It's not just across space, particles can also be entangled across time, both past and future, and there seems to be no limit on the number of particles that can be entangled together. We know how to tune particles together by starting them out in the same time and place, however it may be possible to tune in a time and place without ever having been there before. When we physically travel from point A to point B we are really doing a type of space tuning at the expense of time, but there are probably other ways to go about the transformation.
The electric and magnetic components of an electromagnetic field are possibly just paired forms of time and space.