Duda Jarek
Senior Members
Posts
533 
Joined

Last visited
Content Type
Profiles
Forums
Calendar
Everything posted by Duda Jarek

What is the size and shape of single optical photon?
Duda Jarek replied to Duda Jarek's topic in Physics
You write "Different experiments give different results", so I ask for elaboration, but instead of giving any example you write further "You should be able to evaluate some basic QM experiments."  which ones? Like creationists claiming "many examples" which cannot be explained by evolution, asking for example they give e.g. eye ... https://en.wikipedia.org/wiki/Evolution_of_the_eye Size of photon makes sense also in QM: e.g. as width of wavepacket, as uncertainty of quantum position operator, through adding terms in WKB approximation etc. Please be more specific. 
What is the size and shape of single optical photon?
Duda Jarek replied to Duda Jarek's topic in Physics
Great, so please elaborate which experiments you are referring to, and let us try to understand/discuss differences between their evaluations. 
What is the size and shape of single optical photon?
Duda Jarek replied to Duda Jarek's topic in Physics
From one side, can we directly measure processes inside a star? Rather not, but does it prevent us from searching for models of what actually happens there? Also rather not: we can build selfconsistent models based on general knowledge, and tune details of what we don't know to get agreement with measurements of indirect consequences. Similarly with microscopic physics  for which human observer is just a system of atoms governed by the same objective physics  on which we should focus on, like some properties of EM wave created by single atom deexication: optical photon. From the other side, while QM might be the final description, it is built on classical mechanics: as Feynman ensemble, through quantization etc. And we directly experience classical mechanics  emerging from the quantum one, also being its approximation  e.g. the initial one in WKB semiclassical approximation ( https://en.wikipedia.org/wiki/WKB_approximation ). If there are technical difficulties with complete quantum description of shape/size of optical photon, a natural approach is starting with approximations: like classical, semiclassical  you are welcomed to extend to complete quantum description (or complement the set of articles). Feynman diagrams are in another approximation: perturbative of QFT in momentum space. Their Dirac deltas in momentum space mean infinite size plane wave. To model finite size in position and momentum space there are e.g. used wavepackets ( https://en.wikipedia.org/wiki/Wave_packet ) : of bounded product of widths in position and momentum space in Heisenberg principle/Fourier transform. The question of size of single photon is e.g. about such width of wavepacket in position space. Even better would be experimental arguments I am especially asking for  like this minimal duration of ultrashort laser pulses. 
What is the size and shape of single optical photon?
Duda Jarek replied to Duda Jarek's topic in Physics
The question is size in whatever view you want, like distortion of quantum position operator e.g. E[(xE[x])^2]. I have posted at least 3 papers trying to do it from classical or semiclassical approximation of quantum mechanics, also started with and mostly ask for experimental suggestions. Instead, as for creationists, there is no discussion, only some nonsense excesses that we cannot even ask such holy/quantum questions. Being Dirac delta in standard Feynman diagrams: in momentum space, doesn't mean being perfect point but a plane wave: filling entire Universe. 
What is the size and shape of single optical photon?
Duda Jarek replied to Duda Jarek's topic in Physics
But quantum mechanics is built on the classical one, e.g. through the quantization procedure. Classically we have single trajectory (or history of field) optimizing action, to take it to QM we e.g. take Feynman ensemble of such trajectories (field histories) instead (allowing to derive classical as approximation). In QM we have e.g. wavepackets  isn't single optical photon such a wavepacket? Photon is EM field  we should be able to say anything concrete about this EM field configuration/evolution  as wavepacket, or as quantum ensemble, or through distortion of position operator etc. Otherwise it is very similar to creationism: just blindly repeating "God created"/"It is quantum" as universal answer supposed to resolve every question. 
What is the size and shape of single optical photon?
Duda Jarek replied to Duda Jarek's topic in Physics
"The size and shape of single photon" http://dx.doi.org/10.4236/oalib.1107179 has nice looking models of photon: The big question is how true they are??? Sadly, while many claim that physics is nearly solved, we know nearly nothing about such basic questions like EM field configuration and dynamics of photon (wavepacket) ... 
What is the size and shape of single optical photon?
Duda Jarek replied to Duda Jarek's topic in Physics
