Questions tagged [polarization]
Polarization characterizes the oscillations in time the electromagnetic field is doing in the plane perpendicular to the propagation direction of a wave
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Why do we actually see the sun?
I haven't yet gotten a good answer to this: If you have two rays of light of the same wavelength and polarization (just to make it simple for now, but it easily generalizes to any range and all ...
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Why is the $S_{z} =0$ state forbidden for photons?
If photons are spin-1 bosons, then doesn't quantum mechanics imply that the allowed values for the z-component of spin (in units of $\hbar$) are -1, 0, and 1?
Why then in practice do we only use the $...
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Difference between spin and polarization of a photon
I understand how one associates the spin of a quantum particle, e.g. of a photon, with intrinsic angular momentum. And in electromagnetism I have always understood the polarization of an EM wave as ...
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What is the reason that Quantum Mechanics is random?
We know quantum mechanics gives a random result when we observe a particle that's in a superposition, but why is it random? One of the explanations I've heard is that because light comes with those ...
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How do Optically Active Compounds Rotate Plane Polarized Light?
I am not sure if this is more of a Chemistry or a Physics question, but in my Organic Chem class we discussed that chiral molecules will rotate plane polarized light. However, my professor did not ...
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Difference between electric field $\mathbf E$ and electric displacement field $\mathbf D$
$$\mathbf D = \varepsilon \mathbf E$$
I don't understand the difference between $\mathbf D$ and $\mathbf E$.
When I have a plate capacitor, a different medium inside will change $\mathbf D$, right?
$\...
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How can any light get past a polarizer?
The sun sends out unpolarized light. There are infinite degrees in which these photons are oriented. A polarizer only lets in light of one specific orientation.
In statistics, the infinitesimal area/...
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Why can adding more polarization filters increase the amount of light that goes through them?
I am having some difficulty accepting the implications of the equation governing the intensity of light passing through polarization filters,
$$ I = I_0 \space\cos^2\theta $$
with $\theta$ being the ...
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Three polarizers, 45° apart
If light is passed through two polarizing filters before arriving at a target, and both of the filters are oriented at 90° to each other, then no light will be received at the target. If a third ...
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Are the fast axes on Thorlabs quarter-waveplates mislabeled?
Some members of my lab are performing a polarization-sensitive experiment where they need to use a quarter-waveplate (QWP) with the fast axis in a specific direction. In the process of carefully ...
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What happens if you remove the polarization filter from a computer monitor?
Have a look at this youtube video (and some extra footage here). Here I will post a gif showing in short what it is about:
It shows that if you remove the polarizing filter from a pc's monitor and ...
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What is polarisation, spin, helicity, chirality and parity?
Polarisation, spin, helicity, chirality and parity keep confusing me. They seem to be related, but exactly how they are related is unclear to me. Can someone maybe give a short overview about what ...
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Why is reflected light polarised?
Why is reflected light polarised?
I have learnt about Brewster's angle, and how at a particular angle all light reflected is polarised, but do not understand why. Is this something that could be ...
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Why does the intensity of unpolarized light reduce to half after passing it through a polarizer?
When unpolarized light is polarized with two polarizers, the intensity becomes $I=I_0\cos^2(θ)$ (Malus's law). But when unpolarized light is polarized with only one polarizer, the intensity is reduced ...
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Are these sunglass lenses linearly polarized or what?
This is a difficult question to phrase, so please bear with me. I found some cheap sunglasses and pulled out the plastic lenses which are polarized. For clarity, I have labeled them as lens-1 and -2 ...
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Why are rainbows brighter through polarized glass?
I was standing outside in very light drizzle, sun behind me. I saw a rainbow. I know why they occur but...
I was wearing polarized sunglasses. As an experiment, I turned my sunglasses through 90 ...
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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 ...
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Why can't my eye see itself in the mirror through polarizing 3D-glasses?
I found a pair of polarizing "3D glasses" lying around, and tried to look at myself in the mirror while wearing them.
To my utter confusion, when closing the left eye and only looking through the ...
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What do the names "E mode" and "B mode" mean? Where do they come from?
This has been bugging me a bit since the BICEP announcement, but if there are any resources that answer my question in a simple way, they've been buried in a slew of over-technical or over-popularized ...
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How do coherent isotropic radiators evade the hairy-ball theorem?
The concept of a spherical electromagnetic wave is a nice fiction, which is sometimes called upon in introductory optics textbooks, but it runs into a deep topological problem in the form of Brouwer's ...
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Where does energy go when light passes through a polarising filter
Suppose a polarised light has intensity $I$.
When it is passed through a polariser (also known as Polaroid) whose transmission axis is at angle $\theta$ with E vector the intensity becomes $I\cos^2\...
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Will table sugar twist polarized light?
I recently saw this awesome video by Steve Mould where he explained that a sugar solution in water will turn polarized light in the clockwise direction.
The explanation basically boils down to sugar ...
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Why does stacking polarizers of the same angle still block more and more light?
I have some sheets of polarization film. They came in a big box, all stacked at the same angle. I noticed that the entire stack of them lets almost no light through, even though they're all at the ...
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Conversion of polarized light to unpolarized light
Unpolarized light can be converted into polarized light. However, can polarized light be converted into unpolarized light? If so, how can this be done?
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What ways are there to measure the local polarization of a laser beam?
