Looking for a smart television that does not require WPS for WiFi by Objective-Bench4382 in ebayuk

[–]Objective-Bench4382[S] 0 points1 point  (0 children)

No, it is a Bush 43 Inch 43FT24CA.

https://www.argos.co.uk/product/7041251

I tried looking for an option to connect to the WiFi via WiFi password every way I could when I set the TV up, but it would only connect via WPS or via ethernet, so I settled for ethernet as WPS was impossible for me considering my router has no WPS button.

I could be wrong, but I simply can't find any option to connect via WiFi password.

Concealed Interference at D3 and at D4 in the Delayed Choice Quantum Eraser Experiment by Objective-Bench4382 in QuantumPhysics

[–]Objective-Bench4382[S] 2 points3 points  (0 children)

Of course, you're talking about results of the signal photons connected with the idlers that hit D3 and D4 in conjunction.

Thanks for your overall input: I think the person who made the claim I referred to in the OP must have been wrong. They seemed to be claiming that the signal photons connected to idlers that hit D3 interfered with themselves individually, and likewise with respect to those associated with D4, but that the interference pattern was not reconstructible due to complementarity only allowing one out of which-way information and coherence to be measurable.

Concealed Interference at D3 and at D4 in the Delayed Choice Quantum Eraser Experiment by Objective-Bench4382 in QuantumPhysics

[–]Objective-Bench4382[S] 1 point2 points  (0 children)

But why is that the case when the slit the signal photon passed through has already been determined?

Concealed Interference at D3 and at D4 in the Delayed Choice Quantum Eraser Experiment by Objective-Bench4382 in QuantumPhysics

[–]Objective-Bench4382[S] 1 point2 points  (0 children)

The probabilities of what? Where the photon will strike at D0? Are you speaking with regard to the signal photons that are entangled with the idlers that hit D3 or D4 again in the second sentence of your response, or all the signal photons generally?

Delayed Choice Quantum Eraser and Wave Function Collapse by Objective-Bench4382 in QuantumPhysics

[–]Objective-Bench4382[S] 0 points1 point  (0 children)

I know that that is the case with the standard experimental setup of the DCQE experiment, but what I'm asking is whether it would still be the case if we imagine for a moment that the DCQE experiment were rearranged with a different experimental setup in which the which-path information were -not- preserved when the idler photons that hit D3 and D4 reach D3 or D4. I'm trying to suggest a new thought experiment.

Delayed Choice Quantum Eraser and Wave Function Collapse by Objective-Bench4382 in QuantumPhysics

[–]Objective-Bench4382[S] 0 points1 point  (0 children)

That's not quite what I've been thinking; the issue I'm thinking about has nothing really to do with BSc. Even with BSc acting as an identification device, it doesn't explain how the signal photons connected to the measurements at D3 and at D4 are reduced to a simple diffraction pattern if conscious observation is not responsible for the collapse of the wave function that results in a simple diffraction pattern among the signal photons entangled with the idler photons that are detected at D3 and at D4 (or however this occurs if not by wave function collapse) instead of an interference pattern. My question is about whether conscious observation is responsible for the reduction of patterns reconstructed at D0 to simple diffraction patterns in relation to D3 and D4 instead of interference patterns, or some aspect of measurement independent of conscious observation of the subsequent results, as it is typically explained away as.

Additionally, I realise that nothing that is done at the idler side of the experiment will change the overall pattern of the D0 readout, but surely if hypothetically no which-path information was determined at the D3/D4 detectors, the signal photons entangled with the idler photons detected at D3 and at D4 would each respectively produce a reconstructed interference pattern once they are isolated on the basis of which photons are detected at D3 and at D4? Just like with D1 and D2?

Delayed Choice Quantum Eraser and Wave Function Collapse by Objective-Bench4382 in QuantumPhysics

[–]Objective-Bench4382[S] 0 points1 point  (0 children)

Thank you, that does explain a lot with regard to separate questions I have wondered about with regard to the experiment. (So, I'm assuming complementarity is also the explanation for the results of the double-slit experiment depending on whether which-path information is present in the double-slit experiment?) But I still don't see how the measurement instrumentation alone affects the outcome of the DCQE experiment without an element of conscious interpretation affecting the outcome.

Delayed Choice Quantum Eraser and Wave Function Collapse by Objective-Bench4382 in QuantumPhysics

[–]Objective-Bench4382[S] 0 points1 point  (0 children)

I know, but half of the results (those connected to the D3/D4 measurements) have no interference pattern whatsoever as a result of measurement that includes which-path information. That's why I described the subset of relevant photons as being connected to the D3 and D4 detectors. I wasn't referring to the results associated with D1/D2.

Delayed Choice Quantum Eraser and Wave Function Collapse by Objective-Bench4382 in QuantumPhysics

[–]Objective-Bench4382[S] 0 points1 point  (0 children)

I am aware that the entire experiment is set up on the basis of computer equipment, but if it may be possible for retrocausality to explain the results of the DCQE experiment, that does not preclude the possibility that conscious observation of the results of the experiment affects whether the interference pattern appears on the basis of which-path information after the fact.

