Delayed choice Definition and 116 Threads

Is theory around Delayed Choice remote polarization entanglement swapping of photons derived from Time Dependent Schrodinger equation (TDSE) or Time Independent Schrodinger equation (TISE)? I say the answer is no. I collectively group TDSE and TISE under the umbrella SE. And the following...

Hi People, In Kim's real setup for interference patterns we use a beam splitter as 50:50 (reflectance,transmittance rate), lets assume we use 20:80 (%20 reflectance, %80 transmittance) for beam splitter what could we observe in this situtation on detectors (except D3,D4)? Dont forget we use...

Hello Dear Physicists, I know this question probably discussed many times before. But I need a clear answer about this setup in case there is no beam splitter. What is gonna happen in this situation? My classical intuitions say I will see a correlated interference pattern on both screens(or...

Hi everybody. Some years ago I came across a video on youtube where they talked about an experiment with small and large envelops, when the small ones were placed into the large ones and then it resulted in something interesting. It might have been an instance of delayed choice, but I am not...

Hi. I’ve seen a number of schematic diagrams for the Delayed Choice Quantum Eraser experiment. Some include a prism to make the two idler photon paths diverge. However, the prism is shown refracting the ‘idler rays’ in a way which contravenes Snell’s law. E.g. see prism marked ‘PS’ (not the...

A follow-up question from a previous thread: https://www.physicsforums.com/threads/is-entanglement-swapping-a-result-of-post-selection-or-a-result-of-a-quantum-operation-called-a-bsm.1047772/. So my point of view is this: there are systems 1-4 (which refer to photons 1-4 in...

Under several historical experiments, measurement back-action has exhibited the ability the suppress a system's transitions to other states, especially when measurements are taken at a high frequency in time. This phenomena has become known as the Quantum Zeno Effect. In short, a quantum...

This is a follow-up video I made to a previous one on common misconceptions about the experiment. I'm interested in people's opinions here about how close the simulated experiment is to the real thing (e.g. there have to be some compromises due to the simulator not having free space propagation...

This was my attempt at making an explanatory video discussing some of the misconceptions about the experiment. I'm looking for feedback on how it could have been better. In particular, based on some of the confusions in the comments on the video, it's clear to me that I should have e.g. gone...

Based on Wheeler's delay choice experiment, the following results of experiment1 can be achieved. Experiment 1, the light passed through the BS1, 50% of the light is transmitted on optical path A, and then passed through the polarizer P2(the polarization angle is 135°),and the polarizer P3 (the...

I'm fascinated by the delayed-choice quantum eraser (DCQE) experiment from Kim et al. 1999. As I understand from the paper, the observer at the signal beam detector d0 (the screen) never sees an interference pattern, but the "lump" sum of all possible outcomes at the idler photon detectors...

Hi all; This goes under the heading of experimental predictions... gone awry. Let me say from the start that I think I've got something wrong, and would have no problem having it pointed out to me. I'm a newbie, and I've been boning up on basic quantum physics phenomena on Youtube, and...

The below experimental setup is of the sort one finds frequently discussed in the delayed choice quantum eraser (QE) experiments, such as that of Kim et al. (https://arxiv.org/abs/quant-ph/9903047) I extracted only the essential part I'm wondering about and did not find a satisfying answer in...

At 12.00h a specific event is being expected in Berlin, whether the wall ist teared down, or not. The sender is in Berlin and wants to send the information about the event to the recipient on the moon. Both sides know about the possibly upcoming event. As the light takes 1 second to the moon...

A laser gun pumps one photon at a time that goes thru an SPDC process and two entangled photons are generated...photon A and photon B... Photon A is sent to Bob who has a standard DS setup located a couple of meters away from the laser pump... since the photon is in superposition of states he...

<Moderator's note: 2 threads merged as it is an identical topic.> Given Kim's version of DCQE, let's say Bob in on Earth looking at d0, Alice is on Mars holding the prism that deflects the idler coming from (a) to d3 or (b) to d4. After the experiment run ends Bob should get clump at d0 without...

