0
votes
0answers
11 views

Is there a simpler way to calculate the diminishing fringe pattern of a single edge?

A single edge diffraction pattern is different than a slit or multiple slit diffraction pattern. The pattern is not equally spaced and the fringe spacing's get smaller and smaller diminishing ...
0
votes
0answers
39 views

Using local U(1) Transformation to solve Problem in Path Integral [duplicate]

When we develop photon path integral, we assume that the current is always conserved. But if we consider interaction between electron/positron and photon, the Noether current is conserved only when ...
2
votes
1answer
55 views

Large wavelength limit of gluons

Does there exist a classical limit of QCD? I mean in the sense of wave particle duality of eg photons. Is there any similar thing for gluons?
1
vote
1answer
70 views

Spectral series' formula of a given atom (other than hydrogen-like)?

The hydrogen spectral series is given by the Rydberg formula: The energy differences between levels in the Bohr model, and hence the wavelengths of emitted/absorbed photons, is given by the ...
1
vote
1answer
214 views

What does the magnetic field of the (quantum-mechanical) electron look like?

While a treatment of electron spin can be found in any introductory textbook, I've noticed that the electron's magnetic field seems to be treated classically. Presumably this is because a quantum ...
0
votes
1answer
86 views

Macroscopic Forces from QED

In QED the carrier for electromagnetic interaction is a photon, while macroscopic forces are due to electromagnetic interaction (by macroscopic forces I mean: normal force, object collision, friction ...
3
votes
0answers
87 views

Double Slit Experiment with Two Independent Sources

Imagine a variation on the double slit experiment. I'll describe it in 2D using the $x-y$ plane. The $x$-axis is impenetrable other than the two slits, which are positioned at $(-1,0)$ and $(+1,0)$. ...
1
vote
3answers
64 views

Excitons in metals-do they exist?

Recently I red an article "Surface Enhanced Fluorescence". It is a topical review by Emmanuel Fort and Samuel Gresillon. Here it is: ...
7
votes
1answer
310 views

Box normalization

Whenever we study free fields, the solutions of these fields (or particles, whatever feels most comfortable) are always given by plane waves. The dispersion-relation $\omega=\omega(k)$ will of course ...
2
votes
1answer
58 views

Can a single photon induce current in a very small coil?

As I know from Lenz's law, I can induce current in a coil just by changing the magnetic field flux inside the coil. As I know from physics course, photons are electromagnetic waves (so they are the ...
8
votes
2answers
977 views

Is frequency quantized?

I'm aware that there're some questions posted here with respect to this subject on this site, but I still want to make sure, is frequency quantized? Do very fine discontinuities exist in a continuous ...
2
votes
0answers
65 views

Electromagnetic force interaction

As far as I know, the electromagnetic force only interacts on particles with electrical charge, but I was told that the electromagnetic force was involved in the following reaction: ...
1
vote
0answers
39 views

Quantum fluctuations in the non-relativistic limit

Is there any way to describe quantum fluctuations in ordinary quantum mechanics? For instance, a proton fluctuating into a proton-$\pi^0$ state and then back to a proton? What are the relevant ...
1
vote
0answers
38 views

spread of fock state distribution and infinite revival time of rabi oscillation in spontaneous emission

In cavity QED for a 2-level atom, the revival time for oscillation b/w the states $\left|\ e\ 0\right\rangle$ and $\left|\ g\ 1\right\rangle$ (absorbing the same photon that is emitted) is said to be ...
2
votes
1answer
86 views

Angular momenta of photon

$A^\mu$ can have multipole expansions in classical electrodynamics. This gives rise to dipole photon, quadrupole photon etc. For dipole photon $j=1$ (In electrodynamics books they write it as $l=1$). ...
3
votes
1answer
83 views

What low-level process drives a frequency-doubling crystal?

I was reading about second-harmonic generation (SHG) crystals (or frequency-doubling crystals) used to produce green laser light from IR. What low-level process in the crystal is actually driving ...
6
votes
2answers
176 views

No non-trivial UV asymptotically free and IR free

How it could be proven that a non-trivial theory cannot be both asymptotically free and IR free (g=0 both in the UV and IR with some interpolating function in between)? This is of course contrary to ...
3
votes
1answer
88 views

Did the Goudsmit-Uhlenbeck analysis of spin consider relativity?