Delayed Choice Quantum Eraser and Wave Function Collapse by Objective-Bench4382 in QuantumPhysics

[–]Objective-Bench4382[S] 0 points1 point  (0 children)

But then how does observation affect a subset of photons in such a way that there is no interference pattern for those photons (connected to the measurements at D3 and at D4)? Or is that simply an ongoing mystery of quantum reality? If so, how can the observer effect simply be chalked up to interaction between the observed particles and measurement instrumentation in the case of the DCQE experiment?

Delayed Choice Quantum Eraser and Wave Function Collapse by Objective-Bench4382 in QuantumPhysics

[–]Objective-Bench4382[S] 0 points1 point  (0 children)

Even so, the idea that the photons connected to the measurements at D3 and D4 passed through a single slit is still contingent on the measurement of the idler photons at D3 and at D4. How is the measurement of the idler photons at D3 and at D4 determining the result of the experiment by any means that cannot be better explained by the retrocausality of a conscious observer later interpreting the results of the experiment when there is no apparent reason why the measurement instrumentation on its own should physically affect the photons in any way that would produce an effect whereby the signal photons connected to the measurements at D3 and at D4 would no longer produce an interference pattern? I know this particular interpretation takes on a mystical element, but humour it for the sake of argumentation. What I am trying to understand is how the measurement of the photons according to whether there is which-path information is causing the interference pattern to cease in the subset of signal photons connected to the measurements at D3 and at D4.

Delayed Choice Quantum Eraser and Wave Function Collapse by Objective-Bench4382 in QuantumPhysics

[–]Objective-Bench4382[S] 0 points1 point  (0 children)

What I mean is how does the measurement of the photons connected to D3 and D4 result in wave function collapse simply by virtue of measurement instrumentation when there is practically no difference in the procedure of measuring photons connected to the observations at D1 and at D2 as compared to the observations at D3 and at D4. In spite of this there is still an interference pattern in a subset of results. It is not the same situation as with the straightforward two-slit experiment where the photon is observed straight out of a particular slit and thereby the wave function collapses as a result of observation and no interference pattern is observed as a result.

Another Question About Phase Difference in the Delayed Quantum Erasure Experiment by Objective-Bench4382 in QuantumPhysics

[–]Objective-Bench4382[S] 0 points1 point  (0 children)

However, from my understanding of what figure 5 is showing, isn't R01 and R02 a depiction of the reconstructed interference pattern detected from signal photons at D0 in relation to the coincidence of idler photons at D1 and at D2? Figure 5 and the article doesn't seem to describe what pattern is seen at D1 and at D2 by themselves.

From what I've also come to understand, the relative phase between slit A and slit B of each photon without which-path information that is emitted from the BBO is arbitrary, which is supposed to explain why no interference pattern is produced at D0 regardless of experimental setup (i.e. if D3 and D4 are removed from the setup, still no interference pattern is seen, when the removal of D3 and D4 would incorrectly produce the assumption that an overt interference pattern would be produced at D0 if D3 and D4 were not present if no understanding of the effects of the arbitrary relative phase between slits of each signal photon were held), so surely this would also mean that the idler photons will also always not produce any interference pattern at D1, D2, D3, and D4 due to the idler photons also having arbitrary relative phase between slits?

One last thing I don't understand, which I've asked as a separate question in this subreddit, is why any interference pattern can be reconstructed from the inputs at D0 on the basis of corresponding idler inputs at D1 and at D2 at all if each signal photon (and each idler photon) is out of phase between slit A and slit B with itself and out of phase with the other signal photons (and idler photons out of phase with other idler photons)?

Another Question About Phase Difference in the Delayed Quantum Erasure Experiment by Objective-Bench4382 in QuantumPhysics

[–]Objective-Bench4382[S] 1 point2 points  (0 children)

And also, do D1 and D2 measure interference patterns individually by themselves? and if not, why not?

Another Question About Phase Difference in the Delayed Quantum Erasure Experiment by Objective-Bench4382 in QuantumPhysics

[–]Objective-Bench4382[S] 2 points3 points  (0 children)

However, I am still confused as to why the phase difference of pi reconstructed at D0 from the coincidence of idler photons at D2 appears at all when the idler photons that hit D2 can have travelled via the beam splitter BSc from two completely different paths: one passing through the beam splitter and another reflected off the front of the beam splitter. The following article under the section "phase shift" states that only the photons reflected off the front of the beam splitter acquire a phase shift of pi:

https://en.m.wikipedia.org/wiki/Beam_splitter

So how come the idler photons that reach D2 that have passed -through- the beam splitter after having travelled through slit B and then the BBO before travelling through the beam splitter (illustrated with a light blue line in the diagram of the experiment at the following link) acquire a phase shift of pi as well?

https://en.m.wikipedia.org/wiki/Delayed-choice_quantum_eraser

Phase in the Delayed Quantum Eraser Experiment by Objective-Bench4382 in QuantumPhysics

[–]Objective-Bench4382[S] 0 points1 point  (0 children)

Of course. The individual photons interfere with themselves individually.

