Coherent Definition and 158 Threads

I have been doing some reading into Glauber Coherent States and I am struggling to get a grasp on how they are composed, ie. how to determine when they exist. I kind of get the idea (qualitatively speaking) let me try to explain what I think; - They are composed of superpositions of many of...

Does anyone know how to add more than two coherent sources that have different phases? An example might be a sound source and a receiver with sound reaching the receiver directly and by two reflections via different paths - maybe off a hard floor and hard ceiling. There's a good document...

Dear all: I knew the coherent state is the eigenstate of annihilation operator with a complex eigenvalue, which seriously disturbed me of thinking it. Can anyone give me a simple and understandable picture of what is it, thanks a lot in advance.

Hi. Coherent states of light, which correspond to classical em wave, are eigenstates of non-Hermite annihilation operator. Fock states are eigenstates of Hermite number operator. Are Fock states are expressed by combination of coherent states? If yes, how? Thank you in advance. ref...

Suppose you have two coherent microwave beams, one beam at 45 degrees to a reflecting wall and the other one at 90 degrees, with the two beams pointing to the same point on the wall. If the two beams are 180 degrees out of phase and destructively interfere at the point on the wall, will the...

I'm brushing up on squeezed coherent state and have seen them defined in terms of position and momentum squeezing and in terms of amplitude and phase squeezing...is there a relation between the two? Am i missing something obvious :p ?

Monochromatic vs Coherent - URGENT. PLEASE HELP! Hey guys, I have this exam tomorrow, and i am so confused between monochromatic and coherent waves. Can someone please explain them and the difference between them to me. The more i read the more i get confused. Thank you kirollos

is it necessary ffor coherent waves to be of same frequency? bcoz everywhere i read its written dat they must have a constant phse difference. but can't they have frequencies dat are simple numerical multiples of each other? like 256 512

is it necessary for coherent waves to be of same frequency? because everywhere i read its written that they must have a constant phase difference. but can't they have frequencies that are simple numerical multiples of each other? like 256 512

i mean what more are coherent waves except 'having constant phase differnce'?i mean it is nt necessay for them to be in phase .they can be out of phase but must have a cnsstant phase diff. say pie/2 radian so what i mean to ask is that is it necessary for coherent waves to be of same frequency...

Hi. What physically gives light its coherence length and why does it increase for narrow bandwidths? My thoughts are that the broader the optical bandwidth the more frequency components and thus wave crests (and troughs) of each will spread apart more rapidly than quasi-monochromatic...

Experimentally how do we make sure that the ejected electrons are coherent?

hi, Our teacher told us, that interference occurs, if two waves are said to be coherent. but doesn't it have also something to do with the polarization of the two waves? so can one observe interference, if one has: circular or ellipctical polarized waves, when these two have a constant...

What is the difference between coherent light and polarized light?

I want to know the projective Hilbert space of coherent state and squeezed state.Thank you very much!

Homework Statement Given that a^+|n\rangle=\sqrt{n+1}|n+1\rangle a|n\rangle=\sqrt{n}|n-1\rangle and that the other eigenstates |n> are given by |n\rangle=\frac{(a^+)^n}{\sqrt{n!}}|0\rangle where |0> is the lowest eigenstate. Define for each complex number z the coherent state...

By coherent photons, I mean ones that are in phase (like what comes out of a laser). I would guess that they can be no closer than the size of the atom that emitted them. If adjacent atoms simultaneously emitted photons, that would give the minimum separation. For the photons to be any closer...

Homework Statement Show that, for all complexe numbers \alpha, a has a unique eigenvector |\alpha\rangle that is nothing else but the coherent state \psi(x)=\frac{e^{-\frac{i}{2\hbar}\langle X\rangle\langle P\rangle}}{(\pi\ell^2)^{1/4}}e^{-\frac{(X-\langle...

This is a very vague question, but I hope by asking it, we can pin down an answer eventually. In optics, there are such things as "Coherent Imaging" and "Incoherent Imaging." From what I understand, the degree of coherence has to do with the size of your Point Spread Function (PSF), a.k.a...

Hey, there is something I don't really understand about the path integral (functional integral) formalism in QFT: Why do you need to introduce a coherent-state representation of the Dirac fields in order to evaluate their path integral? Where is the crucial point why it doesn't work like...

As I understand, it is postulated that only coherent states in LQG correspond to classical spacetimes. Is the ground state of LQG a coherent state? Otherwise, what principle selects that the universe should be in a coherent state?

Hi everyone, I have the following question about coherent states: It is known that the creation operator has no eigenket. However, the action of a creation operator a^{\dagger} on a coherent ket |\alpha\rangle can be written as a^{\dagger}|\alpha\rangle = \left( \frac{\partial}{\partial...

Thank you ZapperZ for introducing these new peer-review papers. This one is of particular interest to me. I believe I may have some insight into this issue. In the normally constructed RC circuits using discrete components, the reactions of the individual components to signal frequency...

Could anyone explain me (or give reference to a book) what is coherent population trapping (in optics). Is it somehow connected with Electromagnetically Induced Transparency (I also don't know how it works). Thanks for any replies.

