Quantum Entanglement Communication (QEC)

Quantum entanglement describes a phenomenon where two particles can be measured at the quantum level (position, momentum, spin, polarization) and found to be perfectly correlated, so that measuring the quantum state of one particle reveals the quantum state of the other (regardless of distance).

Entangled particles can further be manufactured. There are several processes to do so, but the most common involves using spontaneous parametric down-conversion, the splitting of one photon into two photons of lower energy using a non-linear crystal. Sustaining entangled photons is difficult, however, so the process needs to be transferred to more stable elements. By repeatedly striking two larger atomic particles with a stream of entangled photons, these two particles atoms can, over time, be brought into an entangled state. And this is where pre-Interstellar thinking broke down.

The theory was that, once entangled, the two particles would continue to influence each other so that when one was acted upon, the other would register the same change. In reality, acting on one particle simply removed it from its entangled state unless, by chance, the action brought the particle full circle back into the entangled state.

The following analogy applies:

I have two 12-hour clocks which are identical in age, design, and state of repair. If I set both to exactly the same time (and maintain them at the same gravitational constant), checking the time on one will reveal the time on the other. If I change the time on one, it will only match the other if I move it 12 hours forward or backward. The clocks show the same time, but they are different clocks.

The advent of the Icarus drive and negative-gravity manipulation changed the paradigm in that space-time could be curved in a concave manner so that a signal could be transmitted through hyperspace in a straight line. The energy requirements for sending such a signal across meaningful distances was, however, prohibitive. It wasn't until of a anywhere but at fold points--which the Federal Fleet only discovered by retrieving FTL communication technology on the homeworld of an extinct alien species--which is why the Fleet's FTL comm network relies on fold point gates to maintain the mercenary boards and the galactic stock and commodity exchange, among other classified systems. Since the Fleet's network is not available for non-Fleet use, a viable FTL communication method was still to be found.

It was only in the mid 500s (interstellar calendar) that the use of quantum entanglement for communication was revisited. By subjecting the trapped particle to an intense NG field (with a similarly intense power requirement) an almost unmeasurably small fold corridor can be forced into existence between two entangled particles, so that "moving the hands on one clock moves the hands on the other, because they are the same clock," as a super artificial intelligence explained to its human colleagues. Because the notion was wrapped up in SAIs' metaphysical concepts, because humans were ill-suited to visualizing 5-dimensional physics, and because the SAIs later tried to exterminate the human species during the Second Interstellar War, the explanation is both distrusted and impossible to contradict.

In the end, it was expensive (both in credits and infrastructure) but it worked.

Quantum entanglement communication devices (QECs) use NG-emitters and large amounts of energy to create a stable low-bandwidth connection between two points. Because they involve negative gravity, they can only be used in space (see the Sydney Accords). Once activated, interruptions in power will result in the destruction of the bridge, requiring another paired QEC to be transported to the two parties.

In around 1200 Interstellar, the Federal Fleet began offering access to a non-QEC Interstellar stock and commodity exchange, as well as a mercenary board for companies in good standing (most notably, the Combine). Nothing is known about how this new FTL network functions, other than it is only made available on planets with Fleet administrative offices and fold point gates. All further information is highly classified, but rumors speak of technology discovered by the Fleet in the ruins of an advanced alien civilization when the Fleet fled into dark space after the Second Interstellar War.