0
votes
0answers
27 views

Energy in an electromagnetic wave

A radio antenna creates EM waves through switching the polarization in the antenna at a certain frequency. I assume the the energy of the photons produced in this process amount to E=hf for each ...
22
votes
3answers
1k views

Why is an electron still an elementary particle after absorbing / emitting a photon?

When an electron absorbs a photon, does the photon become electron "stuff" (energy); or, is it contained within the electron as a discrete "something"?
2
votes
0answers
31 views

How to formulate collapse in polarization subspace of a photon?

I am wondering how to describe the collapse of a photon state when it is measured in the polarization degree of freedom (say by a filter which let pass just one particular polarisation). Let the free ...
1
vote
2answers
122 views

Size of a photon

When detecting radio waves in space, we use very large telescopes or arrays of telescopes. But according to QM, aren't photons point particles when measured? Does a photon with a large wavelength ...
2
votes
2answers
78 views

Suppose a light wave with wavelength 3m. What happens if one tries to contain that wave within a 1m container?

Suppose a light wave with wavelength 3m. What happens if one tries to contain that wave within a 1m container? If I'm going about this entirely the wrong way or have wrong conceptions about light ...
3
votes
0answers
53 views

Optical Bloch Oscillation

I have a doubt about how the optical Bloch oscillations happen in a 1D photonic crystal. I try to explain: in a photonic crystal with discrete translational symmetry in one direction I superimpose a ...
0
votes
1answer
37 views

What is the significance of the difference in the eigenvalue equations of Bloch functions for electrons vs photons?

any text on photonic crystals will highlight the almost perfect analogy between electrons in a periodic potential and photons in a periodic dielectric. The analogies are: $$V(\vec r + \vec R) = ...
2
votes
0answers
43 views

Relection of light [duplicate]

If I recall my physics correctly, and it was a long time ago, when a photon strikes a reflecting surface that specific photon is not what is reflected--rather the photon excites an electron which ...
0
votes
1answer
108 views

Photons and proper time

Why is there no proper time without inertial frame? In question n°95054 I learned that there is no proper time zero and no proper distance zero for photons because they are no inertial frames. That ...
2
votes
1answer
152 views

How do electrons and photons interact?

Two electrons, or an electron and a proton, interact with each other because of the Coulomb potential, which can also be seen in the Schrödinger equation (which is the equation that describes the ...
-2
votes
1answer
162 views

Resolution of the EPR paradox using relativity of simultaneity

A simple explanation for photon entanglement experiments Example: Quantum teleportation La Palma-Teneriffa in 2012 (distance 143 km) - Photons were entangled in such a way that when measuring ...
0
votes
1answer
76 views

Why photon-electron energy transfer can't occur in steps or does it?

The process of exchange of energy between a photon and an electron only occur after a specific energy called work-function of the material. Thus, the energy transferred is quantised due to the fact ...
4
votes
5answers
280 views

Does a photon instantaneously gain $c$ speed when emitted from an electron?

An excited electron looses energy in the form of radiations. The radiation constitutes photons which move at a speed $c$. But, is the process of conversion of the energy of the electron into the ...
4
votes
2answers
103 views

Does the photon emitted by an electron falling to a lower energy level have a direction?

When an electron falls from an energy state to a lower one, electromagnetic radiation is emitted. Is this equally emitted in all directions (as a spherical wave) and can we only give it a direction ...
1
vote
1answer
41 views

Photon number conservation during scattering

I was reading this writeup on the Kompaneets equation and the Sunyaev-Zel'dovich effect. On page 3, section 2 the author states There is no way to increase the mean energy of a planckian ...
0
votes
0answers
53 views

Quantum eraser double slit experiment

In the quantum eraser double slit experiment, does the photon (or wavefunction) pass through one slit or both slits when different polarizers are placed over the slits?
2
votes
0answers
54 views

The nature of the probability distribution for the energy of a photon released via stimulated emission

The vanilla description of stimulated emission (e.g. in the context of an inverted population laser gain medium) says that a photon with some state vector specifying its energy / polarization / ...
5
votes
2answers
132 views

Quantum barrier for photons [closed]

In quantum mechanics, a particle may tunnel through a barrier it would not be able to surmount in a classical sense. My question is this: What are all the factors that may prevent a photon from ...
4
votes
4answers
323 views

Detecting a photon without changing it: Does it break conservation laws?

