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

12
votes
4answers
2k views

Entanglement, real or just math?

I'm new here, actually this is my first question so I'll just get to it. In quantum entanglement when something acts on one particle the other one reacts also, just in reverse (more or less). From ...
4
votes
2answers
298 views

Entanglement of Mixed Quantum State

As per Wikipedia: Quantum entanglement is a physical phenomenon that occurs when pairs or groups of particles are generated or interact in ways such that the quantum state of each particle cannot ...
2
votes
2answers
171 views

Wouldn't 3 or more particle entanglement allow passing classical information?

My (simple) understanding of entanglement is that by measuring the spin of one entangled particle, the other entangled particles' spin changes to the opposite of measured particle. This act of ...
0
votes
1answer
85 views

Study the center and interior of a black hole using quantum entanglement

Having just watched the latest in a long line of space movies; Interstellar tries to combat the problem of studying the center of a black hole and understanding what's going on inside. My question is, ...
-1
votes
4answers
128 views

How do we know that quantum entanglement is instantaneous?

Is it a mathematical certainty demonstrated through some proof or is this simply what observation shows? How sensitive are the measurements that determines the "communication" (I know... It is not ...
-2
votes
1answer
163 views

Thought experiment on graviton breaking the speed of light [closed]

The effect of gravity travels at the speed of light. Suppose we can entangle a pair of gravitons (which are only theoretical, but who knows for sure?) and separate them over a vast distance. Hold on - ...
0
votes
3answers
200 views

What is the difference between maximally entangled and maximally mixed states?

To my understanding, mixed states is composed of various states with their corresponding probabilities, but what is the actual difference between maximally mixed states and maximally entangled states? ...
2
votes
1answer
316 views

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 ...
2
votes
3answers
330 views

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 ...
0
votes
1answer
80 views

Why is the distance in non-local entanglement for teleportation limited by time

In a recent paper, researchers described a system that can teleport a quantum state without the need for the entangled particles to actually "meet" each other. I'm reading, in particular, ...
5
votes
3answers
326 views

Would 2 entangled atoms decay at the same time?

I have a very basic understanding of entanglement and radioactivity. But say 2 uranium atoms are entangled and then 1 of them decays, what would happen? Would the other atom decay as well? Or if not ...
7
votes
3answers
374 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
2answers
45 views

Can entangled particles stay in sync when one of them is travelling near light speed?

Can entangled particles stay in sync when one of them is travelling near light speed? I ask this because it means that time would be experienced at different speeds for both particles and could allow ...
1
vote
2answers
147 views

Spin Control and Entanglement

I have a thought-experiment sort of question and I don't know where to start. Suppose you have an entangled pair, e1 and e2, and you split them. Then BEFORE reading them, you spin control e1 to +, ...
2
votes
1answer
77 views

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 ...
-3
votes
1answer
674 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 ...
0
votes
0answers
70 views

What Quantum Entanglement is NOT? [closed]

What are the most insightful experiments on Quantum Entanglement undertaken in the last few years showing what it is not? What insights did we gain from does constructive failures? Is there a current ...
3
votes
1answer
71 views

Are all properties entangled when one property is entangled?

When one or more particles are quantum entangled by say their spin property, do their other measurable properties (e.g., momentum, polarization, whatever?) become entangled as well?
1
vote
0answers
120 views

About long range entanglement [closed]

“topologically non-trivial” ground states have long-range entanglement. Is this possible to process the quantum information with help of the studies in topological non-trivial ground states for ...
1
vote
1answer
127 views

Is it enough to use only sigma criterion to calculate expected value for ideal Bell's test experiment?

Let's build some custom distribution for particle measurement result in CHSH test. Let's assume ideal particles and detectors. Let's also assume that each particle has hidden parameter $z$. Parameter ...
4
votes
6answers
564 views

Explanation for the EPR-like paradox

I am trying to understand the process of Quantum Entanglement for use in Quantum computers. The problem I have is this: Suppose some nuclear process emits an electron-positron pair. Now after ...
16
votes
4answers
2k 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
3answers
79 views

How are Superposition and Entanglement related?

How are Superposition and Entanglement related? I don't know much of Quantum Mechanics. I am CSE student and got started with this Quantum Computing. It is interesting! If anybody can help me on ...
1
vote
0answers
29 views

Could a travelling quantum object transport an on-board monitor to restitute information later? [closed]

Could a pair of identical "automated observers" such as a camera inside a capsule, be made to travel slowly along different paths, and then be recovered to play back a film of its on-board ...
4
votes
3answers
105 views

Is there a unitary, linear bijection between (1) Maximally Entangled and (2) Factorizable States?