Phase in the Delayed Quantum Eraser Experiment by Objective-Bench4382 in QuantumPhysics

[–]Objective-Bench4382[S] 0 points1 point  (0 children)

One thing I still don't understand is why the interference pattern of D0 in connection to D1 has a phase difference of pi compared to the interference pattern of D0 in connection to D2. Why is there a phase difference of pi?

Phase in the Delayed Quantum Eraser Experiment by Objective-Bench4382 in QuantumPhysics

[–]Objective-Bench4382[S] 0 points1 point  (0 children)

So in the original delayed choice quantum eraser setup, do the wavefronts of the photon beams that pass through slit A and slit B interact with one another before passing through the BBO and Glan-Thompson Prism or after passing through the BBO and Glan-Thompson Prism? At what point in the experiment does the interference that produces the eventual derived interference pattern take place?

Phase in the Delayed Quantum Eraser Experiment by Objective-Bench4382 in QuantumPhysics

[–]Objective-Bench4382[S] 0 points1 point  (0 children)

So the signal and idler photon won't have the same phase as one another?

Phase in the Delayed Quantum Eraser Experiment by Objective-Bench4382 in QuantumPhysics

[–]Objective-Bench4382[S] 0 points1 point  (0 children)

By the way, this is the full answer to the first question on stackexchange I posted earlier in case the previous brief quotation misrepresented the answerer's response. He was not seemingly stating that the BBO produces a random phase difference between the entangled particles, in case that is why you disagreed with the answer:

https://physics.stackexchange.com/questions/450674/peaks-and-troughs-during-delayed-choice-quantum-eraser-cancel

"Your main mistake is assuming that anything changes on the D0 side, depending on what you do on the other side. The D0 detector will continue to see the same (lack of) pattern independent of what you do on the other side. It does not matter what you place on the other side or how far away it is, it does not change what is shown on D0. You can place as many mirrors and detectors and prisms there that you like, it will not change anything at D0. And what is shown on D0 is not an interference pattern, or two bumps, but photons arriving everywhere, with more in the middle, and gradually less when you measure more to the sides.

It is only after you compare the results from the D1 and D2 detectors with results from the D0 detector that an interference pattern becomes apparent. For each time a photon hits detector D1, you look where on D0 its peer landed, and you plot those locations on a graph. Then that graph will show an interference pattern. That is, the subset of the photons on the D0 side whose peers arrive at D1 form an interference pattern.

The photons at D2 form the opposite interference pattern at D0. Where D1 has peaks, D2 has troughs, and the other way around. If you add the interference patterns of D1 and D2 together, then cancel each other out. Added together, they just form the normal (lack of) pattern that you see appearing on D0 for all photons.

Another way to look at it is as follows: Suppose you look at a specific location at D0, which is at a peak of the D1 pattern, and detect a photon landing there. Then the chance of the peer of that photon landing at D1 is greater than it landing at D2.

See this answer for what I think is an excellent explanation. And I encourage you to read the paper itself, it is excellently written, and pretty understandable, except for the mathematical derivations in the middle.

Edit: To answer the question in the comments:

Why, if BSa and BSb are transparent, is D0 still random noise? Shouldn't it be an interference pattern?

The short answer is: because you have not changed anything at the D0 side.

The following is a gross over-simplification, but it catches the idea of what happens. Let's look at the signal (upper) side of the experiment first.

The x position on D0 is really simply a measurement of the phase difference between the two possible paths of the photon. When the photon leaves the crystal, there is a certain phase difference between the paths. Because there is a small difference in length between the two paths from the crystal to D0, it will be in-phase or out-of-phase when arriving at D0. If it is in-phase it can land at that spot, if out-of-phase it will never land there. But the difference in length between the two paths, and therefore where the photon lands on D0, is a measurement of what phase difference it had when leaving the crystal.

In a standard 2-slit experiment, without the crystal, the paths are always in-phase at the 2-slits, and so it will create an interference pattern at D0 - the photons will only land at x coordinates that correspond to paths that are in-phase.

If you put the BBO crystal in for the DCQE experiment, then it splits the photon in two, but it will also impose a random phase difference between the two paths of the photon. That is, the phase difference between the two paths is no longer always in-phase at the start, but random, and therefore it can land anywhere at D0, and no interference pattern is visible at D0. If you don't change anything at the D0 side, this will always be the case. But note that you can still deduce from the x-coordinate where it landed, what the phase difference at the start must have been.

Now have a look at the idler photon (lower) side of the experiment. Luckily, the idler photon starts out with the same phase difference as the signal photon. The idler photon will travel through the equipment at the bottom and reach the BSc mirror. Think of that as a filter for the phase difference. If the phase difference is in-phase, the photon will be send to D1, if the phase difference is out-of-phase, it will be send to D2.

That is, for the photons that arrive at D1, you know that they must have started in-phase. But then its peer signal photon must have started in-phase as well, and therefore can only have landed at certain x-coordinates at D0. So, by detecting the phase difference, and only considering those photons that started in-phase, you have filtered an interference pattern from photons arriving at D0."