This is about an article published on ScienceMag: Nondestructive Detection of an Optical Photon. I don't have access to full text, but you can see a brief transcription in this link. Basically, it ...
4
votes
1answer
270 views

Some doubts about photons

I am reading Berkeley Physics Course vol. 4 (Quantum Mechanics) , chapter 4 (photons). (1) Section 46: book says: consider a typical photon emitted by the source. It can be regarded as a a wave ...
2
votes
0answers
86 views

How do we show that photons generated by a constant electric current are distributed according to a Poisson distribution?

I saw the answer sometimes ago in a book "Quantum Electronics" or similar title. I don't remember the author since I lost the book. The book sets ( I believe so ) a constant electric current $I$ in a ...
0
votes
0answers
73 views

Photons angular momentum / spin

I have a textbook that says that photons have a spin of absolute value $\hbar$ and at some other point, they say that it has angular momentum of absolute value $\hbar$. Now, since they are different ...
2
votes
0answers
92 views

How to calculate angular momentum per second for a photon beam? [closed]

Given a photon polarization state $$|\phi\rangle = \frac{3}{5}|x\rangle + \frac{4i}{5}|y\rangle,$$ a beam of photons transmit $N$ photons per second in such a state. An L-polarized photon has an ...
0
votes
0answers
45 views

Has advanced radiation been detected experimentally?

I would like to know whether there has been an experimental detection of advanced radiation. I seem to recall reading about such an experiment but I can't find any reference to it on the interwebs so ...
6
votes
3answers
329 views

How can we interpret polarization and frequency when we are dealing with one single photon?

If polarization is interpreted as a pattern/direction of the electric-field in an electromagnetic wave and the frequency as the frequency of oscillation, how can we interpret polarization and ...
0
votes
1answer
215 views

How to determine the amount of light energy (photons) being released from an incandescent light bulb?

I have got this all down pat: 1.Collision with a moving particle excites an atom. 2.This causes an electron to jump to a higher energy level. 3.The electron falls back to its original energy level, ...
0
votes
0answers
162 views

Is the Copenhagen interpretation still valid?

"The secret lives of photons revealed" - physicsworld.com. It seems that this experiment violates the Copenhagen interpretation. Is it still valid? Can you please give me more insight on this ...
1
vote
1answer
139 views

How does the uncertainty principle make a photon beam spread out?

I'm reading about uncertainty principle, and something has been bothering me for quite a while. There is the formula: $$\sigma_x \sigma_p \ge \frac{\hbar}{2}$$ I know what this means: the more you ...
3
votes
1answer
460 views

Decay of metastable state: spontaneous vs. stimulated emission.

I have a question about the upper laser level (the metastable level) in a 3-level laser system. I will call the ground level of the 3-level laser system by "g" and the metastable level by "m". The ...
1
vote
0answers
37 views

Casimir Effect and polarization of photons

I have read Casimir's derivation of the Casimir fore between 2 parallel plates and have been told that in reality, the Casimir force should be twice as large due to the 2 polarization states of ...
0
votes
2answers
240 views

The Quantization of Photon Energies

Despite Planck's constant being in $E=hf$, it would appear to me that energy is still not discrete, as frequency can be an fraction of a Hertz that one wants. How does this imply that electromagnetic ...
2
votes
0answers
139 views

Adiabatic quantum evolution of single photon or biphoton system

The prerequisite for adiabatic quantum evolution of single photon or biphoton system is as follows. We have to prepare a single photon or biphoton quantum system which has a ground and a higher level ...
6
votes
2answers
589 views

Slowing down light in an opaque crystal for a whole minute

I just read about a team of physicists at the University of Darmstadt, Germany, that managed to completely slow down a beam of light that traveled through an opaque crystal (article here). How is it ...
3
votes
1answer
153 views

Energy of an EM wave compared to energy of a photon

Several posts on this forum ask the question about the role of amplitude in calculating the energy of an Em wave. This struck me as odd since I learned that E=hv. There is no amplitude in the Planck ...
2
votes
1answer
190 views

Can a force stop a Photon since Photons have momentum and What does momentum mean when talking about massless particles?

