All Questions
Tagged with electromagnetic-radiation quantum-electrodynamics
173
questions
2
votes
0
answers
31
views
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 $+1,-1$ ...
- 613
0
votes
0
answers
64
views
From a QED perspective, how is light created and propagated?
Using QED, what happens, exactly, when light is created?
Let's say an electron loses energy by dropping to a lower orbital, causing quantum of energy to be "emitted." What is that energy ...
- 109
2
votes
0
answers
97
views
How does a photon look like in QFT? [closed]
It is very well known that in QFT the particles are excitations of the field. But how exactly is a free photon looking like in spacetime? What is it shape in free space? And what is in fact in the ...
- 651
0
votes
0
answers
81
views
Quantizing the electric field without quantizing vector potential
I am trying to quantize the electromagnetic field, without using the vector potential. I start with a Fourier expansion:
$$\begin{equation}
\vec{E}(\vec{r},t) = \sum_{\epsilon} \vec{\epsilon} \int \...
- 1,258
1
vote
0
answers
34
views
QFT view of lower light speed of light in medium [duplicate]
In classical EM theory, if we have a medium whose dielectric coefficient is independent of wavelengths (suppose we filter the incoming signal to a certain frequency band), then the waveform gets to ...
3
votes
2
answers
124
views
Are EM waves telling us the probability of finding a photon?
I feel like I've been frequently presented with an interpretation of EM waves that goes something like this:
Light is an oscillating electromagnetic field. Because changes in the electric field ...
- 203
0
votes
0
answers
23
views
Direction of magnetic field, current carrying conductor and its motion
In Fleming's left hand rule, we can see that if current is in direction of middle finger and magnetic field in the direction of fore finger, the thrust must act on the direction of the thumb. These ...
1
vote
2
answers
65
views
Why does an oscillating charge emulate an oscillating dipole in the far field limit?
I understand Thomson scattering as: When an EM wave is incident upon a charge causes it to oscillate in turn releasing energy as another electromagnetic wave.
In an Electrodynamics lecture we took a ...
- 13
1
vote
2
answers
88
views
Which theory/model explains electrons movement inside a transmitting antenna? [closed]
I have an understanding of electrical circuits, however I am very interested to know more about electromagnetic waves radiation.
In particular I want to know how an oscillating voltage causes the ...
0
votes
1
answer
89
views
Spherical Electromagnetic Radiation Propagating Inwards
Suppose I produce a large number of photons subject to the following conditions:
The photons are produced at (approximately) the same time at (approximately) the surface of a sphere (if I'm not ...
- 115
2
votes
2
answers
76
views
What is the interplay between radiation and photon creation?
While trying to provide an answer to this question, a question popped into my mind. When a charge accelerates, is there always a photon associated with that radiation, or multiple photons? For ...
- 873
5
votes
3
answers
1k
views
Why does light interact with normal matter but not with other light?
Why does light interact with normal matter but not with other light?
Assumptions:
Light does not interact with other light at all.
Light does interact with other matter, i.e reflection/refraction.
1
vote
2
answers
117
views
On the level of Newton's particle theory of light
Huygens and Maxwell have wave theories about light.
On the other hand Planck and Einstein have theories about particle nature of light and could explain blackbody radiation and photoelectric effect ...
- 1,409
1
vote
3
answers
127
views
QED photon path (direction of photon emission)
In QED we look at all possible path a photon could go from S to P, and I understand the most significant contributions to the final arrow are the few near straight paths connecting S and P while other ...
- 161
0
votes
0
answers
36
views
Role of "cavities" in quantum light absorption
I am currently studying the basics of Quantum Electrodynamics, and I have learned from this that photons are the quanta of excitation for given field modes. In other words, when a photon is absorbed, ...
- 366