Photon Definition and 1000 Threads

When a photon is at a large distance fom it's starting position then the wave is spread-out laterally. How can a wavefront for one photon collapse instantly over a massive surface area?

Hi , so , i am not asking this question for invisibility or anything like that, but i do have a few questions. First off, i know that photons have no charge, but is there any way that electro magnetic pulses can effect their path when the copper coils that make the electro magnet are at very...

I have a question concerning the paper "Quantum imaging with undetected photons". http://arxiv.org/abs/1401.4318 In the schematic (Fig. 1) a photon (idler) is created at NL1 and passing the object at O to be reflected further to NL2. It is then stated in the paper "By reflection at dichroic...

Hello everyone: Here is the problem: Under thermal equilibrium, photon's number can be described as the photonic density of state (PDOS) * occupation number(ON). Also, the photon's flux can be described as PDOS * ON * effective particle velocity into certain direction ( V) The occupation...

Just a quick question on photon orbital angular momentum. In the equation for photon energy: E2 = p2c2 + m2c4 Is OAM counted in the p2c2 part? Or does the above equation only apply to photons with normal momentum and there is another term for the angular momentum? The normal relation for p...

Homework Statement Close to a Schwarzschild black hole, a photon is emitted between r = 2(mu) and 3(mu), where \mu = \frac{GM}{c^2} . The photon is emitted at an angle (alpha) to the radial direction. At r = 2(mu), the highest angle that the photon can escape at is (alpha) = 0; at r = 3(mu)...

I saw in a recent review paper- Engineered quantum dot single-photon sources (Rep. Prog. Phys. 75 (2012))- a discussion about how a "timing jitter" problem lead to reduced indistinguishability of single photons, which I find very hard to understand. According to the paper, for quantum-dot-based...

Homework Statement In the photoelectric effect, it is assumed that a single electron absorbs a single photon. But, there is a certain probability that a single electron may simultaneously absorb two identical photons from a high-intensity laser. How would such an occurrence affect the...

A photon's momentum vector points in the direction of its propagation but interacts with particles off its axis. How this directional preference is revealed by QM? Is there an ontological picture of the photon's propagation?

So I have been thinking about the photon gas, and I have read several papers talking about how a Carnot cycle could be created for it. This is fantastic, and it is something I am quite comfortable with. All of the papers present the P-V diagram as the "golden" Carnot cycle for the photon gas...

Bonnes fetes de Noel. When an excited electron returns to its ground state a photon is emitted. Suppose that the electron's spin skip from +1/2 to -1/2 (around z)and that the photon has a momentum parallel to z. I suppose that this photon has a circular polarization around z (Is it true?) The...

I have been getting conflicting information so here are my questions, re: 1. Single photon interference 2. Interference between two photons 3. Two-photon interference 1. Some literature says that only single photon/particle interference exists. Can two photons interfere with each other? 2...

A photon has “zero” rest mass, but it does have Energy, But with zero Mass , E=MC^2 yields E=0 I am confused !

There are many things that confuse me, my wife, my job, but at the moment, mostly a photon. I am a photon, t=0, since v=c. Ok, but t=0 is accurate to infinity to the power of infinity, for a photon. it doesn't even aproche infinity, it starts there. To be causal, in any other inertial frame...

i read some where that four momentum of photon is null vector that's why photon have zero rest mass.but i cannot get it.please help

[Moderator's note - split off from this thread as a new topic. Well its probably off the topic in this thread [Moderator's note - you got that right], but perhaps its the way the statement above is structured. Can one really observe a photon to start? My understanding is , when a photon is...

Can a Massless Photon create Mass? Is Electrostatic Induction a form of “Mass Transfer through the process of Absorption”? A new star is created. The star generates massive Magnetic Fields. What happens to the hydrogen particles, Nebula, when they are influenced by the Magnetic Field? If the...

For internal photon states, is it necessary to sum over the longitudinal polarization state in addition to the transverse states? And if so, does the ordinary Feynman-gauge propagator take care of this? Thanks!

While planing some simple experiments us encountered such a problem: what is exactly photon momentum? p_ph = ?

If a large mass of matter and anti-matter collided to form a black hole, I assume they would anihilate and you would have a black hole made of photons. Now considering the black hole as a container of photon, there must be a net pressure pushing against the confines of the gravity. The force of...

Hello! I am an undergraduate student currently pursuing my Bachelor's before I attain my PhD in Particle Physics. I do however have an exciting concept I would like to have to my name before I disclose it to the world; therefore, I was wondering how this would happen, and if it is possible...

Generally, all that matters is the amplitude of the wavefunction. You usually can't even MEASURE the phase unless you are making a particle interfere with itself. With photons, however, the real & complex components seem to appear as electric and magnetic fields. Is there anything equivalent...

It is known that the penetration depth of photon into a material depends on the energy of the photon, density and atomic number of the material; because the photon energy is normally smaller than the potential against the penetration of photon, which is the potential barrier, so the incident...

A photon traveling from its source at light speed is said to not experience time and therefore be everywhere at once. Well not exactly, it can only be everywhere at once along its projected path assuming the photon's path in a vacuum is not altered by anything. Time itself cannot alter the...

