It is very well known that in QFT the particles are excitations of the field. But how exactly is a free photon looking like in spacetime? What is it shape in free space? And what is in fact in the excited area? I will not post suggestions. Just wanna read how physicists imagine it.
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$\begingroup$ It looks like an electromagnetic wave $\endgroup$– By SymmetryCommented Apr 9 at 14:33
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$\begingroup$ QFT is relativistic QM, in that sense photons in QFT inherit the particle-wave duality view from QM. $\endgroup$– Lucky CharmsCommented Apr 9 at 15:14
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$\begingroup$ Do you mean a photon on the visible spectrum or to either side of it? $\endgroup$– WookieCommented Apr 9 at 15:40
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$\begingroup$ A photon is the electromagnetic field you're used to. If you add more photons, the field strength increases. The field strength is uncertain, because the number of photons in a location is uncertain. In the limit of large $N$, the uncertainty decreases and you get classis electric/magnetic fields. $\endgroup$– AccidentalTaylorExpansionCommented Apr 9 at 16:01
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$\begingroup$ @AccidentalTaylorExpansion Photon in QFT is excitaton of the EM field which is basic element of reality. The classical EM is a huge collection of many coherent photons. So a photon can not the classical field. Rather the opposite. $\endgroup$– MercuryCommented Apr 9 at 17:22
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