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First Quantum Byte Created
gila_monster writes "Juice Enews Daily is reporting that the Institute of Quantum Optics and Quantum Information at the University of Innsbruck in Austria has created an entanglement of eight quantum particles, yielding a quantum byte or 'qubyte,' or eight qubits. The formal paper was published in the December 1 issue of Nature. A qubyte with eight ions provides a computing matrix of 65536 mostly independent elements. No word in the article about whether they were able to actually use the qubyte for computing."
The phrase "mostly independent" doesn't sound completely reliable to me in a world where a single 0 or 1 can change the entire meaning of data or functionality of software.
Still, with some engineering experience it's easy to fill in what the article omits. Science moved forward and technology implementations will catch up and find a way to overcome issues like these. In fact, some data mirroring with checksums might already be more than sufficient and quantum particles offer sufficient improvements in data/space ratios that duplication should not be a concern.
Read the post here. It (and a few responses to it) describe why this doesn't violate quantum theory.
Likely they've tried to get as many bits as possible and just now reached eight. Since eight bits are a byte, eight bits are a newsworthy milestone.
Umm... No.
One qubit has four states. So its actualy an 8-qubit integer.
(go through the powers of x^4: 4,16,64,256,1024,4096,16384,65536)
A qubit has an uncountably infinite number of states: choose any two complex numbers A and B such that |A|^2 + |B|^2 = 1, and they define an allowed qubit. On the other hand, when you measure a qubit's state, you can get one of two results: 0 (with probability |A|^2) or 1 (with probability |B|^2).
I can't find the original article, so I don't know where this 2^16 business is coming from, but I assure you that a qubit does not have four states -- the only useful numbers for counting a qubit's number of states are infinity (quantum states) and two (possible measurement results).
If someone can link the paper this comes from, I'd be interested in reading it: I'm doing a MSc in quantum computing right now, so I might be able to decipher the source of this 2^16 stuff.
That doesn't make sense at all.
If a qubit is both 0 and 1 at the same time it allows for precisely 1 state (which is either 'not useful' or 'completely random' depending on your point of view.
To store data you need at least 2 independent states. That still leaves you the problem than you can't store 65536 values in 8 bits.
Quantum cryptography already did get there first.
Real Daleks don't climb stairs - they level the building.
I found this at Caltech, a piece on quantum computers. I've never really taken quantum computation seriously -- it just seemed too far-fetched. If they've really got 8-bits, maybe quantum computing will matter in my lifetime.
From reading the piece, it sounds like we will have some major problems with our current cryptographic systems if quantum computers become available.
http://www.thebricktestament.com/the_law/when_to_
You've kind of answered your own question..
The massive parrallel computation with a single element means you can solve *certain* problems in, for example, 2n instead of 2^n steps. But yes, then you get a bit matrix of answers, and reading them all out takes the same amount of steps as classical computing. But, your only usually intristed in some of the answers, so you can then use another algorithm (eg Deutsch-Jozsa) to read those out, again faster than classically.
So you get a substantial decrease (ofton exponential) in the time taken to solve *cetain* problems. Some of these problems would simply be impossible to solve in any reasonable timescales (eg milennia) using classical algorithms.
You understand this wrong.
A qubit indeed can have one of a continuum of states. For example, if you think of the photon polarisazion, each linear polarization direction corresponds to a distingt state, and then there are the circular and elliptic polarized states as well. Indeed, you can map the states of a qubit onto a sphere (embedded in ordinary 3D space), which is called Bloch sphere. Every point of that sphere corresponds to a (pure) state of the qubit. (Note that the Bloch sphere is not the Hilbert space, but for single qubits, it's IMHO much easier to understand things in the Bloch sphere picture)
Now if you measure, you basically choose a direction on that spere, and you get just one of two results. e.g. if you think of the sphere as Earth's surface, and let's assume you have chosen the direction of the Earth's rotation axis for measurement, then if the state of the qubit (before measurement) is actually the North Pole, you get with certainty one result (which, for obvious reasons, I'll call "North"), and if the state is the South Pole, you get with certainty another result (which I'll now call "South"). However, even if the state is something else, your measurement will never give anything but "North" or "South". The probability to get "North" grows the closer the state is to the North Pole, and equivalently for the South Pole. If the state is at the equator, the probability of getting North or South is the same, i.e. the result of your measurement is completely unpredictable.
Now the funny thing is that after you measured North or South, for an ideal quantum measurement, the state actually is the corresponding Pole, no matter what it was before.
If you map the states described by the article with the Bloch sphere, and say you map the states 0 and 1 to the North and South pole, then the states you named `0 and `1 would be two antipodal states on the equator, say on the zero meridian and on the 180 degree meridian (unlike in the hilbert space, the directions now are not in 45 degrees, but actually orthogonal). That is, if the state is `0 or `1, then any measurement in the north-south direction will give completely unpredictable results. Of course if you choose the direction of the `0 and `1 states (I'll call that the equatorial direction from now on), then those states will create a predictable result, while the North and South pole states will get completely unpredictable results.
Now the nice thing for encryption is that if you don't know if the state was prepared in the North-South direction or the equatorial direction, there's no way for you to know if what you got for a measurement is a prepared state, or just random garbage. Moreover, since measuring in the wrong direction changes the original state (and therefore destroys the information which was originally in there), you'll be able to notice if someone tries to eavesdrop your connection.
The Tao of math: The numbers you can count are not the real numbers.
AFAICT, a byte denotes 8 identifiable positions (not to be confused with states). Each position has traditionally had 2 possible states. If quantum theory allows 4 states per position a qubyte can have 65536 permutation states.
Remembering that you are going to die is the best way I know to avoid the trap of thinking you have something to lose.
Anonymous Coward is on a text based browser right now, so I have to log in to reply. Anyway, here's the philosopher's song: mp3 file.
You crappy mods should listen to it. Maybe it'll help your sense of humour!
Which means there should be a 16 qbit machine by 2025, the 32 qbit machine by 2045... hmm. How unhelpful.
//Information does not want to be free; it wants to breed.
I think we can be sure that if somebody had unlocked the secret of quantum computing there's a chance they'd say so at some point.
Ummm... not quite. There's lots of quantum computing currently being done - 4 qbit computers exist in several places (or can be brought into existance on demand, anyway). Quantum computation requires entanglement and manipulation of entangled bits. Well, the former is the hard part - that's what's been managed here. A major step forward - I recall 6 qbits was the record about a 18 months ago. Entangled bits are quite delicate - so that's the next challange. Now that they can entangle this many bits, they just need to manipulate them. That'll come with time.
"But everyone should know everything." -markab