Pretty much as the title says. I am interested in the two particle system, each particle having two dimensional quantum states; naturally if there is a generalisation I'd be interested in that too. ...
0
votes
2answers
447 views

What's the Cause of Quantum Entanglement? [duplicate]

What is the cause of quantum entanglement? When two particles become entangled what property of them basically changes as to establish a link between them and how the information is exchanged between ...
0
votes
0answers
71 views

Entanglement entropy vs entropy

I just read that if you have a pure density matrix state on a product space, then a way to define entropy in a subspace is to take the reduced density matrix state and define $S = 1- ...
2
votes
2answers
368 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 ...
3
votes
2answers
119 views

Basic quantum entanglement question [duplicate]

Please consider commenting on this basic quantum entanglement question or point me to articles that may enhance my knowledge. Does quantum entanglement only occur in pairs, or can three or more ...
6
votes
2answers
3k views

Bells Theorem for Dummies, How does it work?

I've been reading up on theoretical physics for a few years now and I feel like I am starting to get an understanding of particle physics, at least as much as you can from Wikipedia pages. One thing ...
0
votes
0answers
46 views

Uncertainty Principle - measuring momentum on one entangled particle, position on the other

If two entangled particles are sent far apart and then at exactly the same time the position of one, and the momentum of the other, is measured, won't this mean that, because the corresponding values ...
0
votes
2answers
67 views

With the quantum entanglement experiment what exactly do they mean by “one particle instantaneously affects the outcome of the other”

It sounds like if you measure the spin of one particle, the other particle immediately registers as the opposite spin without anyone touching the detector. Is this what they mean?
0
votes
2answers
73 views

Successive measurment of incompatible variables on an entangled state

Suppose I have 2 particles in an entangled state with opposite spins far away from each other, both stationary with respect to the lab. At time t=0 I measure the spin of both particles in the x ...
3
votes
1answer
230 views

Some applications of the Einstein-Podolsky-Rosen (EPR) paradox?

If you were to explain the Einstein-Podolsky-Rosen paradox to high school students (age 16, with no particular strength in math), what kind of intuitive example would you provide to make things ...
0
votes
1answer
65 views

A question about entanglement of formation and decomposition

In the answer of this question, the last paragraph says that If you know one decomposition which is optimal for Entanglement of Formation for a given state $\rho$, you can obtain the optimal ...
1
vote
1answer
65 views

Finding all decompositions of mixed states

Some quantities, such as the entanglement of formation, are defined using a quantity that is minimized over all possible decompositions of a mixed state. A closed form can be found for this in some ...
2
votes
1answer
209 views

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, ...
0
votes
2answers
181 views

Calculating states of entangled and disentangled qubits

I'm writing a quantum computer simulator (about 8 qubits) and I know most of the basics (i.e. how to calculate the effect of a quantum gate on a qubit). But I have hit a wall. Is it possible, with ...
1
vote
0answers
41 views

Information loss from entanglement and cosmological horizons?

Suppose we have a qubit P in an unknown quantum state. Unknown as in we didn't prepare it, and don't know how it was prepared either. Without measuring the qubit in any way, we encode it into two ...
1
vote
2answers
64 views

A Quantum Telephone [duplicate]

You are an astronaut, traveling through space, but you ran out of fuel and need to get a hold of Houston immediately. How do you do it? You previously gave Houston one of two quantum particles that ...
-3
votes
1answer
147 views

Quantum entanglement and special relativity PARADOX

Imagine two entangled atomic clocks. After we entangle them, we measure the time: it does has to be the same , right ? Now lets suppose that we entangle them , but don't measure them, then we plant ...
7
votes
2answers
695 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
1answer
254 views

Quantum teleportation and no-communication theorem

According to the Wikipedia article for the No-communication theorem: In very rough terms, the theorem describes a situation that is analogous to two people, each with a radio receiver, listening ...
0
votes
0answers
75 views

Is FTL information transfer possible in an experiment involving entangled particles and an “available” black hole?

We consider the classical entanglement experiments involving Alice and Bob, and their entangled particles. It is proved that nothing that happens at Bob's end has any immediate effect on Alice's ...
7
votes
2answers
387 views

Entanglement and simultaneity

According to the special theory of relativity, distant simultaneity depends on the observer's reference frame. And, according to the quantum theory, in the case of two entangled particles, a measure ...
1
vote
0answers
27 views

Sufficient criterion for su(2) invariant spin-1*spin_s bipartite density matrix

SU(2) invariant spin-1 and spin-S bipartite density matrix is given by $\rho ^{1,S}=\frac1{3*(2S+1)}[1+\alpha {S^A_i\times S^B_i}+\beta S^A_{ij}\times S^B_{ij}]$, i j varies from ...
2
votes
4answers
614 views

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 ...
0
votes
0answers
21 views

Spin statistic in spontaneous parametric down-conversion

In a spontaneous parametric down-conversion a photon will be converted into two photons with half energy and correlated polarization. How the spin from the ingoing photon will be transfered to the ...
1
vote
1answer
68 views

Are quantum-entangled particles affected by relativistic speeds? [duplicate]

In my answer to a recent question on World Building, I suggested that quantum-entangled particles would be a good way for ships traveling at relativistic speeds to communicate. My understanding is ...
1
vote
1answer
52 views

What's the chance that each photon of an entagled photon pair passes through two polarizers?

This is a pretty basic question I think. But it's quite hard to find actual experimental results on the web (or maybe I don't know the right keywords). I'm new to quantum mechanics and want to ...