It's frequently mentioned in introductory quantum mechanics texts that Goudsmit and Uhlenbeck conjectured that the magnetic moment of an electron was due to angular momentum arising from the electron ...
5
votes
1answer
183 views

Photons traveling backwards in time?

Imagine that two widely separated charged particles $A$ and $B$ exchange a photon. Because they are far apart one can imagine that there is a major contribution to the photon propagator that travels ...
0
votes
0answers
181 views

Probability of absorption and emission of photons

Suppose you have a single electron in a box, and you shoot a single photon at it. How does one calculate the probability that the photon will be absorbed and the particle excited? Or that the photon ...
4
votes
1answer
173 views

Revisiting the microscopic concept of Touching with some more questions

This question is regarding the amazing answer given by Terry Bollinger at this Phys.SE post. I think this answer is very helpful but i do have some standing questions. He says Once the bonding ...
0
votes
1answer
55 views

Pair production at high laser intensity?

Using high laser intensity to produce electron-positron pair, is it still required interaction with nucleus as is the case when gamma rays are used? What causes the pair creation ?
5
votes
1answer
90 views

Classical EM neglects electron recoil?

Imagine two electrons $A$ and $B$ at rest. Electron $B$ is at a vertical distance $r$ above electron $A$. Let us assume that the electrons are constrained to move on horizontal rails. At time $t=0$ ...
0
votes
0answers
50 views

The electron and classical dynamics

Can I use Newtonian laws of dynamics and kinematics applied to electrons (like $F = ma$ and $s = s_0 + v_0 t + at^2/2$)? If not, why not? I know that everything in principle behaves in a quantum ...
1
vote
1answer
439 views

Covariance of the Dirac equation and Infinitesimal Lorentz transformation

Okay, I've got really desperate now. I've spend 10 hours of work (for a few days) trying to prove 'trivial' equation in Quantum Electrodynamics. To anybody who want to write an answer for my questions ...
1
vote
1answer
254 views

Formula for Rabi frequency

I have calculated the dipole transition elements of electronic states $\langle a|D_1^m|b \rangle$ following the book of Cohen-Tannoudji (Complement $E_X$) and tried then to calculate from that the ...
0
votes
2answers
788 views

Why electrons can't radiate in their atoms' orbits?

It's an old-new question (I found only one similar question with unsatisfactory (for me) answer: Where did Schrödinger solve the radiating problem of Bohr's model?) It's strange for me how all books ...
5
votes
1answer
1k views

Why do some materials reflect (metals) and other materials reflect and refract (glass) from the quantum perspective?

Recently I was asked to explain the difference between reflection and total internal reflection from a purely conceptual standpoint (no math). Let me explain what I already know. Reflection and ...
5
votes
3answers
307 views

Fundamentals of Quantum Electrodynamics

In quantum electrodynamics, the classical Hamiltonian is obtained from the classical electromagnetic Lagrangian. Then the classical electric and magnetic fields are promoted to operators, as is the ...
3
votes
1answer
299 views

Electron in Magnetic Field can lead to non-Hermitian Hamiltonian?

Consider a charged quantum particle in a magnetic field. The Hamiltonian can be written using minimal coupling: $$ H = \frac{1}{2m} \left( \mathbf{p} - \frac{e}{c} \mathbf{A}(\mathbf{x}) \right)^2 $$ ...
1
vote
1answer
45 views

Charge in terms of wavefunctions

For a charged quantum particle, say, an electron or a quark, how in the particle's wavefunction is the electric charge represented? Is it truly possible to represent electric charge using the wave ...
2
votes
1answer
288 views

Which is this formula Feynman talks about in the QED book?

I am reading the fantastic QED Feynman book. He talks in chapter 3 about a formula he considers too complicated to be written in the book. I would like to know which formula he talks about, although I ...
-2
votes
1answer
345 views

QED photon propagator to one-loop order gets different answers

I'm a self-studying 14-year-old who has a passion for particle physics. I'm currently trying to calculate the QED photon propagator to one loop. However, in all the places I've looked, even with the ...
6
votes
1answer
298 views

Can a photon exhibit multiple frequencies?

