Quantum entanglement is the mechanism by which quantum correlations between two sub-systems survive even after being physically separated from an interaction region. The correlations could in principle survive without neither time nor space constraint.

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Why are results of Bell's experiments considered to “break realism”?

Related to my previous question (Why would classical correlation in Bell's experiment be a linear function of angle?), as a newbie in quantum mechanics, I am also unable to find the reason to why ...
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Entangled Electrons

What attribute would help determine in a spaghetti of tangled-entangled electrons, which two are the respective entangled electron pairs, since obviously there is an attribute other than charge or ...
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Entanglement in single particle state

Is it possible that we have entanglement in different degrees of freedom of a singe particle. like spin and linear momentum .
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2 entangled electrons in QFT

In field theory, by quantizing a dirac field, we can obtain a creation operator for a single electron of definite momentum, of definite spin up or down, these respectively are: ...
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Entanglement entropy of 1D chiral Fermion

I was told that the entanglement entropy $S_E$ on the ground state of a (1+1)D conformal field theory (CFT) follows the logarithmic behavior $S_E=\frac{c}{12}\ln L$ where $L$ is the length scale ...
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Non-unqiue basis sets of reduced density matrix in quantum mechanics/decoherence

In Why decoherence solves the measurement problem by Art Hobson: $|\psi \rangle _{SA} = c_1|s_1 \rangle |a_1 \rangle + c_2 |s_2\rangle |a_2 \rangle$ which is a wavefunction that describes non-local ...
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Thought experiment using quantum entanglement in position and its effects

Consider we have two atoms $a$ and $b$. They are entangled with each other in position and momentum, with some wavefuction describing them in position space that is $\Psi(x_a, x_b)$. This ...
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Is this double “double slit experiment” involving entanglement possible?

The experiment goes as follows: Put a particle emitter (photon, electron etc.) between a pair of double slits. The emitter launches pairs of particles that are entangled in such a way that if one ...
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How does QFT help with entanglement?

I'm a bit confused. QFT is claimed to incorporate both Quantum Mechanics and Special Relativity. Therefore it should address the problem of non-locality caused by entanglement. However when I search ...
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Does first quantization perturbation theory imply a large scale web of electron entanglement?

My question may seem quite esoteric given the title, but I think it's relatively straightforward when explained properly. Imagine a relatively simple situation of 2 hydrogen atoms (numbered 1 and 2), ...
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In quantum entanglement are the 2 sub atomic particles exhibiting all possible values before being measured

I have been reading a lot about quantum entanglement when I came up to a part which says that before measuring one of the particles there is a 50:50 chance that a particle will be one of the pair but ...
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How do I describe two entangled electrons in the same state except for a different spin

I am trying to formulate the wave function that describes two entangled electons having the same position but opposite spin. According to the Pauli exclusion principle this should be possible. And ...
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If I have created a polarization-entangled photon source, would I be able to create a qubit?

In my laboratory, I have already obtained a polarization-entangled photon source. It was created via the Spontaneous Parametric Downconversion process of 2 BBO crystals. The next question is that ...
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Is space-time a Kantian concept - just a concept of the working mind? [closed]

Is space time a Kantian concept – that is, just a concept of the mind at work? That is that there is no ‘out there’ – it’s in the ‘mind’? Relativity might work but it certainly requires a stretch of ...
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196 views

How to explain in simple terms why Entanglement is more than just complicated hidden variables

I haven't taken a graduate level physics course on quantum mechanics so I get lost in the strange looking equasions. It's hard for me too see in any of the explanations of how quantum computers and ...
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110 views

Quantum Mechanics and Entanglement

I'm hearing a guy ( Tom Cassidy ), which supposedly has a master in physics, saying that what we expect in a physical experiment ( for example, observing some particle ) can actually interefere with ...
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258 views

wave-particle duality and entanglement

By fundamental definition of a entangled system we can say that if we know the quantum state of one subsystem then we can describe the state of another subsystem. A particle possess wave-particle ...
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209 views

Could the collision of two pairs of quantum entangled protons cause a temporary “wormhole”? [closed]

I recently read this article from MIT News. I then started thinking about how a particle accelerator creates a temporary microscopic black hole. My question is: If quantum entangled pair $A$, ...
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191 views

Can we use quantum entanglement as a way to send information or data? [duplicate]

Can we use entangled particles to transmit information or data such as TCP/UDP packets? If so why hasn't this been done yet? Surely the costs of bringing this to market are much cheaper than laying ...
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135 views

What would happen if two entangled particles collided?

Does that is even possible? I have almost zero knowledge in quantum physics, it is just a curiosity that popped in my mind.
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136 views

Quantum entanglement and uncertainty

I have a question about measuring entangled particles and the uncertainty principle. I know that this has been asked before, but I am still not clear on the explanations, so I will try to explain why ...
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What are the requirements on conditional unitaries for overcomplete bases?

On way to describe "pure" decoherence (that is, decoherence with respect to a basis that doesn't involve transitions between basis states) between a system $\mathcal{S}$ and an environment ...
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How does cryptochrome produce quantum entanglement?

I found this video on the net, which explains how a bird called "European robin" uses a trick based on quantum entanglement to see the earth's magnetic field. I am just asking if some of you know any ...
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University of Delft results regarding quantum teleportation of information

I have a college-level understanding of Physics. A recent study from the University of Delft in the Netherlands that seems to suggest that quantum teleportation of information (as in "communication of ...
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How to understand the equivalence between Andreev reflection and Cooper pair injection?

