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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Questions about entanglement from a laymen/quantum hobbyist

Please note I am not a physicist I just read every article I can on it, I understand a good amount on it though. But no maths. (currently trying to learn the maths) By what means can we as humans ...
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Does the passage of time effect a photons entanglement with another?

I recently read an article about "Delayed-choice entanglement swapping". Here is an excerpt from the article: Delayed-choice entanglement swapping consists of the following steps. (I use the ...
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Is This A Working Time Machine? [duplicate]

picture taken from this video for those who do not like to click on youtube links youtube video - retrocausality through Double Slit & Bose The answer will probably be no, but i am interested ...
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Entanglement, Bohr-Einstein Debate, Bell's Inequality

On BBC episode The Secrets of Quantum Physics (Part 1) Jim Al-Khalili explains quantum mechanics for the layman. In the first half, he does a very good job; in the second half, either he thought his ...
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Entanglement g-2-experiment - Which components do I need?

I would like to measure whether my source emits entangled photon pairs. To that order I want to build a g-2-experiment, which measures photon coincidence counts as a function of time delay between ...
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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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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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257 views

ER = EPR and Time Travel

In Maldacena-Susskind paper arXiv:1306.0533, they propose an idea of $$\text{ER = EPR}$$ the relation between the wormhole and the quantum entanglement. which ER means Einstein Rosen (ER) bridges, ...
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Questions on entanglement entropy

If the spatial entangling surface is $M$ then it seems that one way to get the entanglement entropy is to think of the QFT on the manifold $S \times M$ where $S$ is a 2-manifold with the metric, ...
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Concurrence in higher dimensions?

Does anybody know of any calculation of the concurrence for some mixed state other than the qubit-qubit case (which was solved by Wootters)?
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Are the electrons in a quantum hall edge state entangled?

I am reading the paper on Quantum Energy Teleportation by Yusa, Izumida and Hotta(This article), and it seems that they are assuming that the quantum hall edge state is a quantum correlated state, ...
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Spin polarization of decay products

A relativistic moving particle, e.g. muon $\mu^+$, described by its four-momentum vector $p_\mu$, charge $e$ and with a given spin polarization, ${\bf S}=(S_x,S_y,S_z)$, decays into three particles, ...
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Why do we think that quantum entanglement implies action at a distance? [duplicate]

Possible Duplicate: Why quantum entanglement is considered to be active link between particles? I am a layman trying to read into quantum mechanics. As I understand it quantum entanglement ...
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Exploring beyond event horizons

In the expanding universe the velocity of separation between galaxies depends upon how far they are. If they are much far away will they have relative velocity of separation greater than speed of ...
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How come the concept of an instant of time is such a controversial topic with relativity, but with entanglement it's completely acceptable?

When talking about relativity most people say that a universal instant of time doesn't exist, but when talking about entanglement most will say that the particles are both measured instantaneously. ...
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Has anyone actually “seen” entanglement?

I want to know if the following has been done experimentally; after the spin (or any other characteristic with a probability of 50%) of 2 entangled particles has been measured, we change the spin of ...
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What is coherence in quantum mechanics?

What are coherence and quantum entanglement? Does it mean that two particles are the same? I read this in a book called Physics of the Impossible by Michio Kaku. He says that two particles behave in ...
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Is there any theoretical limit to the distance at which particles can remain entangled?

As for as I understand (which is admittedly very little) particles that are created together become entangled. Currently, the experiments using entangled particles are over relatively short distances ...
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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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Does measuring destroy entanglement

Before measuring a quantum particle(photon) it exists in a superposition state, once we observe(measure) it, it settles in one of the possible states(destroying superposition). For entangled ...
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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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Is it possible to bind an entangled electron to the outer shell of an atom or just a proton?

Say we start with an entangled electron--positron pair and we separate them. I want to take the entangled electron and bind it to a proton or the outer shell of an atom. Is it possible to do this ...
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What is time teleportation?

I read this article about time teleportation. Can someone explain the concept better?
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What is the difference between Quantum teleportation and Radio waves?

