17 votes

Is my understanding of the delayed choice quantum eraser correct?

This is going to be a long answer because there is a lot to unpack here. I'm going to briefly go over your questions about your understanding, then analyze the experiment from the video in detail, ...
benrg's user avatar
  • 26k
11 votes
Accepted

Understanding the quantum eraser from a quantum information stand point

The answer is structured as follows: I will first give the quantum circuit corresponding to a normal double slit (or interferometer), then the circuit where the which-way information has been ...
Norbert Schuch's user avatar
10 votes

Is my understanding of the delayed choice quantum eraser correct?

The video that you watched on YouTube is full of gross errors and cannot be relied on to get an accurate picture of the quantum eraser experiment. The underlying error in the video is that it claims ...
David Reishi's user avatar
8 votes
Accepted

Why doesn't delayed choice quantum eraser experiment imply retrocausality?

This experiment implies retrocausality if you assume a classical way of thinking. The point of these experiments is to demonstrate that either retrocausality is real or the physics of the world are ...
Cort Ammon's user avatar
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7 votes
Accepted

Can post-selecting on the screen in the Delayed Choice Quantum Eraser experiment be used to predict the quantum-eraser measurement results?

You're over-interpreting these sketches - they are only sketches, and their specific details can't really be used to make any real predictions. Here is a more accurate version of those sketches, with ...
Emilio Pisanty's user avatar
6 votes
Accepted

What Prevents Delayed Choice Quantum Eraser Experiment from Being Used to Predict the Future?

You are misunderstanding what information you get from each of the sensors. And by information I mean the peaks and troughs in the image formed by the photons, that can be further interpreted by ...
Nighteen's user avatar
  • 176
5 votes
Accepted

Delayed Choice Quantum Eraser without retrocausality?

The short answer is that you're right. The delayed choice experiment doesn't require backwards-in-time shenanigans, and all the pop-science articles implying this to be the case are basically garbage. ...
Craig Gidney's user avatar
  • 6,154
4 votes

Quantum Eraser Experiment says nothing?

Your interpretation is essentially correct, although the specific numbers you keep referencing are a red herring. (More to the point, the number of counts is just proportional to how long you run each ...
Emilio Pisanty's user avatar
4 votes

Double slit experiment with 'interaction free measurement' to read out the 'which route' information

If "which route" information is collected, positively or negatively, the interference pattern will vanish. Thus, if you have a live bomb, you will only see a single band of light (and then the bomb ...
Cort Ammon's user avatar
  • 47.3k
4 votes
Accepted

Interference pattern in delayed choice quantum eraser

In the usual double-slit experiment the photon is in the superposition of states corresponding to holes A and B. \begin{equation} |DS\rangle=\frac{1}{\sqrt{2}}|A\rangle+\frac{1}{\sqrt{2}}|B\rangle \...
OON's user avatar
  • 8,269
4 votes
Accepted

Peaks and Troughs during delayed-choice quantum eraser cancel?

Disclaimer: I am not a physicist, and don't know the details of QM, but have read a lot about the DCQE experiment, and feel I understand how it works intuitively. And I feel that a serious question ...
fishinear's user avatar
  • 885
4 votes

Does simply putting a photon-splitting crystal after a double slit break the interference pattern?

Your proposed configuration does not show any interference. In the Quantum Eraser experiment, what's getting "erased" is the which-way information, not the interference. The SPDC stage (which you ...
Emilio Pisanty's user avatar
4 votes
Accepted

Are photons locked in time, and does this explain the "delayed choice quantum eraser" experiment?

Photons are elementary particles, part of the SM, they are traveling at speed c in vacuum, when measured locally. The world line (or worldline) of an object is the path that object traces in 4-...
Árpád Szendrei's user avatar
3 votes

Why doesn't the quantum eraser violate the no-deletion theorem?

