# Questions about entanglement from a laymen/quantum hobbyist

Please note I am not a physicist I just read every article I can on it, I understand a good amount on it though. But no maths. (currently trying to learn the maths)

By what means can we as humans entangle two particles? How does (just examples are fine) it happen in nature? And I would guess technically there could be a particle in me entangled with a particle in another person; maybe my future wife?

I think the answer to the first is... We make them by shooting a photon at a half silvered mirror and somehow it splits and one bounces off the half silver while the other one leaves and we capture the one, and wait for the other and capture it too. Then measure one and measure the other and see they are the same?

EDIT: One more question. From one of the answers two entangled particles have the same wave function. Does this mean every particle with the same wave function is entangled? Can an electron and photon or any two arbitrary particles or groups of particles(molecules) entangle?

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It doesn't make sense to say that particle 1 has a wavefunction, and particle 2 has a wavefunction. The Schrodinger equation gives the solution for the ONE wavefunction that describes both particles. A wavefunction is a description of the whole system, not each particle individually. For unentangled systems, we can describe the wavefunction of the system as a product of the states of individual particles, but there is still just 1 overall wavefunction. – Kevin Driscoll Apr 10 '13 at 19:25
Maybe this classical wave example will help: Throw a stone in the middle of a quiet pool. Radially spreading waves will start. These are entangled , it means their direction and angle is predetermined by the solution of the fluid equations. There are many waves. While this is going on throw a second stone at another point. Radial waves will start from that point, but they will not be entangled with the first waves because they are the solution of different boundary conditions ( a different point and time).Each wavefront is moving independently of the other wave front. – anna v Apr 11 '13 at 5:11

The answer is more difficult. This is an introductory answer without mathematics.

Entangled photons is a current research topic, trying to entagle more every time. One "easy" way is to allow to deacy a particle into two other particles, altough you would end with 2 entangled particles rather than photons. With matter antimatter anihilation you could have two entagled photons by the mechanism:

$e^+ + e^- \longrightarrow \gamma + \gamma$

The same mechanism would apply in nature.

More entangled photons

In order to have particles (or photons) entagled, they need to have a common wavefunction, that is usually destroyed with measure, or almost any interaction. From here to your future wife its more complicated.

For more in entaglement read Chris J. Isham's Lectures on Quantum Mechanics, Mathematical and Structural Foundations.

Keep learning the maths, as it is foundamental in physics, and for it's understanding.

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And there is no manner to use it to bring information from the future, or teletransport instantly information or matter. With information I refer to comunication, as it sems that the entagled particles know how the other has collapsed. – Angel Joaniquet Tukiainen Apr 10 '13 at 18:42
I edited to post with one more question, please respond too if you would! – KDecker Apr 10 '13 at 18:47
Not the same, but common, different types of particles can be entangled. It's a bit dificould to show without product Hilbert spaces. In principle they could, but keeping the entaglement will be impossibly hard. – Angel Joaniquet Tukiainen Apr 10 '13 at 19:00
And the first, is every particle with the same wave function entangled? Does every matching wave function collapse in the same way when observed in the same way? – KDecker Apr 10 '13 at 19:04
First->No. Second-> No, due the probabilistic nature of quantum mechanics. And I suggest thath you should read the FAQ for how to do the follow up of the answers. – Angel Joaniquet Tukiainen Apr 10 '13 at 19:30