The Entanglement device is a means of faster-than-light communication that is instantaneous, but only works at very low bandwidths.  First invented by the legendary engineer, Kroah Dashan, the entanglement device works on the same principal as the star-gate, but at much smaller scales.

Few Entanglement Devices are made, because they have a mass and a cost approaching that of a star-gate, while only allowing a very limited amount of information to pass through.  Like star-gates, entanglement devices operate only in pairs constructed together, and then separated after activation. 

The Empire of 1,000,000 Suns only made limited use of entanglement devices, using them mainly for large-scale coordination of naval fleets.  The Planetary League made more extensive use of them, typically placing a small number per colony as part of a communication network.  Even with the instant speed of the entanglement device, communications were still slow due to the low bandwidth.  Because of this, Gazillion, inc.  made a lot of money with its own parallel network of entanglement devices built in corporate outposts near Planetary League colonies.  The Holy Empire of Man largely abandoned this technology because of its anti-intellectual culture.  In Era-3, the Galactic Republic improved the design, allowing for higher bandwidth, smaller size, and lower cost.  Consequently,  Entanglement devices became much more widely used during Era-3.

Clock Pulsers

A special application of entanglement device technology is the Clock Pulser which was invented during Era-1 in the Gazillion Corporate State.  The only information this device can receive is a single bit that pulses at a regular rate, connected to a remote timing device.  Because the clock pulser operates through the action of a fluctuating quantum field, it allows for the synchronization of timepieces, even in places with intense gravitational fields, or on high-speed spacecraft (where the pulsers appear to change speed, but are able to maintain synchronization).  Clock pulsers are all cubes, one meter on a side, weighing about twenty metric tons, because of the unique physics, and exotic matter needed to make them work.  The Planetary League operated a galaxy-spanning network of these devices synchronized to a hyper-accurate atomic clock on Earth.  This was the basis of the Galactic Standard Calendar, the standard time-keeping scheme of the League.  All colonies of the Planetary League, and most capital ships had at least one of these devices in order to maintain proper timekeeping.

Clock pulsers do not work in hyperspace; however, and when a ship with a spatial compression device emerges from higher dimensions, it needs to re-synchronize its clock with a local timekeeping source.  Occasionally, especially if the ship has been through a hyperspace storm, the ship will arrive at a point in time that was unexpected at the outset of the journey.  This seems to be related to the phenomenon of cosmic drift.