For an atom, the single photon electric dipole selection rules for the magnetic quantum number require that delta_m = -1, 0 or +1. As I understand, the physical explanation for this set of selection rules is usually related to the conservation of the projection of the angular momentum on the...

Hello, Given an electromagnetic wave that is, from a classical point-of-view, not circular polarized. Does that correspond in QM to photons with the ZERO spin eigenstate? Thanks in advance.

Can we say that a point light source (turned off) together with a two slit interferometer and say a photographic plate detector exclude certain photon modes? Light does not go to certain parts of the photographic plate so can we say that the source (turned off), the interferometer, and the...

I was reading a section of a chemistry textbook describing electron energy shells. It compares the electrons to light saying that electrons energies are quantized and so are light energies. Electrons can only jump from one specific energy level to another with no intermediary energy levels. I...

First: a question about spin. When we say that an electron has spin 1/2, we mean that it can have the values ħ/2 or -ħ/2. So when we say that a photon has spin 1, I would expect this to mean that the measurement of a photon would give values either ħ or -ħ. But then I am confused by the...

Hi I am trying to write the probability of photon emission due to transition of electron in feynman's path integral formulation. I am stuck trying to figure out the action corresponding to the photon emission. Would anyone shed some light on this? Thanks

I’ve read that the particle responsible for the transmission of the electromagnetic force is the photon. Another way to say this is that the photon is the carrier of the electromagnetic force. Having that in mind, let’s suppose that we have an electron resting in vacuum, and suddenly an electric...

I was reading Schwartz's qft book. I saw the proof of ward identity taking pair annihilation as an example. he claimed he didn't assume that photon is massless in this derivation. but i have confusion with this statement. gauge invariance is a fact related to massless particles. now he has...

Is there any known limit to the energy of a photon? I've seen a reference to pair production in the highest bracket over 1.02 MeV and I've seen references to energies from cosmic sources in the TeV range which aren't very well understood but is there any theoretical limit?

Is it one wavelength of EM wave? I have googled for this and I can't find an explanation for what a photon is in terms of EM waves.

If time stops at the velocity of light, how can a photon oscillate with a frequency? Frequency is defined with cycles/second.

I know that QM and GR have not net been combined, so perhaps this is a foolish question, but I'll try anyhow. A photon traveling in the vacuum, has energy h/λ. That energy is fixed. It never varies in any circumstances (true?) except one. That one is the expansion of space time; i.e. the...

supposing a constant acceleration Vertically a horizontal incoming photon is considered. We know that in the frame of the lift the vertical speed of the photon will increase, hence its horizontal one will decrease and then the photon trajectory has a vertical asymptote ?

I know that photons and other particles of comparatively smaller dimension show dual nature. But why? Can someone help me? :confused:

In the double slit experiment, when we send out one photon at a time, what does the appearance of minima in our interference pattern mean? When a single photon is fired, I understand (using "understand" very loosely) that the photon will interfere with itself. When this happens, does it still...

Noob question ahead. So basically I'm reading about atoms and photons in my textbook at the moment and I came across excitation and why atoms emit photos with certain wavelengths when hit by white light. The claptrap doesn't really matter, what I'm confused and curious about is how many times...

Do really is the presence of an antiparticle of photon possible in the cosmos? Does it have one?

Consider the above experimental setup. Here the source can emit one photon at a time. The output from the source is sent to a beam splitter which divides it into three possible paths of equal probability. Splitter 2 further splits the path 3 into two paths of equal probability. We have...

QM started as a non-relativistic theory for microscopic particles. Then there were the attempts to make it relativistic and the results of those attempts suggested that you can't have a relativistic system with a fixed number of particles. But things are a bit different for photons. A...

Following the premise of Einstein, man cannot travel at light speed due to the overwhelming increase in mass during the hypothetical attempt. However, a photon has no such limitation... it travels at it's constant. Therefore, if a photon travels from the surface of the Earth into space...

I recently thought about this. Let's say there's a hydrogen-like atom with a transition energy \omega. If it is hit with a photon of frequency \omega, it will make a transition to the excited state, so the change in internal energy is \omega. But by conservation of momentum, the atom will also...

I know that a photon has no mass when it is traveling at the speed of light, however my question is, can a photon have mass when traveling through a medium, i.e. when its speed is less than c? I have done some reading but cannot find an answer. From this reading I have got the following: We...

I'm a beginner in quantum optics. I always become confusing when the material's refractive index is complex. This time is about the photonic density of states. We know that if the material is not absorbing or dissipative, meaning the refractive index is a real number, the local photonic density...

A photon with wavelength lambda = 0.1050 nm is incident on an electron that is initially at rest. If the photon scatters at an angle of 60.0 degrees from its original direction, what are the magnitude and direction of the linear momentum of the electron just after the collision with the photon...

For example, thermal energy exists and has no mass, but is carried by particles which have mass. A photon is described as a particle - how can a photon exist on its own, travel in space and even push other particles with mass if it has no mass itself?I am not sure if that thread should be in...

Am I right when I say that you can orbit the photon sphere and still be not pulled towards the Event Horizon but you need to orbit (In your spaceship) at the speed of light?