Entanglement Definition and 870 Threads

Lets' say you have an entangled pair of electrons with spin up and spin down. What is its eigenvalues.. is it.. Eigenvalue 1: Electron A with spin up Eigenvalue 2: Electron A with spin down Eigenvalue 3: Electron B with spin up Eigenvalue 4: Electron B with spin down But it's supposed to be...

I feel like a ping pong ball on the question of whether or not total energy of a pair of electrons changes when they become entangled or disentangled. I began with a mental model similar to electrons in orbitals. Emit a photon and drop into a lower energy state until reading the ground state...

The below is very amateurish, so please correct/modify where needed. Just curious to know the technicalities i.e. how experiments, involving entanglement, are conducted - from a technical perspective For example - Let's take the Bell's tests Entangled pairs would/could be created via SPCD...

Hello, It's my understanding that the US can control Quantum Entanglement up to a distance of 89 miles. Can this be shielded against, like EMF can be shielded against; and what materials are necessary? Thanks, John

As I understand it, faster than light communication is not possible, but I have a specific example which concludes that it is and I'm trying to find the mistake. The scheme uses two things 1) An entangled Bell pair ## | \phi \rangle = | 0 0 \rangle + | 1 1 \rangle## ( neglecting normalization )...

We can have speed more than light in Quantum entanglement... but i want to know can we improve it with some tests? Are there any tests that can improve that? [mentor's note: this post has been edited to clean up the formatting and remove some unnecessary text]

1. A photon does not experience time, does a photon experience space? (between interactions?) 2. When photon is bound between electron orbital levels it is "stuck" there and hence experiences time? When an electron jumps to a lower orbital it will emit a photon, this photon would then move at...

Hi, I have 16 years old, I am planning to be a physicist in the near future, and I have 3 doubts, could you guys answer to me? 1. Does quantum entanglement proves that everything is connected? http://phys.org/news/2015-01-popper-againbut.html#nRlv 2. 'The Observer Effect' and 'The Uncertainty...

Is it possible, in principle, for an experiment to distinguish between an ensemble of pure states and an ensemble of mixed states? If so, how? In particular, I am thinking of an ensemble of particles whose spin has been measured, one at a time, on the "Vertical" axis. The ensemble consists of...

Hi all, I'm not really seeing why entanglement is such a big deal, if total spin was 0 and the particles it creates can only have spin 1/2 and spin +1/2 then if one is down the other must be up, so they have spins designated at birth so to speak, what makes us think they don't have spin till...

In my thought experiment (it seems that others have asked a similar question, but I have a more specific question in my list below), we have a physicist outside the event horizon of a black hole. He has many entangled particles and sends some into the black hole. Is / Could there be some...

Hi guys, a dumb chemist here. There is a paper http://arxiv.org/abs/1412.4007 by David Edward Bruschi. It stirred some interest between my Polish colleagues and friends, but none of us is skilled enough to understand the details, so we prefer to see it discussed by others.

During entanglement photons get into an indeterminate state. The outcome of the photon state, on measurement, would now be random. Does this mean that, some of the, information the striking photon was carrying prior to transferring its energy to two entangled photons irretrievably lost? Even...

I have a quick question about what is going on with the following scenario: There are three planets: A, B, and C. They are arranged in the following manner: A is 4 light years away from B and 2 light years from C; the distance between B and C is 3 light years. Now suppose that there are two...

http://www.bbc.co.uk/programmes/b04v85cj I searched in this forum and no one has mentioned this. What are the thoughts of general physicists regarding Al-khalili presentation how the robin bird eyes use quantum entanglement? Searching at the net producing the following...

Hi there. I have spent most of today reading and researching entanglement. Most website say something along the lines of if one photon has been observed to have a spin state of up, the entangled pair will automatically become spin down. They also say that if you change of interfere with one...

I would like to create entangled photons at radiowave frequencies. To do this I thought it might help to understand as much details as possible how entangled photons are created by parametric down-conversion. Since the down-conversion doesn't happen often, what are the special conditions? Are...

I've been studying Bell's theorem out of curiosity tonight after watching a BBC documentary about quantum mechanics (The secret of quantum physics - 1. Einsteins nightmare). The episode ended on Bell's theorem disproving locality and showing Einstein to be wrong. So I went and did a little...

I am at odds over how Hawking Radiation can cause a problem with entanglement - or even how the pair particle to a Hawking particle can enter a black hole. The notion behind Hawking Radiation, as I understand it, is that a particle divides above the event horizon creating two entangled...

Homework Statement Determine which qubits are entangled: ##|\psi\rangle=\frac{1}{2}(|000\rangle+i|010\rangle+i|101\rangle-|111\rangle)## Homework EquationsThe Attempt at a Solution [/B] My idea was to first calculate the density operator ##\rho = |\psi\rangle \langle\psi|## and then find...

I am trying to read some of the experiments on entanglement. Is the pair of photons or electrons created by a laser hitting crystal? If this is so, then a pair of particles emerges? If this is also so, what is the big deal where the measurement occurs? The particles are created together at...

Hi, I have some general questions on Quantum Entanglement? 1. Is there a maximum distance between the two objects before it does not work? 2. Has it actually been proven/tested? If so can anybody provide some further information on this? Thanks, Ward

If one of two entangled particles passes the event horizon of a black hole, will the entanglement still exist? Because that would mean information can come from a black hole.

I have read that one particle's state responds to the partner's measured state, and this can occur billions of miles away. Since we can not conduct the experiment "billions of miles away", how have physicists come to the conclusion about the apparent limitless distance for this action? What...

