# Tagged Questions

Quantum mechanics describes the microscopic properties of nature in a regime where classical mechanics no longer applies. It explains phenomena such as the wave-particle duality, quantization of energy and the uncertainty principle and is generally used in single body systems. Use the quantum-field-...

64 views

### What's the chance that two atoms would swap electrons?

Suppose two atoms are falling away from each other with velocity $v$ each. Suppose they have evenly distributed momentum among their electrons. Suppose one atom swaps an electron with the other atom. ...
77 views

### How does the wave function change upon a boost? [on hold]

I was recently thinking about Lorentz invariance description of a particle. In special relativity is based on the invariance of $$\text{constant} = c^2t^2 - x^2 - y^2 - z^2$$ I was wondering if ...
69 views

### Does electron absorb energy?

According to my teacher, an electron is point sized and it does not absorb or release energy. Moreover, my teacher says their orbital absorbs energy rather than the electron. If that is the case, then ...
588 views

### Quantum Mechanics in Electric Field

I am working on a problem which looks like this. Consider a charged particle with charge $q$ trapped in a box of length $L$ with finite constant potential $V_0$ on both ends. A constant (static) ...
93 views

53 views

23 views

### What is the maximum limit for concurrence for a multiparticle state derived from a symmetric hamiltonian? [on hold]

What is the limit for the Entanglement of a multi particle state? Say I have N spins and a symmetric Hamiltonian. Is it 1 or more? Is there a limit at all? I thought it would be 1, since that value ...
199 views

### Rigorous Mathematical Proof of the Uncertainty Principle from First Principles [duplicate]

While looking at an intuitive explanation for the Heisenberg Uncertainty Principle (related question below), there was a mention of an axiomatic approach to establishing the uncertainty principle. ...
20 views

### Quantum Confinement in Quantum Dots

I have seen it referenced in several places that an electron will behave classically in a bulk material but as the dimension of the material in which the electron exists is limited below the electron'...
68 views

### Which charge to use in the Dirac quantization condition?

I have a follow-up question to Dirac magnetic monopoles and quark fractional electric charge quantization, regarding whether the "unit of electric charge" in the Dirac quantization condition should be ...
2k views

### What is a completely positive map *physically*?

I am sure this question is really stupid, but I could not refrain from asking it in this forum. This can be considered as a continuation of this question. ...
141 views

### Thermionic emission, delayed emission and predissociation

In molecular photodissociation, the thermionic emission, delayed emission and predissociation are the same? Otherwise, what is the difference between them? My question is not about the solids, but I ...
66 views

### Is the use of term Measurement appropriate in quantum physics

It may not sound like a physics question, but I think, it is. When we measure spin of an electron in a certain direction, we are actually, setting it up in that direction. That does not sound like ...
633 views

### Can 3 photons be combined to give a spin-0 projection?

Motivation: The neutral pion decays to 2 photons ($\pi^0\to\gamma\gamma$) most of the time. For the decay of the neutral to 3 photons ($\pi^0\to 3\gamma$) we have an upper limit on the branching ...
67 views

### Express state as eigenkets

This is very basic but I just suddenly got confused. Any state can be expressed as complete set of eigenkets with discrete eigenvalues: $$|P\rangle = \sum^n c_n |p_n\rangle$$ I understand the above. ...
56 views

### Relationship between position and momentum matrix elements

I am going through Faist's Quantum Cascade Lasers book. In the first section of the fourth chapter, he asserts that (in the context of a perturbative analysis of electronic transitions) the ...
49 views

### How to make a double slit electron interference as a home experiment? [on hold]

I want to see electron interference making my own experimental equipments. Do you think it is possible? Especially, double slit, how can I have it?
34 views

### Why can the y and z-components of spin be measured simultaneously? [duplicate]

I have a gut feeling that this is wrong. By the uncertainty principle where $x,y,z$ are the $x,y,z$ components of spin $$\sigma_{y}\sigma_{z}\geq \frac{\hbar}{2}\langle x \rangle$$ and it can be ...
35 views

### Are all kinds of energy quantized? [duplicate]

I was reading this answer of David Z about meaning of "Quantum" that this question came in mind: If light is quantized (i.e. is a integer multiples of some unit $\hbar c/k$), are other kinds of ...
204 views

51 views

### What is the process of a photon transforming into an electron and positron? [duplicate]

How did they come into existence from a photon? Is it really understood how the process works? Is there even a process or is it just something fundamental?
72 views

### Why is gravity viewed as a force? [on hold]

Before I say my thoughts on this I wanted to state that most of my knowledge on physics and such is from college books, and not from actual instruction. From my understanding of forces, there must be ...