All Questions
32 questions
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Is the spatial spread of the wave function over large distances the rule or the exception in quantum mechanics?
In quantum mechanics, I've read that wave functions for individual particles technically extend over all space, though the probability density tends to decrease with distance. This suggests that a ...
- 501
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62
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Is electron correlation in Quantum Chemistry a consequence of many-body entanglement?
Electron correlation is largely defined in Quantum Chemistry as the set of properties that the celebrated Hartree Fock Approximation cannot model accurately. One popular example is the phenomenon ...
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134
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Another Entanglement Question - Can you tell if the wave function of an entangled particle is collapsed?
Apologies for the additional question on a topic that seems to be queried relatively frequently in this forum -
I was unable to find an explicit answer to this specific question in searching physics ...
-4
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2
answers
396
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Are two entangled waves actually a single wave packet?
If two quantum particles are entangled they can no longer be fully described individually. The two of them together have only one wave equation.
Doesn't this mean that we are actually dealing with a ...
- 523
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85
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Question about Relativistic effects on Quantum entanglement [duplicate]
Let us consider the case where there are two entangled electrons, one with A and the other with B; whose spin Z can be measured. Let the state of the system be $$\frac{1}{\sqrt{2}}\left ( |00\rangle + ...
user279008
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129
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Postulate of wave function collapse and entanglement
Can we say that a measurement on a system of $k$ entangled particles is the cause of the collapse of the wave function into $k$th states simultaneously?
- 1,532
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1
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125
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The intepretation and maths behind the many-worlds interpretation of quantum mechanics
recently I started reading the book "Something deeply hidden" by Sean Caroll. In the book he talks about the many-worlds interpretation of quantum mechanics as a more elegant way of thinking ...
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Quantum entanglement information through time of collapse
(I've tried my best to find an existing question that asks this question exactly)
From what I understand, given two entangled particles, one held by Alice and one by Bob, when a measurement is done by ...
- 111
2
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1
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611
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Fermionic (or Bosonic) state vs Entangled state
One can see that the wavefunction for a system of two electrons (not very far apart) is one that cannot be written as a tensor product of individual states.
The same is true for a bosonic state.
For ...
- 1,461
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1
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137
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Can two particles have exactly the same statevectors?
I have a query:
Let us have 2 particles and 2 corresponding wavefunctions, under two incompatible Hamiltonians ( $H_1,H_2$).
$$\Psi_1(x_1,t_1)= e^{-x_1} e^{i\sin(\pi t_1/3)}+e^{-x_1^2}e^{i\cos(\pi ...
- 340
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1
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109
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Entanglement and continuous basis sets
I've usually seen entanglement discussed when dealing with discrete basis sets. For example, if we consider the Hilbert space $\mathcal{H}_0\otimes\mathcal{H}_1$, where both $\mathcal{H}_j$ are two ...
- 1,320
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3
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474
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What determines whether two quantum particles will "interact?"
The concept of quantum particles interacting is confusing to me. By "interact" I mean that thing particles do where they become entangled and exchange information and wavefunction collapse ...
- 1,435
2
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0
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107
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How to imagine wavefunction branching?
This is a question particularly geared toward the Many Worlds interpretation, but I think it could be translated to other approaches as well.
I am not sure I understand exactly what sort of events ...
- 749
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0
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126
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Entanglement entropy inequalities for a sum of wavefunctions
I am learning about entropy in quantum mechanics, and I am trying to develop some tools and intuition. One tool that I have found very helpful has been
$$\sum_{i=1}^k \lambda_i \mathbb{S}[\rho_i] \...
- 2,382
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How is the non-local nature of quantum entanglement explained?
From what I understand, Einstein tried to introduce real but hidden variables to remove the apparent non-local nature of quantum entanglement, but Bell's inequality showed local realism isn't possible....
- 1,108
2
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2
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109
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Is it possible to determine whether the photons in a given ensemble are entangled to a third party?
Suppose Alice sends Bob 2 ensembles with 1 billion photons each (or as many photons as you want). In one of the ensembles each of its photons are one of an entangled pair at parallel polarizations ...
