Photon Definition and 1000 Threads

My question is does the photon that is absorbed by an atom on the detection screen have exactly the same energy as the photon that left the 'gun' source? Hence, does the wave packet representing a photon lose some of its energy when it impinges on the double slit barrier, so that when the...

Non-relativistic Bremsstrahlung is discussed classically in Rybicki “Radiative Processes in Astrophysics” where Larmor’s formula is used to find the power radiated in a collision between an electron and a Coulomb field. The Fourier transform of the pulse allows for a description of the pulse in...

I have hopefully what is regarded as simple and straightforward questions. If we have the attached set up (comprising a source for photons entangled as |H>|V> - |V>|H>), polarizing beam splitters (PBS) and a wave plate that converts |H> to |45> and |V> to |135>. How does one calculate the...

This is a thought experiment I had with myself a couple of weeks ago. I have never seen it proposed. But please be kind I am not physicist but just a hobbyist. So this experiment is specifically for entangled photons. So here goes. I was thinking of something going faster and faster and time...

Hi guys. Imagine that in the exact instant when a massive particle A crosses the event horizon of a black hole, a Photon does the same,so that they have a race toward the singularity. Who will win the race? Will they have still different velocities?

Let's assume the following sine signal sent by a low frequency (100 kHz) transmitter. I think with the information that the sending power is 1 watt and the starting phase is 0 the signal is fully described. Are the following assumptions correct?: 1. The frequency of all photons leaving the...

On the image you can see a photon starting at point A at t=0. The photons travels along the sine function and arrives point C. I knot that this takes T=λ/c. But this is the time for a object traveling directly from the origin to point C and not along the sine wave! If the photon travels...

This sounds interesting to me. I would appreciate the opinions of more knowledgeable and physics oriented forumists. The paper is in Science (I don't think its open access). Here is the abstract:

Hello all: Reading about HB-11 start up and they mentioned laser induced magnetic field : How is that created and the size of the magnetic field is in kilo Tesla range anyone heard of that Best Hagop

Do photons, I'm not sure how to express this, "experience" time? Since they move at the speed of light does time not exist for them? If time does not exist, how is it possible for anything to happen to them. If interacting with matter requires a change in their condition, how can a change in...

Summary:: Based on this diagram can someone explain how atom of hydrogen gas can be made to emit photons of different energies?

My car aircon recirculation button often turns off by itself. I guess this happens when the aircon is cold enough. Problem is. When it turns off and the indicator light disappears, the pollution outside gets into my car and my pm2.5 monitor registers 20x higher. What kind of photon detector...

I cannot see how a photon can be detected and yet remain the same photon. I am thinking that the description "If a detector is place at each slit so that we know which slit the photon passsed through, the interefence patten does not form" is sloppy and in error.

Does the following picture which I think shows the guiding field for electron in the double slit experiment have a corresponding image when the experiment is done with photons? Thanks for any help.

I am wondering what happens in the case of 100 entangled photons with a polarization angle of 0 degrees (or 0 and 90) that interact with Alice at 22,5 degrees and Bob at 45 degrees in a Bell Experiment. Do I get a count of 85 for Alice and 50 for Bob, which means a maximum coincidence count...

Einstein coefficients tell us that there is some probability for an atom to go from E_1 to E_2 given by the coefficient of absorption. This is fine, but why is there only one coefficient (absorption) going from E_1 to E_2 and two for the transition E_2 to E_1? Spontaneous emission makes sense...

Quick question: let's say we have an atomic electron in the ground state which requires, say, one "unit" of energy* to jump up to the next orbital energy state. If a photon arrives with a bit more or less than this, say 1.00003 or 0.99997 units of energy, is there some finite, non-zero...

Most sources I come across on the topic of photon interference focus on the phase differences, but neglect discussion on the wave amplitude. Wave amplitude diminishes with distance; a single photon's energy does not. So in a double slit experiment with photons being emitted one at a time, if...

This is a very special case. In my 50 years studying physics I have never seen any discussion of photons having orbital angular momentum. Any angular momentum for photons in orbit around a black hole must be a GR question. I have not specialized in GR but I don’t recall any discussion of it. I...

I'm aware of the numerous threads on the subject "light inside glass" there have been in the past, in case you will indicate me an appropriate one, but I haven't been able to find a clear answer to the questions: 1) Do photons really exist inside a (homogeneous, linear, transparent, refracting...

In A.P. French's Special relativity the author said, The mass and length of the box are irrelevant here. He said the momentum of the radiation is ##E_{radiation}/c##. We know that the momentum of a single photon with energy ##E_{photon}## is ##p_{photon}=E_{photon}/c##. So is...

A tachyon or tachyonic particle is a hypothetical particle that always travels faster than light. Most physicists believe that faster-than-light particles cannot exist because they are not consistent with the known laws of physics. - Tachyon definition The photon is a type of elementary...

I have some questions about this video. I have watched other videos in this series. Otherwise very nice series, but I think there may be mistake. Isn't the video flawed because it forgot forgot 0'th component of 4-fector ##A## aka ##\varphi## in 3-vector representation, I think it because...

In the loop integral for the one-loop correction to the photon propagator in QED, the dominant term, after Wick rotation and angular averaging, has the form (omitting uninteresting factors) $$(1-2/d) e^2 \eta^{\mu\nu}\int_0^\infty \frac{p^{d+1}}{(p^2+\Delta)^2}dp,$$ where ##p## is the absolute...

According to the 2nd postulate of Special Relativity, speed of light in vacuum is the same in all inertial reference frames. If I take a beam of photons and see the other photons in the beam from a frame of reference of a single photon, do they look stationary or moving at the speed of light...