Can a photon be a superposition of multiple frequency states? Kind of similar to how an electron can be a superposition of multiple spin states.
-2
votes
2answers
582 views

A thought experiment with Heisenberg's Uncertainty Principle [duplicate]

Possible Duplicate: Could the Heisenberg Uncertainty Principle turn out to be false? Thought Experiment Ponder, for a moment, if I had a cube with 10cm sides which I'll name The Box. By ...
1
vote
2answers
145 views
3
votes
2answers
297 views

Energy spectrum of a Dirac electron

How do you explain easily "The spectrum of an electron in a repulsive potential " and hence "bound state of charge conjugation" in Dirac hole theory ?
4
votes
2answers
329 views

Why possibility for X-ray to excite inner electrons higher than outer electrons?

It seems X-ray absorption spectroscopy is usually ascribed to the interation between photons and inner electrons. Does it mean inner electrons are much preferred by X-ray photons to outer electrons? ...
4
votes
3answers
203 views

What is predicted to happen for electron beams in the Stern-Gerlach experiment?

The Stern–Gerlach experiment has been carried out for silver and hydrogen atoms, with the result that the beams are deflected discretely rather than continuously by an inhomogenous magnetic field. ...
1
vote
3answers
261 views

What is the 'quantum-developed' or 'relativistic-developed' equation of the electrostatic force?

Quantum electrodynamics (QED) is the relativistic quantum field theory of electrodynamics that is the first theory where full agreement between quantum mechanics, special relativity and ...
1
vote
1answer
78 views

How Lyman transition (to the ground state from higher excited) happens ? The dipole selection rule is +/- 1?

How are the lyman series observed when the dipole selection rule is +/-1 in l change for hydrogen atom ?
0
votes
2answers
564 views

Why 2s state is lower in energy that 2p state in atoms?

The s orbital have higher probability to be closer to the core and feels larger attraction than the p orbital and on average is further away and in addition p has repulsive potentilal l(l+1)h^2/2mr^2. ...
1
vote
2answers
254 views

How did QED diverge from quantum mechanics mathematically?

We have either Heisenberg or Schrodinger picture of quantum mechanics world. So, how did quantum electrodynamics come from mathematical formulations of quantum mechanics? Also, QED seems to have ...
2
votes
0answers
96 views

After quantization of electron vibrations, do we need electrons anyway?

The title question is not ment in a general context, but one in which goes to the plasmon theory. In that case, how is are the statistics (boson vs. fermions) of plasmons determined? And is there an ...
2
votes
1answer
42 views

Will an entangled idler electron induce a current in a conductor if the signal elctron's spin is measured?

I'm assuming a hypothetical setup as follows: Two labs (Alice and Bob) exist. Each has one electron of an entangled pair. At Alice, the electron travels through free space towards a magnetic field of ...
3
votes
4answers
298 views

Does the wave nature of a particle refer to the wave function?

In quantum mechanics when we talk about the wave nature of particles are we referring in fact to the wave function? Does the wave function describes the probability of finding a particle (ex: ...
8
votes
2answers
694 views

Deriving Planck's radiation law from microscopic considerations?

In the usual derivation of Planck's radiation law, the energies or frequencies $\omega$ of the oscillators depend on the measurements $L$ of the black body. The model is such that the only ...
6
votes
4answers
356 views

Can an Electromagnetic Gauge Transformation be Imaginary?

The Hamiltonian of a non-relativistic charged particle in a magnetic field is $$\hat{H}~=~\frac{1}{2m} \left[\frac{\hbar}{i}\vec\nabla - \frac{q}{c}\vec A\right]^2$$. Under a gauge transformation ...
8
votes
1answer
72 views

Relativistic corrections to quantum mechanics of Coloumb potential

Systems of charged particles (such as atomic nuclei and electrons) can be described by nonrelativistic quantum mechanics with the Coloumb interaction potential. A fully relativistic description is ...
1
vote
4answers
297 views

Interaction of matter with EM fields

For the interaction between electromagnetic fields and matter, when do we have to include quantization of the EM field and when we can ignore it? when do we have to include quantization of atomic ...