Delayed choice Definition and 116 Threads

Hello I have a question just out of curiosity...suppose you set up a delayed choice quantum eraser experiment and the technologies were available to super miniaturize your detectors, and instead of having a single double slit you have several double slit walls set up in alignment that are ultra...

Hello I have been looking at the results published by Kim et Al and am a little bit baffled by one of the graphs shown in fig 4. which shows the single detector counting rate of Do. The rate is very approximately constant across the whole range and averages about 280000 counts per second. Very...

Hello everyone, I actually have three questions: 1. Am I missing an important detail in my understanding of how the delayed choice quantum eraser experiment is done? 2. How does one account for what takes place in the experiment without using the concept of "retrocausality" (effect before...

The recent thread about the delayed choice experiment made me want to understand the experiment as a quantum circuit. I made this: (contrast with http://www.nature.com/nphys/journal/v8/n6/images/nphys2294-f2.jpg) The left hand side is the qubit-holding wires and gates to apply, with Alice...

My mind was blown upon discovering this experiment. Subsequent attempts at putting my brain back together have all failed miserably. All posts trying to demystify the experiment have either appeared flawed or were too complex for my primitive liberal arts brain to understand. Now I fear such...

This is a variant associated with the Scully and Druhl signal-idler photon delayed choice experiment, as described and discussed in Brian Greene's Fabric of the Cosmos. The commentary notes the "delay" may be configured to happen a very (years) long time after the photons pass the two...

I have been mulling over various aspects of delayed quantum erasure and came upon the following puzzle. It is about the famous 'delayed choice quantum eraser' of Kim, Kulik, Shih and Scully. The paper says (1st para of 2nd column on p2) that the path length from the BBO crystal that generates...

A Delayed Choice Experiment: Sorry, could not resist!

This thread is about my not understanding the conclusion that scientists came to that the photon makes a 'decision' on how to travel. In a simple interferometer experiment, a photon displays interference fringes only when a second beam splitter is present. According to Wiki, this led scientists...

I'm familiar with the delayed choice experiment, and I'm trying to suss out this new setup. http://www.sciencealert.com/reality-doesn-t-exist-until-we-measure-it-quantum-experiment-confirms Reading this article is not very beneficial if there's a confounding typo. Paragraph 10: Should that...

Hello, I signed up cause I was going through the Quantum Eraser threads, but couldn't find an answer to my question. It's about this version from 1999/2000 of the elaboration on the classic double slit experiment: Results seem quite straight forward. Wherever we have "path information" the...

I'm trying to understand the delayed choice quantum eraser experiment without consciousness. As I understand it, photons will either interfere or not depending on whether or not "which-path" information is randomly hidden and rendered unkowable to the experimenter. That is, rather the by any...

How would MWI explain the delayed choice quantum eraser? http://en.wikipedia.org/wiki/Delayed_choice_quantum_eraser#The_experiment_of_Kim_et_al._.282000.29 I don't see how this can be explained with MWI. If the idler photon hits detector 1 or 2, an interference pattern can be seen on the...

When you have the delayed choice quantum eraser, and you make it really really big and you put a measuring device just before the prism where the entangled photon will hit (Kim et al experiment). Does that mean that when that measuring device is 1 light year away and the people operating it can...

I found other threads with the same title on this forum but my question is somehow differ. I think this was the most simple DCQE with double slits: http://arxiv.org/pdf/quant-ph/0106078v1.pdf For a short summary: the experimental setup uses an entangled pair of photons (p and s). The s-photons...

Sorry if it's a silly question but I was trying to find such an experiment and wasn't successful. What I am thinking is, in the standard delayed choice quantum eraser, the dispersion pattern on the screen correlates to whether or not we can detect which path the electron took. What if the...

Hi all, Okay, I'm writing this post keeping in mind that FTL communication (or even backward in time communication) are impossible. However, I fail to understand why this would be impossible using the delayed choice quantum eraser, so my question is: where is the error in my logic here...

