Timeline for Does a radio receiver "collapse" a radio wave function?
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| Nov 21, 2022 at 23:27 | comment | added | Jagerber48 | performed. I thought Hanbury-Brown Twiss radio interferometry was an example of a quantum radio wave experiment, but apparently those results can be explained classically. But like I said earlier in this comment, there are experiments using quantum states of microwaves whose detectors are amplitude sensors. | |
| Nov 21, 2022 at 23:25 | comment | added | Jagerber48 | @JohnDoty I admit that my analysis is more geared towards intensity, not amplitude detection. I haven't yet gotten a complete understanding of how to understand amplitude detection in a quantum regime. BUT I will say that in cavity QED experiments using superconducting qubits the states of the microwave field are quantum (i.e. single photons in the cavity at times) and amplitude measurements are made in this regime. For example squeezed states of microwaves have been realized and sense with amplitude detectors. That said, maybe you're right that now quantum radio wave experiment has been | |
| Nov 21, 2022 at 23:00 | comment | added | John Doty | @Jagerber48 But that's not what we see in radio broadcasting. The receivers see an amplitude that reflects the antenna pattern. We don't see a phenomenon like "No term will have detection on two detectors." The receivers don't see quanta: quanta may be present in principle, but they are so thoroughly hidden that there's no way to test the extrapolation of quantum theory to the radio case. No test means no physics. But, of course, the classical theory as applied to radio is extremely well tested. | |
| Nov 21, 2022 at 22:49 | comment | added | Jagerber48 | proportional to the solid angle subtended by the detector and the magnitude of the spatial EM mode at the location of that detector. I'm not saying anything more than this, and I don't think this is that complicated. I'm not suggesting we need to model the electron field in the detector, for example (though that could be done in principle but not in practice). I'm just suggesting that we can better our intuition a little bit by pushing the Heisenberg cut back by one more step than people might usually do. (2/2) | |
| Nov 21, 2022 at 22:47 | comment | added | Jagerber48 | @JohnDoty I'm saying that the field emitted by, say an atom, is a state of the EM field that has spatial structure like a radial outgoing dipole antenna. If we push the Heisenberg cut back a little bit then the this EM field interacts with an array of detectors in a spherical pattern around the emitter. After the interaction, if we push back the Heisenberg cut a little bit, the state of the system will be a superposition state with terms like "no detection" "detection on A" "detection on B" etc. No term will have detection on two detectors. The coefficient for each term will be (1/2) | |
| Nov 21, 2022 at 22:26 | comment | added | John Doty | @Jagerber48 The "physics" where you wave your hands and claim that "in principle the theory is not that complicated" is disconnected from the phenomena. But the phenomena are the subject matter of physics. | |
| Nov 21, 2022 at 17:50 | comment | added | kdtop | @Jagerber48 Thanks. This was a good note. I'm satisfied with this and no separate question needed. | |
| Nov 21, 2022 at 2:42 | comment | added | Jagerber48 | @kdtop I could best answer your follow up question if you posted it as a separate question and link it in these comments. The upshot is the radio wave pictures you see probably describe the radiation through a multipole radiation pattern. This pattern can also be used for the emission of optical EM fields. For example an atom transitioning from $P\rightarrow S$ will emit a photon whose spatial pattern is a spherical dipole pattern, i.e. emitting in both directions. It's true that in many cases we imagine light as a beam with a dominant direction, but there are more general possibilities. | |
| Nov 21, 2022 at 2:38 | comment | added | Jagerber48 | @JohnDoty I agree that there is a version of "fields only" that would be intractable of modern computation devices. Nonetheless, in principle the theory is not that complicated. It's not much more complicated than the detection of classical waves. I guess my main point is that just because a detector click is localized in space and time doesn't mean we need to interpret photons as "particles". Rather clicks are localized interactions between a delocalized field mode and a localized detector. See arxiv.org/abs/1204.4616 for more info. | |
| Nov 20, 2022 at 22:26 | comment | added | John Doty | @kdtop Electromagnetic waves can be broadcast. If you're detecting them as photons, the photons show up at particular places. | |
| Nov 20, 2022 at 22:20 | comment | added | kdtop | Follow up question: It seems that photons are shown as packets WITH DIRECTIONALITY -- i.e. a photon might be traveling in the direction of Jupiter OR towards Venus. But radio waves seem to be described as traveling BOTH ways. How does QFT handle this? | |
| Nov 20, 2022 at 22:17 | comment | added | kdtop | @Jagerber48 I loved everything about your post -- except the Many Worlds stuff which seems to me to be a non-falsifiable theory outside the realm of actual science. I agree with your rant about photons, but I think not all do. John Doty makes a good point that at the end of the day there will be just one spot that lights up on a photo detector. It seems that at that point it is acting like something localized. The points you two make after that went over my head. :-) | |
| Nov 20, 2022 at 22:12 | vote | accept | kdtop | ||
| Nov 20, 2022 at 20:19 | comment | added | John Doty | Really? Do you know how hard it is to do this in the accurately in the particle picture? GEANT is quite a large code. The wave picture informs certain low-level parts, but overall, to do a fully entangled wave model is beyond computation. | |
| Nov 20, 2022 at 20:11 | comment | added | Jagerber48 | @JohnDoty The detectors have nonlinear interactions with the EM field. You can calculate the probability that the interaction activates the detector above a certain threshold and you’ll get the same predictions as the “particle” picture just with a non particle interpretation. | |
| Nov 20, 2022 at 19:59 | comment | added | John Doty | Electromagnetic energy incident on a photoelectric detector behaves like particles. That's a real phenomenon. That's what we base our models on. You can wave your hands and insist that it's just waves, but to capture particle phenomena that way is a prohibitively complicated approach in practice. | |
| Nov 20, 2022 at 17:58 | history | answered | Jagerber48 | CC BY-SA 4.0 |