As written e.g. E[(xE[x])^2]  expected value of squared distance from the center of such wavepacket ... just any estimation of size photon, preferably experimental  e.g. minimal duration of laser pulse, weakening transmission through very narrow hole etc. 
What is the size and shape of single optical photon?
Duda Jarek replied to Duda Jarek's topic in Physics
In quantum mechanics we have wavepackets  why shape of wavepacket from production of single photon is meaningless? Size is e.g. mean deviation from the center of particle (E[(xE[x])^2] in position space) for its energy density. 
What is the size and shape of single optical photon?
Duda Jarek replied to Duda Jarek's topic in Physics
Many nonlinear optics effect kind of split photons e.g. SPDC: https://en.wikipedia.org/wiki/Spontaneous_parametric_downconversion Regarding absorption of half of photon, I would say that it happens e.g. in spin echo: photon rotates spin by pi, here they are rotated by pi/2: https://en.wikipedia.org/wiki/Electron_paramagnetic_resonance#Pulsed_electron_paramagnetic_resonance SergUpstart, quatnum physics is built on classical e.g. through quantization, Feynman ensembles of classical scenarios. So we can ask what are dimensions of energy density of photons averaged over such ensemble. 
What is the size and shape of single optical photon?
Duda Jarek replied to Duda Jarek's topic in Physics
EM field as consequence of electron dynamics travels with speed of light: ~0.3 nm per attosecond. Here is some paper trying to model emission of photon from hydrogen: https://link.springer.com/chapter/10.1007/0306480522_20 
What is the size and shape of single optical photon?
Duda Jarek replied to Duda Jarek's topic in Physics
Sure such photon dynamics is extremely complex, but it doesn't mean we should just neglect this fundamental problem of understanding physics. For example while naively quantum processes are instant, reaching such measurement possibility, turns out e.g. that photoemission takes a few dozens of attoseconds: https://science.sciencemag.org/content/328/5986/1658  there is some concrete hidden electron dynamics leading to EM field wave of the photon, we should at least try to understand. The ellipsoid view is probably only an approximation of energy density shape, to understand e.g. MachZehnder there should be also some pilot/theta wave flying the second path, like from http://redshift.vif.com/JournalFiles/V16NO2PDF/V16N2CRO.pdf : 
What is the size and shape of single optical photon?
Duda Jarek replied to Duda Jarek's topic in Physics
I have just found another  2021 with more sophisticated models: "The size and shape of single photon" http://dx.doi.org/10.4236/oalib.1107179 Sure, these might be just the beginnings ... but asking for EM field configuration of photons is valid question, also from quantum perspective: as Feynman ensemble of classical ones  we can ask for e.g. dimensions averaged over such ensemble. 
What is the size and shape of single optical photon?
Duda Jarek replied to Duda Jarek's topic in Physics
The basic difference between classical mechanics and quantum, is that in the former we have single trajectory optimizing action, while in the latter we have Feynman ensemble of trajectories, fields etc. So the question can be seen: what is mean size of such photon's energy density  averaged over quantum ensemble. QM cannot be used to completely neglect such a basic question of physics, and we have also experimental arguments like quoted above. 
What is the size and shape of single optical photon?
Duda Jarek replied to Duda Jarek's topic in Physics
"Detecting" by who, what? This is very subjective question, while I am asking for objective EM field configuration  telling anything concrete about it. While this is a difficult question, there are at least these two articles, most importantly  providing experimental arguments (quoted in post above). What do you think about them? 
What is the size and shape of single optical photon?
Duda Jarek replied to Duda Jarek's topic in Physics
Photon is EM field, the basic question is energy density distribution of EM field for single photon  some rho ~ E^2 + B^2 ( https://en.wikipedia.org/wiki/Electric_field#Energy_in_the_electric_field ). Can we say anything concrete about this energy distribution, preferably based on experimental arguments like mentioned above? Ps. Paper by different author: https://arxiv.org/pdf/1604.03869 
Optical photon is produced e.g. during deexcitation of atom, carrying energy, momentum and angular momentum difference. So how is this energy distributed in space  what is the shape and size of single photon? Looking for literature, I have found started by Geoffrey Hunter, here is one of articles: "Einstein’s Photon Concept Quantified by the Bohr Model of the Photon" https://arxiv.org/pdf/quantph/0506231.pdf Most importantly, he claims that such single optical photon has shape similar to elongated ellipsoid of length being wavelength λ, and diameter λ/π (?), providing reasonably looking arguments: Is it the proper answer? Are there other reasonable answers, experimental arguments?

