Entangled Definition and 270 Threads

Are quarks that made up a proton or neutron naturally entangled at all times? If not. When do they lose entanglement or reestablish entanglement? If they are always entangled. How about between two protons/neutrons or more. Are they all entangled?

Hello If I entangle to atoms in close proximity to each other, is there any way I can separate these atoms by a large distance and maintain their entanglement? Thank you.

According to Scientific American June 2011: "A neat experiment in 2003 proved that larger systems, too, can remain entangled when the leakage is reduced or somehow counteracted. Gabriel Aeppli of University College London and his colleagues took a piece of lithium fluoride salt and put it in...

have fullerene molecules (buckyball) been (quantum) entangled yet?

I would find it helpful to have a list of where entangled particles come from (perhaps there is a good internet site with such a list that someone could post?). Along those lines I would like to start and refine such a list of entangled particles, what is entangled and get some feedback on the...

Referring to this paper: http://arxiv.org/abs/quant-ph/0611109 it appears that experiments were performed with correlation effects between entangled particles separated spatially (in the form of TLD cystals). There is funding available for this avenue of research especially in the commercial...

If I give you a black box and two photons go out of it (not necessarily in opposite directions), how can we know if the photons are entangled?

I'll admit I have a very small understanding of this phenomena in general. I read once that entangled particles are emitted as pi mesons decay. What I am unclear about is how do scientists know when to be ready to capture them and how do they contain them? Any help would be much appreciated.

I have been developing an entangled lotto game to simulate a simple Bell gedanken experiment described by David Mermin in his article: "Is the moon there when nobody looks? Reality and the quantum theory" where the polarizations are measured at 120 degree angles. I know this is not possible for...

Allow me to create a scenario and ask questions first, then subsequently make an admission of ignorance. Assume we create a device (the source or repeater) that produces two beams of entangled photons at a steady, pulsing rate. Each beam is focused on a target at a far-away station. The...

I'd like some informed opinion on the following scenario, which in a certain article forms the basis of a controversial claim. Suppose an entangled spin anti-correlated pair of particles are generated by some process. Particle A flies off along the +z direction, particle B along the -z...

Let us say we have a EPR type experiment using entangled electrons. If the two observers have their detectors orientated so that they make correlating detections, then as I understand it, if one observer makes positive detections of electrons with "up spin" then the other observer has to make...

I was trying to search for a similar topic, but as I haven't found one here it goes. Thought experiment: Periodically emitted chain of single photons of non-polarized light is split into two entangled pairs and they are traveling apart from each other. One going toward point A, the other toward...

Isn't it that in entangled electron pair, it's random which side will have up and down spin... the two sides should produce opposite spin but the order is random.. however I'm confused by the following statements: "Recall that when you measure an electron's spin in one direction you...

all right so alice has one atom of the entangled triplet and bob the other two atoms bob is going to always measure in horizontal basis so alice sends a message by measuring in the horizontal basis or vertical when bob measures always in the horizontal basis he will know in what...

Hi, This is my first post here. I have done some reading on quantum mechanics and am curious to know more. I know about the double slit experiment and the interference pattern produced. I have also read of entangled pairs. My main question is: If you have a pair of entangled...

Whenever you read about entangled particles, and how measuring one of them "immediately" changes the other, the problem of faster than light travel is usually dismissed with "o, but you can't use it to transmit information, so it doesn't contradict relativity". However, I think there's a more...

I was wondering, what is the farthest two particles can interact and still become entangled, and what form of interaction would this require, gravitation? Also, would this be assumed the same in regards for the entanglement of macroscopic objects?

I have a question I havnt been able to figure out by reading or googling: If we have an entangled pair of particles, and we measure one, thus collapsing its wavefunction, 'when' does the other particle collapse? 'Instantly' begs the question of 'in which reference frame?' For instance...

I'm an outsider with only casual reading of QM. I have read that with respect to spin, electrons must complete eight 90 degree turns to summersault back to their original state (while you and I require only four such turns). Has this been verified to be the case with entangled electrons as...

Entangled “Frankenstein” Photons Entangled "Frankenstein" Photons David R. Schneider (David@DrChinese.com) Abstract: The H> and V> outputs of a Polarizing Beam Splitter can be combined to restore the original input superposition state, as long as no knowledge is obtained regarding the path...

Hello, I have a state of two registers (A and B) which is in the following form respect to the computational basis: |v> = \frac{1}{N}\sum_{k=0}^{N-1} |k>_A |f(k)>_B I don't know how to prepare this state, it is externally given. I would like to extract the value of f(\hat{x}) for some...

I have been reading quite a bit about bell pairs lately and would like to know about the actual experimental behavior of them. Here is a summary of my current understanding: Take two particles A and B entangled in such a way as the spin of each is opposite to the other, or in other words, a...

Hi, I can't get my head around this question. Homework Statement The Bell state: |\psi\rangle = \frac{1}{\sqrt{2}}\left(|\uparrow_1\rangle|\downarrow_2\rangle +|\downarrow_1\rangle |\uparrow_2\rangle \right) Find the correlation coefficient of the measurement of the spins in the directions...

I want to know if its possible to change (control)the spin up or down of 1 entangled particle so it would be possible to transmit data throughout the universe instantly.

SpectraCat and I have been discussing what happens to entangled photons after encountering a polarizing beamsplitter (PBS). A beer rides on the outcome (in addition to one I already won), so you know I can't let this go. SpectraCats says: collapse of the wave function occurs at the PBS. I...

