The other commentator has dealth with QT; it's not yet a really available commercial technology, and it's not even clear that it lets you send data outside of your light cone which might violate causality.
I would like a cite for your bandwidth claim, but remember it's not bandwidth that matters - orders and market data are fairly small packets of data - but latency. The usual problem with radio systems is that you don't have a nice clean signal "edge" that you can recover, you need to apply some processing to the signal. That might be pure analog (heterodyne reciever) or A/D or pure digital (convolve to recover data from QAM). This processing delays the signal.
Our approach is to do all the processing in an FPGA connected to a 10G line. This allows us to use various tricks to start sending the first byte of the trade before the final byte of the market data packet is recieved.
It says "Principal Engineer" on my business cards; I'm a consultant for a small firm.
You mention latency, I know about that and I was not sure if I should've mentioned it, or not, but decided not to. That's because I thought you would know from my writing that I know about latency pretty well.. However, you know that the topology of a system defines if, a system is as strong as it's weakest link. Because I don't know how the latency in the given wireless system is, I can tell you that.
Oh man.. Can't I say anything on HN without having a scientific proof, or what? holy moly... What am I, everyone's slave? Do yourself a favor, just ask politely next time and I will do that, when time allows. But accusing somebody of being a bullshitter, without having any proof yourself, except that your work on HFT stuff is creating an "unfriendly" atmosphere. If being right matters more for you than being helpful, then that's your problem, but it doesn't help to improve the atmosphere in here. And sorry, if you feel attacked or something in any way, it's absolutely not my intention to do that.
My arguments are mostly about the difference between "QT can be done in the lab" versus "QT can be done outside of the lab with commercially available equipment", and also "can QT transmit information faster than c?". The answer to the latter appears to be no: http://physics.stackexchange.com/questions/34653/is-it-possi...
Your argument in all honor, but it doesn't make sense, because I said that "it will be there soon enough for commercial purposes". Again, I didn't say that it's commercially available today for you to sell to your customers.
StackOverflow is not a good source, especially that thread, it is full of bad answers. I've read all of them. The first poster said: "Those quantum states may encode classical information." The poster of the question has obviously no clue about physics and nobody in there mentioned teleportation of quantum entangled states, which you should know, is instant.
Here's a more detailed explanation, if you prefer that:
If you have a particle (such as a photons, electrons, or molecule) and have it physically interact with another particle, and then separate them, the result is that they can then both be described as being in the same quantum mechanical state. Basically, they are now the same, in factors such as position, momentum, spin, polarization, etc.
However, because we are dealing with quantum mechanics, the state of those particles remains undefined until measured (because it would then be forced to assume a specific state).
Now, how does this relate to instant data teleportation, you say? That’s the interesting part. You see, quantum entanglement is a form of quantum superposition (which I talked about in the aforementioned post about some quantum mechanics). This means that each particle that you have can be in any state. (Remember: observing a particle will force it to become a specific state). However, when you observe one of the particles, it will become a certain state, while the other particle becomes the opposite state. The change is completely instantaneous, and the particles can be anywhere — you could have your second particle on the other side of the planet and it would assume an equal and opposite state of it’s entangled counterpart. Instant data transfer.
Say you had a binary bit you wanted to transfer. First, you must entangle the bits. Then, put one of them on the other side of the globe. Observe one of them, forcing it to assume a certain state, and the other will instantly change. Like magic. Source: [1]
Ask me about latency here…
However, you drifted the discussion to QT. My initial post was originally trying to say that data can be transfered wirelessly faster than with a cable, or at least as fast. Latency cannot in such a system cannot be generalized, because it is dependant on the technology in the receiving side. If the receiving side uses optical fiber, you would need an architecture as described in [2].
"If you have a particle (such as a photons, electrons, or molecule) and have it physically interact with another particle, and then separate them, the result is that they can then both be described as being in the same quantum mechanical state. Basically, they are now the same, in factors such as position, momentum, spin, polarization, etc.
However, because we are dealing with quantum mechanics, the state of those particles remains undefined until measured (because it would then be forced to assume a specific state)."
No they are NOT in the same quantum mechanical state at the moment of entanglement. They are, as you said later, undetermined until measurement (or better, until the collapse of the wavefunction). So they are not the same before, unless you accept the completely discredited theory of local hidden variables (cf. Bell's Theorem). They are connected, by the spooky action at a distance, and at the moment of measurement of one, the other will react accordingly. But before that measurement neither are in any state at all.
