# Tag Info

## New answers tagged superconductivity

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I will answer your second question because it's the one with which I'm more familiar. The question we're answering is: "Why does current in a superconductor move with no resistance?" To understand this we should first understand why normal metals have nonzero resistivity. Imagine an electron in the metal and suppose it is traveling in some direction. If ...

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When an isolated superconductor goes through the superconducting transition, $T_c$, a symmetry is broken. The electrons above $T_c$ have an assortment of different phases, whereas below they "choose" one macroscopic phase. This "choice" is analogous to that of a magnetic material going through its Curie temperature or the 'ball on a sombrero' example. This ...

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The short answer is it comes from the current and/or voltage difference applied across the junction. A longer answer should be of interest I believe, so here it goes. The phase in the superconductor circuit stands for a redundant degree of freedom that you can never measure. This redundancy is important: it somehow means that a voltage is meaningless ...

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Perhaps it is worth asking, "Why would the order parameters have the same phase?" But the phase difference $\phi$ across a Josephson junction can be forced to change by the application of a voltage across the junction, $$U(t) = \frac{\hbar}{2 e} \frac{\partial \phi}{\partial t}$$ where $U(t)$ is the applied bias. The picture I have in my head is - the ...

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Diamagnetic materials (including superconductors) experience a force in a magnetic field gradient, in the direction of decreasing field. If the force is in the opposite direction of the force of gravity this is referred to as levitation. Even a live frog has been levitated However, this does not directly lead to improved spaced travel. You need energy to ...

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