Hi all, the annihilation operator satisfies the equation \hat{a}|n>=\sqrt{n}|n-1> and \hat{a}|0>=0 so the matrix of \hat{a} should be http://www.tuchuan.com/a/2010020418032158925.jpg and zero is the only eigenvalue of this matrix. The coherent state is defined by...

Hi! I hope this is the right forum. I know how laser works (population inversion, electronic transitions etc...), but I can't understand why the light emitted is coherent

Hi all I read in a book that coherent means when two waves are monochromatic and have a definite phase relationship. What is meant by a definite phase relationship?

Hello, I need to calculate diffraction picture produced by source generating partially coherent illumination. I read Born and Wolf, Goodman and still I do not have complete understanding. Suppose we have source with size d, simple object (let's take opaque rectangle) and detector. According...

does coherent LIGHT waves with a constant phase difference MUST have the same frequency? what about LIGHT waves with the same frequency only? will it be not coherent??

So is this the ability for light waves to add up and subtract interms of interference? But I am confused as to what a non-coherent light sorce would be. I mean is it when the light waves are not organised enough? So there is no effect of interference through diffraction? or is it that there is...

Homework Statement In a classroom demonstration, a beam of coherent light of wavelength 550 nm is incident perpendicularly onto a pair of slits. Each slit has a width w of 1.2 x 10^-6 m, and the distance d between the centers of the slits is 1.8x10^-5 m. The class observes light and dark...

On the wiki page on coherent topology, and more precisely, topological union (aka topology generated by a collection of spaces) (http://en.wikipedia.org/wiki/Coherent_topology#Topological_union), it is said that if the generating spaces {X_i} satisfy the compatibility condition that for each...

Can two independent sources of light be coherent?

Does anyone know why a harmonic potential gives rise to coherent states? In other words, what is special about a quadratic potential that causes the shifted ground state to oscillate like a classical particle without dispersing so as to saturate the uncertainty principle? Any help or insight...

Fourier series vs Integral: just one "coherent" notation? Hi all, notations for Fourier analysis always confuse me. I understand that the "volume" normalization factor can be disposed of either in the definition of the Fourier coefficient or in the definition of the Fourier series (or...

Homework Statement Can someone tell me clearly what are cohernt waves and is it must for every coherent waves to be monochromatic? Homework Equations The Attempt at a Solution

Alright, I'm sure I'm missing something extremely simple, but in Griffiths (and another text I'm reading) coherent states are mentioned as eigenfunctions of the annihilation operator. I just don't understand: a) how you can have an eigenfunction of the annihilation operator (other than |0>) if...

Hi, I've been reading these forums for quite a while and now it seems like a good moment for my first post. I'm doing simple coherent transport calculations in tight-binding approximation. The device Hamiltonian matrix H_D is connected to two ideal leads, characterized by the unit cell lead...

A coherent fiber bundle is very useful in transmitting images. Let's say we have a gaussian beam from a laser as our source. Now the acceptance angle(2*alpha) is determined from the location of the beam waist, right? The light ray will then go down the fiber core with the use of a converging...

A laser beam is split into two beams. After traveling some distance they cross each other's path. I was just wondering this crossing will have any effect on the beam properties or not. More basically, if two coherent beams one heading north and the other heading east cross each other at origin...

Homework Statement I have a task to move a camera attached to a robot arm along the surface of a sphere. The requirments are, * Z axis of the camera coordinate system should always point to the origin of the sphere. * X-Y plane of the camera coordinate system shold be always in the...

I'm trying to interpret a research paper on single photon ionization using extreme UV attosecond laser pulses, and I realized I have some very basic questions concerning electrons in an atom. Technically, the answers to these questions are found online and in the literature, but the wording...

Hi: Is it possible to generate coherent white light? This is sort of like laser light except it gives out all wavelengths of visible light at equal intensities at the same time. Is this possible?Thanks, Radium

What is coherent length? and how it is affected interference

hi, can anyone kindly explain to me what's 'coherent time' and 'duration of wave packet (photon)' in white light interference ?

hi, i really confused about this two term. As i read from a book, ' in the Young's double slits experiment of light, if the time difference (that resulted from the path difference because of the two slits) is longer than the duration of each 'burst' (the photon),the received waves must come...

i've just encountered coherent states while studying the quantum oscillator, and I'm trying to understand some of the semiclassical properties of them. can someone give me a brief description of what they represent in the system and of how they vary in time?

Hello experts, I've had some fun reading the posts in the various forums, and now it's time for me to ask a question. Is it possible to scatter light off of a BCS semiconductor such that the light can be considered to scatter from the coherent state of many Cooper pairs, rather than just...

Coherent state... "Re"? So we're talking about coherent state of harmonic oscillator... and for |psi(x,t)|^2, we came up with an equation... that has a term with "Re" in it. Does anyone know what I'm talking about or should I type up the whole equation? What does the "Re" mean?>?>

How can the same source of monochromatic light produce 2 waves that are incoherent or coherent for that matter? (Is this even a valid question?) What does coherence really mean beyond the definition of "waves that have a constant phase difference" could anyone clarify this? thanks.