Quantum Entanglement: Entanglable particles?

[nuiluidwde]

All the scientific documents explaining QE that I have read always refer to the entanglement of photons, and yet some news reports state that ions such as beryllium and magnesium have been entangled (http://www.livescience.com/strangenews/090603-maco-entanglement.html) so that instead of just their spin or polarization being entangled, their movement becomes intrinsically linked, so they will vibrate in opposite directions, for example.

Is this correct, can ions be entangled, and can anyone explain how? Would it mean that atoms could then be entangled, or that even larger things could be, such as compounds, or even something macroscopic like two pure aluminium balls? And can this type of entanglement be used to transfer or split energy between two or more particles?

 

[DrChinese]

All the scientific documents explaining QE that I have read always refer to the entanglement of photons, and yet some news reports state that ions such as beryllium and magnesium have been entangled (http://www.livescience.com/strangenews/090603-maco-entanglement.html) so that instead of just their spin or polarization being entangled, their movement becomes intrinsically linked, so they will vibrate in opposite directions, for example.

Is this correct, can ions be entangled, and can anyone explain how? Would it mean that atoms could then be entangled, or that even larger things could be, such as compounds, or even something macroscopic like two pure aluminium balls? And can this type of entanglement be used to transfer or split energy between two or more particles?

Welcome to PhysicsForums, nuiluidwde!

Conceptually, anything could be entangled. On the other hand, usually entanglement refers to systems of 2 identical particles. Sometimes the system consists of more than 2 particles, and sometimes the particles are not completely identical, but those situations are more complex than is probably worth discussing at this time.

You can have entangled photon pairs (easiest to create), entangled electron pair (harder), or entangled ion pairs (harder still). When a pair of particles are entangled, they can be entangled on one or more observable properties such as spin/polarization, momentum, position, energy. The entangled properties obey the Heisenberg Uncertainty Principle (HUP).

To entangle a pair of particles (or objects), they must be placed in a superposition of states. Essentially, you must not be able to distinguish one from the other. All that you will know is that the combined properties have a particular value, but you will not know that value for either particle. I.e. net momentum is zero, net spin is zero, etc. So measuring an attribute for one immediately tells you the value for the other.

 

[nuiluidwde]

Thanks DrChinese , that explanation was perfect, I feel I understand it quite well now, except for how to put two particles (other than photons) into a superposition, but I guess that's what's being investigated at the moment and the crux of the scientific research.