Because they're talking about two completely different things. The quantum no-deletion theorem tells you that there is no linear unitary transformation $U$ that will take two copies of the same state ...
Emilio Pisanty's user avatar
3 votes

Why are my interference patterns completely out of phase?

The diagrams represent light coming out of the screen towards us. There are therefore oscillating electric and magnetic fields in the plane of the screen. We don't need to consider the magnetic field, ...
Philip Wood's user avatar
  • 35.4k
3 votes

Delayed erasure experiment

No, an interference pattern will not be detected. The universe does not care whether the which-way information is "detected" in any way ─ the only thing that matters is that the which-way information ...
Emilio Pisanty's user avatar
3 votes

Help creating a DYI delayed-choice quantum eraser experiment for teens

It's a bit late to matter, but there was never any possibility that your experiment could work as you hoped. Everything that happens in Scientific American's "quantum" eraser experiment is ...
benrg's user avatar
  • 26k
3 votes

Is a quantum eraser instantaneous?

The interference pattern only appears after the diagonal polarizer. I just performed the experiment with a Michelson interferometer. I place polarizers orthogonal to each other in each path of the ...
Lambda's user avatar
  • 4,721
3 votes

Why doesn't delayed choice quantum eraser experiment imply retrocausality?

Suppose you have a bowl containing two red slips and two black slips. You draw a slip. If it's red, you draw another one. The second one will be black in about 2/3 of the trials, because there are two ...
benrg's user avatar
  • 26k
3 votes

Delayed choice quantum eraser and changing the past?

The results of quantum physics are indeed hard to describe in everyday language, so you get professional scientists talking about quantum eraser experiments as if they changed the past. But they do ...
Andrew Steane's user avatar
3 votes

If humans can be shrunk down to the quantum level, does this mean that the shrunk human will experience time slower as they have smaller mass?

I am doing some research about "time travelling" by shrinking humans to the quantum level. For educational purposes I will explain why this is impossible. Atoms and molecules are the sizes ...
3 votes

Could the quantum wave function collapse under these settings?

A measurement is simply an interaction between the object being observed and some measuring device. Whether a human looks at it, or the device is subsequently taken to a dump etc etc is entirely ...
Marco Ocram's user avatar
3 votes

If two people perform the double slit experiment, why does the pattern disappear for both if only one observes which slit the electron goes through?

What a person knows or doesn’t know is not a factor in the appearance or not of interference. The rule is: if it is possible in principle to derive the which path information from the setup, there ...
DrChinese's user avatar
  • 943
2 votes
Accepted

Does the Delayed Choice Quantum Eraser require the signal and idler photons to be entangled?

Depends on the experiment; more recent versions usually choose to use entangled photons because they are completely non-classical, but earlier versions did not. Experiments that don't depend upon ...
Peter Diehr's user avatar
  • 7,165
2 votes

Why does the interference patterns in delayed choice quantum eraser cancel out? Why/how does it have a phase shift?

Delayed_choice_quantum_eraser#The_experiment_of_Kim_et_al. [...] Now R1 and R2 shows an interference pattern These two patterns of coincidence counts both arise as a function of "x" (see the ...
user12262's user avatar
  • 4,248
2 votes

What does the quantum eraser experiment say about reality?

I think this a good read: http://jamesowenweatherall.com/SCPPRG/EllermanDavid2012Man_QuantumEraser2.pdf There is a fallacy when we usually think of the quantum eraser, especially the delayed choice ...
Ian Emnace's user avatar
2 votes
Accepted

Understanding the delayed choice quantum eraser from a quantum information stand point

NOTE: This answer has now been merged into Understanding the quantum eraser from a quantum information stand point (part IV). Let me start by copying the first part of my previous answer which ...
Norbert Schuch's user avatar
2 votes

Delayed Choice Quantum Eraser without retrocausality?

Old question, and the physical part of it has already been explained sufficiently by the other answers. I'd like to answer your question: If it IS yes, then why is there any discussion at all about ...
fishinear's user avatar
  • 885

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