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Ansible Design (FTL Communication)

### Modulation of BBO-Entangled Light

Assuming this [Video of Entanglement in Action](https://www.youtube.com/watch?v=wGkx1MUw2TU) is not incorrectly hiding some additional filter operation, it seems (from the video) that you can quite obviously modulate an entangled pair of photons so that a Receiver gets a clear and measurable on/off signal.


### Question
So, assuming this is true, what is the design of an Ansible (FTL communication system)?


### Entangled Photon Pumps
The simplest generator of entangled photons would be a LED ultraviolet (UV) pen laser shining into a Barium Borate (BBO) crystal. The BBO crystal will, mostly, do nothing, and the UV beam will pass through. A small amount of the UV light will be down-converted into two near-infrared photons leaving the crystal at +45 and -45 degrees.

=== . . . BBO <

This is pretty cheap and reliable, not requiring any special technology. 

### Network Setup

One of the entangled beams is sent to Alice and the other entangled beam is sent to Bob. Bob will send and Alice will receive.

Alice <--|-- Pump --> Bob

Since measuring breaks entanglement, if Alice were too close (|) to the Entangled Pair Pump then her action of receiving would break entanglement before Bob has a chance to modulate his half of the beam: No Communication.

Bob modulates. Like we see in the video, Bob agrees vertical will mean (1) and horizontal will mean (0). A long zero will mean the line is idle.

Since Alice needs to receive several entangled photons to clearly identify Bob's modulation (0 or 1). Because she has to wait, the maximum data transmission rate is going to be 1/10th or 1/100th of the number of photons the Pump can produce.

### Performance

Alice <-- Pump --> Bob

Ideally, Alice will just be the tiniest bit further from the Pump than Bob. In that case, both of them are receiving their half of the entangled pair at the same time. In this case, Alice sees the information at the exact time Bob modulates it.

Alice <---|-- Pump --> Bob
        a   b      b

But, it is much more likely that Alice will be further from the pump than the ideal distance. In this case, Bob's photons are at the location (|) when Bob modulates them. That means Alice will see Bob's message a / c seconds after Bob sent it, as measured by some universal stop watch.

### Replies

Alice <---|-- Pump1 --> Bob

Alice <-- Pump2 --|---> Bob

A second pump must be set-up, closer to Alice than Bob, for Alice to be able to send meaningful replies. However, the components are the same, just configured for Alice to be the sender and Bob the receiver.

### Odd Cases

Since Bob and Alice are both manipulating half of an entangled photon pair that was generated hours ago (assuming Alice is on Pluto and Bob on Earth), then communication is not immediately interrupted if Pump1 or Pump2 breaks.