All Questions
Tagged with quantum-electrodynamics quantum-mechanics
395
questions
3
votes
2
answers
106
views
Parametric down-conversion - QFT necessary?
In quantum optics, one ususally starts by quantizing the free electric field and obtains an expression for the electric field operators:
$$ E(\vec{r},t) = \sum_{\vec{k},p} C_{\vec{k}} \vec{e}_{\vec{k},...
- 31
0
votes
0
answers
22
views
Radiation reaction in the ground state of an atom [duplicate]
In a typical bound energy eigenstate of an atom the magnitude of the wave function is time independent only phase changes in time. So I expect no radiation reaction force in the ground state. However ...
0
votes
1
answer
62
views
Destructive interference pattern perpendicular to photon's propagation direction
I'm studying the interference pattern for light. For example, the following is the interference pattern for double slit experiment:
I'm curious to know if there is an existing interference pattern ...
- 81
4
votes
1
answer
86
views
What happens if obstacles (walls) been put where destructive interference occurs in double slit experiment?
If photon doesn't have probability to be in dark (destructive interference) area, what will be the effect of adding obstacles (walls) in the dark (destructive interference) area for the double slit ...
- 81
0
votes
0
answers
33
views
Equivalence of Pauli equation and photon picture
The motion of a charge in EM potential is described by the Pauli equation ( which is the non relativistic limit of Dirac eqn). On the other hand, we know that the EM potential is nothing else than the ...
- 141
0
votes
0
answers
21
views
Feynman trajectories of a photon from entangled pair
In a pair of Entangled photons does any of the two photons has the Feynman trajectories of the other one? Must the possible trajectories of photon 2 be taken in the Feynman's path integral for the ...
- 651
0
votes
1
answer
425
views
Is Feynman's Compton scattering diagram the same as the one in most books?
Feynman used the following Compton scattering diagram:
Whereas most books use this diagram in their derivation:
Is there a way to relate the two? Feynman's diagram makes more sense to me ...
- 187
1
vote
2
answers
78
views
Tightly-focusing a single photon
I'm curious about the feasibility, both theoretically and experimentally, of tightly focusing (or spatially trapping) a single photon to guarantee its precise targeting. If it’s possible, isn’t it ...
- 342
1
vote
2
answers
53
views
The relative phase of photons in two-photon absorption
In two-photon absorption (TPA), the relative polarization of the two photons about to be absorbed simultaneously by an atom is crucial in determining the TPA rate. However, there is a lack of ...
- 342
1
vote
1
answer
62
views
How to correctly interpret $\hat{\sigma}_{eg}^i \hat{\sigma}_{ge}^j$?
I am trying to figure out the paper of Asenjo-Garcia et al.: PHYS. REV. X 7, 031024 (2017).
Specifically, in e.g. Equation (5):
$$ \mathcal{H}_{eff} = -\mu_0 \omega_0^2 \sum_{i,j = 1}^N \mathbf{D}^* \...
0
votes
0
answers
25
views
Does ballistic electron transport require low temperatures?
It is my understanding that ballistic conduction mainly occurs at very short distances. Now a redditor claimed it only takes place under extremely cold temperatures but I found an article published 22 ...
- 439
0
votes
0
answers
22
views
Field theory behind dipole traps / optical tweezers
I'm trying to re-construct an explain for how an optical tweezer traps a neutral atom with a non-zero dipole.
It began something like this:
"The vacuum is filed with short-lived dipoles form by ...
- 21
2
votes
0
answers
55
views
Why does the spontaneous emission rate scale with energy?
Good afternoon,
the standard description of spontaneous emission in quantum optics is - to my knowledge - via coupling of an excited atom to vacuum modes of the em-field, which are still occupied at $...
- 21
1
vote
1
answer
132
views
Thrid law of thermodynamics and quantum mechanics
Third law of thermodynamics says that it is impossible to reach absolute zero temperature in finite numbers of operations. According to quantum mechanics, every system has energy levels and ground ...
- 119
2
votes
1
answer
84
views
Localized wavefunction and double slit experiment
I am trying to have better understanding of localized wave functions. Apparently free particle de Broglie waves are NOT normalizable and act as delocalized functions which was the original rationale ...
- 291