Quantum teleportation over 143 kilometres using active feed- forward What is the difference between Quantum teleportation and radio waves?
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Weak measurement and Hardy's paradox

How the notion of weak measurement resolves Hardy's paradox?
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Is entanglement a classical phenomena?

If I have an entangled state shared between two parties Alice and Bob $$\frac{1}{\sqrt{2}}|00\rangle+\frac{1}{\sqrt{2}}|11\rangle....(1)$$ then the reduced density operator of Alice's side is ...
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A naive question about topologically ordered wavefunction?

Topological entanglement entropy (TEE, proposed by Levin, Wen, Kitaev, and Preskill) is a direct characterization of the topological order encoded in a wavefunction. Here I have some confusions, and ...
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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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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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Von Neumann Entropy: varying definitions

I have seen different authors define von Neumann entropy in different ways. In particular, some use the natural logarithm and others log to base 2. What is the reasoning for this? Does it make any ...
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What properties are entangled in quantum entanglement?

When two particles are entangled, one can measure the properties of one of the particles and instantaneously know the properties of the other. This is because the two particles possess the same ...
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275 views

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: ...
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Can two distinct spatially separated many-body systems in the ground state contain entangled particles?

In particular, I am asking if two distinct many-body systems (e.g. system A and system B) separated at some arbitrary distance will necessarily be found to contain entangled particles (such that ...
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488 views

Spin up, spin down and superposition

I'm just starting to study quantum mechanics. Please explain the error in this thinking: You set up decay of two $\pi$ mesons and get $2\mathrm{e}^-$ on Mars and $2\mathrm{e}^+$ on Earth. On Earth ...
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Local measurement of entangled particle pairs and interpretation of state

This just started to bother me after reading yet another entangled particle question, so I hate to ask one myself, but... If we have two entangled particles and take a measurement of one, we know, ...
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An error in my understanding of entanglement

Based on my knowledge of quantum entanglement, I can set up a scenario which leads to a contradiction with the No-communication theorem. Please help me find the flaw. Suppose Alice wants to ...
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I don't understand the no-communication theorem

I don't understand the no-communication theorem. Okay, first I'll say the bit I do understand about it: if Alice and Bob both have two atoms, such that Alice's atom 1 is entangled with Bob's atom 1, ...
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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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Deriving entanglement entropy from Renyi entropy

My questions are based on this paper - http://arxiv.org/abs/0905.4013 Firstly I want to know as to whether some assumptions are needed about the relationship between the systems $A$ and $B$ for the ...
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Does the reduced density matrix describes a real mixed state?

Suppose that we have two entangled particles A and B with pure state vector $|\psi\rangle=a|0\rangle_A |1\rangle_B + b|1\rangle_A |0\rangle_B \hspace{1cm}(1)$ When we take the partial trace over the ...
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What's the relationship between quantum entanglement and the relativity of time?

Apologies in advance for what may be a stupid question from a layman. In reading recently about quantum entanglement, I understood there to be a direct link between entangled particles, even at ...
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Quantum communication

Is it possible to get two atoms to opposite quantum states of one another so when I change the state of first one, the state of the other one changes too? Is it possible to move them to another place ...
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What is “quantum locking”?

I've always assumed that "quantum locking" was a term invented by the writers of Dr Who, but this video suggests otherwise. What is quantum locking? Is it real?
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How is it that Quantum entanglement does not let you transmit infomation?

when I was first introduced to entanglement I was told that "it is a phenomena that allows information to be transmitted faster than light", however, as I kept reading up on it, this seemed to be an ...
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Is there non-trivial multipartite entanglement not witnessed by the spectra of reduced states?

A lot of analysis of multipartite entanglement is based on examining the spectra of various reduced states. (E.g. area laws.) Of course one generally needs not just the $N$ local states of each ...
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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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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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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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988 views

EPR-type experiments and faster-than-light communication using interference effects as signaling mechanism

I understand that faster-than-light communication is impossible when making single measurements, because the outcome of each measurement is random. However, shouldn't measurement on one side collapse ...
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Can we determine whether or not a particle is entangled?

Suppose Shaniqua and Tyrone have four pairs, a, b, c, and d, of entangled particles. They take their particles and go very far apart. If Tyrone can determine whether or not a particle is still ...