I've looked at the DCQE paper by Kim, et al (arXiv:quant-ph/9903047) but I was not able to follow the math leading to the calculation of the patterns R_01, R_02, R_03, and R_04. Specifically, I was hoping to understand the source of the pi phase shift between R_01 and R_02. Is there a property...

How accurate is this statement: After the photon passes through the detector, it then passes through the eraser. The eraser is an electronic device that alters the wave-function of the photon, just like the detector is an electronic device that alters the wave-function of the photon. This guy...

What I understand from the delayed choice double slit experiment, is that , only after we see in the detector of the whereabout of the particle, we get the patter according to it. That is if we have destroyed the detector and then we observe the screen we get an wave pattern. Barbecue we didn't...

Consider the below (figure 1), an electron gun is made to emit electrons one by one through two slits S1 and S2. There is a screen at the other side and a pair of telescopes (with electron detectors inside them) T1 and T2 trained on the slits S1 and S2 respectively. We can choose to bring down...

I've heard we can rule out retro-causal effects if we think of the photon as both being a wave and a particle simultaneously. However I understand wave-particle duality as being the sum of all possible paths taken by a particle to a detector whilst being impossible to predict individual paths...

From what I have read online, decoherence is an irreversible process that gives the appearance of wave function collapse. For example, a macroscopic measuring device will always interact with the particle it is trying to measure, and the particle becomes entangled to this environment, and...

http://www.bottomlayer.com/bottom/basic_delayed_choice.htmThis link is from wiki's . And my question is whether we can delay the choice？If we watched the photon which has passed the slit，did we have enough time to take measure to remove the screen？ We watch！ And the speed of the photon is as...

Sir, I've gone through wheeler's delayed choice experiment recently...i've got few couple of doubts in it..Please clarify them...Actually Wheeler wanted an answer for his questionthat "what happens when a single photon, presumably already determined to get detected as part of a two-slit...

OK, a quick intro to the delayed choice quantum eraser is at wikipedia (http://en.wikipedia.org/wiki/Delayed...quantum_eraser ). I have attached a figure of the modified DCQE. In this setup there is no delay, there is no choice, and there is recombination of the idlers instead. In the...

In the delayed choice quantum eraser experiment of 2000 (DCQE http://en.wikipedia.org/wiki/Delayed_choice_quantum_eraser) which I have attached a simplified figure for, there is the use of a downconversion crystal which converts pump photons into two photons of half the energy, signal and idler...

This comes from Greene's Fabric of the Cosmos: Wheeler imagines a cosmic version of the delayed choice experiment in which the light source is not a laboratory laser but instead, a powerful quasar in deep space. The beam splitter is not a laboratory variety, either, but is an intervening...

It is claimed that DCQE is equivalent to a single-photon double-slit setup. However, In this experiment, the 351.1nm Argon ion pump laser beam is divided by a double-slit, which means the actual photon rate is 1013 times higher than in a single-photon setup. Consequently, it makes it possible...

Can someone list the different interpretations of QM and how they differ in their predictions on the nature of reality, and what wave function collapse really is? I keep flip flopping between thinking the weirdness in QM is just our human minds not comprehending reality correctly and...

Hello, the delayed choice quantum erasure experiment seems really intriguing and although many sources seem to state that the results are what has been predicted by quantum mechanics, I'm having a very hard time understanding the results conceptually. What is exactly happening that causes there...

Hi, I'm in desperate search of an article related to Interaction Free Measuremnt and Measurement Theory: John Archibald Wheeler, "The 'Past' and the 'Delayed-Choice Double-Slit Experiment'," pp 9–48, in A.R. Marlow, editor, Mathematical Foundations of Quantum Theory, Academic Press (1978)...

"I was convinced that light must be causing the collapse of wave function, but Wheelers Delayed Choice Experiment seems to have confirmed otherwise. We can determine the state of a particle (ie wave or point) by choosing to observe, even if the decision about whether or not to observe is made...

does this experiment violate any type of causality?

