Following of the impulses of an neutron star (in principle!)
A pulsar is born after the death of a star, a supernovae. When the star is collapsing, a small fast rotation pulsar is the small remainder. It collapses to a ball of same ten miles in diameter. Its magnetic field is the reason for the high energetic pulses. pulsar is a star, that has shrink after a supernovae explosion. To a small ball of perhaps 6 miles in diameter. This ball is turning around now very fast. Caused thought is high magnetic field pulses by high energy were send out in space. We can recognize them in optical, radio or x-ray area. How fare away are pulsars in space? You can find 1100 pulsars in a cube of 1000 parsec. One parsec is 3,3 light years. So we can find 10.000 up to 100.000 pulsars in our milky way.
Entanglement
Imagine a pulsar as one giant atom.
The stream of photons, with is coming out on both sides of the pulsar, could be entangled. You can see this by a stimulated atom.
But what is the special with coupled photons? Coupled photons know each other. They know each other, even when the are separated on long distance. If one of this photons changes its polarization the other one will change its one immediately.
So, this can cause data communiction with superluminar velocity. Imagine, just behind a pulsar there is a sun with planets. And, on this planet there are intelligent creatures. How could we measure the polarization of the radiation of a pulsar.
And now, there is the Science fiction story PULSAR CP1199.