kochSnowflake wrote:

You can jam a neutrino emission the way you can jam any modulated energy emission; the methodology is no different to radio jamming. You broadcast white noise 'loud' enough to hide the meaningful signal.

If the sun doesn't jam inner system communications, I think it's safe to say that neutrino communications can never be jammed: 50 trillion neutrinos produced by the sun are passed through every human body on Earth, every second.

kochSnowflake wrote:

Poorly chosen example, perhaps; although, given that one of the salient facts about the TITANs is that transhumanity doesn't know what they were capable of, and they definitely had one FTL transport technology - the Pandora gates - early warning sounds like a damn good idea to me! But say you're an AGI share trader on Extropia, trading shares in Venusian hypercorps. Just occasionally, you'll be able to make a killing if your trading partners on Venus can let you know to buy or sell before everyone else knows, even if your time advantage is measured in seconds. It takes the equivalent of an SMS message, no? "SELL ALL (insert several-digit number identifying a hypercorp) NOW". Or say you're a sleeper agent operating in a Jovian habitat. "ACTIVATE CONTINGENCY ALEPH SEVEN". When the engine shows a diagnostic warning on your antimatter courier, talk to tech support and the reactor's designer in instant realtime over IM. The point's not that I think that it can replace or rival conventional comms; QE comms do have niche applications, but ones that are sufficiently interesting and useful that I think people will pay for the expensive production, transport etc. of qubits. That's why the question of where they come from is interesting to consider.

At some point, speed becomes a non-issue. For instance, if I decide to take a trip to the Philippines, I will use my cell phone to send a message to my family denoting that I am on my way. It doesn't matter that there is a time delay for my message equivalent to about 550 milliseconds, because in comparison to the 12 hour trip it'll take me to get there, the message is instantaneous. In the case of something coming from the Earth and heading to the sun, even if it is heading at twice the speed of the fastest Earth ship, it is looking at a travel time of at least weeks, if not months, in contrast to the minutes that the message will take to get there at neutrino speeds. Most of the examples you've given have been emergency scenarios. Forcing a quick sale of bad stock before the knowledge hits the market would probably qualify as an emergency function, as would activating a sleeper agent instantly rather than hours. It perfectly validates one of it's two primary functions, emergency broadcasts. The only other function it perfectly serves, it completely monopolizes... FTL communications are absolutely necessary to communicate from exoplanets, since even the nearest neighboring star will have a time delay of [i]at least[/i] 8 years between transmission and response to the outer edges of the Solar System. However, in the former scenario it does have limitations. For instance, your sleeper agent might be confused why there is a qubit reservoir in his home, or attached to his body, to facilitate the triggering signal. Knowledge of an FTL attack might be worthless if your qubits do not target its destination, or if you do not know its destination in the first place (Pandora gates are also a form of teleportation, and nothing short of jumping through yourself will tell you where the other end is). Remember, QE transmissions are a resource-limited communication system nearly equivalent to a pair of cups on a string... there is only one possible receiver.

kochSnowflake wrote:

I understand the limitations of the technology. I never argued that it replaced neutrino communications. I think we can agree that there are uses for the technology, yes? That people in the EP setting are, in fact, using QE communications? Then they need qubits. My only interest was that, given that they are using the technology, given that they will need qubits, they need to get them from somewhere. When the book makes a fuss of the difficulty in producing and transporting them, I can only assume that the number of sites actually producing them must be relatively low. If the number of qubit factories in the solar system are on the order of 10^1, then the trade routes distributing them become very important, and political control of them becaomes entirely relevant to the setting in general. Yes? If, on the other hand, the number of qubit factories is on the order of, say, 10^5, then the situation is different. You clearly think the technology is irrelevant to the setting at large. For that to be true, there must be widespread qubit production. That kind of implication was what prompted the original question.

Whoa, hold up there. I never, at any point in time, stated that the technology is irrelevant to the setting at large. I have explicitly stated, on multiple occasions throughout this thread, that emergency broadcasts (to a certain degree) and communication from exoplanets require such technology. Even your own examples essentially prove the former. However, I have also stated that it is not a necessity, and not something that is literally so essential to society at large that its trade is essential to function. Most exoplanets colonies, while maintaining communication with the Solar system, are autonomous and are fully self-sustained. No common threats are capable of near-light speed travel, and largest majority of communications don't occur over the vast distances that FTL communications would be useful for anyways. The primary users of qubits (those in control of Pandora gates) likely produce their own reservoirs. Like a few other technologies (quantum computers immediately come to mind), its use is niche enough that demand likely doesn't outstrip supply by any means. It is declared the rarest form of communication for a reason.

Making entangled particles is pretty easy and currently done in hundreds of labs every day. A modern method is to hit an electron in a quantum dot with a laser pulse to produce a photon, which is entangled with the electron (see http://www.computerweekly.com/Articles/2009/10/02/237961/Photonic-machin... ). Another method involves getting the two gamma ray photons emitted in a Cobolt 60 decay. In EP I would guess there are plenty of ways of entangling particles. In fact, there might be ways of entangling any two particles: http://www.springerlink.com/content/rr30r71713313482/ The real trick is to put the entangled particles into conditions that prevent them from interacting with *anything* that can interact with their entangled degrees of freedom (before use). I can imagine something like a nanoscale Penning-trap for antimatter, keeping entangled particles suspended in a magnetic field until use. The qubit factory manufactures these traps and fills them at the same time, hopefully not disrupting the entanglement. Over time some will decay anyway, so during use the device will try to use the next qubit, if it fails it moves to the next one and tries again. Qubit trap stores are likely very dense and shielded blocks of nanocircuitry. They are equivalent in complexity and precision to massive blocks of nanoprocessors. But the real cost is the assembly process, which requires extreme precision nanoassembly that respects entanglement. I think in the long run this might become cheaper, but maintaining the isolation is always going to be a challenge.