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# Questions tagged [josephson-junction]

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9 votes
4 answers
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### What does the $I$-$V$ curve in josephson junction mean?

According to the $I$-$V$ curve for Josephson junction tunneling for S-I-S (superconductor-insulator-superconductor), Do we have any tunneling current for $0< V\leq V_c$? If yes, then why don't we ...
• 1,573
6 votes
1 answer
1k views

### Analogies between Fraunhofer diffraction and Josephson junctions

There are several analogies between diffraction patterns and Josephson junctions, especially between a double slit experiment and two Josephson junctions in a superconducting ring (like this): Both ...
• 313
5 votes
2 answers
2k views

### The Hamiltonian for Josephson Junctions

In the Feynman Lectures on physics, Feynman says the amplitudes across a Josephson Junction should be related by the following, where the subscript denotes the side of the junction that the amplitude ...
• 139
4 votes
1 answer
153 views

### Inconsistency in microscopic derivation of the Josephson effect?

My question is related to, but different from, other questions in this platform (see this, this and this). One of the few places I have found in literature that provide a microscopic derivation of the ...
• 1,540
3 votes
1 answer
655 views

### Regimes of Josephson junction

There are several formulas to describe critical current in Josepshon S-N-S junction mainly based on Eilenberger and Usadel equations for quasi-classical Green's functions. The starting point is the ...
• 2,080
3 votes
1 answer
103 views

### Lagrangian for a non-linear wave equation

I have the following wave equation that I am trying to understand better: $$\frac{\partial^2 \varphi}{\partial t^2}-\frac{\partial^2 \sin{\varphi}}{\partial x^2}=0.$$ This equation describes an LC ...
• 51
3 votes
1 answer
1k views

### Josephson junction: why do we need a capacitance in parallel to the inductance in the description?

To start: I am really a huge beginner in Josephson junction. I need to understand the electrical equations associated to it, I don't need to go in the superconducting physics and I would like to stick ...
• 1,410
3 votes
1 answer
667 views

### Current Voltage characteristic of Josephson Junction

I'm having trouble understanding what the current voltage characteristic of a Josephson Junction looks like. When we first looked at the voltage state of a Josephson Junction we got the following ...
• 31
3 votes
0 answers
178 views

### What can I expect to see in a oscillator exhibiting bifurcation?

I have a program which aims to simulate a Josephson Bifurcation Amplifier. I am currently trying to obtain a plot of the probability of bifurcation as a function of the ratio between the driving and ...
• 3,668
2 votes
1 answer
439 views

### Josephson junction characteristics

Is there a physical interpretation for the characteristic frequency and voltage of a josephson junction? $$\omega_c = \frac{2 \pi I_0 R}{\Phi_0}$$ $$V_c = I_0 R$$ $I_0$ is the critical current ...
• 1,395
2 votes
1 answer
310 views

### Microscopic derivation of the Josephson effect

In section 18.7 of Bruus & Flensberg the authors provide a microscopic derivation of the Josephson effect. The hamiltonian on both sides of the tunnelling junction is just the typical BCS ...
2 votes
1 answer
262 views

### Computing flux modulation of the energy spectrum in a DC SQUID

I've been reading some work by Y. Chen et al's paper on tunable couplers for transmon qubits (you can find the work at https://journals.aps.org/prl/pdf/10.1103/PhysRevLett.113.220502) and wanted to ...
2 votes
0 answers
89 views

### Josephson supercurrent measurement in a lab

This may be a very trivial question but I am a theoretician and can't find the answer to this question for the life of me. Is it possible to actually measure the Josephson supercurrent flowing through ...
• 155
2 votes
0 answers
26 views

• 182
1 vote
2 answers
195 views

### Resistively and Capacitively Shunted Junction (RCSJ) Model of Josephson Junction Numerical Solution

I'm trying to write a program to plot the I-V charateristics the josephson junction using a python program for some given values of resistance $R$, capacitance $C$, and critical current $I_0$, using ...
• 143
1 vote
1 answer
85 views

### What makes cooper pairs hop to another superconductor?

I know the derivation and how the Josephson effect works. But if we just have two slabs of superconducting material placed together with an insulator between them, what makes the initial hopping occur?...
• 251
1 vote
1 answer
21 views

### Thermal Smearing in Josephson Junction

I'm basically trying to simulate a josephson junction at a particular temperature. As per some of the plots I could find, the rise in temperature leads to a rounding of the I - V curve. I was ...
• 143
1 vote
1 answer
36 views

### Unitary Transformation Taking a 4$\pi$ Periodic Wave Function to 2$\pi$ Periodic Wave Function

I am reading the following paper, which discusses Majorana fermions in Josephson junction arrays. Initially, the paper starts with a model such that the wavefunctions are $4\pi$ periodic. These ...
1 vote
1 answer
70 views

• 13
0 votes
0 answers
607 views

### What is the difference between a Josephson junction and a superconducting tunnel junction?

I am wondering if there is any difference between a Josephson junctions and superconducting tunnel junctions. I appreciate a good explanation.