London penetration depth that's defined for superconductors has a similar equation to skin depth in conductors derived from maxwell's equations. Are they equivalent?
Physically they are not too much equivalent, because the skin depth is due to a dissipation effect, i.e., the finite electric conductivity while the London penetration depth is related to the effective photon mass within a superconductor due to the Anderson-Higgs mechanism.
Yes, from a practical point of view they are somewhat similar.
However, there are not "the same thing"; you can for example not replace the skin depth by the penetration depth when e.g. calculating EM properties.
The EM properties of superconductors at low frequencies (frequencies much lower than the energy of the gap) behave pretty much like perfect conductors from a EM point of view. The main difference (for type II superconductors) is actually presence of a fairly significant kinetic inductance, rather than the penetration depth.
Insights auto threads is broken atm, so I'm manually creating these for new Insight articles.
Towards the end of the first lecture for the Qiskit Global Summer School 2025, Foundations of Quantum Mechanics, Olivia Lanes (Global Lead, Content and Education IBM) stated...
Source: https://www.physicsforums.com/insights/quantum-entanglement-is-a-kinematic-fact-not-a-dynamical-effect/
by @RUTA
If we release an electron around a positively charged sphere, the initial state of electron is a linear combination of Hydrogen-like states. According to quantum mechanics, evolution of time would not change this initial state because the potential is time independent. However, classically we expect the electron to collide with the sphere. So, it seems that the quantum and classics predict different behaviours!
The wavefunction of an atomic orbital like ##p_x##-orbital is generally in the form ##f(\theta)e^{i\phi}## so the probability of the presence of particle is identical at all the directional angles ##\phi##. However, it is dumbbell-shape along the x direction which shows ##\phi##-dependence!