Coherence describes properties of correlations among physical quantities of waves, with special emphasis on constant phase differences and frequencies in common. Such collective linkages enable stationary (temporally and spatially constant) interference.

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How to find the width of a sinc function? [on hold]

I took the data of visibility by varying the distance between two slits in the YDS experiment. I plotted the visibility vs the distance between two slits and fitted with sinc function. The width of ...
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Production of entangled photons by spontaneous down conversion [on hold]

I have found that the conditional uncertainty product of position and momentum of any one photon produced in the spontaneous parametric down conversion process using a gaussian pump beam decreases ...
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Non coherence of Fermions and Bosons through $U(1)$

I "know" the textbook answer why we cannot write, $$ |\psi\rangle = a|j=\tfrac{1}{2}\rangle + b|j=1\rangle $$ as "each term in the quantum superposition transforms differently under $U(1)$", $$ ...
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Polarized Coherent Beam Hits a Polarizer Off-Polarization Angle While Varying Distance?

Just wondering about an experiment that should be easy to perform on an optical bench: A coherent beam is polarized. It then hits another polarizer which is set to permit a polarization angle off ...
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20 views

How to find Intensity from field of train of pulses?

Lets say there is process that emits a field $E$ every half cycle of a driving laser pulse (in particular, high harmonic generation). The total field is $$ E(t) = \cdots + ...
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Finding the appropriate fitting function for a coherence length measurement

I'm studying Coherent Optics in Experimental Physics, and I intend to determine the coherence length of a two beam interference. To do that, I used an He-Ne laser, a Michelson interferometer and a ...
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What is the shape of the MTF curve in coherent imaging?

For incoherent imaging, the shape of the diffraction-limited MTF curve would look roughly like a triangle, with normalized contrast starting at 1 for zero spatial frequency and decreasing to 0 at the ...
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54 views

Would a collection of entangled particles behave like a superfluid? [closed]

Superfluidity of a Bose-Einstein condensate comes from the fact that all the particles are found in the same quantum state. They are described by the same macroscopic wavefunction. They never collide ...
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Connection between coherence and monochromaticity of a light source?

Is there any connection between the coherence ( length, time ) and monochromaticity of a light source?
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37 views

“Classical” Coherence

I'm having a couple of courses where the concept of coherence is quite important. I know the traditional definition of coherence and it's connection to the phase of a wave. But often, I found, that ...
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137 views

Conservation of quantum coherence?

Is coherence conserved under unitary transformation? As we saw in the process of generating entanglement, coherence between states of the subsystem is transferred to quantum correlations (related to ...
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61 views

Time-coherency of “incoherent” light

Even "incoherent" light as the one of a light bulb has some coherency, and would interfer in the double-slit experiment (even if more blurry because the different wavelengths don't trigger the same ...
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29 views

How to tell whether a wave is coherent or not? [closed]

I know that coherency means constant phase difference,but how to figure it from equation? Are all sinusoidal waves coherent?
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Re-entering superposition

I've realized that I'm somewhat familiar with what happens when an system in a superposition is "measured". But not at all with what happens after. Example: If there is an electron in a ...
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What is a wavefront?

For this picture Anna wrote: "Incandescent light is incoherent because it comes from many sources and the same is true for sunlight. By passing the light through the one slit he created a single ...
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95 views

What makes the radiation behind slits coherent?

Have a look on the sketch To get such a intensity distribution of light behind a slit we presuppose that all the light that moves on the two lines is coherent; of the same wavelength AND the same ...
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59 views

Are these waves coherent? [closed]

Are these two sinusoidal waves coherent? Note that it is not on y-t graph. And $x_1 \neq x_2$ but time taken to cover both the distances is same (which means same frequency). i.e. $t_1 = t_2$ ...
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176 views

Is this wave spatially coherent?

Is the following wave (the solid lines representing the intensity maxima) spatially coherent? I've been seeing different, seemingly contradictory definitions of spatial coherence. Some places ...
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24 views

How can I simulate two fluorophores with a reticle?

Fluorophores typically emit in an incoherent fashion. I thought I could simulate two fluorophores (e.g. single molecule fluors) with a reticle. My concept was to make two small holes in a chrome ...
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Can thermal states of light be monochromatic?

As one can read from the quantum optics textbooks each mode of light of a certain frequency, spatial configuration and polarization can be considered as a quantum harmonic oscillator. One can imagine ...
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How is the temporal coherence of a pulse defined?

I am having problem with the concept of coherence and photon degeneracy. The temporal coherence of pulse is defined in Born and Wolf as: $$t_c=\lambda^2/c\Delta\lambda$$ (The time a photon takes to ...
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Entanglement and coherence

I have come across a wonderful review of entanglement by Chris Drost in his answer to this post. One part that left me puzzled was: (This post is merely an attempt to understand a portion of Chris' ...
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60 views

Why, in order to obtain distinct interference, is a small distance between the two waves essential?

This is quoted from Concepts of Physics by H.C.Verma: In order to obtain a fairly distinct interference pattern, the path difference between the two waves originating from coherent sources should ...
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56 views

Connection between Polarization and Coherence in optics

It is not completely clear to me how the notions of polarization and coherence, in optics, work together! I quite understand both of them but it's still hard to grasp their deep connection. I'm quite ...
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Do stars produce spatially coherent light? Why?