I have been thinking about this recently. Say two quantum particles, or two clusters of quantum particles, exist in the same universe. 1 is on, for lack of a better term, one side of the universe, one on the other. They are entangled. Because of the distance between them, one is in the...

Homework Statement With respect to the Rarity-Tapster experiment which shows the interference pattern of photons as support for the idea of quantum entanglement...what would the graph look like if these photons behaved like ordinary Newtonian particles? Homework Equations There is a graph...

I would like to know if the density matrix spectrum is always discrete or if it is possible it has a continuum spectrum. It is clear that a pure density matrix has a discrete spectrum but it is not obvious in general. I have heard that all compact operator has discrete eigenvalues and if it has...

I would like some help understanding some parts of spontaneous parametric down conversion (SPDC).In the Wikipedia article on the topic…http://en.wikipedia.org/wiki/Spontaneous_parametric_down-conversion…the third figure from the top is labeled “An SPDC scheme with the Type II output”. The figure...

I learned the principles of quantum physics and the basic mathematical techniques quite some time ago. The only discussion of quantum entanglement concerned the EPR paper. There have been many advances in the field since that time, including the somewhat mysterious phenomenon of quantum...

Disclaimer, I'm no scientists, and i know enough to get my self into trouble, however Every time i hear about quantum or quantum computers or such, and its experimental data, its never proved in my mind that the particles where ever in superposition (if that's the tight terminology). every now...

Hi everyone I am working on entanglement between an atomic system and its spontaneous emission but I don't know how to connect this kind of entanglement with quantum computation, I have read in different articles that entanglement is somehow essential in applications like quantum communication...

When the two polarizers are set 60 degrees apart, for example, QM prediction is 25% correlation. It is already different than what is believed to be classical or "expected" result. So what is the point of testing more than one angle in a single experiment? And what difference does it make when...

Do you know if there are experiments on particles having interacted which illustrate the Neumark dilation theorem?

If I had a factory that produces pairs of gloves. And I packed one box with the left glove and another with the right. Then I sent the first box to the north pole and the second to the south pole. Now I have no idea which box contains which glove, When sending the identical boxes to their...

In its broadest sense, quantum entanglement means that two 'particles' separated by distance, and moving away from one another, behave as if they are next to one another. In a mental experiment, you can imagine what the world might look like to these two particles as they zoom away from one...

What is Quantum Entanglement, and what does it do? I attempted at learning via online articles.

One theory I've heard and which I find interesting is that entanglement between any pair of two-state systems could be explained deterministically by a spacelike connection which can only communicate something relative, like a phase difference, and which is essentially holding the ends...

my question is about the no-communication theorem in quantum mechanics: Assume that i have a pair of entangled photons which are entangled on their polarization. also assume that i send one to alice and another to bob. and alice wants to send a message to bob. no communication theorem states...

I understand that 'roughness' in the universe is explained by inflation, because quantum fluctuations in density get separated farther than their Hubble sphere--far than any influence (distance greater than speed of light) between them. Some areas by quantum chance have higher density and can...

Depending on who one asks and their interpretation of QM, entanglement seems to be either: a) No problem at all. It's just a matter of information. If you knew one entangled electron was spin up, then the other must have been spin down by inference of the prepared state of the system. b)...

Quantum entanglement is a concept that has captured my imagination and has intrigued me very much in the past few years in which I've become interested in quantum physics. Immediately upon reading about it for the first time, I realized that quantum entanglement could be applied in a new...

Pardon my wording as I do not have a solid background in physics, while pondering The effects of observation on a particle changing its state upon observation, and the "theory" that the particle in question went back in time to change its state, My idea or hypothesis on this was that it might...

If I observe two particles that are entangled enter two different black holes and wait, will there eventually be 2 entangled photons radiating out of the black holes or do the black holes take possession of the entanglement as the 2 particles enter their respective black holes and said black...

I have a couple of questions about entanglement and decoherence! 1. Sometimes you read that, strictly speaking, all electrons are entangled with one another. But can that be right?! Isn't it at least the case that electrons have to have interacted with one another in the past in order to...

... for a dissertation in the final year of a physics degree? Over the summer we will be presented with a number of projects for our final year, we have been told that we may be allowed to choose our own if it is suitable. I have a genuine interest in quantum entanglement and was wondering if...

I am a law student and have no training whatsoever with regard to quantum mechanics, and I have been struggling to wrap my head around quantum entanglement in particular. I've been trying to find videos which would explain exactly what would occur in the following scenario, which I believe is...

The concepts of general relativity seem to fit (sorta) well with quantum physics, but how does the quantum world fit with general relativity? Specifically, I'm wondering if entanglement has any grounds that you can derive from GR?

I have a question on the tension between special relativity and quantum mechanics, so please correct the category if this question is in the wrong location. I was looking at the write-up of an experiment: “Causality, relativity and quantum correlation experiments with moving reference frames”...

Hi all! I am currently reading a review "Area law for the entanglement entropy" by Eisert, Cramer and Plenio (2010). From what I understand: 1. In one dimension, for local gapped models, we have an area law for entanglement entropy. 2. In one dimension, some models with long range...

This idea is brought on by this paper: http://arxiv.org/abs/1210.5646 and the idea proposed by Asher Peres: http://arxiv.org/abs/quant-ph/9904042 is it possible to have delayed choice multi-entanglement swapping? i.e. create four pairs of photons – 1+2, 3+4, 5+6 and 7+8. Measure photons 1...