I enjoyed your explanation about the quantum simulations detailing the photon behaviors. All the best Maria.

@maria_violaris

6 ай бұрын

Thanks!

Another great video! Really like the 3D glasses analogy. Thanks for sharing.

@maria_violaris

6 ай бұрын

Thanks! Glad you like the analogy 😄

I like your presentation; however, that is not actually what is known as the "delayed-choice quantum eraser" experiment, although you do present an "eraser" and you "delay" the measurement in your circuit (assuming that the time uncertainty is small enough to allow that). In the actual experiment, both, an interference and non-interference pattern, are "decided" by the quantum system itself, not by the researcher. In the actual experiment, the researcher changes the angle between two pieces of equipment to show that those patterns take place regardless of the relative position. On the other hand, I do agree that your particular setup can be interpreted in terms of "instructions" that can be set at the start even if both measurements are performed at space-like separated locations later on, even if both are not simultaneous. Certainly the same could be said about the "delayed-choice quantum eraser" experiment but it is more complicated. A more simple way to explain that the "delayed-choice quantum eraser experiment" does not imply retrocausality is just to say that measuring correlation of events does not imply causality. If you really want to call your experiment the "delayed-choice quantum eraser", then you might as well call a Bell-type experiment a "delayed-choice quantum eraser" experiment: try to explain violation of Bell-type inequalities even if there is a "delay" in one measurement. In this case, it is not as easy to explain any "erasure" of information after a "delayed-choice" by thinking in terms of "instructions" that can be set at the start of the experiment....

How is it practically possible to create a device, and a detector, that emits and detects only single photons? How can one be sure that a only a single photon is actually detected? How are these double-split experiments really done so that one can be sure that the quantum effects are actually effects of a single particle and not something that occurs because the experiment is "polluted" by more photons? I am really interested in the fundamental aspects of the wave / particle duality, but even though I understand the basic theoretical principles (and mathematics) I find it hard to see how it's actually translated into a rigid experiment that fully demonstrates these fundamental theoretical properties. I guess I have a hard time understanding why we need to view a photon as a point-like particle in the first place, instead of just saying it never is a point moving in space, but rather a fuzzy wave packet that always exhibit these interference patterns when the interference is not ruined by decoherence with the environment (such as a detector).

@maria_violaris

6 ай бұрын

Thanks for the questions! For the first point about experimental single-photon sources and detectors: creating these is technologically challenging, but possible and has been done, so there's now various different ways of creating devices to emit and to detect single photons. One example method of creating single photons uses "spontaneous parametric down conversion": we direct a beam of high-energy photons at a specialised crystal, and then a spontaneous process in the crystal causes it to emit a pair of lower-energy photons. Only a small number of photons in the high-energy beam are converted into low-energy pairs, so the output photons get emitted one pair at a time. Detecting one photon from the pair signals the presence of the other photon, which you can then use for single-photon experiments. For the second point: I indeed don't think that we need to view a photon as a "point-like particle" (though that may be a reasonable approximation for some contexts). Understanding decoherence removes the need to imagine the photon as somehow "flipping between being a wave or a particle depending on whether we are watching or not", as we can explain both behaviours in one go using the photon's wave-function and ability to become entangled. It's also worth mentioning: to really understand the physical nature of a photon, we need "quantum field theory" (QFT), which shows us that "particles" are all stable configurations (excitations) of an underlying quantum field. A photon is an excitation of the quantum electromagnetic field. For more on this theme, I recommend Vlatko Vedral's blog post and paper entitled "The Everything-is-a-Quantum-Wave Interpretation of Quantum Physics", both are accessible online.

@realdarthplagueis

6 ай бұрын

@@maria_violaris Thanks for your answer!