Why the hate on "theoretically"? In the example you gave, they could have removed "Theoretically", and that sentence of the article *would still* have been a correct statement. It's talking about the energy consumption of the processor, not the limitations of the power source. Your suggested substitution ("Not really") would've been wrong.
Provided the qubit state can be transfered to photonic qubits, then it should be possible to scale the entanglement up so that it can involve more than a single nitrogen vacancy "having the entanglement lasts for milliseconds helps in this regard. Furthermore, qubits based on nitrogen vacancies aren't too hard to scale, since it is a solid-state material "no vacuum pumps required, thank you very much. Finally, the longevity of the entanglement should also enable the development of a refreshable quantum RAM.
There are a bunch of different ways to represent a qubit, the fundamental unit of quantum computation. They all have advantages and disadvantages. I myself work with photonic qubits. Using photons it's actually considerably easier to get and hold coherence (high-quality quantum correlations) for as long as you need it than in other representations. But one of the problems with photons* is that they always travel at the speed of light (well der), and while that's great for communication, it's not so good if you actually want to store quantum information somewhere. So finding a good way to keep coherence for a reasonable length of time for something stationary is useful work.
*The other problem with photons is that they are relatively difficult to get to interact with each other. There are only a few situations where there is any appreciable interaction between two photons.
Not the ACB's fault. It's the South Australian Attorney-general that's preventing it. To implement the R18+ rating for games requires all the state and federal attorney-generals to agree, and he's the one bass-ackwards idiot saying no.
I was just discussing entanglement swapping with my supervisor the other day, actually. Neat concept. Roughly, person A has two entangled photons, A1 and A2. Person B has similar, B1 and B2. They both send their 1 photons to C. C entangles A1 and B1 and because of this, A2 and B2 are now entangled. This can then be used to generate a bit of a key.
We were actually discussing it in the context of producing entanglement between ions (good for storage/memory) and photons (good for transmission), since in the real-world it's unlikely actual repeaters will receive photons from both parties at the same time so that the entanglement can be swapped.
If by "conventional" you include the one-time pad, properly used, then quantum cryptography is possible to crack. The issue is that the one-time pad is relatively difficult to use properly.
One of the canonical examples of the power of quantum cryptography, BB84, is basically just a secure way to negotiate between two parties a one-time pad (thus the process called quantum key distribution, QKD). If there is someone listening in as the negotiation takes place, quantum mechanics means that (1) they often get useless information and (2) they often disturb the transmission in a way that can be detected (with exponentially increasing probability).
I'm less familiar with newer quantum crypto strategies (if I've overlooked something, please point me to it), but from my understanding it pretty much boils down to this. Basically, if you can brute-force crack a random string (which is what the result of a one-time pad should produce, arguably), you can crack quantum crypto. But then, if you're cracking random strings you can probably find whatever you like in them.
That's roughly correct, however the caveat to QC is that the end result must be some sort of amalgamation of all the "parallel" runs. I.e. you can't have all your parallel runs produce different outputs, and look at each output independently.
It ties in with superposition. You can know some sort of "final answer" by processing superposition states, but you can't know intermediate answers (or the results of each individual "parallel run") without collapsing the superposition-solution into a single intermediate answer. So, basically, you'll randomly get *one* of all the possible intermediate answers.
That still didn't come out as clear as I'd hoped. QC is tricky stuff.
0F I'd call "wicked cold". I wouldn't call 100F "wicked hot". Just hot. I've lived through 100F days, and worse. Don't know if I'd want to try a 0F day.
But then, I am an Aussie. This might be biased, a bit.;-)
He just said he got screwed as a buyer. It seems PayPal has (or at least had, if they've since changed) pretty poor if any safety net for *either* party.
"Dust particles" aren't single atoms of dust. The definition you're thinking of applies moreso to the physical sciences than any other setting. Whereas here, it seems to be used to mean a very tiny clump of something.
