Questions tagged [coherence]
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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Coupling a single mode laser to multimode fibre - does this reduce coherance?
If I have a single mode laser coupled to a multimode fibre with imperfect overlap between the laser mode and the fibre core, the light will propagate in several LP modes.
In this case, does the light ...
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Loss of coherence in the double-slit experiment
Let's suppose we perform the double-slit experiment, using two detectors to detect which slit the particle has passed through. I describe the detectors using quantum mechanics, so they are represented ...
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Are temporal coherence (for classical EM waves) and quantum coherence related concepts?
For my wave optics class, I was taught that the temporal coherence of a light source is the average time interval for which the phase of that light is predictable, after which the source will undergo ...
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Why is a monochromatic wave temporally coherent for all time delays $\tau$?
I've been learning about coherence of waves and the Wikipedia page on says a monochromatic electromagnetic plane wave is coherent because:
A wave containing only a single frequency (monochromatic) is ...
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Significance of the phase of the condensate as compared to that of the regular Fermi sea in the Anderson-Higgs mechanism
I do not fully understand how the phase of the charged Cooper pair condensate is different from the phase of e.g. the Fermi liquid in a regular metal.
The state of the metal (any quantum state really) ...
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When to add signals coherently and incoherently?
I just learned in transmission electron microscopy about coherent and incoherent summation. I can't seem to wrap my head around the fact that intensities can be added incoherently. Why can you do that?...
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Spontaneous emission and coherence
Assume I prepare a linear superposition $\frac{1}{\sqrt{2}}(|g \rangle+|e\rangle)$ between a ground and excited level for a large number of "atoms" (it can by any multilevel system, not ...
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Relation between a diagonal element of a density matrix and the off-diagonal elements in the same row/column [duplicate]
In a density matrix $\rho=(\rho_{ij})$, the diagonal elements $\rho_{jj}$ contains the information about the probability $|\rho_{jj}|^2$ that the $j$-th eigenstate is occupied by the system. Meanwhile,...
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Quantum Coherence [closed]
Coherence is a term frequently used in quantum mechanics. However, I struggle to get the bigger picture. In fact, it seems like some definitions contradict each other. Could someone provide a basic ...
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Necessity of Coherence for Interference in the Context of Indistinguishable Photon Paths
I've been studying the interference phenomena observed in the double-slit experiment and came across a concept that piqued my interest. It is well understood that for interference patterns to form, ...
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Transition from Coherent to Incoherent Light / Partially coherent Light for Imaging
I want to know how to model partially coherent/incoherent light for imaging applications.
Usually, you find mathematical treatments of imaging just for the extreme cases.
For the coherent light, there ...
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Is it possible to model unidirectional evolution of an atom-photon system using the Schrodinger equation?
The physical system I'm imagining is pretty simple: suppose there's an atom in free space with three states $|g_0\rangle, |g_1\rangle, |e\rangle$ initialized to some superposition of $|g_0\rangle$ and ...
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Why do light bulbs don't produce coherent waves? [duplicate]
My textbook says that light ways produced by light bulbs are not coherent but it doesn't describe the reason.
I was wondering how could two waves not be coherent regardless of the source they are ...
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How to understand the spatial coherence of light?
Can I understand spatial coherence in the following way (I'm not sure if it's correct)?
As shown in the diagram:
Each wavefront or wave surface on the left is irregular, so it is spatially incoherent.
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How monochromatic waves can be incoherent?
Is it possible to have a monochromatic wave which is incoherent? On the one hand, it could be obtained by irradiating a laser beam on a strongly scattering medium like white paper. But on the other ...
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