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22 pages, 826 KB

Open AccessArticle

Josephson Junction Dynamics as a Ride on a Roller Coaster

by Ciro Nappi, Carlo Camerlingo and Roberto Cristiano

Physics 2025, 7(1), 2; https://doi.org/10.3390/physics7010002 - 16 Jan 2025

Cited by 1 | Viewed by 2377

We discuss the dynamics of a roller coaster cart driven by a constant force along the suspended track of a winding roller coaster. The track is assumed to be arbitrarily long and specially shaped. It is composed of semicircular track portions, in the form of valleys and hills, standing vertically in the same plane. This is a mechanical analog of Josephson junction electrodynamics. To demonstrate the explanatory potential of this analogy, we focus particularly on the conditions of de-trapping of the cart from one of the valleys of the track. This mechanical process has its analog in non-noise-generated premature switching to the finite voltage state of a Josephson junction. Full article

(This article belongs to the Section Physics Education)

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12 pages, 1620 KB

Open AccessFeature PaperArticle

Axion Field Influence on Josephson Junction Quasipotential

by Roberto Grimaudo, Davide Valenti, Bernardo Spagnolo, Antonio Troisi, Giovanni Filatrella and Claudio Guarcello

Materials 2023, 16(17), 5972; https://doi.org/10.3390/ma16175972 - 31 Aug 2023

Cited by 5 | Viewed by 1883

Abstract

The direct effect of an axion field on Josephson junctions is analyzed through the consequences on the effective potential barrier that prevents the junction from switching from the superconducting to the finite-voltage state. We describe a method to reliably compute the quasipotential with stochastic simulations, which allows for the spanning of the coupling parameter from weakly interacting axion to tight interactions. As a result, we obtain an axion field that induces a change in the potential barrier, therefore determining a significant detectable effect for such a kind of elusive particle. Full article

(This article belongs to the Special Issue Physics and Application of Superconductivity)

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13 pages, 12885 KB

Open AccessArticle

Bio-Inspired Design of Superconducting Spiking Neuron and Synapse

by Andrey E. Schegolev, Nikolay V. Klenov, Georgy I. Gubochkin, Mikhail Yu. Kupriyanov and Igor I. Soloviev

Nanomaterials 2023, 13(14), 2101; https://doi.org/10.3390/nano13142101 - 19 Jul 2023

Cited by 27 | Viewed by 3211

Abstract

The imitative modelling of processes in the brain of living beings is an ambitious task. However, advances in the complexity of existing hardware brain models are limited by their low speed and high energy consumption. A superconducting circuit with Josephson junctions closely mimics the neuronal membrane with channels involved in the operation of the sodium-potassium pump. The dynamic processes in such a system are characterised by a duration of picoseconds and an energy level of attojoules. In this work, two superconducting models of a biological neuron are studied. New modes of their operation are identified, including the so-called bursting mode, which plays an important role in biological neural networks. The possibility of switching between different modes in situ is shown, providing the possibility of dynamic control of the system. A synaptic connection that mimics the short-term potentiation of a biological synapse is developed and demonstrated. Finally, the simplest two-neuron chain comprising the proposed bio-inspired components is simulated, and the prospects of superconducting hardware biosimilars are briefly discussed. Full article

(This article belongs to the Special Issue Nanoscale Quantum Optics)

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16 pages, 8476 KB

Open AccessArticle

Phase Diffusion in Low-E_J Josephson Junctions at Milli-Kelvin Temperatures

by Wen-Sen Lu, Konstantin Kalashnikov, Plamen Kamenov, Thomas J. DiNapoli and Michael E. Gershenson

Electronics 2023, 12(2), 416; https://doi.org/10.3390/electronics12020416 - 13 Jan 2023

Cited by 8 | Viewed by 3972

Abstract

Josephson junctions (JJs) with Josephson energy

E_{J} ≲ 1

K are widely employed as non-linear elements in superconducting circuits for quantum computing operating at milli-Kelvin temperatures. In the qubits with small charging energy

E_{C}

( [...] Read more.

Josephson junctions (JJs) with Josephson energy

E_{J} ≲ 1

K are widely employed as non-linear elements in superconducting circuits for quantum computing operating at milli-Kelvin temperatures. In the qubits with small charging energy

E_{C}

(

E_{J} / E_{C} ≫ 1

), such as the transmon, the incoherent phase slips (IPS) might become the dominant source of dissipation with decreasing

E_{J}

. In this work, a systematic study of the IPS in low-

E_{J}

JJs at milli-Kelvin temperatures is reported. Strong suppression of the critical (switching) current and a very rapid growth of the zero-bias resistance due to the IPS are observed with decreasing

E_{J}

below 1 K. With further improvement of coherence of superconducting qubits, the observed IPS-induced dissipation might limit the performance of qubits based on low-

