All Questions
80 questions
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Can experiment distinguish the basis in which a singlet state is represented?
Let $\left(|\uparrow\rangle,|\downarrow\rangle\right)$ and $\left(|\nearrow\rangle,|\swarrow\rangle\right)$ be two bases of the $2$-dimensional Hilbert space $H$.
Can an experiment distinguish ...
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Measuring electron spin with multiple Stern–Gerlach apparatus at an angle
To separate the two spins of electron of a particular direction, we use Stern-Gerlach apparatuses to apply a non-uniform Magnetic field. Suppose we have two identical electrons and we know their spin ...
- 111
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2
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170
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Are all Bell tests valid only for linearly-polarized photons? [duplicate]
In https://arxiv.org/abs/1407.2605, it is argued that all photons are necessarily circularly polarized, and linearly-polarized photons must be a superposition of such circularly-polarized photons. ...
- 1,175
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301
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Entanglement, measurements and correlation
I am studying for my quantum mechanics exam and I came across the following question, I hope I reason correctly.
Consider two spin-$\frac{1}{2}$ systems one of which is measured by Alice and one ...
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3
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866
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Which is the difference between entangled spins and classical coins?
I'm trying to understand why entanglement has no classical analog.
I imagine the usual well known example: Charlie prepares two spins in the entangled states. Alice and Bob measure them using their ...
- 139
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Is it possible to affect spin probability of an entangled particle?
Say I have entangled particles A and B. Assuming we are talking about photons, we have 50/% chance of particle A being spin up.
Is it possible to affect the probability of particle A to be spin up ...
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175
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Can two spin 0 particles be entangled?
Imagine that I have some kind of collision between two spin-0 particles that conserves the number of spin-0 particles, and I divide my lab in half with detectors on both sides called left L and right ...
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Quantum entanglement of spins
Suppose we have a pair of spins in the state $\left|\Psi\right>=\frac{1}{\sqrt2}(\left|\uparrow\downarrow\right>-\left|\downarrow\uparrow\right>)$. We know that the measurements of the spins ...
- 263
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160
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EPR Paradox clarification
Basically, the paradox works like this:
Two entangled particles (A and B) are a light year apart.
1. Measure the X spin of A
2. Measure the Z spin of B
You ...
- 101
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117
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Entanglement swapping proves there are no time paradoxes?
I am trying to make sense of the Delayed Choice Entanglement Swapping:
In the entanglement swapping procedure, two pairs of
entangled photons are produced, and one photon from each pair
is sent ...
- 395
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590
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Children of entangled particles
Theres a photo on the wikipedia page Quantum Entanglement there's a image of a photon being split into two entangled photons via crystal. I used this picture to demonstrate the scenario below.
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Why we cannot transfer information using a spin entangled singlet? [duplicate]
In QM and QE effects an entangled particle pair is called also a singlet with some properties of the two particles like spin, non-locally correlated. However, there is no transfer of information ...
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57
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Can entanglement cause a chain reaction at distance after measure one particle? [duplicate]
if we have two electrons with their spins entangled like this:
And if we measure the spin on the left electron, then right electron spin also change like this:
So, my question is, do this spin ...
- 327
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57
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Total spin of Entangled Electrons
If, say, the z-spins of two electrons are maximally entangled (so that their composite state can be given by $|\Psi\rangle = \frac{1}{\sqrt{2}}(|u\rangle|d\rangle + |d\rangle|u\rangle)$, how do you ...
- 1,073
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99
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Intuition for Results of a Measurement of Entangled Spins
Suppose I have a source that produces pairs of spin-1/2 spins in the entangled state
$$ \frac{1}{\sqrt{2}} \left( \mid\uparrow_z\uparrow_z\rangle + \mid\downarrow_z\downarrow_z\rangle \right). $$
The ...
- 1,576
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65
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Why can't we create energy/momentum by selectively measuring the spin of entangled particles?
