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.

learn more… | top users | synonyms

1
vote
1answer
933 views

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?
56
votes
10answers
5k views

Quantum Entanglement - What's the big deal?

Bearing in mind I am a layman - with no background in physics - please could someone explain what the "big deal" is with quantum entanglement? I used to think I understood it - that 2 particles, say ...
1
vote
0answers
78 views

Equivalence of simple formulations of qubit entanglement

I'm reading some very elementary treatments of quantum computation and am unsure about the correspondence among "definitions" of qubit entanglement. One definition states that (1) the bits of a ...
-2
votes
1answer
659 views

Does this experiment on wave-particle duality and complementarity disprove quantum mechanics and prove the EPR viewpoint on it?

I recently read Photons act like they go through two paths, even when we know which they took, at Ars Technica, which reports on the paper Wave-particle dualism and complementarity unraveled ...
3
votes
1answer
1k views

three-particle quantum entanglement

So I know that two particles can be entangled in a quantum way, but is it possible that more than two particles be entangled in a quantum way? Most descriptions provide with two-particles cases, so I ...
7
votes
3answers
354 views

Quantum Entanglement Versus Inflation in the Early Universe?

Quantum entanglement is one of the most fascinating and mysterious phenomena in nature. It needs no interactions, or any sort of exchange for it to take place. It is possible, not against any rules of ...
0
votes
1answer
780 views

Quantum circuit, two control not gates

Consider the quantum circuit in the picture below: We have a Hadamard gate followed by a CNOT gate, this puts the 2nd & 3rd state in the bell state $\beta_{00}=\frac{1}{\sqrt2}(\mid 00\rangle ...
1
vote
1answer
121 views

Data For Quantum Entanglement

Is there any publicly accessible data that shows quantum entanglement empirically. I want to see what these researches are seeing that is showing them that indeed this phenomenon is real. Also, any ...
4
votes
2answers
877 views

When and how did the idea of the tensor product originate in the history quantum mechanics?

At some point in the history of quantum mechanics, it was accepted that a single particle is described by a wavefunction which is a function of the position of the particle $\mathbf{r}$, denoted: ...
11
votes
1answer
1k views

Quantum dimension in topological entanglement entropy

In 2D the entanglement entropy of a simply connected region goes like \begin{align} S_L \to \alpha L - \gamma + \cdots, \end{align} where $\gamma$ is the topological entanglement entropy. $\gamma$ is ...
13
votes
1answer
484 views

Can path integrals be used to understand entanglement?

I like path integrals. I prefer to try to understand quantum phenomena in terms of path integrals rather than Hamiltonian mechanics. However, most of the standard texts on quantum mechanics start from ...
3
votes
4answers
747 views

Why is quantum entanglement so important?

Entanglement also allows multiple states to be acted on simultaneously, unlike classical bits that can only have one value at a time. Entanglement is a necessary ingredient of any quantum ...
6
votes
1answer
763 views

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.
4
votes
0answers
171 views

Information scrambling and Hawking non-thermal radiation states

Could a very small black hole where half of its entropy has been radiated, emit Hawking radiation that is macroscopically distinct from being thermal? i.e: not a black body radiator. Or would the ...
1
vote
2answers
150 views

A foundational question about entanglement

The recent Nature article http://www.nature.com/news/data-teleportation-the-quantum-space-race-1.11958 prompts me to ask this question, which is of the same tenor as that asked at the recent Perimeter ...
3
votes
1answer
366 views

System with no entanglement but consuming quantum discord

I have come across an article which talks about quantum discord (Observing the operational significance of discord consumption. M. Gu et al. Nature Physics 8, 671–675 (2012) doi:10.1038/nphys2376), ...
2
votes
2answers
745 views

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 ...
5
votes
1answer
213 views

Logic behind topological orders

Long-range entanglement (LRE) is the main feature of topological orders. The string-net condensation model was constructed to exhibit LRE. But the many-body systems of such models do not look like ...
2
votes
0answers
65 views

How to make timelike entanglement in the laboratory?

http://io9.com/5744143/particles-can-be-quantum-entangled-through-time-as-well-as-space http://arxiv.org/abs/1101.2565 How to make timelike entanglement in the laboratory? How to test whether mixed ...
1
vote
1answer
281 views

Controlling the outcome of a quantum measurement through translational entanglement

According to the paper: A. S. Parkins and H. J. Kimble, Phys. Rev. A 61, 52104 (2000). http://pra.aps.org/abstract/PRA/v61/i5/e052104 You can entangle position and momenta of two atoms by using ...
3
votes
2answers
223 views

Understanding a Physics Paper on Quantum Teleportation of Continuous variables

The paper I am trying to understand is here: http://pra.aps.org/abstract/PRA/v49/i2/p1473_1 The paper describes the quantum teleportation protocol in a general case with continuous dynamical ...
1
vote
2answers
388 views

