Questions tagged [josephson-junction]

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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 ...
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0answers
16 views

Supercurrents in DC squids with irregular loops

There is a good chance that the answer to this question is rather trivial, but it somehow seems to escape me for the moment. I'm considering the case of a DC squid; a loop with two Josephson ...
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1answer
34 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 ...
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0answers
14 views

Which is the difference between Josephson and Rabi oscillations?

Consider a bosonic Josephson junction, such as a Bose-Einstein condensate trapped in a double-well potential. What are Josephson oscillations and what are Rabi oscillations? In what do they differ?
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1answer
69 views

Why do excited states of charge qubits have higher charge sensitivity than the ground state?

Lets define charge qubits as two coupled superconductors connected by a Josephson tunnel junction governed by the Hamiltonian \begin{equation} H = 4 E_C \left(n - n_g\right)^2 - E_J \cos{\phi} \end{...
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0answers
68 views

Characteristic lengths in SNS Josephson Junction

An S-N-S Josephson junction is formed by two Superconducting (S) leads separated by a normal metal (N) which acts like the weak link. While studying, I often encounter the words diffusive, long, ...
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35 views

Origin of Josephson voltage equation?

i cant find a satisfying explanation, and I cant figure it out myself, a derivation for the josephson equation: $$U(t)=\frac{\hbar}{2e}\frac{d\phi}{dt}$$ where $U(t)$ is the voltage, and $\phi$ is the ...
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0answers
22 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 ...
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0answers
61 views

Josephson energy versus magnetic field in S-Nanowire-S junctions

I was reading the proposal Microwave transitions as a signature of coherent parity mixing effects in the Majorana-transmon qubit by Ginossar and Grosfeld (2014) in which they envision a superconductor-...
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0answers
210 views

Original derivation of the Josephson effect

In my efforts to understand Josephson's original derivation of the effect that bears his name, I was led to Eqs. 3.68 on pg. 69 from Tinkham's book (Introduction to Superconductivity, McGraw-Hill, 2nd ...
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0answers
285 views

Josephson junction exceeding the coherence length of the cooper pair

In this recent paper http://arxiv.org/abs/1504.03286, the authors present the data that they measured Fraunhofer-like diffraction pattern in a Josephson junction with graphene sandwiched between ...
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1answer
128 views

Definition of Josephson current

Consider a system of two superconductors (with Hamiltonian $H_{SC1}$ and $H_{SC2}$) weakly tunnel coupled via some intermediate system, i.e. an insulator, a ferromagnet, a quantum dot, etc. (described ...
4
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1answer
423 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 ...
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370 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.
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4answers
3k views

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
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2answers
825 views

What is the temperature dependence of the critical current in weak links?

I am now working on hybrid Josephson junctions that are supposed to be tunnel junctions, so that the temperature dependence of the critical current should be $$ I_c (T)=\frac{\pi}{2}\frac{\Delta(T)}{...
6
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1answer
825 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 ...
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0answers
70 views

Why are the Fermi levels of two different superconductors in a Josephson junction the same?

ELECTRON TUNNELING AND SUPERCONDUCTIVITY (Fig. 10A)– This is Giaever's Nobel lecture about how to measure the energy gap of each superconductor using a Josephson junction. I wonder why we can assume ...
3
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0answers
171 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 ...