Suppose we perform a Bell violation type experiment with spin, i.e. we have a stream of entangled, spin-anticorrelated particle pairs and we are to measure their spins along different axes.
Now for ...
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67
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Quantum entanglement of a particle [duplicate]
I recently got to know that two particles are entangled and they share information instantly no matter how far they are kept from each other. It is also said that if one particle is kept at one side ...
- 172
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38
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Using entangled qubits to communicate [duplicate]
After reading up on quantum mechanics considering entangled qubits I was asking myself this simple question:
If one qubit (A) positioned on earth is entangled with another qubit (B) which is - say - ...
- 271
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2
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512
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How to produce a given entangled state of two quantum bits?
I was watching Leonard Susskind's video series on quantum entanglement, where he looks at the spins of two electrons. In particular, there are entangled states of the form $$\alpha\left|\uparrow \...
- 407
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2
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62
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If 2 electrons are entangled $[a] [b]$. if we throw a photon at $-[a]$ will it come out of $[b]-$? [closed]
i was confused as to what will happen when two electrons which are entangled and then if one is exposed to light. will the absorption and emission theory still work and if so how will it work in this ...
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202
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Faster than light communication protocol via GHZ-state
I had a chat with a guy recently who claimed that multipartite entanglement might actually be used for superluminal communication, and his argument is very simple.
Suppose that 2 observers (Alice and ...
- 199
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230
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Do particles remain entangled even after repeated measurements in different directions?
If we measure the spin of an electron along the $x$-direction and it turns out to be up then we know that upon measurement along the $y$-direction and in turn along the $x$-direction, the probability ...
user218113
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Does quantum entanglement, in and of itself, make the constituent particles more sensitive to external fields and forces?
I just watched PBS Space time episode called, 'Navigating with quantum entanglement'.
At about 10:25, host Matthew O'Dowd says that Peter Hore of Oxford University reviewed the evidence for quantum ...
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67
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Question regarding entanglement
Could the paradoxical nature of entanglement be the result of a change in the nature of quantum properties, or an incomplete understanding of such, instead of non-locality?
- 1,687
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Measurements of spin correlations: Alice goes back to Bob and compares results
Take a fully entangled two-photon state, like
$|\Psi>=\frac{1}{\sqrt{2}}\big(|+->-|-+>\big)=\frac{i}{\sqrt{2}}\big( |yx> - |xy> \big)$
where one photon is sent to Bob and the other to ...
- 427
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1
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404
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Is quantum entanglement contradictory with Schrödinger's cat?
As I understand, an electron spin is in a superposition state until the spin is observed. Due to the observation, it will either be spin up or spin down.
Due to quantum entanglement, if one electron ...
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74
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Cat State With Largest Number of Particles
I am wondering what is the largest number of particles that went into creating a successful cat-state? This article gives examples of 6 spins and 4 photons. I am wondering if there have been cat-...
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2
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172
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Creating entangled electron pairs using Stern-Gerlach apparatus?
The following is a drawing of the sequential Stern Gerlach experiment.
As we can detect the fraction of the electrons passing through each magnet, I suppose it is possible to detect how many ...
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Bell's inequality in Claude Cohen-Tannoudji's Quantum Mechanics Volume III
Claude Cohen-Tannoudji et al, Quantum Mechanics Volume III, 2020 edition, Chapter XXI.F-3-b.$\alpha$ (F-7) on p.2210 states
$$\big\langle\hat A(a)\hat B(b) \big\rangle={\cal P_{++}+P_{--}-P_{+-}-P_{-+}...
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Isn't There A Much Simpler Way To Explain Why Quantum Entaglement At Distance Isn't Utile - That Spins Already Exist & React To Detection Predictably? [closed]
Tell me if this concept works for explaining in a much simpler way, why purposeful entanglement outcomes like FTL communication cannot work - and without relying on complex analyses of 'spooky action',...
