1
vote
2answers
94 views

How do photons “decide”?

I was reading that when horizontally polarized light hits a vertical Polaroid all the light is blocked out. But when the Polaroid is off the vertical, some but not all photons "decide" to jump into ...
9
votes
1answer
135 views

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 ...
1
vote
1answer
39 views

Can a single photon be polarized non-linearly?

I want to check if I correctly understand polarization. Considering a single photon travelling in vacuum, it can only be polarized linearly under the same direction at any time, right? When we talk ...
1
vote
2answers
123 views

Why are results of Bell's experiments considered to “break realism”?

Related to my previous question (Why would classical correlation in Bell's experiment be a linear function of angle?), as a newbie in quantum mechanics, I am also unable to find the reason to why ...
1
vote
1answer
56 views

Problem regarding quantum mechanical notation of photons

I have recently been reading about spontaneous parametric down conversion(SPDC). I do clearly understand the process. What has been intriguing lately is the notation. For those of you who are ...
2
votes
0answers
41 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 ...
3
votes
1answer
100 views

Polarisation of light is a wave concept or applicable to photons as well?

I have a very fundamental question. We explain polarisation of light assuming wave nature of light. Is it still valid if we assume light as photons? Or in other words, polarisation is a wave concept ...
0
votes
0answers
47 views

What is the difference between orbital angular momentum of photons and their polarization

What is the difference of OAM of photons and their polarization?
7
votes
1answer
171 views

Is the third spin vector of a photon always suppressed?

I like to tell people interested in light polarization that the photon is a vector boson for which the third spin axis, the one in the direction of travel, is suppressed due to photons being massless ...
7
votes
3answers
614 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 ...
6
votes
3answers
1k views

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 ...
3
votes
1answer
85 views

Polarization in Lasers and Liquid Crystal Displays

When we talk about Polarization in Lasers we mean placement of the crystal at Brewster angle to block the s-polarization and only the p-polarization will survive. How do we compare the term ...
4
votes
3answers
1k 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
59 views

How does a photon leave trace of its polarization state in a photon detector but not trace of which direction it came in?

Some quantum erasure experiments involve polarization of photons. In one such experiment with a double slit, a horizontal polarizer is used in front of one slit, and a vertical polarizer is used for ...
7
votes
1answer
201 views

If light is linearly polarized, does it have some spatial extent?

If light (a photon) is linearly polarized, say vertically, does it have some vertical spatial extent (perhaps in amplitude)?
3
votes
2answers
245 views

What is a photon's speed inside a dieletric?

We know that EM waves are slowed down in a dielectric. But at what speed does the photons that make up the wave travel? Do they always travel at the speed $c$, but colliding/being absorbed and ...
1
vote
0answers
182 views

Polarization photon and Stokes parameters

I have the following situation: About the polarization of the photon, I introduce the basis: Horizontal polarization $|\leftrightarrow>=\binom{1}{0}$ Vertical polarization ...
18
votes
4answers
2k views

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 ...
3
votes
0answers
329 views

How does one calculate the quantum propagator for a massless photon

So I want to calculate the quantum massless photon propagator. To do this, I write $$ A_\mu(x) = \sum\limits_{i=1}^2 \int \frac{d^3p}{(2\pi)^3} \frac{1}{\sqrt{2\omega_p}} \left( \epsilon_\mu^i (p) ...
4
votes
3answers
258 views

How many photons does it take to measure a linear polarization?

A star emits perfectly (100%) linearly polarized light at an arbitrary angle. How many photons must you detect to measure this angle to a precision of n binary digits? (with greater than 50% ...
1
vote
1answer
176 views

Quantum Cryptography

First question was a little bit ambiguous. Photons are passed through a linear polarizer that is oriented $\theta$ degrees again the photon passes through another linear polarizer that also have a ...
3
votes
1answer
962 views

What are the polarization states of the photons in a polarized and unpolarized light?

The photons are completely polarized, i.e their polarization states can be expressed as $a|R\rangle+b|L\rangle$, where $|R\rangle$ and $|L\rangle$ are two helicity eigenstates of the photon. For ...