Entanglement Definition and 870 Threads

I thought there were already some posts about this, but I can't find them.:frown: In this article of Anton Zeilinger et al. they perform an experiment which suggests FTL or retrocausal influence. Alice and Bob both produce their own polarisation-entangled photon pair, both send one photon of...

I've tried to find a relevant thread to post this in, but all seem to be way above my knowledge level and / or are very old. Perhaps this is not even the correct forum because my question assumes there is entanglement and we've also found a way to utilize it.. Anyway, I just read this article...

If we have 2 particles A and B with entangled spins like in the EPR case. we know by the pauli matrices that there is an uncertainty relation between the x and z spin direction for example so what happens if we Alice measures the spin in the x direction while simultaneously Bob measures the spin...

I'm slighting confused about the experiments which try to prove that Bell's Inequality is violated. Here's what would satisfy me that Bell's Inequality has been violated: we measure the spin of a photon and its entangled pair at time 1, then at time 2 we change the spin on photon 1 and measure...

Why does this whole quantum entanglement thing impress anybody? When you look at articles in the lay press, they tell you that there is an "instantaneous" communication from one particle to another. But as these posts clearly show, there is no communication involved at all. There is just this...

Hello everyone. Today I was pondering quantum mechanical phenomenon, and I was focusing on quantum entanglement specifically. I came up with an interesting theory - and while it has no mathematical proof or possible way of experimenting with it - I still want to hear what you guys have to say...

Hi, I have some questions concerning entanglement. 1. If it's possible (theoretically) to simultaneously measure both entangled particles. Then what will the measurements give? 2. The wave function is supposed to hold the info about both entangled particles...it's a superposition. When you...

Quantum Communication. All systems described by quantum mechanics can display so-called entanglement, for example, the spin of one electron cannot be known in advance of a measurement yet will be perfectly correlated with the other, even if it is in a distant location. This has recently been...

Hi, Can two free electrons in a vacuum become entangled as a result of a collision between the two? I have seen examples of electrons being entangled when bonded to atoms and in other circumstances, but not in this case. Can anybody shed some light on this topic? And, more...

Comments, please: http://www.nature.com/nature/journal/vaop/ncurrent/full/nature15759.html Loophole-free Bell inequality violation using electron spins separated by 1.3 kilometres B. Hensen, H. Bernien, A. E. Dréau, A. Reiserer, N. Kalb, M. S. Blok, J. Ruitenberg, R. F. L...

How does many worlds reconcile with entanglement? Is it just that in one world the particles were up/down, and in another world they were down/up?

Imagine that one has a single photon of 632nm. It enters the back end of an open-ended HeNe laser tube - one with no mirrors - and along its path, causes the emission of another photon. According to the wikipedia entry on stimulated emission (https://en.wikipedia.org/wiki/Stimulated_emission)...

When interpreting the results of the two channel Bell test, I believe there were roughly 40 nanoseconds between when the particles were created and when they hit the polarized lens. It is believed that sometime during this time information passes between the entangled photons so that they match...

Hi This is my first post and I have come here as I cannot find an answer anywhere else. So, my physics knowledge is limited to what I learned in High School, supplemented with the odd bit of further reading via books and the internet. However, many of the concepts I learned about I find...

What I understood from Quantum Entanglement (QE), is that measuring the spin of one of two entangled particles in one location gives the spin of the other particle in other location no matter how far is the later. What I can also understand is that the same concept is applicable in the classical...

I know this is a strange request; I certainly hope not unwelcomed here. I am not a physicist or a student of such, I'm just a humble tattoo artist in need of two equations - as I have a client that wants these equations designed into a piece: 1) the/an equation explaining the entanglement of...

When two photons' spins are entangled, measuring one spin gives you the spin of the other. My question is, after one of the particles is measured, does it still retain its entanglement? Could you keep measuring photon A's spin to get photon B's spin?

If two parties share some entangled state, one party accelerates. Does that affect the joint state? This is coming from quantum information theory's point of view. I remember there were some pure states that becomes mixed states under acceleration (or vice versa). I wonder what happens if half...

I think entanglement swapping shows the difference between measurement and observation. A measurement isn't as important as observation at least to subatomic particles. Here's some key points...

When the spin of an entanglement particle is established, it is said that the corresponding spin of its entangled twin is revealed immediately, (via wave collapse?), and that this interaction can occur across a substantial distance. It has also been said that this immediate interaction can occur...

i have a doubt, can quantum entanglement be our future source of sending signals to space without waiting a lot of light years to reach? please someone explain how quantum entanglement works in space and particles.

Although there are numerous questions about entanglement and FTL communication, I can't find anything directly related to this. I proposed a method for FTL communication via GHZ multi-particle entanglement at...

I am not a physicist but felt compelled to create an account to pose a question/idea. Don't beat me up over this please... I was reading on Quantum Entanglement and how entangled particles seem to pass information between them at "faster than light" speeds. Now, given that entanglement is an...

Does anyone know of QM notes (or a review article) that covers entanglement, the measurement problem, Bell inequalities, decoherence, or the delayed choice experiment (or the more recent mesoscopic experiments). So to speak the more modern and the exciting aspects of QM. I think closest to that...

Two particles cannot be entangled in respect to position and momentum, I've read. But can particles be entangled by all other properties, including either position or momentum? For example by energy, momentum, spin and polarization (+some other(s)?) between two photons. I've read in some other...

