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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Rotation of electric field vector or polarization
Given a circularly polarized light field. I am using complex notation to represent the field,
$$\vec{E}(z=0, t) = \frac{1}{\sqrt2} [ \hat{x} (\cos(\omega t) - i \sin(\omega t)) + \hat{y} (i\cos(\omega ...
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"Remembering" the polarization in the BB84 protocol
I am trying to understand the essence of the BB84 protocol and by watching this video,
https://www.youtube.com/watch?v=uiiaAJ3c6dM&t=171s
I cannot manage to understand the following. Alice is ...
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Why is polarization $\mathbf{P}$ proportional to the $\mathbf{E}$ field, but magnetization $\mathbf{M}$ proportional to the $\mathbf{H}$ field?
Why is the polarization intensity $\mathbf{P}$ proportional to $\mathbf{E}$ (electronic filed), while the magnetization intensity $\mathbf{M}$ proportional to $\mathbf{H}$ (magnetic filed), when the ...
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Shadow from Direct Sunlight Visibly Brighter When Viewed Through Polzarized Lens?
I searched this site for about 10-20 minutes using both Google and its built-in search. Wasn't able to find any question similar to this one.
I've taken Physics 1+2 and an introduction to modern ...
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Can spin really be measured in an arbitrary direction?
If I am in the computational basis (given by unit vector ${z}$) and have a ket $|0\rangle$, and I have $\sigma = (\sigma_x, \sigma_y, \sigma_z)$, the Pauli matrices, then my ket is an eigenfunction of ...
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A "plausible mistake" in Born and Wolf book
I am reading Born and Wolf book Chapter 1 and specifically section 1.6 "Wave propagation in stratified medium" (wrt. 7th edition). I think that there is some error in the equation which is ...
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Why is no flickering observed in polarized filters?
Consider a computer screen which emits horizontally polarized light and a polarized filter. If you rotate the filter 45° relative to the screen, then it will let through roughly 50% of the light from ...
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Calculating polarization
In this paper, authors prove experimentally that it is possible to create time-crystals. It is my understanding, reading the paper, that they have measured the polarization of the system, however, I ...
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What happens if you try to polarize a photon in the time direction?
In the comments on a video explaining some part of quantum mechanics, there was a comment about rejecting unphysical solutions to some equation, such as time-polarized photons.
As far as I'm aware, ...
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Are Maxwell's equations inconsistent? [closed]
Maxwell's equations in linear homogeneous matter:
$$
\begin{eqnarray}
\nabla\cdot\mathbf{E}&=&\frac{\rho}{\epsilon},\tag{1}\\
\nabla\times\mathbf{E}&=&-\frac{\partial\mathbf{B}}{\...
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Twisting a laser with the Quantum Zeno Effect
I thought of an experiment in QM with a predicted result that seems kind of absurd to me, so I want to know what I am missing in my mental model. I tried to perform the experiment using a consumer-...
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Computational methods to calculate piezoelectric tensors from Berry phase and phonon approaches [closed]
Recently, I have been exploring methods for computationally calculating piezoelectric properties(tensors), such as Berry phase and phonon-based approaches. I would greatly appreciate any insights into ...
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How is the polarization transfer formula in hyperon decay derived?
In the decay process of spin-1/2 hypron to spin-1/2 baryon and spin-0 meson (such as $\Lambda \to p + \pi$), the polarization vector $\mathbf{P}_D$ of the daughter baryon is given in terms of the ...
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Impact of a non-ideal Beam Splitter (BS) in QKD protocol
I’ve noticed that in the BB84 protocol the Beam Splitter (BS) is typically assumed to be ideal. I'm wondering whether this is a reasonable approximation, or if the imperfections of real BS devices ...
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Feynman rules for outgoing photon
This question is related to the Feynman rules of QED.
A general photon state is characterized by its momentum and spin, and it can be written as $$|k,\varepsilon\rangle\equiv\varepsilon^\mu a_\mu^\...
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Why does electromagnetism attenuate so much faster than gravity?
Electromagnetism and gravity are both inverse distance-squared laws, so why is gravity affected so much less by distance?
