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### Physical source of photon frequency [duplicate]

In QM it's taught that the frequency of a photon emitted when an electron drops from a higher-energy state to a lower-energy state is $\Delta E/h$. In E&M, it's taught that the source of an ...
25k views

### What is Chirped Pulse Amplification, and why is it important enough to warrant a Nobel Prize?

The 2018 Nobel Prize in Physics was awarded recently, with half going to Arthur Ashkin for his work on optical tweezers and half going to Gérard Mourou and Donna Strickland for developing a technique ...
3k views

### Why do electrons in an atom occupy only the stationary states?

When we talk about the elementary problems in quantum mechanics like particle in a box, we first calculate the energy eigen-function. Then we say that the most general state is the linear combination ...
1k views

### Can a quasiclassical electron wave packet in elliptic orbit be formed from bound hydrogen-like eigenstates?

Position probability densities of eigenstates of hydrogen-like systems have axial symmetry, so that the wavefunction too much resembles the circular orbits in Bohr's model. I'd like to have a ...
2k views

### Is there any time-dependent hydrogen atom Schrödinger equation, solvable analytically?

It's well-known that hydrogen atom described by time-independent Schrödinger equation (neglecting any relativistic effects) is completely solvable analytically. But are any initial value problems for ...