In the delayed choice quantum eraser (DCQE), such as the walborn paper, link below: http://arxiv.org/PS_cache/quant-ph/pdf/0106/0106078v1.pdf" we try to find out the polarization/path via quarter wave plates (see diagram on page 7 of the paper) Now does not entanglement break (i.e...

Assuming the setup of Kim, Yoon-Ho; R. Yu, S.P. Kulik, Y.H. Shih, and Marlan Scully (2000). "A Delayed Choice Quantum Eraser". Physical Review Letters 84: 1–5. arXiv:quant-ph/9903047. Bibcode 2000PhRvL..84...1K. doi:10.1103/PhysRevLett.84.1 (See...

Einstein suggested a version of the DCQE back in 1931. And here is the proof, courtesy of Google News Archives: http://news.google.com/newspapers?id=muBPAAAAIBAJ&sjid=kFQDAAAAIBAJ&pg=3486,1697134&dq=quantum&hl=en

I have long been puzzled by the whole idea of delayed choice experiments with photons. In a photon's frame of reference there is no distance traveled between emission and absorption; the distance has contracted (Lorentz-Fitzgerald) to zero. More relevantly there is no time duration either...

Delayed choice quantum eraser – Yoon Vs Walborn experiment/paper is it true that in the Walborn experiment we manipulate p, but in Yoon paper we do not? The below link discusses the Walborn paper: http://grad.physics.sunysb.edu/~amarch/...

The behavior of the particle at the slits seemingly depends on what the photon encounters after the particle has passed through the slit(s). Does this prove that: 1. Particles can go back in time and do stuff? 2. Has quantum erasers been done using electrons or molecules like buckyball...

Wheeler's delayed choice experiment is a thought experiment proposed by John Archibald Wheeler in 1978. Wheeler proposed a variation of the famous double-slit experiment of quantum physics, one in which the method of detection can be changed after the photon passes the double slit, so as to...

Hello, I'm uncomfortable with the usual description of this experiment and wonder if this is justified. In a nutshell, when (in the usual double-slit setup) detectors are placed between the barrier and the final screen -- such that an electron, say, has already passed the two-slits -- an...

I know the Delayed Choice Experiment has been beaten to death in the forum. But I was wondering if anyone can answer this question. Would the results of the DCE seems so odd if we accept that light is really a spread out wave. That is assuming that the particle nature light is really just...

Many physicists (especially experimentalists) seem puzzled by the delayed choice experiments (DCE), because, as they argue, such experiments seem to change the past. Here I discuss DCE from the point of view of (not 1, not 2, not 3, but) 7 major interpretations of quantum mechanics: 4 variants...

I've been thinking about this weird experiment for a while and came up with a couple of insights: * This experiment presents before us the paradox between our concept of time, and the photon's nature of living outside of time. For the photon, the idler and the signal were measured at the...

Hi, I would like to ask some questions regarding "delayed choice quantum eraser experiment". (I think it is possible for those who are familiar with this experiment to skip the text and go ahead into questions 1 and 2.) It is mentioned e.g. on these links...

I'm a very thickheaded layperson so be warned, I'll probably require a lot of patience. Anyway, I'm having a very difficult time understanding the delayed choice quantum eraser experiments. It seems to me that it is implying that either the idler photon is going back in time and changing the...

I'm sure there's been a lot of posts on this before, but even after taking a look at some of them, this experiment is still eluding my understanding. I'm aware that there's no backwards causation--and that the eraser causes interference by random 'categorization'--but I'm nonetheless...

I have read that these experiments have been successful and do not cause a disagreement with QM. But I can’t quite determine what was learned. So what did they prove or disprove? Is there a simple explanation? I thought they were designed to determine if wave collapse breaks either locality or...

Delayed Choice Revisited. Here is a very cut down summary of Wheeler's delayed choice experiment (hope I got it essentially correct): When a wave packet is half way between the screen and the double slits, a decision is made by the observer as to whether to look for a photon or a wave...