You are (mostly) correct. However, your example is of one relatively simple aspect of quantum mechanics. You haven't even touched on the real meat of quantum mechanics: Superposition, entanglement, action at a distance, wave-particle duality, many worlds interpretation... all that "spooky" junk. I'd like to see an intuitive, understandable explanation of that. Honestly, I would.
Sure. I was confused why Robin would be reporting on science myself until I realised Robyn was a different guy (that was a long while ago now). My reply was just to state the facts; I didn't mean to insinuate that you were putting Robyn down.
I do think Robin could make an amusing science report, though...
I'd like to see you discharge a car battery in a picosecond or less, let alone in a unidirectional single-wavelength coherent beam of infrared light. Good luck with that.
It might not be a whole hell of a lot of energy in total, but it'll still burn a hole through your face.
[N]obody understands QC, and anyone that does can't simplify it for the rest of us
You've just summed up the entirety of quantum physics. Really, it's impossible to simplify it enough for the general public to both know what it means (as in, the behaviours it predicts) and "understand" it in any intuitive way. Hell, most physicists don't understand it in that sense. It just isn't intuitive (for common definitions of the word). So some of the time (probably more than we'd like to admit) we just plug in the math. And it works.
While I agree it seems to be surrounded in hype, and while I'm unfortunately unable to access the paper itself (my university doesn't subscribe to IEEE Transactions on Information Theory, apparently), your comment about evesdroppers seeing the key is without merit. The whole point of quantum cryptography is that by employing superposition and state collapse, a key can be negotiated between two parties with an exponentially high probability that any evesdropper listening in will be detected, due to their back-effect of measuring the communication channel. (I might have muddled the terminology a little, but the concepts are true.) So you shouldn't have to worry about an evesdropper because they will make themselves known just by listening in.
That is exactly the point of quantum cryptography. The cryptographic key is the one time pad, negotiated between two parties, using superposition (and in some cases entanglement) in order to come to agreement on the pad and at the same time detect evesdroppers.
*sigh* Dude, the whole point of the bi-state cat is that both alive and dead is exactly the state the cat ends up in. It's a superposition until you measure it. That's why it's so bizarre. Schrodinger's cat is a zombie.
Slashdot Mirror
Why the hate on "theoretically"? In the example you gave, they could have removed "Theoretically", and that sentence of the article *would still* have been a correct statement. It's talking about the energy consumption of the processor, not the limitations of the power source. Your suggested substitution ("Not really") would've been wrong.
With the money I saved installing free software I could afford hookers!
Thanks, free software! *two thumbs up*
The last paragraph of TFA is notable:
There are a bunch of different ways to represent a qubit, the fundamental unit of quantum computation. They all have advantages and disadvantages. I myself work with photonic qubits. Using photons it's actually considerably easier to get and hold coherence (high-quality quantum correlations) for as long as you need it than in other representations. But one of the problems with photons* is that they always travel at the speed of light (well der), and while that's great for communication, it's not so good if you actually want to store quantum information somewhere. So finding a good way to keep coherence for a reasonable length of time for something stationary is useful work.
*The other problem with photons is that they are relatively difficult to get to interact with each other. There are only a few situations where there is any appreciable interaction between two photons.
Not the ACB's fault. It's the South Australian Attorney-general that's preventing it. To implement the R18+ rating for games requires all the state and federal attorney-generals to agree, and he's the one bass-ackwards idiot saying no.
The point being, of course, that it's a subjective call.
I was just discussing entanglement swapping with my supervisor the other day, actually. Neat concept. Roughly, person A has two entangled photons, A1 and A2. Person B has similar, B1 and B2. They both send their 1 photons to C. C entangles A1 and B1 and because of this, A2 and B2 are now entangled. This can then be used to generate a bit of a key.
We were actually discussing it in the context of producing entanglement between ions (good for storage/memory) and photons (good for transmission), since in the real-world it's unlikely actual repeaters will receive photons from both parties at the same time so that the entanglement can be swapped.
If by "conventional" you include the one-time pad, properly used, then quantum cryptography is possible to crack. The issue is that the one-time pad is relatively difficult to use properly.