Measuring the polarization of a laser beam is a simple enough task if the polarization is the same everywhere. You can even buy commercial polarimeters.
How do you go about it if the light beam has ...
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Is a single photon always circularly polarized?
While trying to understand polarization in quantum field theory, I wondered how a single photon could go through a linear polarizer. I found a paper which asked "Is a single photon always circularly ...
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Photons with half integer angular momentum - what's happening?
I have just read this article - what is happening?
Analysing these beams within the theory of quantum mechanics they predicted that the angular momentum of the photon would be half-integer, and ...
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Why does it seem like a broken magnet's poles flip?
I just took a rare earth magnet out of an old hard drive. Lacking an appropriate screwdriver, force was used, and the magnet broke into two pieces; one about a quarter of the original size and one ...
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Is true black possible?
Black is the absence of light because it absorbs light, but when we create black paint or black objects, light is always reflected, either in all directions in matte or smoothly in shiny black objects,...
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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 it?)
Basically, light has a net angular momentum of zero, insofar as ...
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If photons carry 1 spin unit, why does visible light seem to have no angular momentum?
Spin 1 silver atoms have a definite spin axis, e.g. up or down along an axis labeled X. This in turn means that they carry angular momentum in an overt, visible fashion.
However, spin 1 photons do ...
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Why can a solution show optical rotation?
Why can a solution show optical rotation? A solution, as a liquid, is rotationally isotropic, right? So, even if the molecules are chiral, because of the random orientation of the molecules, shouldn't ...
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Can circularly polarized light induce magnetization?
In optics, we usually consider a non-magnetic medium where the magnetization $M$ is zero, while the polarization P is proportional to the electric field $P=\epsilon_0\chi E$. $P$ is induced by some ...
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How do we know from representation theory that a massless spin-1 particle has only two polarizations?
In chapter 8.2.3 of Schwartz' textbook "Quantum Field Theory and the Standard Model", the author states the following,
Finally, we expect from representation theory that there should only be two ...
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What is the difference between the properties of Electron spin and Photon polarization/helicity?
What is the difference between a photon's polarization/helicity and an electrons spin half? I know that the photon is spin 1 but isn't its polarization analogous to spin half?
This question stems ...
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Trouble with polarizing filters
I have bought two cheap polarizing lenses for camera: New View Filtro Polarizzatore Circolare CPL Filter 58mm per Camera (Amazon Italia)
I have done the following observations:
If I put them one ...
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3D glasses giving the opposite effect to that expected
I have just finished watching the new Star Wars movie (The Force Awakens), and during the end credits, text is shown upon a background of stars. Wearing the 3D glasses, I noticed that the text appears ...
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Why, in spin sums, we sum over final spin states and average over initial states?
I am reading Halzen's book about quarks and leptons and on page 120 he talks about spin sums.
He says that in order to calculate the amplitude between unpolarized states we have to sum over FINAL ...
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Is the direction of the electric field relative to the magnetic field in an electromagnetic wave a convention?
In an electromagnetic wave.
Could the magnetic field be mirrored around the xy-plane? Is there a specific reason that the 2 fields are oriented this way? Is it just a convention?
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Why does light not polarise off metallic surface?
I am aware that light partially polarizes upon reflection off a non-metallic surface, however, why is it that this only occurs for non-metallic surfaces?
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How do color filters placed in front of a light source, change the color of light that passes through?
For instance, placing a blue transparent folder in front of a desk lamp, makes the light that shines through it appear blue.
From what I understand some red car lights do not have red light sources, ...
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Can polarised light become unpolarised light as it travels through space?
Is the polarization of a light beam permanent? I mean, does the polarization change as it travels through vacuum?
If so, what causes it to change?
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Why photon only have helicity other than spin? [duplicate]
When learning angular momentum in quantum mechanics, a spin 1 particle have 3 states. Then I saw from sakurai's modern quantum mechanics that photon's two polarization are just like spins, but with ...
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What's the $\ell$ in the Bicep2 paper mean?
The BICEP experiment's recent announcement included the preprint of their paper,
BICEP2 I: Detection of $B$-mode polarization at degree angular scales. BICEP2 Collaboration. To be submitted. BICEP-...
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Polarization of the lowest mode of a Gaussian beam
Most introductory analyses of Gaussian beam optics work within Helmholtz scalar optics, and therefore they ignore the beam's polarisation. Because of that, I'm not clear on what are the possible ...
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DIY Quantum Eraser Experiment by the Scientific American: Is this really quantum?
Click here for the publication.
Having performed this experiment, I have gotten clean results. Essentially, a double slit is made by putting a photon beam in the way of a wire with orthogonal ...
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How to tell whether photons are entangled?
Suppose you have some sort of a "black box" system - you know nothing of its inner workings. The system has two outputs, let's call them A and B, and it occasionally emits photons - one photon from ...
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Why do atomic charges balance?
Atoms are described as having a nucleus at the center with electrons orbiting (or maybe the nucleus with a high probability of being in the center and the electrons more spread out).
If this is so, ...
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Why is the quantum Venn diagram paradox considered a paradox?
I've just watched this video on YouTube called Bell's Theorem: The Quantum Venn Diagram Paradox
I don't quite understand why it is considered a paradox
At 0:30, he says that as you rotate 2 ...
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