Questions tagged [josephson-junction]
55 questions
9
votes
4 answers
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 show it in the diagram? If no, why don't we have a…
P.A.M
- 1,629
7
votes
1 answer
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 are based on the interference of QM…
bernd
- 343
5
votes
2 answers
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 or potential belongs to:
$i\hbar \frac{\partial…
Bob
- 149
4
votes
1 answer
Is the phase of the Landau-Ginzburg order parameter constant in a superconductor?
The most general for of the Landau-Ginzburg free energy is$^1$
\begin{align}
F_s(T)&=F_n(t)+\int_{V}…
Feynmate
- 2,199
4
votes
1 answer
What does a mechanical Josephson Effect look like?
This question is related to my research work in physics concerning the brittle-ductile-transition (BDT) in solid state mechanics, which ended quite some time ago and is summarized in my thesis from 2013, and though I have quit any serious research…
thomashennecke
- 141
4
votes
1 answer
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 Josephson Effect is in section 18.7 of Bruus &…
Lucas Baldo
- 1,918
3
votes
0 answers
Cooper pair box Hamiltonian and parity
Reading Ref. 1, in the section about the authors discuss the simplest examples of qubits, among which there is the charge qubit, built from a Cooper-pair box (CPB). After writing the CPB Hamiltonian in the number/charge…
Feynmate
- 2,199
3
votes
1 answer
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 ladder except the inductors have been replaced with…
S Thomas
- 51
3
votes
1 answer
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 hamiltonian, on one side (with fermion operators $c,…
Kouta Dagnino
- 187
3
votes
1 answer
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 graph:
After that we analysed the RCSJ model and we…
runrun
- 31
- 2
3
votes
1 answer
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 on this if possible on the answers.
My question…
StarBucK
- 1,688
3
votes
0 answers
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 natural frequency of the system.
The…
turnip
- 3,768
3
votes
1 answer
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 Nambu-Gorkov equation and then some…
WoofDoggy
- 2,190
2
votes
0 answers
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 a Josephson junction in a lab? Specifically, can…
SlothForeva
- 155
2
votes
0 answers
Equality of Bose Lattice Hamiltonian and Josephson Array Hamiltonian
I am currently reading the paper Boson localization and the superfluid-insulator transition by Fisher, Weichman, and Fisher. Equation 2.1 defines the Hamiltonian of a Bose Lattice gas as
$$
H = -\sum_{i}(-J_0 + \mu + \delta \mu_i)\hat{N}_i + 0.5 V…
user261609