One of the canonical examples of the power of quantum cryptography, BB84, is basically just a secure way to negotiate between two parties a one-time pad (thus the process called quantum key distribution, QKD). If there is someone listening in as the negotiation takes place, quantum mechanics means that (1) they often get useless information and (2) they often disturb the transmission in a way that can be detected (with exponentially increasing probability).
I'm less familiar with newer quantum crypto strategies (if I've overlooked something, please point me to it), but from my understanding it pretty much boils down to this. Basically, if you can brute-force crack a random string (which is what the result of a one-time pad should produce, arguably), you can crack quantum crypto. But then, if you're cracking random strings you can probably find whatever you like in them.
That's roughly correct, however the caveat to QC is that the end result must be some sort of amalgamation of all the "parallel" runs. I.e. you can't have all your parallel runs produce different outputs, and look at each output independently.
It ties in with superposition. You can know some sort of "final answer" by processing superposition states, but you can't know intermediate answers (or the results of each individual "parallel run") without collapsing the superposition-solution into a single intermediate answer. So, basically, you'll randomly get *one* of all the possible intermediate answers.
That still didn't come out as clear as I'd hoped. QC is tricky stuff.
0F I'd call "wicked cold". I wouldn't call 100F "wicked hot". Just hot. I've lived through 100F days, and worse. Don't know if I'd want to try a 0F day. But then, I am an Aussie. This might be biased, a bit. ;-)
http://en.wikipedia.org/wiki/Newcastle_earthquake
He just said he got screwed as a buyer. It seems PayPal has (or at least had, if they've since changed) pretty poor if any safety net for *either* party.
"Dust particles" aren't single atoms of dust. The definition you're thinking of applies moreso to the physical sciences than any other setting. Whereas here, it seems to be used to mean a very tiny clump of something.
You are (mostly) correct. However, your example is of one relatively simple aspect of quantum mechanics. You haven't even touched on the real meat of quantum mechanics: Superposition, entanglement, action at a distance, wave-particle duality, many worlds interpretation... all that "spooky" junk. I'd like to see an intuitive, understandable explanation of that. Honestly, I would.
You can make them out of other things. Copper for example: http://www.theregister.co.uk/2007/11/09/nanotube_acronyms/
Sure. I was confused why Robin would be reporting on science myself until I realised Robyn was a different guy (that was a long while ago now). My reply was just to state the facts; I didn't mean to insinuate that you were putting Robyn down.
I do think Robin could make an amusing science report, though...
http://everything2.com/index.pl?node_id=1854217
For the record, http://en.wikipedia.org/wiki/Robyn_Williams is a well respected science journalist in Australia. No, he's not the other guy.
http://en.wikipedia.org/wiki/Will_it_blend
I'd like to see you discharge a car battery in a picosecond or less, let alone in a unidirectional single-wavelength coherent beam of infrared light. Good luck with that.
It might not be a whole hell of a lot of energy in total, but it'll still burn a hole through your face.
While I agree it seems to be surrounded in hype, and while I'm unfortunately unable to access the paper itself (my university doesn't subscribe to IEEE Transactions on Information Theory, apparently), your comment about evesdroppers seeing the key is without merit. The whole point of quantum cryptography is that by employing superposition and state collapse, a key can be negotiated between two parties with an exponentially high probability that any evesdropper listening in will be detected, due to their back-effect of measuring the communication channel. (I might have muddled the terminology a little, but the concepts are true.) So you shouldn't have to worry about an evesdropper because they will make themselves known just by listening in.
But how do you transmit that pad between parties?
That is exactly the point of quantum cryptography. The cryptographic key is the one time pad, negotiated between two parties, using superposition (and in some cases entanglement) in order to come to agreement on the pad and at the same time detect evesdroppers.
*sigh* Dude, the whole point of the bi-state cat is that both alive and dead is exactly the state the cat ends up in. It's a superposition until you measure it. That's why it's so bizarre. Schrodinger's cat is a zombie.
Does the EULA let you *use* it without Windows, though? (Seriously, I'm too lazy to check for myself.)