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6
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486
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Problem regarding quantum entanglement and special relativity
So this question is about the strange phenomenon of quantum entanglement, or "spooky action at a distance", as Einstein called it. In particular, it's about the simplest conceivable case of ...
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1
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Is there anyway to know when the wave function collapse?
If we get 2 entangled particles and move them away from each other, is there a way to put one of them is some kind of "sensor" that would tell if the entangled particle have been measured?
If yes, how ...
- 141
1
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247
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Will an entangled system give different measurement then just correlation? [duplicate]
I have read this question:
Correlation vs. entanglement for composite quantum system
Entangled states can produce nonclassical correlations, but this is not necessarily the case.
So far so good.
...
- 29.3k
1
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4
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1k
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What happens to entangled particles when one of them is measured?
Imagine two entangled photons came into existence and one of them is being measured. We have altered one of the quantum states of the photon and caused its wavefunction to collapse and then we ...
- 13.1k
2
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1
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140
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If I have a two-electron problem, and I measure the position of one electron. What happens to the quantum description of the other?
Suppose I have a two-electron system, and they are left alone for a long time, such that I do not know where each of them is. I then measure one electron at position $\vec r_1$. Does this collapse the ...
- 1,420
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2
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147
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Are wave functions built of other wave functions?
I have heard the term wave function used in a number of contexts describing both quantum objects (electrons, etc) and more macroscopic objects (atoms, birds, cats, etc). Is it correct to say a lithium ...
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2
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398
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Reality, locality, and universality in the EPR paradox
Apologies if this has been asked before. I did some searching but didn't see it anywhere asked quite like this. Thanks in advance for any insights.
Caveat: I am an organic chemist and thus ...
user223099
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3
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967
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Is BEC the same as entanglement?
I understand that Bose Einstein condensate is:
A Bose–Einstein condensate (BEC) is a state of matter of a dilute gas of bosons cooled to temperatures very close to absolute zero. Under such ...
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388
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Why does the separability of the hydrogen wavefunction vary under different reference frames?
I know that two particles are entangled when their Hamiltonian contains an interaction part, but it seems to me that for the ground state of the hydrogen atom $\frac{1}{\sqrt{\pi}}\left(\frac{1}{a_0}\...
- 465
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3k
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What processes cause the collapse of a wavefunction and break entanglement?
This question states that measuring the spin of an entangled particle causes the collapse of the wavefunction and thus the entanglement is broken.
Then this question states that we don't know what ...
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If two particles are entangled and you collapse the wave function of one of the particles. Does the other particle collapse as well?
Let's suppose you entangled two photons, you separate the photons, and then you measure the polarization of one the photons collapsing its wave function. The wave function of the other photon ...
- 297
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1
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608
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Mathematical formulation of partial wave function collapse
If given a wave function which is an element of a Hilbert space $\mathcal{H}$ which is a tensor product of two other Hilbert spaces $\mathcal{H}_1\otimes\mathcal{H}_2$, how do you formulate ...
- 161
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0
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262
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Why is the wavefunction not a hidden variable?
Consider the following standard case of an entanglement experiment:
We prepared two electrons A and B with states
$$\lvert A\rangle=a_1\lvert \uparrow\rangle+a_2\lvert \downarrow\rangle$$
$$\lvert B\...
- 935
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364
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Single quantum particle in beam splitter, with different systems located in each channel
Suppose a quantum mechanical particle enters a beam-splitter, which sends its wave packets into two mutually orthogonal channels, $C_a$ and $C_b$. Suppose that $C_a$ also contains System A, with ...
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1
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279
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Can different components of a wavefunction become entangled with different systems?
Imagine a $z$-basis spin Stern Gerlach experiment where a single "particle" is put through the apparatus.
Upon exiting the Stern Gerlach magnets, the result is the sum of two states. One state is ...
- 887
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1
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1k
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What does the notation $|x_1,x_2\rangle$ mean?
I would like clarification on an equation in the paper "Free matter wave packet teleportation via cold-molecule dynamics", L. Fisch and G. Kurizki, Europhysics Letters 75 (2006), pp. 847-853, DOI: 10....
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