Yes, I know the thread name sounds like something you might see on the cover of Discover (or sadly, Scientific American these days). Hey, I could have called it: Proof that the future changes the past! Because that is precisely what happens. The subject relates to entanglement swapping. In...

I have read quite a bit on here and elsewhere, but am still coming to terms with pure, mixed, entangled and product states. I know a state is either mixed or pure, but then is engtaglement a sub-class of being mixed? Or a sub-class of being pure? Or is entangled another name for pure? Or...

Alain Aspect's experiment: In the Alain Aspect experiment, the two entangled photons will indeed both go through their respective polarizers. I'm hip with that. I'm also hip with Aspect's diligence in making it a "two-channel" testing apparatus. What I don't understand is why should...

Homework Statement Suppose we define states [0] and [1] be the basis which [0] = (1,0) and [1] = (0,1). There are two things I want to ask. Are the following states product or entangled states? (i) [Xi] = \frac{1}{2} ([00] + [01] + [10] - [11]) (ii) [Xi] = \frac{1}{\sqrt{10}} ([01]...

Homework Statement In a quantum information setting: I'm trying to find a circuit to construct the state \frac1{\sqrt3} \left( |00\rangle + |01\rangle + |11 \rangle \right) The Attempt at a Solution This state is entangled, and so I've been playing with different input states to...

I'm not a physicist but here goes. What happens if you have two entangled electrons A and B. What if B goes against what is probable and collapses onto a star 10 billion light years away traveling away from its "twin" electron back on earth. Would the two electrons still be entangled, even...

We know that if, for example, two particles are entangled in a state like: |Ψ>=a |0>|0> + b |1>|1>, then measuring an observable on only one of the particles it makes the interference dissapear. But isn't it impossible to measure both particles simultaneously in order to maintain the...

Can entangled protons be maintained in a crystal lattice for an indefinite period of time? The following papers seem to support this contention. I need the help of the Forum’s readers to critique this research and the assertions the authors are making. Dr. Francois Fillauxa and Dr Alain...

Hi I've been struggling to understand entanglement for some time now, and find that most explanations assume some basic knowledge that I don't have. Please could somebody help clear up a very basic query for me? If two photons are entangled, and we have no knowledge of their state of...

Everything I've read has said that causality in the universe isn't violated because entangled particles don't transmit information (because measured values are random compliments). All of this spoke about measurement. If entangled atoms are created (such as those 2006 on), can properties...

How does a entangled state evolve in the time?? How can i get the state for 't' arbitrary??

"Einstein's 'Spooky Physics' Gets More Entangled" I wanted to just prompt a discussion about what is happening in this interesting article. Does this mean the information channel is stable for multiple excitations? And can the channel carry classical information? Feel free to point out...

I am a Combat Medic in the US Army and have a few questions to ask. I am not a physicist nor would I pretend to be. I am just a curious mind. I am very new to this so these questions may be very simple. 1. Is it possible to capture an entangled particle? 2. If so can these particles be...

Ok, here's my problem... In the EPR experiment it is described that if entangled particles are required to be able to cancel each others spin's then no mater how far apart these particles are, if one is measured you can instantly infer the state of the other particle. Why would the other...

Say we have two electrons in a spin entangled state about the z-axis |01> + |10>. One electron travels off to our left, the other to our right. The right electron passes through an inhomogeneous magnetic field with gradient solely in the z direction (Stern-Gerlach type), and subsequently...

If you encounter a single particle (photon, electron, etc.) in space, can you perform any measurement that will tell you whether that particle was entangled with another particle just prior to the measurement? More generally, can you determine if a particle is entangled if you know nothing about...

Given the hypothesis that everything that exists came from an original singularity, would it not follow, in physics, that everything is "entangled"? I don't know, maybe I'm way-off here, but somehow it seems plausible.

Can particles that already exist become entangled, or must they arise entangled in order to be entangled? Is there any theory about how entanglement works? When and how was entanglement first observed?

If you run Grover's algorithm on the first qubit of any of the Bell states, does it destroy the entanglement? If not, wouldn't it be a way to communicate faster than light?

Let we have two qubits A and B. First qubit has eigenstates |A0> and |A1>, and second has |B0> and |B1>. Let them be in the entangled state, described with vector c1 * |A0> * |B0> + c2 * |B0> * |B1>| where c1 and c2 are complex numbers with |c1|^2 + |c2|^2 = 1. Then what is density...

Hi! This may be a stupid question, but here goes. Is it possible to do a measurement to determine if a photon's waveform is entangled with another photon? You don't need to know who it's entangled with, and it's all right for the measurement to disrupt the entanglement. If this is...

say an ensemble consisting of N IDENTICAL bipartite systems. The system can be in either of the two situations. A) Two particles in a bipartite system are entangled as |psi>= 1/sqrt(2) ( |00> + |11> ) so the density matrix is rho1 = |psi> <psi| = 1/2 *{1 0 0 1} * {1...

Say we have a BELL state |B00> = cos(a) |00>+ sin(a) |11> then for a (just one) pair of entangled particles, we keep one on location q, the other one in location w; the one in q forms a system Q, the one in w forms W. ( 'x' in a function like |v> x |w> indicates a tensor product)...

what happed to the other, if one entangled particle is "destroyed" if one entangled particle is "destroyed" what is the state of the OTHER particle? Situation 1 two entangled particles, A and B(assume have mass). if A is "destroyed", say it hit a wall :). What happen to the B's...