Is it that electrical charges tend to pretty much completely balance out ...
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Rayleigh-Jeans criteria in cavity radiation requiring 2 possible states of polarization
Reference to question is p. 9 in Eisberg, Resnick's
Quantum Physics of Atoms (1985). Dealing with
the "allowed values of the frequency in a 1-dimensional cavity of length $a$": I do not ...
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Point charge above semi-infinite dielectric [closed]
Question: Let $z>0$ be vacuum, and $z < 0$ be a dielectric with susceptibility $\chi$. If there's a charge $q$ at position $(0, 0, a)$, what is the bound surface charge density $\sigma_b$ due to ...
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Why the polarization vectors must be orthogonal to the wave vector $\textbf{k}$?
M. Srednick in his book "quantum field theory" says on page 341 that
"In order to satisfy the Coulomb gauge condition $(\nabla\cdot \textbf{A}=0)$, the polarization vectors must be ...
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Polarization states of virtual photon?
I was working through a problem on BhaBha scattering (at tree level), and I am confused about the polarization of the virtual photon. As it is virtual it means that it cannot lie on its mass shell, I ...
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Calculation of visibility in Young's double slit experiment [closed]
I am working on a homework problem that asks me to calculate the visibility in Young's double slit experiment.
A monochromatic and linearly polarized light is used in a Young’s double slit experiment....
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On the meaning of "effective" in Maxwell potential equation
Writing Maxwell equations in terms of the scalar and vector potentials I came across the definition of effective charge density and effective current density; respectively $\rho_{eff}=\rho-\nabla \...
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Sun turns blue when seen through a crossed polariser/analyser
It was sunset, and we were looking at the sun through our polariser/analyser setup. When the angle between P and A was zero, the sunset looked normal (albeit with an expected reduction in brightness).
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What is the relation between the polarization $\mathbf{P}$ and the electric field $\mathbf{E}$ in piezoelectric and flexoelectric materials?
I'm currently trying to understand electromechanical coupling effects in dielectric media, especially the link between the polarization density field $\mathbf{P}$, and the electric field $\mathbf{E}$, ...
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Electric field of bound charges
I'm a physics student taking a first course on electromagnetism. I can't figure out how bound charges (or polarization charges) must be thought of. As I've thought to understood until now, in ...
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Polarization ellipse - Relating the ellipticity angle to the field parameters
I am working through Zangwill's Modern Electrodynamics. In section 16.4, he presents two results that relate the polarization ellipse's orientation angle ($\alpha$) and ellipticity angle ($\gamma$) to ...
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X-effect from Variable ND Filter photography
I’m trying to understand what’s happening when using a variable ND filter in photography.
A variable ND filter is placed in front of the lens to control the amount of light that reaches the sensor. It ...
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What is the equivalent of magnetic permeability in electrostatics?
I'm trying to figure out the different analogies that can be made between electrostatics and magnetostatics.
For instance, as I understand it, the magnetomotive force is the equivalent of both the ...
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How does polarization manifest on the level of the quantum numbers?
Polarized light (or any EM wave) works by having an unidirectional orientation of the transverse EM waves. Fine, but that is a description of light (EM radiation) by EM fields. Deeper with a layer, we ...
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Why Mueller matrix of quarter-wave plate of which fast axis is horizontal is this?
In Hecht's book, the Mueller matrix of the quarter wave plate with the fast axis in the horizontal direction is
$$M=\begin{bmatrix} 1& 0& 0& 0\\ 0& 1& 0& 0\\ 0& ...
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Correct definition of right-circularly polarized and left-circularly polarized
This is a simple question. I am just wondering about the correct definition of left and right circularly-polarized light. I thought that if I point my thumb in the direction of propagation, then in a ...
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Can normed Jones vectors represent partially polarized light?
It is known that physically distinct Jones vectors$^\dagger$ live on the surface of the Poincaré sphere. The partially polarized states live on the interior of the Poincaré sphere. The degree of ...
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Circular polarized light on a polarizer
I just studied polarization which made me curious.
What will be the difference observed when circular polarized light is incident on a polarizer compared to that of unpolarzised light?
What will be ...
