Is ## \frac{V_T}{\beta} ## the Crossover Frequency in Josephson Junctions?

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SUMMARY

The discussion centers on the equation for Josephson Junctions, specifically examining whether ## \frac{V_T}{\beta} ## represents the crossover frequency. The participants confirm that inertial effects can be neglected at frequencies up to several hundred megahertz, leading to the simplified equation ## \beta\frac{d\theta}{dt}+V'(\theta)=V(t) ##. The derived expression for the rate of change of theta, ## \frac{d\theta}{dt}=\frac{V_T}{\beta}[\frac{V(t)}{V_T}-\sin(\theta)] ##, establishes that ## \frac{V_T}{\beta} ## is indeed the crossover frequency, denoted as ## \omega_{co} ##.

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  • Understanding of Josephson Junctions and their equations
  • Familiarity with differential equations in physics
  • Knowledge of classical mechanics, particularly inertial effects
  • Basic concepts of electrical engineering related to voltage and current
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Physicists, electrical engineers, and students studying superconductivity or oscillatory systems will benefit from this discussion, particularly those interested in the dynamics of Josephson Junctions.

LagrangeEuler
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Homework Statement


## \alpha \frac{d^2\theta}{dt^2}+\beta\frac{d\theta}{dt}+V'(\theta)=V(t) ##
Inertial effects are negligible at frequencies of up to several hundred megahertz, so the first therm can be neglected.
I'm not sure if that means that
## \beta\frac{d\theta}{dt}+V'(\theta)=V(t) ## (1)
or
## \frac{\beta}{\alpha}\frac{d\theta}{dt}+\frac{V'(\theta)}{\alpha}=\frac{V(t)}{\alpha} ## (2)
With using ##V'(\theta)=V_T\sin(\theta)##
authors get
## \frac{d \theta}{dt}=\omega_{co}(\frac{V}{V_t}-\sin(\theta)) ##
where ##\omega_{co}## is classical crossover frequency.

Homework Equations


The Attempt at a Solution


From (1) I get
## \frac{d\theta}{dt}=\frac{V_T}{\beta}[\frac{V(t)}{V_T}-\sin(\theta)] ##
so is ##\frac{V_T}{\beta}## crossover frequency? Tnx for the answer.
 
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The inertial term is the one with the second derivative wrt time, so (1) is correct.
 
Tnx.
 

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