I am reading about this most famous experiment in physics, the double-slit experiment. My question is very simple: in the "Delayed Choice" version, have they done the test where they close BOTH SLITS (at once) after the photon has passed the slits?? If so, what have been the result? Can you...

Hello everyone. I want to ask some questions about dcqe experiments results which are bugging my mind. It is so hard to find reliable sources in my native language so I'm here. Also sorry for my scuffed english. Assuming we all know the famous experiment setup, I am directly passing to the...

Hello, Disclaimer: I have read other posts and understand it is important to reference ‘sources’ and that popular science articles / videos can be a source of annoyance. However, I am struggling to: A. Find an answer to my question, and/or B. Understand if my question is even valid. I hope...

What is the value of "delayed choice" experiments? Disclaimer: I do realize that nearly any experiment deserves to be performed even to make sure the QM theory predicts the results of such experiment right. So I have no objections to the work of people which implemented these sorts of...

I'm delightfully reading the Grand Design by Hawking-Mlodinow. After many years, I became persuaded from it that Feynman's interpretation as multiple paths of interference patterns in the double slit experiment and, more generally, his path integral approach to quantum mechanics, are superior to...

What exactly happens during the time gap between the detectors being activated, and the eraser subsequently wiping out the information after the results screen has received the photons? For example, do we "observe" the interference pattern being absent and then (gradually or immediately)...

I heard many people saying that the delayed choice experiment means that future events can affect the past. I doubt it as I believe that the wavefunction of the particle collapses as soon as a measurement is made. It does not matter where the detector is placed. As long as there is a detector...

Hello! Does anyone here have raw data from a delayed choice quantum eraser experiment that you wouldn't mind sharing? Ideally, data from all the detectors, not just coincidence counts that the analysis usually focuses on? Or, are you aware of any data repository where data from quantum physics...

In Delayed choice quantum eraser experiment (https://en.wikipedia.org/wiki/Delayed_choice_quantum_eraser) entangled photons are sent on different paths. They reach their detectors at different times. The one arriving early is called a signal photon. The photon that arrives at its destination at...

Googling for some unrelated topic, I stumbled upon Quantum Mechanics in an Evolving Hilbert Space. A lot of the math in this paper is beyond my present level, but some of the more descriptive passages made intuitive sense to me. Based on this, my question is, is the formalism of an evolving...

As almost everybody knows, DCQE experiment only shows interference after the data analysis, never in the first instance, regardless of future events for idler photons. https://en.wikipedia.org/wiki/Delayed_choice_quantum_eraser So, my question is, why you cannot see interference with this...

Hi. The Wikipedia article on the delayed choice quantum eraser is mostly about Kim's experiment where there's IMHO not really a 'choice' about the erasure of the path information, at least not by the experimentators. Have such experiments also been performed where this choice is more...

I've been thinking about a communication system that could allow faster than light communication. The basic principle that would make this system work come from the double-slit experiment and Wheleer's delayed choice experiment, taking advantage of the different patterns that would appear on a...

This delayed choice quantum eraser experiment captured my attention and after deep thought about it, I find it really startling and totally punishing to my common sense. My question is: Can you predict the future, say, a human's mind, using the quantum eraser? I imagine a modified version of the...

Hi. I found slightly different depictions of the Mandel quantum eraser experiment (1991). They are all from German sources, but I think they are pretty clear nonetheless. The first is from a German schoolbook: The second is from here: They claim that interference appears when the origins...

I know that clarifications about delayed choice experiment was asked million times, and I understand the idea, but I was not able to find the discussion of this particular situation anywhere, though I tried hard. This setup is described in Brian Greene's Fabric of the Cosmos book (note my...

