# Tag Info

### 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, ...
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### Delayed Choice Quantum Eraser: Am I missing something here?

This question was cross-posted to physics forums word for word. I'll give the same basic answer I gave there. Consciousness is never part of any quantum mechanical explanation. Every experiment runs ...
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### 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 ...
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### 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 ...
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### 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 ...
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### 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 ...
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### 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. ...
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### 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 ...
• 124k
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### 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 ...
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### 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-...
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### 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 ...
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### 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 ...
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### 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 ...
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### 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 ...
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### 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 ...
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### How does which-slit information destroy interference?

You can think of the double slit pattern as caused by the interference of two branches of the wave function, say $|L\rangle$ and $|R\rangle$. Now assume that there is which way information because of ...
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### 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 ...

### 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 ...
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### 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 ...
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### Delayed Choice Quantum Eraser: Am I missing something here?

Am I missing an important detail in my understanding of how the delayed choice quantum eraser experiment is done? Yes. I'll respond to your list of your understanding. How does one account ...
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### 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 ...
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### 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 ...
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### Delayed Choice Quantum Eraser without retrocausality?

According to your description I agree with you that a prediction, that idler photon is more likely detected at D1 or D2, based on knowledge where signal photon hit D0, is possible. In your simplified ...
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### In the delayed choice quantum eraser, what would happen if we were to send the second entangled particle into a blackhole?

I wrote up a lot of this stuff a while ago on my github, if it helps -- not specifically what happens if we black-hole the second qubit, but all of the math you'll need to understand the basic ...
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### Taming the delayed choice quantum eraser experiment

The Wikipedia webpage "Delayed choice quantum eraser" offers a simplified explanation of this experiment. "In the basic double slit experiment, a beam of light (usually from a laser) is directed ...
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### Shor's algorithm with adversary - can (delayed) erasure of value qubits cripple calculations?

Here from an eagles eye perspective: No matter what Eve does will lead to a measurable difference in Bobs states, otherwise superluminal communication would be possible. Does Bob need to use (perform ...
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