The 1D transverse field Ising model is usually solved in quantum way, but we can also solve it classically  parametrize angles of spins and use Boltzmann ensemble of sequences of spin angles: Pr(σ)∝exp(−H(σ)) for σ=((cos(αi),sin(αi)))i∈Z getting Markov process of angles, which can be easily approximated with Maximal Entropy Random Walk, for example getting below joint distributions for (αi, αi+1) for various parameters (Section III here ) : As intuition suggests, there is some thermal wobbling of spin directions: (anti)aligned for dominating J, in x axis for dominating h. However, in quantum approaches there are only considered spins in four directions, so should we imagine that intermediate angles are obtained by superposition? Should there be thermal wobbling of spin directions as in densities above? What are the differences in interpretation and predictions between such looking natural classical treatment and the quantum one?

Ok, I have finally looked closer (paper: https://link.springer.com/article/10.1140%2Fepjc%2Fs1005201859186 ). So basically they believe that B mesons should decay symmetrically to electrons and muons, but they observe slight asymmetry: ~15% more to electrons with 3.1 sigma (~1/1000). Mesons is huge family: https://en.wikipedia.org/wiki/List_of_mesons Beside kaons (~500Mev), we mainly know pions: charged have ~140Mev, ~10^8s lifetime, mainly decay to muon + neutrino ... but also have rare decay to electron + neutrino ( https://en.wikipedia.org/wiki/Pion#Charged_pion_decays ). B mesons ( https://en.wikipedia.org/wiki/B_meson ) have ~5GeVs ... while pions have very asymmetric decay into leptons, I have to admit that I don't understand why slight asymmetry for other mesons is surprising (?) Anyway, in discussed "biaxial nematic perspective", mesons nicely fit fluxons forming loop with additional internal twist (corresponding to strangeness), maybe hopfion (diagram below from https://en.wikipedia.org/wiki/Hopf_fibration ). The three types/quarks are from performing such loop along one of 3 axes of biaxial nematic. Mesons are configurations being local energy minima  their asymmetry of decay into various leptons is completely unsurprising.

studiot, thanks, probably as usual it is matter of adding/modifying terms to Lagrangian  in practice used in perturbative approximation, literally adding terms to Taylor expansion. But this is description not understanding, neglecting basic questions like of field configuration behind given Feynman diagram, mean energy of fields in given distance from electron etc. Or renormalization literally subtracts infinite energy by hand  where exactly it subtracts it? Shouldn't it in fact subtract some energy density  from e.g. energy density of electric field, to make it integrate to finite energy. Search for deeper models  effectively described by something close to Standard Model, is just no longer ignoring such basic questions. Like of regularized EM field around electron  including renormalization procedure, this way integrating to finite energy. Or explaining basic properties of physics  instead of inserting them by hand, e.g.:  Why electric charge is quantizatized? In liquid crystal experiments: because it is topological charge.  Why we have 3 leptons? In biaxal nematic view: because we have 3 spatial directions.  Why leptons also need magnetic dipole. ... because of hairy ball theorem.  Why proton is lighter than neutron? ... because baryons require charge, which in neutron needs to be compensated.  How nuclei overcome Coulomb repulsion? ... by being bind with fluxons.

There are more longrange interactions for liquid crystals, e.g.: dipoledipole: "Novel Colloidal Interactions in Anisotropic Fluids" https://science.sciencemag.org/content/275/5307/1770 Coulomb (!): "Coulomblike interaction in nematic emulsions induced by external torques exerted on the colloids" https://journals.aps.org/pre/abstract/10.1103/PhysRevE.76.011707 Skyrme models are for strong interaction ... so why can't we model all? These liquid crystal systems are for uniaxial nematic  one distinguished axis everywhere ... bringing a question about natural generalization: biaxial nematic: 3 distinguished axes in 3D (4 in spacetime adds gravity)  giving particlelike configurations resembling 3 leptons, neutrinos, baryons, nuclei ...

