the low frequency critical current noise in Nb/AlO$_{\mathrm{x}}$/Nb Josephson junctions. Unshunted junctions biased above the gap voltage and resistively shunted junctions biased near the critical current, $I_{c}$, have…

Superconductivity · Physics 2009-11-13 Shawn Pottorf , Vijay Patel , James E. Lukens

Quantum fluctuations in a current biased Josephson junction, described in terms of the RCSJ-model, are considered. The fluctuations of the voltage and phase across the junction are assumed to be initiated by equilibrium current fluctuations…

Superconductivity · Physics 2009-11-07 Y. Levinson

Superconductor-semiconductor hybrid materials have been extensively used for experiments on electrically tunable quantum devices. Notably, Josephson junctions utilizing nanowire weak links have enabled a number of new gate-tunable qubits,…

By using analytical and Worldline Monte Carlo approaches, we investigate the effects induced by quantum phase fluctuations combined with quasiparticle subgap and shunt resistances on a small-capacitance Josephson junction. By using the…

We present a theory for the nonequilibrium current in a mesoscopic Josephson junction which is coupled to a normal electron reservoir, and apply it to a chaotic junction. Large sample-to-sample fluctuations of the critical current $I_{\rm…

Superconductivity · Physics 2007-05-23 P. Samuelsson , H. Schomerus

Operation of Josephson electronics usually requires determination of the Josephson critical current $I_c$, which is affected both by fluctuations and measurement noise. Lock-in measurements allow obviation of $1/f$ noise and, therefore,…

Superconductivity · Physics 2021-12-09 Razmik A. Hovhannisyan , Olena M. Kapran , Taras Golod , Vladimir M. Krasnov

With a large portfolio of elemental quantum components, superconducting quantum circuits have contributed to dramatic advances in microwave quantum optics. Of these elements, quantum-limited parametric amplifiers have proven to be essential…

Semiconductor-based Josephson junctions provide a platform for studying proximity effect due to the possibility of tuning junction properties by gate voltage and large-scale fabrication of complex Josephson circuits. Recently Josephson…

Mesoscale and Nanoscale Physics · Physics 2019-03-27 William Mayer , Joseph Yuan , Kaushini Wickramasinghe , Tri Nguyen , Matthieu C. Dartiailh , Javad Shabani

We present the measurement of superconductor / ferromagnetic Josephson junctions, based on an epitaxial Nb bottom electrode and epitaxial Fe20Ni80 barrier. Uniform junctions have been fabricated with a barrier thicknesses in the range 2-12…

Superconductivity · Physics 2009-11-11 C. Bell , R. Loloee , G. Burnell , M. G. Blamire

Transport is called nonreciprocal when not only the sign, but also the absolute value of the current, depends on the polarity of the applied voltage. It requires simultaneously broken inversion and time-reversal symmetries, e.g., by the…