It is well know that Andreev reflection dominates the subgap transport at the normal metal-superconductor interface. An incident electron can be reflected as a hole in the Nambu space, which ...
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Beginner Quantum Mechanics Questions and Theories [closed]

So, I recently read the following article: http://www.preposterousuniverse.com/eternitytohere/quantum/ and I have some questions on some of the things it discussed, as well as some theories of my ...
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Entropy before and after collapse of the wavefunction/ and interpretation?

Seems like it might be pretty rudimentary but I want to see if my thinking is on the right track as well as what the result means. The question is, is the entropy of the collapse of a wavefunction or ...
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EPR Experiments and Monogamy

Normally in an EPR experiment two measurements are performed on entangled particle pair. Only the particle pair is treated quantum mechanically and it is usually prepared in a state like $$ ...
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How does one produce entanglement?

In practice, when entangling two particles (say two electrons), is creating an entangled state purely a matter of bringing them close enough together? What I mean is, to make their wave functions ...
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Reeh–Schlieder theorem in QFT and entanglement in biological systems

Context: There have been a few papers out recently which mention how photosynthesis in plants might have connections to entanglement, or even perhaps that entanglement is causing photosynthetic ...
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Entangled event horizons

Assuming it is possible in principle to entangle the degrees of freedom of the event horizons of two black holes, and that this is something that can be done, either after the black hole is formed, or ...
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353 views

What's wrong with this faster-than-light gedankenexperiment?

It is common wisdom - and mathematically proven - that quantum entanglement cannot be used to bypass the relativistic speed limit and transfer information faster than light. So there must be something ...
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On Bell inequality and bound entangled states

I have recently seen some presentation slides of Michał Horodecki (slide number 77) in which he discussed the following conjecture. Bound entangled states satisfy all Bell inequalities The ...
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651 views

Quantum entaglement and the arrow of time

I have seen several claims to that quantum mechanics is required to explain the arrow of time which I take to mean the macroscopic irreversibility of physical systems. This is presumably to resolve ...
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Entanglement: Is it possible to prepare and reset probabilities to send information?

I'm pretty certain that the answer to the question in the title is a no, but I don't understand why. I have some basic misunderstanding of quantum processes that I’d like clarified in the form of ...
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How do we know quantum entanglement exists/happens? [closed]

We know that this strange behavior is there but I am not to able grasp, how do we know it exists? Have we ever tried any experiments confirming this? Do we make use of this?
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What happens when an electron jumps through the event horizon of a black hole?

If quantum teleportation is performed into a black hole (by an electron for example), what happens to that electron? Let's say a hydrogen atom is very close to a black hole and the electron jumps ...
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Quantum entanglement as practical method of superluminal communication

As I understand it (from a lay physics perspective), quantum entanglement has been experimentally demonstrated - it is a reality. As I understand it, you can measure something like the spin of an ...
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Why can't I use Bell's Theorem for faster than light communication?

I read this description of Bell's theorem. I understand he's restating it slightly, so there may be incorrect assumptions there, or I may have some. I think Bell's theorem should lead to FTL ...
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Why is this entangled?

I am studying a book of quantum computing and the author gives an example of a four qubits separable! He writes: Let $\left|ψ\right> = \frac 1 2(\left|00\right> + \left|11\right> + ...
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Trace as integral

Consider a system of two entangled harmonic oscillators. The normalised ground state is denoted by $\psi_0(x_1,x_2)$. I've been taught that a density matrix is constructed as $\rho = ...
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Definition of momentum-entangled particles

When we can say that two particle are momentum entangled ? I just read an article where it's said that two momentum entangled particles share the same momentum value in opposite directions no matter ...
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How could there be a truly “pure” state?

If the Universe did start from a single point, then wouldn't all particles be fundamentally entangled? How then could there be a truly "pure" state?
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What is the Reduced Density Matrix?

The difference between pure and mixed states is the difference in their density matrix structure. For density matrix $\rho$ of mixed state the trace of $\rho^{2}$ should be less than 1. For pure ...
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Determination of entangled states

The definition of an entangled state $|\Psi\rangle$ is that it CANNOT be factored into $$|\Psi\rangle=|\psi\rangle_1\otimes|\phi\rangle_2$$ I am kind of confused on what is meant by a quantum ...
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Particles entangled after the big bang

Is that true that the big bang caused the quantum entanglement of all the particles of the universe so every particle is entangled to each other particle of the universe?
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Why isn't quantum entanglement just a lack of information?

From this question and answer from joshphysics, I didn't understand one thing, even after reading the comments: Why should assume that entangled electrons will only "decide" their state after ...
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Why do we want to entangle qubits?

The title is pretty much all I want to ask. Why are qubits entangled? To my knowledge (which isn't that deep) a quantum register can be realized without entangling the qubits.
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Particle/antiparticle annihilation and entanglement

This is a basic question. Suppose that A and B are completely entangled particles and so are C and D. If B and C are antiparticles that annihilate each other will A and D be entangled as a result. It ...
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Quantum entanglement: does it necessarily imply superluminal information transfer? [duplicate]

From what I understand, information is communicated instantly between two quantum-entangled particles regardless of the spatial distance between them. However, does this necessarily imply superluminal ...