If I understand correctly, the existance of astronomical interferometry implies coherence of light produces by stars. The temporal coherence can probably be achieved by wavelength filters. But what ...
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Coherence theory and spatial/temporal coherence

I'm working on a beyond the Standard model (BSM) experiment (on its theoretical side, actually) and I really need to understand better the concepts of spatial and temporal coherence. The rough idea ...
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What is the relationship between coherent states and quantum coherence?

What is the relationship between coherent states and quantum coherence? To me coherent states were only talked about in regard to Quantum Harmonic Oscillator, whereas coherence and decoherence on the ...
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coherent length measurement of a monochromatic laser source

i need to learn about how to measure coherent length of a monochromatic laser source.I know that I can use michelson interferometer or spectrometry.For laser which has long coherent length michelson ...
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103 views

Is it possible to produce coherent light with a thermal source? [closed]

Coherent light means monochromatic light and alle waves have the same phase difference. This is given for laser, where the resonator is a potential box and the outgoing waves have the same phase ...
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Understanding quantum coherence in biological processes (Magnetoreception)

Moved my questions to the top. Context below. Why is the strength of the electric field and the coupling constant being compared to the inverse coherence time? What is the inverse coherence time? Is ...
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105 views

Does chirp (GDD, TOD ) affect the temporal coherence of a laser?

Lets say we have a laser beam with finite temporal coherence. A broadband spectrum with a transform limited pulse of 100fs. If we measure its temporal coherence when the pulse is transform limited ...
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Micro gripper for conveying tiny objects

Figure below shows a micro gripper used for conveying very small objects (i.e. the spherical object in Figure) and putting them in desired place using capillary force principal in a liquid bridge. To ...
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242 views

Quantum coherence and decoherence

In Quantum Mechanics coherent states are defined as eigenstates to some annihilation operator. Afaik this notion is due to Roy Glauber. Now, I just read that if you have a spin-state for example, ...
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254 views

Coherence of spin state

In my textbook the coherence of a spin state $|\psi\rangle $ is measured by the quantity $|\langle \uparrow|\psi| \downarrow \rangle|$. The thing is that I am not sure how this quantity is related to ...
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Spatial coherence of SLED light (width of active region?)

As far as I know, super-luminescent diodes (a.k.a. SLEDs) have a very similar structure to laser diodes, except that the front faces of the active region are tilted to prevent the sort of reflections ...
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333 views

Convert normal white light to laser-like light?

Is there a probable device that can convert white light to laser-like light without the need of an electrical stage in-between? I'm thinking of something along this level. A very precise filter and ...
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Coherence length requirement for interference

One property of light sources that is usually stated, which is of particular importance when trying to create interference fringes, is the coherence length (or coherence time). The equation for the ...
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Schrödinger: Coherent states

A coherent state is called $\Psi_{{\alpha}} \left( x,t=0 \right)$ and is defined by: $a_{{{\it \_}}}\Psi_{{\alpha}} \left( x \right) =\alpha\,\Psi_{{\alpha}} \left( x \right) $ where $a_{{{\it ...
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Simple explanation of Coherent integration radar

I have a physics background, and I'm reading some physics data analysis papers where they keep throwing around the term coherent integration. I've done the google search, but the best answer I could ...
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997 views

What exactly is the “coherence” between waves?

I know, by definition, that coherence means that a pair of waves have constant phase difference. What does this mean? Does it mean they always have a 360 degrees, or 0 degrees phase difference? Or ...
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503 views

Coherent sources for interference

Regular interference pattern can be observed if the two wave sources are coherent. Two sources are coherent if they have the same frequency and constant phase difference. Could someone please ...
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505 views

How is the theory of partial coherent light related to quantum-mechanics?

Background Let me start this question by a long introduction, because I assume that only few readers will be familiar with the theory of partial coherent light and concepts like a mutual coherence ...
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Do the various frequencies of light within sunlight have the same coherence length?

I'm aware that the coherence length of sunlight can be observed with a Michelson-Morley interferometer. I haven't seen any experiment that separated the different colors within sunlight to determine ...
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Is Initial Coherence a Problem in Experiments?

In experiments, or optical setups, is the initial coherence of lasers something to be concerned about? You can calculate interference patterns, but those generally rely on the phase shift between the ...
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In what applications are lasers necessary vs. just convenient?

I’m trying to understand, given the wide array of current laser applications: Which applications actually require laser characteristics, as opposed to just use lasers because they are the most ...
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Spatial and Temporal Coherence

How is it possible to achieve waves which are spatially, but not temporally, coherent? Can this be done with a bandpass filter? Conversely, how is it possible to achieve waves which are temporally, ...
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Calculating the coherence length from a spectrum

I have measured the spectrum of the LED in my interferometry set-up, and now I want to calculate the coherence length from it. A commonly found formula is $l_{coh} = \frac{c}{\Delta f}$, sometimes ...
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Does putting color filters make the sources incoherent?

In Young's double slit experiment a single source is used to illuminate two slits which then acts as two coherent sources to produce interference pattern. But, what if I put color filters on the two ...
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How to modulate the coherence of light field?

I want to use a Ronchi grating to modulate the coherence of incoming light field. The grating is placed at the object plane of an optical system under test. So can anybody answer my question about ...
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163 views

Coherence effect on collecting sun light by mirrors

There are systems that collect sun light in one spot. I wonder, why does it accumulate additively, without destructive interference?