What's the maximum velocity of electrons in a superconductor?

 

A superconductor is defined by the trivial resistance to electron travel.

What is the maximum velocity of electrons in a vacuum ?

7 hours ago, MigL said:

A superconductor is defined by the trivial resistance to electron travel.

What is the maximum velocity of electrons in a vacuum ?

That's not the limit of merit. There is a critical current above which you lose superconductivity.

 

6 minutes ago, swansont said:

That's not the limit of merit. There is a critical current above which you lose superconductivity.

 

Does that mean you can't move too many electrons in a given time; it's rate limited, depending on the dimensions of the conductor?

Edited November 24, 20187 yr by StringJunky

9 minutes ago, StringJunky said:

Does that mean you can't move too many electrons in a given time; it's rate limited, depending on the dimensions of the conductor?

There's only so many electrons available, but there is a current limit, and current depends on the density and speed.

One might assume a single pair, and could then derive a speed limit that corresponds to the current limit, but it's entirely possible that forming a superconductor necessarily dictates a certain number of cooper pairs. I don't know enough about superconductivity to say how many Cooper pairs you will (or must) form.

I just assumed a 'single'  electron pair, and would think its speed would not be limited by any resistance to travel ( as in a vacuum ).
But you're right, for superconductivity to be set up in the first place ( Meissner effect and expulsion of the magnetic field ) would necessarily involve more than a single  Cooper pair.

I don't know much about superconduction myself.

The Kondo effect implies how Kondo  entanglement between electrons arises in a metal with an impurity, at a temperature close to 0 K.https://phys.org/news/2011-06-electrons-entangled.html#jCp https://www.nature.com/articles/ncomms12442

A 'pure' metal becomes a superconductor at a temp. close to 0K and forms cooper pairs and when you split up those pairs, you have entangled electrons.

Is it then correct to say that when you 'remove' resistivity in a conductor you enable (spin)correlation 'bonds' betweren electrons?

you are assuming too much regarding superconduction/entanglement ( possibly ).

The entanglement of a Cooper pair simply means that the quantum state of each individual electron cannot be described independently, and this situation persists even after the pair are separated. IE entanglement continues even after superconductivity ceases, or until an interaction with one of the individual electrons forces a wave function collapse.

34 minutes ago, MigL said:

you are assuming too much regarding superconduction/entanglement

I just wonder how it's related.

In a superconductor you get cooper pairs, when you add a magnetic impurity to the superconductor then you don't form cooper pairs but kondo entanglement which is a many body entanglement.

What can a magnetic impurity do at temperature close to 0K? I've read magnets misbehave at low temperature.https://physicsworld.com/a/magnet-misbehaves-near-absolute-zero/

Edited November 24, 20187 yr by Itoero

I don't know enough about superconductors.
Maybe Swansont can answer your questions, or another member who is more knowledgeable about the subject.

I just know not to jump to conclusions based on a limited amount of information.

3 hours ago, swansont said:

There's only so many electrons available, but there is a current limit, and current depends on the density and speed.

One might assume a single pair, and could then derive a speed limit that corresponds to the current limit, but it's entirely possible that forming a superconductor necessarily dictates a certain number of cooper pairs. I don't know enough about superconductivity to say how many Cooper pairs you will (or must) form.

Cheers.

When you 'cut'  a conducting wire which hangs downward then the electrons don't fall out, the gravitational force  is too weak. But what happens when you do the same thing with a superconducting wire?