Suppose I have an apparatus A that is entangled with apparatus B. In my reference frame, I observe apparatus A, which simultaneously causes apparatus B to do its thing. However, because there exists a reference frame where apparatus B does its thing before apparatus A, it follows that there...

jfizzix submitted a new PF Insights post Measuring Quantum Entanglement? Continue reading the Original PF Insights Post.

Consider the problem of computing the entanglement entropy of two CFTs in the thermofield double state on identical finite intervals in 1+1 dimensions. The Euclidean path integral is then equivalent to computing the 2-point twist correlator on a torus. Given a central charge ##c##, does anyone...

I am trying to understand the mathematics of quantum eraser experiments, in order to deepen my understanding of what is really happening. The paper I am currently working on is: "A double-slit quantum eraser" by S. P. Walborn, M. O. Terra Cunha, S. Padua, and C. H. Monken (2001) in which a...

There's a somehow related set of issues I find myself pondering time and again: In 1995, Ted Jacobson derived Einstein's equations from thermodynamics across a horizon. Roughly, he showed that if the horizon's entropy is given by the Bekenstein-Hawking formula, then the second law of...

Hi guys. I'm studying an article on the measurements of entanglement in a pure bipartite state. I don't understand the definition of the Schmidt rank. It is equal to the rank of the reduced density matrix, isn't it? Is the Schmidt rank continuous and/or additive? I have no found on the net any...

This is a physics question but since it is on a 'universal' scale, I will ask it here. Quantum entanglement. I was watching a panel discussion with Leonard Suskind and others leading theoretical physicists...also watched a Nova program presented by David Green, etc. In both there was a...

enangle 2 electrons. Capture 1 electron by using this method http://news.discovery.com/tech/photo-first-lights-captured-as-both-particle-and-wave-150302.htm. Send an electron from Earth to the moon. Have an detector on the moon that measure a property of entanglement and same with on earth...

as a new proposal for QGhttp://arxiv.org/abs/1502.05385 Tensor network renormalization yields the multi-scale entanglement renormalization ansatz Glen Evenbly, Guifre Vidal (Submitted on 18 Feb 2015) We show how to build a multi-scale entanglement renormalization ansatz (MERA) representation of...

In the context of a photon entaglement experiment, let the observer be in the frame of reference of photon "a". Photon "a" starts its travel to Alice with a relative speed to her = C. If SR holds, photon "b" cannot be moved at all in the opposite direction, when "a" arrives at Alice. And vice...

I read the following in the April copy of Sci-Am in the article on Firewall: "It is a further consequence of quantum theory that a particle can be fully entangled only with one other: if particle B is entangled with particle A, then it cannot also be entangled with particle C. Entanglement is...

Not to repeat what is already said, my thoughts are more or less the 4 points mentioned here: http://physics.stackexchange.com/questions/132007/quantum-entanglement-an-illusion-based-on-a-wrong-assumption The upvoted answer to what gpgemini's said is that this assumption is essentially what...

Can two entangled particles communicate or tell the other particle which quantum state it sould go in if one particle is in a black hole and if so can they communicate if both are inside a black hole?

http://www.engadget.com/2015/03/30/spooky-experiment-proves-quantum-entanglement-is-real/ what is the best way to understand entanglement ? I just want to know your opinions on the subject, because I'm a bit confused There are people who say that "must be some another dimension in which...

Hi guys! I have an unsolved problem. I'm going to calculate the concurrence for pure 2-qubit states: |Ψ>=a| up up >+b|up down> +c|down up> +d | down down > where up and down stay for uparrow and downarrow. The concurrence is defined as: C = 2|ad-bc|≥0 I have found the vector Ψ3= 1/2 (1,1, cos...

The EPR paradox is often described this way: (from Wikipedia) A common presentation of the paradox is as follows: two particles interact and fly off in opposite directions. Even when the particles are so far apart that any classical interaction would be impossible (see principle of locality), a...

Hello, I'm trying to better understand entanglement in the context of measurements and interactions. (1.) Are uncertainty and entanglement linked together? Are the eigenstates of an observable entangled since a measurement of one of them collapses the wavefunction to a single eigenstate, making...

For a system consisting of multiple components, say, a spin chain consisting ofN≥3spins, people sometimes use the so-called geometric measure of entanglement. It is related to the inner product between the wave function and a simple tensor product wave function. But it seems that none used this...

Can quantum tunneling or entanglement can be used for achieving faster than light , If so then How?

i suppose an entangled source one arm is sent to a double slit the other to a polarizer. I read in another thread that the entangled photon does not produce interferences through the slits. What if i put on the other arm a polarizer before the first photon reach the slit? Because of...

Hi All, First, the context for this question can be found in Wilde's Quantum Shannon Theory text on the arXiv, specifically the section starting at the bottom of page 98, entitled "Entanglement in the CHSH Game". My particular question relates to Exercise 3.5.11 on page 100 of the same...

I'd like to understand the math of how something specific in the environment (like photons) can be said to be entangled with a system (like dust particles). Im reading a newbie friendly intro to superposition and entanglement "Home of the Wave Function"... I'd like to visualize entanglement...

A friend of mine, which is not a physicist , told me in a physics class that the moviment could be an illusion, and only time could be real, due to the 'quantum entanglement' experiment, do you guys know what did he mean by that?

Forgive the layman type question but I was doing some reading on Bell's inequality and how it disproves the hidden variable hypothesis in entanglement. The example I looked at was from YouTube I understand the principle of how bell's theorem works and how the tests done on polarisation of...

Is quantum entanglement described in the second quantization procedure of QFT? Or is entanglement only part of the first quantization procedure of quantum mechanics? [Mentor's note - Edited to remove personal speculation]