This is a proposed idea. Using the "Delayed choice" version of the double slit experiment, can you devise a way to send Information (in this case the winning lotto numbers) Into the past? I imagine that one could convert the winning numbers into binary, assigning a 1 for wave experiments, and 0...

Hey, I was watching this video About the quantum eraser experiment (I suggest you watch too, so we would be speaking in the same terms). As I understand it, The experiment goes such that: first the photon enters through the slits as a superposition, then the photon gets measured to gain...

Hello. This topic seems to be discussed a lot of times before. But I still have some questions which was not clarified earlier and I will be grateful if someone will give me explanations :) First of all, to define a context, original experiment setup: (source...

What if our quantum eraser was a black hole? There's talk of event horizons preserving all the information that crosses them? Could we test this hypothesis by seeing whether or not black holes make good quantum erasers? Depending on the distance to the black hole - it might be hundreds...

I've been reading Brian Greene's "The Fabric of the Cosmos" and am currently at the description of the delayed choice quantum eraser experiment. My understanding is that this can be set up so that the idler photons can be measured (long) after the signal photons hit the detector screen. Under...

Is it possible that the reason the delayed choice two slit experiment outcomes occur is because for the photon, traveling at the speed of light, the past, present and future are all as one, and therefore it "knows" what is going to happen and therefore always "makes the right choice" at the...

Hi I have some questions and ideas regarding Bohr's double slit experiment which he extended with a Camera as an illustration of delayed choice. I read about it 40 years ago but can't find a reference to it, I'm hoping it wasn't apocryphal but it's consistent with Q-phys as I know it. The...

I have seen many times mention of measuring the 'speed' of state-change over quantum entanglement, and potentially measuring it. re: wave/particle 'duality' this paper explains everything extremely clearly and dispels such popular notions from my mind for a single particle...

I made some tweaks to the diagram you may have seen me post in threads about delayed erasure. Let me know what you think, what's confusing, etc. Here's the updated version: And the old version:

Double-slit experiments have been done to death, Obtaining and preserving which-path information (or otherwise) for a particle or photon causes its entangled partner to show the probability distribution with or without the interference pattern, violating Bell's inequality and thus proving...

Hi, I studied undergrad pure maths now post grad philosophy, not quantum physics, but please consider the following experiment: Suppose you set up a double slits experiment with a photon detector attached to each slit, and the photon detector attached to a photon transmitter, so the photon can...

Hi! :) I have this question regarding delayed choice quantum eraser - If my understanding is correct then interference pattern will form/not form based on whether there is erasing mirror in path of entangled particle - regardless of time when particle arrive at mirror. Should not it be...

I just came across the delayed choice quantum eraser experiments (kim et al 1999) through Wheeler's astronomical delayed choice thought experiment and I can't stop thinking about it :-( I would like to get some ideas on how people interpret this, either the general physics community consensus...

I watched this video that dumbs down and explains very simply how the quantum eraser works From my understanding: The particle will go thru both slits if not observed (probably wave collapsed). If you setup a device that will detect it (that emits a photon if the particles passes thru) the...

Hi, I have a simple question regarding this experiment: If we were to place a new detector, say D5, immediately after BSa, would it mean that D0 never shows an interference pattern for D5? I think so, as it would seem this should be no different than the result obtained at D3, but just want to...

If I understand the delayed choice quantum eraser experiment correctly, it's essentially set up in the manner as the double slit. The only difference is that the detectors are set up in front of the double slits. It was thought that if there was an interference pattern that appeared then that...

With this new publication in Nature, http://www.nature.com/nphys/journal/v11/n7/full/nphys3343.html, they have proven that "if one chooses to believe that the atom really did take a particular path or paths then one has to accept that a future measurement is affecting the atom's past." Do...

I'm trying to create a simplified diagram of the delayed choice quantum eraser experiment (contrast with the confusing one on Wikipedia and the simplified one on some random site). Here's what I have so far: Context that goes with the diagram: it is understood that an entangled pair of...