Questions tagged [photons]
The photon is the quantum of the electromagnetic four-potential, and therefore the massless bosonic particle associated with the electromagnetic force, commonly also called the "particle of light". Use this tag for questions about the quantum-mechanical understanding of light and/or electromagnetic interactions.
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Energy of photons in perfect mirror box with FRW metric
In FRW metric, distance is described by
\begin{align}
ds^2 = dt^2 - a(t)^2[d\chi^2 + S_k(\chi)^2 d\Omega^2]\\
=dt^2 - a(t)^2\gamma_{ij}dx^i dx^j
\end{align}
where $a$ is the scale factor.
Now by using ...
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Energy and momentum conservation for photon absorption [duplicate]
As an undergrad physics student, I am pondering on this question.
If an (2 level) atom absorbs a single resonant photon, the energy of electronic state increases by $\hbar \omega$. At the same time ...
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Link between photon helicity and polarization of $A^\mu$ electromagnetic potential
From Wigner theorem we know that the irreducible unitary representation of the Poincarè group for massless and spin 1 particle is labelled by the momentum $p_\mu$ and the two possible helicity $+1,-1$ ...
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Could a single gamma ray photon break the Schwinger limit? If so, at what energy?
Is it possible for a ray of light, or even a single photon, to 'break' the vacuum of space?
If so, at what energies (in eV, e.g.) would this happen?
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Polarization analyzer [closed]
My understanding is that the entanglement between two photons is not broken by a polarization analyzer. One will emerge from the Y projector and one will emerge from the X projector. Is this correct?
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Does photocurrent depend on intensity or on number of photons?
Edit: I have realised my mistake. The part of text I read assumed the light to be monochromatic and so in that case, there will be no difference between intensity and number of photons because the ...
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What is a simple example that contradicts the theory that light (photons) could have a super small mass? [duplicate]
The obvious example is that, to bring something that has mass to the speed $c$ requires infinite energy due to special relativity. But what if a kid asked me "What if light/photos had a super ...
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Can photons interact with one another? [duplicate]
Photons can interact with matter, particles, nuclei, etc.
But can they interact with one another?
By interaction I mean any kind of physical interaction: Momentum/Energy transfer, electromagnetic ...
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Is a photon truly massless? [duplicate]
First of all, I am not a physicist or mathematician, not even a hobbyist but the following statements have always puzzled me:
$E=mc^2$
A photon is a desecrated particle of energy.
A photon is ...
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What is the criteria of forming a phonon polariton?
It is well know that, phonon polariton is a quasiparticle formed by the interaction between photons and optical phonons. But, does it mean that, any photons that are resonant with phonons can form ...
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Why does radiation of small wavelength interact with small objects?
I was reading chapter 2 from the book 'Diagnostic Radiology Physics : A handbook for Students and Teachers', and came across the following quote
"X rays of energy of a few tens of ...
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Photonic black holes
"Can a photon turn into a black hole?" - usually the answer to this question is - it can't, because it has zero rest mass. However, when we derive the Schwarzchild Metric initially the $2M$ ...
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Is there a good quantum explanation of refraction? [duplicate]
I'm aware of the classical explanation of refraction which deals with light being a wave that gets "slowed" down while passing from a medium to another. One problem that I have with this ...
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How is light interference explained with photons?
In the classical model of light as an EM wave, interference is a trivial consequence of the linearity of the wave equation. Now, if we model light as collections of photons, how is light interference ...
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The speed of a QM particle
In the original theory of quantum mechanics what is the speed of quantum particles, I am asking this because photons can only travel at the speed of light C. What about mass particles?