Entanglement Entropy

I needed some references which involves, the basic definition and motivation for Entanglement Entropy, and its one or two applications to many-body physics/black holes.
5
votes
4answers
1k views

Entangled electron-positron pair

Usually when we talk about entanglement, we mean entangled spin states (of electrons) or polarizations (of photons). My questions are: Does pair production guarantee the product electron and ...
2
votes
4answers
665 views

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 ...
3
votes
0answers
99 views

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)?
3
votes
2answers
204 views

quantum entanglement at microwave frequencies

Entanglement of optical photons using non-linear crystals has been around for a long time. Macroscopic entanglement using diamonds recently reported in the literature and receiving considerable ...
0
votes
1answer
178 views

Would synchronized dancing be a good way to describe entangled atoms to a laymen?

I was talking my professor about entanglement swapping between light and matter and it is briefly described here: You start out with a crystal capable of doing parametric down conversion of incoming ...
3
votes
0answers
174 views

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, ...
-1
votes
3answers
983 views

Using quantum entanglement to send messages back to the past [duplicate]

Possible Duplicate: Entanglement in time I heard that there is an experiment that uses quantum entanglement to try to send messages back to the past. I am having a hard time understanding ...
3
votes
2answers
288 views

Entanglement measure to classify topological ordered states

I know long-range entanglement is the essence of nontrivial topological ordered states. (Trivial refers to short range entangled and nontrivial refers to long range.) So, entanglement measure at large ...
7
votes
2answers
668 views

Topological Order and Entanglement

I have a question about entanglement in condensed matter physics. It seems that topological order origins from long range entanglement, but what is long range entanglement? It is the same as long ...
2
votes
2answers
654 views

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?
0
votes
0answers
147 views

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 ...
3
votes
1answer
389 views

Defining entanglement in subspaces of tensor product

I have asked the question in math.stackexchange, but perhaps it should be more relevant here. Hence I am re-posting it with necessary reediting. Let $\mathcal{H}=\mathbb{C}^n$ be a Hilbert space. A ...
3
votes
0answers
163 views

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, ...
1
vote
2answers
156 views

Can double entanglement preserve correlations?

We have 2 EPR experiments running in parallel, with Alice having one leg of each (a1,a2) and Bob the other leg of each (b1,b2). Thus (a1,b1) are anticorrelated, as are (a2,b2). Thus also (a1,a2) are ...
4
votes
1answer
414 views

Can entanglement swapping be performed on already-entangled photons, and if so, can it preserve this entanglement over the swap?

Consider 2 uncorrelated photon pairs (a1,a2), (b1,b2) such that (a1,a2) are entangled, and separately (b1,b2) are entangled. We wish to entangle-swap so as to end up with a new entanglement (a1,b1) by ...
3
votes
0answers
84 views

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 ...
2
votes
1answer
278 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: ...
4
votes
12answers
3k views

Could the Heisenberg Uncertainty Principle turn out to be false?

While investigating the EPR Paradox, it seems like only two options are given, when there could be a third that is not mentioned - Heisenberg's Uncertainty Principle being given up. The setup is this ...
3
votes
2answers
495 views

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 ...
2
votes
2answers
352 views

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 ...
1
vote
1answer
289 views

What is the fundamental differences between bound and entangled states

Specifically, are all entangled states considered bound?
4
votes
2answers
3k views

Is quantum entanglement functionally equivalent to a measurement?

I saw the following talk the other day: http://www.youtube.com/watch?v=dEaecUuEqfc&feature=share In it, Dr. Ron Garret posits that entanglement isn't really that "special" of a property. He ...
1
vote
0answers
128 views

Non-Locality and Entanglement

Let’s consider a pair of particles [with their signals] comprising an isolated system. Any change in some property of either particle is due to the signal/s received from the other. Each particle has ...
7
votes
2answers
195 views

Under what assumptions can we split a Hilbert space into subspaces?

I was thinking about an apparently simple question about quantum mechanics, if I am looking at a quantum system described by a Hilbert space $\cal{H}$ under what hypothesis can I define A and B as ...
16
votes
4answers
1k views

Is there an intuitive description of vacuum entanglement?

People often refer to the fact that the vacuum is an entangled state (It's even described as a maximally entangled state). I was trying to get a feeling for what that really means. The problem is ...
1
vote
1answer
146 views

Can entanglement be used to decrease entropy of two systems?

I know that entanglement can create correlation between systems. Would it be true to say that entanglement create constraints between systems? Can constraints be used to lower the total entropy of ...
2
votes
1answer
141 views

Is it possible to send a single photon from a distant planet (say Mars) and detect its arrival at a site on Earth?

My question is specifically whether there exists a technique by which a single photon can be "tagged" or "encoded" in such a way that it can traverse our atmosphere and arrive at some sort of detector ...
2
votes
3answers
107 views

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 ...