E_{J}

junctions. These results point the way to future improvements of such qubits. Full article

(This article belongs to the Special Issue Nanofabrication of Superconducting Circuits)

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12 pages, 9453 KB

Open AccessEditor’s ChoiceArticle

Supercurrent in Bi₄Te₃ Topological Material-Based Three-Terminal Junctions

by Jonas Kölzer, Abdur Rehman Jalil, Daniel Rosenbach, Lisa Arndt, Gregor Mussler, Peter Schüffelgen, Detlev Grützmacher, Hans Lüth and Thomas Schäpers

Nanomaterials 2023, 13(2), 293; https://doi.org/10.3390/nano13020293 - 10 Jan 2023

Cited by 15 | Viewed by 6841

Abstract

In this paper, in an in situ prepared three-terminal Josephson junction based on the topological insulator Bi

_{4}

_{3}

and the superconductor Nb the transport properties are studied. The differential resistance maps as a function of two bias currents reveal extended areas [...] Read more.

In this paper, in an in situ prepared three-terminal Josephson junction based on the topological insulator Bi

_{4}

_{3}

and the superconductor Nb the transport properties are studied. The differential resistance maps as a function of two bias currents reveal extended areas of Josephson supercurrent, including coupling effects between adjacent superconducting electrodes. The observed dynamics for the coupling of the junctions is interpreted using a numerical simulation of a similar geometry based on a resistively and capacitively shunted Josephson junction model. The temperature dependency indicates that the device behaves similar to prior experiments with single Josephson junctions comprising topological insulators’ weak links. Irradiating radio frequencies to the junction, we find a spectrum of integer Shapiro steps and an additional fractional step, which is interpreted with a skewed current–phase relationship. In a perpendicular magnetic field, we observe Fraunhofer-like interference patterns in the switching currents. Full article

(This article belongs to the Special Issue Topological Materials in Low Dimensions)

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9 pages, 1944 KB

Open AccessArticle

High-Quality Ferromagnetic Josephson Junctions Based on Aluminum Electrodes

by Antonio Vettoliere, Roberta Satariano, Raffaella Ferraiuolo, Luigi Di Palma, Halima Giovanna Ahmad, Giovanni Ausanio, Giovanni Piero Pepe, Francesco Tafuri, Davide Massarotti, Domenico Montemurro, Carmine Granata and Loredana Parlato

Nanomaterials 2022, 12(23), 4155; https://doi.org/10.3390/nano12234155 - 24 Nov 2022

Cited by 15 | Viewed by 3856

Abstract

Aluminum Josephson junctions are the building blocks for the realization of superconducting quantum bits. Attention has been also paid to hybrid ferromagnetic Josephson junctions, which allow switching between different magnetic states, making them interesting for applications such as cryogenic memories, single-photon detectors, and spintronics. In this paper, we report on the fabrication and characterization of high-quality ferromagnetic Josephson junctions based on aluminum technology. We employed an innovative fabrication process inspired by niobium-based technology, allowing us to obtain very high-quality hybrid aluminum Josephson junctions; thus, supporting the use of ferromagnetic Josephson junctions in advanced quantum circuits. The fabrication process is described in detail and the main DC transport properties at low temperatures (current–voltage characteristic, critical current as a function of the temperature, and the external magnetic field) are reported. Here, we illustrate in detail the fabrication process, as well as the main DC transport properties at low temperatures (current–voltage characteristic, critical current as a function of the temperature, and the external magnetic field). Full article

(This article belongs to the Special Issue Superconductivity in Nanosystems)

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14 pages, 883 KB

Open AccessArticle

Stabilization Effects of Dichotomous Noise on the Lifetime of the Superconducting State in a Long Josephson Junction

by Claudio Guarcello, Davide Valenti, Angelo Carollo and Bernardo Spagnolo

Entropy 2015, 17(5), 2862-2875; https://doi.org/10.3390/e17052862 - 6 May 2015

Cited by 101 | Viewed by 6547

Abstract

We investigate the superconducting lifetime of a long overdamped current-biased Josephson junction, in the presence of telegraph noise sources. The analysis is performed by randomly choosing the initial condition for the noise source. However, in order to investigate how the initial value of the dichotomous noise affects the phase dynamics, we extend our analysis using two different fixed initial values for the source of random fluctuations. In our study, the phase dynamics of the Josephson junction is analyzed as a function of the noise signal intensity, for different values of the parameters of the system and external driving currents. We find that the mean lifetime of the superconductive metastable state as a function of the noise intensity is characterized by nonmonotonic behavior, strongly related to the soliton dynamics during the switching towards the resistive state. The role of the correlation time of the noise source is also taken into account. Noise-enhanced stability is observed in the investigated system. Full article

(This article belongs to the Special Issue Quantum Computation and Information: Multi-Particle Aspects)

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