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We review recent theoretical and experimental progress in quantum state engineering with Josephson junction devices. The concepts of quantum computing have stimulated an increased activity in the field. Either charges or phases (fluxes) of…

Mesoscale and Nanoscale Physics · Physics 2007-05-23 Yuriy Makhlin , Gerd Schoen , Alexander Shnirman

In thin superconducting wires, phase-slip by thermal activation near the critical temperature is a well-known effect. It has recently become clear that phase-slip by quantum tunnelling through the energy barrier can also have a significant…

Superconductivity · Physics 2009-11-11 J. E. Mooij , C. J. P. M. Harmans

We investigate the dynamics of the phase variable of an ideal underdamped Josephson junction in switching current experiments. These experiments have provided the first evidence for macroscopic quantum tunneling in large Josephson junctions…

Superconductivity · Physics 2009-11-11 G. S. Paraoanu

We propose a new type of Josephson junction formed by two superconductors close to the superconductor-Mott-insulator transition, one of which is doped with holes and the other is doped with electrons. A self-organized Mott-insulating…

Strongly Correlated Electrons · Physics 2007-08-23 Jiangping Hu , Congjun Wu , Xi Dai

We study non-Hermitian Josephson junctions formed by multiple superconductors and discover the emergence of exceptional points entirely determined by the interplay of the distinct superconducting phases and non-Hermiticity due to normal…

Mesoscale and Nanoscale Physics · Physics 2024-12-31 Jorge Cayao , Masatoshi Sato

We present novel low-T_c superconductor-insulator-ferromagnet-superconductor (SIFS) Josephson junctions with planar and stepped ferromagnetic interlayer. We optimized the fabrication process to set a step in the ferromagnetic layer…

Superconductivity · Physics 2008-01-22 Uthayasankaran Peralagu , Martin Weides

Recent phase sensitive experiments on high Tc superconductors, e.g., YBa_2Cu_3O_7 single crystals, have established the d-wave nature of the cuprate materials. Here we discuss how to make use of d-wave Josephson junctions in the…

Mesoscale and Nanoscale Physics · Physics 2009-11-10 Shiro Kawabata , Satoshi Kashiwaya , Yasuhiro Asano , Yukio Tanaka

A growing body of work suggests that planar Josephson junctions fabricated using superconducting hybrid materials provide a highly controllable route toward one-dimensional topological superconductivity. Among the experimental controls are…

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

The evidence for macroscopic quantum tunneling (MQT) in Josephson junctions at low temperatures has been reassessed. Swept bias escape distributions have been modeled with an algorithm-based simulation and the results compared with data…

Superconductivity · Physics 2017-10-26 James A. Blackburn , Matteo Cirillo , Niels Gronbech-Jensen

We study the quantum phase transition properties of a three-dimensional periodic array of Josephson junctions with charging energy that includes both the self and mutual junction capacitances. We use the phase fluctuation algebra between…

Superconductivity · Physics 2016-08-31 T. K. Kopec , Jorge V. Jose

We measure the lifetime ($T_{1}$) and coherence ($T_{2}$) of two-level defect states (TLSs) in the insulating barrier of a Josephson phase qubit and compare to the interaction strength between the two systems. We find for the average decay…

Superconductivity · Physics 2015-05-19 Yoni Shalibo , Ya'ara Rofe , David Shwa , Felix Zeides , Matthew Neeley , John Martinis , Nadav Katz

Dissipationless nonlinearities for three-wave mixing are a key component of many superconducting quantum devices, such as amplifiers and bosonic qubits. So far, such third-order nonlinearities have been primarily achieved with circuits of…

Mesoscale and Nanoscale Physics · Physics 2025-03-26 Constantin Schrade , Valla Fatemi

We study fermion-parity-changing quantum phase transitions (QPTs) in platform Josephson junctions. These QPTs, associated with zero-energy bound states, are rather widely observed experimentally. They emerge from numerical calculations…

Superconductivity · Physics 2018-08-14 Chien-Te Wu , F. Setiawan , Brandon M. Anderson , Wei-Han Hsiao , K. Levin

We have developed a fabrication process for nanoscale tunnel junctions which includes focused-ion-beam etching from different directions. By applying the process to a Nb/(Al-)Al_2O_3/Nb trilayer, we have fabricated a Nb single-electron…

Mesoscale and Nanoscale Physics · Physics 2007-05-23 Michio Watanabe , Yasunobu Nakamura , Jaw-Shen Tsai

Non-equilibrium quasiparticles are possible sources for decoherence in superconducting qubits because they can lead to energy decay or dephasing upon tunneling across Josephson junctions (JJs). Here, we investigate the impact of the…

Transmon qubits are ubiquitous in the pursuit of quantum computing using superconducting circuits. However, they have some drawbacks that still need to be addressed. Most importantly, the scalability of transmons is limited by the large…

Quantum Physics · Physics 2020-12-03 R. Zhao , S. Park , T. Zhao , M. Bal , C. R. H. McRae , J. Long , D. P. Pappas

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 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

We study the Josephson effect of a $\rm{T_1 F T_2}$ junction, consisting of spin-triplet superconductors (T), a weak ferromagnetic metal (F), and ferromagnetic insulating interfaces. Two types of the triplet order parameters are considered;…

Superconductivity · Physics 2017-09-01 Chi-Hoon Choi