A photon's energy is E=hv where v, the frequency, is a wave property. Particles don't have frequencies. But a wave's energy also depends on its amplitude. Where does this come into the energy relation?

Once I have read that we can’t know a actual position of a particle because to see the particle we need to send photons and when we send photons it colides with the particle and change it’s position. Is this true?

What happen if a small energy photon collide an atom in ground state that the gap between energy levels of atom is greater than energy of photon?It seems that the medium absorbs light and transform to heat?

In ground state electron does not emit photon.Can we use QED to explain why in ground state electron does not emit any photons?

I tried to use the Lorentz transformation: ##E^{*}_{\gamma }=\gamma _{cm}E_{\gamma }-\beta _{cm}\gamma _{cm}p_{\gamma }## We have a photon, so it becomes: ##E^{*}_{\gamma }=\gamma _{cm}E_{\gamma }(\beta _{cm}-1)## Unfortunately, the solutions say that the correct way is to use the inverse...

Can a photon with energy greater than energy level difference of atom be absorbed by atom?Is there any case in that photon share a part of energy for atom and keep other part of energy for itself?

In this paper, Cramer references a Sagnac source and mentions it has a half wave plate to vary the entangement vs. coherence by rotating the plate. Look just below figure 1: https://arxiv.org/pdf/1409.5098.pdf What is this setup? My guess is that the half wave plate is right before the...

I have a question on how exactly polarizing filters would influence interference in a Mach-Zehnder interferometer. To explain, I'll show some configurations and what I would expect to happen - please tell me if I am incorrect anywhere. Here is the standard MZI configuration with no filters and...

Summary: MIT researchers have created a material that is 10x blacker than any other material ever recorded. The foil captures at least 99.995% of incoming light. Does this mean that there is practically no EM re-radiated?

I saw a paper on an experiment where a pump beam first went through a double-slit, then was downconverted with BBO. Recently a friend with a PhD in quantum physics said the downconversion will cause the pump's wavefunction to collapse and the implication for this experiment is that the pump...

I was wondering if anybody knew if there was an upper bound on how much energy you can pack into a photon, if such a thing exists. I'm wanting to say no there isn't but it occurred to me that I did not know the answer. Sorry if this is an absurdly easy question but I don't remember reading...

The point that I want to know is how two frequencys react with each other and does electron's frequency wait to reach to higher frequency on that fraction of second when they(photo's frequency and electron's frequency)collapse to each other than go to higher energy level or what?

I'm studying the electron-proton deep inelastic scattering. In the notes that I'm studying from the author states that the time-scale for a virtual photon to interact with a proton is ##τ\sim\frac{1}{Q}##, where ##Q## is the momentum transfer with ##Q\gg M##, which is the mass of the proton. I...

[Mentors’ note: this thread was split from the FAQ at https://www.physicsforums.com/threads/rest-frame-of-a-photon.511170/] I am not an expert! As I understand it, Einstein considered, what a guy standing in a photon will experience if he look at his watch. My understanding says, that the...

My setup: I have the an LED (LED370E) in front of a photodiode (S12915-16R). The photodiode is connected to an ADC (DT5751) which has a counting functionality. The way it works is that it counts how many times the signal goes above a certain threshold and makes a histogram out of it. I know...

Hello, I'm working on a scintillation device to detect protons, I have a disagreement with one professor and I would like your opinion. There is one photodiode model we want to use to measure the light intensity from the scintillators, and we want to relate the signal of that photodiode with...

Suppose I fire a photon with an upward spin towards a hydrogen atom. It is absorbed by the hydrogen atom's electron which subsequently emits a photon when it returns to its ground state. I then fire another photon with a downward spin towards the same hydrogen atom and the same thing happens...

When photon interact with matter there is a force. Do we speak in terms of Newtonian action-reaction? When a photon exerts a force on matter -an action- do we speak of a force on the photon - a reaction? Thanks.

This text https://en.wikipedia.org/wiki/Photon_polarization starts with: "Photon polarization is the quantum mechanical description of the classical polarized sinusoidal plane electromagnetic wave. An individual photon can be described as having right or left circular polarization, or a...

Hello. I have a question. In the book I am reading, They derive the Ubs operator applied on a photon state with the beam splitter at a ratio of 50/50. A beam splitter that is used in the Mach-Zehnder interferometer. I'm having a hard time deciphering whether the formula for beam splitter...

Fermions such as the electron and proton can be described by wave function in momentum and in position, and it is possible to get the momentum wavefunction from space wave function and vice versa by Fourier Transform. what about photons? can photons be described by position wave function? If...

First of, I have no idea what I'm supposed to do with the neutrinos and the photons. Can somebody explain how to handle these? The rest of what I tried is quite straight forward $$\begin{align*}\Delta E &= 4M_p - M_{He} - 2 M_e + E_{\text{Neutrino and Photons}}\\&= 4M_p - (2[M_p+M_n]-E_B) - 2...

I suppose the reason I am able to see myself in mirror and not in wood is the reflection off a mirror is specular whereas wood is diffuse. In reflective material(e.g: silver) when the photon hits the frontline atom, the atom's electrons absorbs the energy and release it back with tiny energy...

Given that electromagnetic waves transport energy via photons, what is the lowest and highest possible frequency of a photon and what physical phenomena do these relate to? It is clear that the larger the wavelength the lower the energy for a photon. so what are the limits of the wavelength?

Hi. I'm learning the optical photon quantum computer from Nielsen's QCQI. Since I'm not familiar with quantum optics, I got some questions about it.Q1. In page 288, the book reads: A laser outputs a state known as a coherent state ##\left | \alpha \right > = e^{- \left | \alpha \right | ^2 /2 }...