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Why do we use $\mathbf{E}$ instead of $\mathbf{D}$ in fundamental electromagnetic equations?
In electromagnetism, there are two kinds of fields, the ones that includes the response of the material $(\mathbf{D},\mathbf{B})$ and the one that only include the contribution of the free charges $(\...
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How many degrees of freedom required to describe the electromagnetic response of a linear isotropic material?
I am confused about complex permittivity, permeability, and conductivity.
My Question:
Ultimately I am trying to figure out what is the minimum (and maximum) number of degrees of freedom needed to ...
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Why TO phonon frequency is sensible to long-range dipole corrections but LO phonon does not?
I am trying to calculate the phonon dispersion relation in some polar semiconductor materials, including SiC, MgO, and GaN.
I found that the frequencies of LO modes in these materials are heavily ...
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Should/can one describe the angular momentum carried by a Photon as a 2 dimensional Hilbert space analogous to an electron spin?
I am currently trying to wrap my head around electron photon interaction processes in Atoms, as for example described here. In particular I am interested in the dependency of the angle between photon ...
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Intuitive explanation for relation between polarization and voltage in piezoelectric materials
As far as I understand, in piezoelectric materials there is a non-zero polarization $P_0$ in the default state (without stress and strain). By deforming the material using mechanical force, the ...
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Can the "Three Polarizer Paradox" be explained classically?
I recently learned of the Three Polarizer Paradox:
If two polarizing films are aligned in the same direction light from
the first polarizer passes through the second. If the polarizers are
opposed at ...
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Alignment of nuclei in a certain direction [closed]
In an assembly of several similar atoms having asymmetric nuclei, how do you align the nuclei in a certain direction rather than random directions?
Here,
'assembly' means 'set of more than one items'....
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Lorentz invariance in scattering amplitudes involving gravitons
Let's consider a 2-to-2 scattering $$(p_1+p_2) \rightarrow (p_3+p_4).$$
Usually, the squared transition amplitude $|\mathcal{M}|^2$ can be expressed fully in terms of the Mandelstam variables
$$s=(p_1+...
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How can I calibrate the experimental setup for the measurement of density matrix of polarization entangled photon?
I need to measure the density matrix of polarisation entangled photons. They are generated by an EPS source. The two photons are split and sent to two SPADs via different optical paths. In front of ...
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Sum of gluon polarizations in polarised Drell-Yan
Let's consider the polarised Drell-Yan process, in particular the process
$$
q_1(p_1,s_1)+g(p_2)\to \gamma+'X'
$$
where $(p_1,s_1)$ are the quark momenta and spin. $q_2$ is the gluon momenta. $X$ is ...
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Is is possible to generate circularly polarized light using a rotating half-wave plate?
Let's assume that I have a laser beam with a frequency $\omega$ that is linearly polarized (say coming out of a laser diode). If I pass it through a half-wave plate (HWP), the light that is ...
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Examples of non-scalar and non-vector waves
Are there any simple examples of non-scalar and non-vector waves, except for gravitational waves? I'm looking for an example in which the wave has more than three independent polarizations.
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Issue with gauge transformation in photon polarization derivation
I'm trying to convince myself about a derivation of the two polarizations of the photon, but I'm stuck in last step.
Here is what I have done so far. I'm using as primary reference a post asked here ...
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LED TE and TM polarization
I’m having some difficulty understanding the concept of polarization in UV LEDs. To summarize the literature, for UV LEDs emitting at longer wavelengths the light they emit is mostly TE polarized, ...
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Radiative and Longitudinal degrees of freedom of EM field
I'm having some issues trying to understand some of the affirmations my professor made in the last class. After working on the Maxwell's equation of the non-static regime for a quite a while, we ...
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Are Stokes parameters Lorentz invariant?
Are the Stokes parameters for polarization relativistic? i.e. Lorentz invariant? And if it is so, then how to show it?
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Infinity Minus Infinity When Computing Electric Potential Difference
I am working on a problem involving a polarized cylinder with its axis aligned along the $z$-axis. The cylinder has a height $L$, radius
$R$ and a constant, uniform polarization
$P$ that is parallel ...