I can respond tomorrow, but in sineGordon the field can be interpreted as of phases of these penulums in lattice  with minimum of gravitational potential every 2pi. For Couder and other hydrodynamical QM analogues (Casimir, AharonovBohm etc.), here are gathered materials: https://www.dropbox.com/s/kxvvhj0cnl1iqxr/Couder.pdf

Energy density, Hamiltonian is a first step  convenient to start with as all the terms have positive conteibutions. It is often timespace symmetric  not distinguish time and space directions. But for solving such model we indeed usually go through the Legendre transform to Lagrangian  both for the least action formulation, and the EulerLagrange equation. I have tried to go this way for the biaxial nematic with Coulomb interaction, but it was too tough for me. Hamiltonian alone can be used to find static solutions, like this kink in sineGordon as minimal energy transition between two vacua. However, electron should be finally a dynamical solution  with this zitterbewegung, de Broglie clock ~10^21 Hz oscillations, confirmed experimentally: https://link.springer.com/article/10.1007/s1070100892251q

Let me bring back my two responses, both are crucial for the model: The number of found particles is in hundreds/thousands now. Some are virtual, like 80GeV boson W in beta decay of 1GeV neutron  this mass should be rather imagined as only shape of energy dependence like for https://en.wikipedia.org/wiki/Effective_mass_(solidstate_physics) What we should target (as configurations being local energy minima) are especially more stable particles and their decay modes e.g. from https://en.wikipedia.org/wiki/List_of_baryons ... and a general behavior in this table is decay with pion or kaon to baryon with lower strangeness. As discussed, there are many reasons to imagine baryons in this biaxial nematic perspective as loop of one vortex around another vortex. We have three types of vortices, allowing for quarklike interpretations. Possible complication of such simplest knot is additional internal twist of its vortex loop around  it should be obtainable in high energy collisions, and should relax by releasing part of this twist as particle  pion, kaon (bottom of diagram below) ... getting nice agreement if interpreting the number of internal twists as strangeness. There are considered strageness 4 baryons (e.g. https://arxiv.org/abs/2011.05510 ). The space of local minima of configuration space can be quite complex: 3 types of vortices, they can contain charge (e.g. hedgehog), additional twist for loop around  can lead to hundreds of metastable states for baryons. In these models we have energy density (Hamiltonian, can be translated to Lagrangian)  usually with some spatial derivatives like stress, temporal for kinetic behavior, and potential (e.g. Higgslike) ... integrating energy density we get mass of particle, usually scaling as in SR thanks to Lorentz invariance. Unfortunately it is quite tough calculation, I have attached for kink of sineGordon a few posts ago. We can parametrize with positions of ansatz configurations like hedgehog, Lorentz transformed for velocities, getting classical mechanics approximations ... with kinetic energy going into mass exactly as in special relativity. Fluxons are quite complex. While they are usually studied in superconductors/superfluids, here they are also needed in vacuum, e.g. to bind nucleus against Coulomb repulsion. Probably the best experimental argument are "magnetic flux tubes"  nearly 1D shining structures seen in Sun's corona, they carry energy density per length  which can be released while shortening in https://en.wikipedia.org/wiki/Magnetic_reconnection Quote from "Physics of Magnetic Flux Tubes" by Ryutova: "Vortices in superﬂuid Helium and superconductors, magnetic ﬂux tubes in solar atmosphere and space, ﬁlamentation process in biology and chemistry have probably a common ground, which is to be yet established. One conclusion can be made for sure: formation of ﬁlamentary structures in nature is energetically favorable and fundamental process. "

studiot, I had long fluxon response, response about baryons and strangeness  both disappeared. This sineGordon kink represents solution minimizing energy e.g. in lattice of pendulums: of phases while twisting by pi. But this is the most basic model  you can find it in hundreds of books and papers  please start with looking closer at external sources.