Momentum measures how hard it is to stop an object. While Photons are massless they still have relativistic mass and energy. My question is can something stop photons other than being absorbed by ...
19
votes
3answers
2k views

Can the photoelectric effect be explained without photons?

Lamb 1969 states, A misconception which most physicists acquire in their formative years is that the photoelectric effect requires the quantization of the electromagnetic field for its ...
5
votes
1answer
164 views

Photons: Collection of Wave Packets that produce a plane wave

Is it possible mathematically for photons, which behave as individual Gaussian wave packets, to combine in such a way that the approximate result is a plane wave at one particular frequency (i.e., the ...
10
votes
2answers
344 views

Born rule for photons: it works, but it shouldn't?

We can observe double-slit diffraction with photons, with light of such low intensity that only one photon is ever in flight at one time. On a sensitive CCD, each photon is observed at exactly one ...
4
votes
2answers
268 views

Discovery of $E=hf$?

How was the equation $E=hf$ discovered? Was the proportional expression between energy and frequency of light $E\propto f$ discovered only by experiment? Or is there some logical(theoretical) senses ...
4
votes
4answers
336 views

What happens when a photon hits a beamsplitter?

Yesterday I read that we can affect the path and the 'form' (particle or wave) of a photon after the fact (Wheeler's delayed choice experiment). Part of what is puzzling me is the beam-splitter. Are ...
0
votes
2answers
514 views

Do excited electrons drop back to same quantum state?

I'm trying to wrap my head around spectroscopy, therefore, I am looking for as complete an answer as possible here, hence why I have broken the question into a different points. Here is what I know ...
0
votes
1answer
154 views

Why is the Heisenberg Uncertainty Principle not obvious give the conservation of mass- energy?

A photons energy is given by $E=h *f$ and momentum $p=E/c$ (spin?) but the photon has no (rest) mass! Therefore it is the ultimate probing tool for looking at any mass position and velocity because ...
4
votes
2answers
668 views

How do particles become entangled?

A person asked me this and I'm just a lowly physical chemist. I used a classical analogy (how good or bad is this and how to fix?) Basically, light has a net angular momentum of zero, insofar as ...
1
vote
0answers
24 views

Does quantum mechanics depend solely on electromagnetic waves? [duplicate]

I am beginning to learn quantum mechanics. Since determining the position of an object involves probing by electromagnetic waves and since i have read a simple derivation of Heisenberg's uncertainty ...
4
votes
1answer
495 views

Is the de Broglie wavelength of a photon equal to the EM wavelength of the radiation?

Is the de Broglie (matter) wavelength $\lambda=\frac{h}{p}$ of a photon equal to the electromagnetic wavelength of the radiation? I guess yes, but how come that photons have both a matter wave and an ...
3
votes
0answers
23 views

Energy needed to raise energy level of an atom? [duplicate]

Suppose I have an atom at rest which is at energy level $E_i$. Would it be possible to raise it to the next higher level $E_{i+1}$ by shooting a photon of energy $E_{i+1}-E_i$ at it? I ask because ...
2
votes
1answer
1k views

Where is the amplitude of electromagnetic waves in the equation of energy of e/m waves? [duplicate]

Does the amplitude of the photon oscillations always stay constant and if it is not - what are the physical differences between the photon with higher amplitude in comparison to the one with the less ...
0
votes
1answer
92 views

EM Waves Energy Loss

Where does the energy go when two photons interfere destructively at a point on a screen in Young's double slit experiment ?
2
votes
1answer
117 views

Physical significance of effective wave function

In Yanhua Shih's book on quantum optics, the coherence functions are expressed in terms of effective wave function. Here are the expressions for single photon wave packets. To derive the coherence ...
3
votes
2answers
760 views

Transfer of electron energy to atoms (heating up of matter by absorption of photons)

If an electron absorbs a photon to get exited to a higher energy level, it should either come back to same state or any other lower state by emitting the required photon. How then can there be a net ...