But at least I've pinpointed the point where you got QT wrong : "Say you had a binary bit you wanted to transfer. First, you must entangle the bits. Then, put one of them on the other side of the globe. Observe one of them, forcing it to assume a certain state, and the other will instantly change. Like magic."
The problem, see, is that, by definition of quantum mechanics, the collapse of the wavefunction is completely random. You can't force a photon to assume the state you want, it'll assume a random state. Then the other photon will indeed assume the symmetrical state. But that's still be the product of the randomness of the first measurement.
In other words, causality has not been violated because no information is transmitted, only randomness. It's like having two connected dices separated by hundred of miles, when you roll a 1, the other rolls a 6, when you roll a 2 the other will roll a 5 etc. So you roll your dice, and you look at it. You got a 4 ! Great. Now you know that somewhere around in the world someone is looking at his own dice and seeing a 3. Did you transmit any kind of information ? No you knew beforehand that the guy would have a symmetrical result. And you can't tell him a message, because it's completely random. How would you say to your friend on the other side of the planet "Hello" ? You just got 5 fours in a row on the dice... Your friend know it. But that has no meaning at all.
Now, of course, you can imagine local hidden variables, that could be read beforehand to influence the result. Or use another way of influencing the result of the wavefunction collapse, so that a message could be transmitted. But that's what I was speaking of when I said that you had first to reinvent the laws of physics. Cause the Bell's theorem and the No Communication Theorem forbid it in the actual understanding of science. Boy I would love to live in an universe where we can so easily violate causality. That would be FUN !
You're talking about old things like Bell's theorem to support your straw man fallacy, but neglect your own saying. States are transmitted instantly and you still misunderstand either willingly or not the possibility of information transmission by this method.
Your words >> "Then the other photon will indeed assume the symmetrical state."
Your causality argument is void, because in no way has this to do with a paradox. That's high-school physics you use to draw the straw man here. You have no references that back your claims and have you even looked at the scientific journals I have sent you? Try to formally disprove those. And I'm all ears again, but here you only defend your position no matter what.
Ok. So I'm doing a strawman... But you're not doing an argument from authority ?
So let's be clear. Bell's theorem is not an "old thing". I mean, what serious scientist argue something like that... (Yep, that's a No true Scotsman ;-) ) I've never encountered any argument in that direction. Of course some people argue against some of the derivations of Bell's theorem, and his test, but against the soundness of the theorem in itself ? For the record : "No physical theory of local hidden variables can ever reproduce all of the predictions of quantum mechanics."
Then people who challenge the consequences of Bell's Theorem, argue for Non Local Hidden Variables (http://arxiv.org/pdf/quant-ph/9906036v1.pdf). But frankly, non locality is not at all in the actual consensus of quantum physicists. It would have huge consequences on special relativity.
So, again, if you want to argue that Non locality is true, welcome to a completely new world of physics. As of today, no one have any proof that non-locality is real. The scientific consensus is that No communication theorem is a much more credible solution to the EPR paradox. I mean of course some people say that proof of NCT are circular. But most only do because they think we can find a better proof of it.
How many serious scientists work on disproving the Non Communication Theorem ? John Cramer ? Some people in his lab ? That's mostly it. And as of today... they found nothing I am aware of.
And then what are your references ? A nature article, published in the vulgarization part of the review and non peer reviewed ? That short blog post that show very limited understanding of the problems with Quantum Entanglement ?
Anyway, if No Com Theorem is false, boy what a world, time traveling become possible, teleportation, several other sci-fi things. That would be great. But probably will never happen.
I would like a cite for your bandwidth claim, but remember it's not bandwidth that matters - orders and market data are fairly small packets of data - but latency. The usual problem with radio systems is that you don't have a nice clean signal "edge" that you can recover, you need to apply some processing to the signal. That might be pure analog (heterodyne reciever) or A/D or pure digital (convolve to recover data from QAM). This processing delays the signal.
Our approach is to do all the processing in an FPGA connected to a 10G line. This allows us to use various tricks to start sending the first byte of the trade before the final byte of the market data packet is recieved.
It says "Principal Engineer" on my business cards; I'm a consultant for a small firm.