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."

Quantum bytes still decryptable?

[LiquidCoooled]

Wasn't there some news recently that the so called quantum bits could be read without disturbing their state.
Which would either break quantum theory, or would mean they are just fabricated bits of information and not quantum bits at all.

The article was here [slashdot.org]

Que?

[Rhinobird]

A qubyte with eight ions provides a computing matrix of 65536 mostly independent elements.

Wouldn't a qubyte just provide an indeteminate number of somewhere between 0 and 255 zombie cats?

Seriously, how do they get a 16 bit number out of an 8 bit qubyte?

Getting there...

[meringuoid]

... Eight qubits? ISTR that Shor's original quantum error correction code requires nine, and there are simpler codes requiring fewer. We're getting here into a scale where some very interesting features of quantum computation can be demonstrated.

Why eight?

[pubjames]

Why did they choose eight 'bits' for their quantum 'byte'? For historical reasons, or is there a logical reason to choose eight? Why not seven, or 42?

I'm not being entirely frivolous - I understand quantum computing is radically different from today's architectures and so don't understand why they are choosing a byte size based on what seems to me to be historical factors.

Re:Quantum bytes still decryptable?

[LiquidCoooled]

Doesn't Quantum theory say you cannot read the state without disturbing the state?
The act of finding the state of a quantum bit collapses the quantum wave and obtains a result, ie you can find out what the value is now, but that may disturb what the value was going to be leading to possibly incorrect answers.

Qubits as described by modern phsyical science do not sound like true theoretical quantum bits and just sound more like tiny transistors.

Re:Que?

[milimetric]

I've read the posts here and I can point you to one source that I know is accurate, easy to understand and in my opinion beautiful:

N. David Mermin [cornell.edu]

This man is a genius. He can also explain his genius which makes him quite unique. I took a class of his and actually understood some stuff. His basic goal is to explain quantum computation to CS students. More on topic, here's the skinny on qubits:

Chapter 1 of his intro class [cornell.edu]

I really wouldn't do justice to the ease with which he explains things to attempt to summarize, but hey, what's slashdot for:

Basically skip ahead to part C if you want to jump right into it. It helps if you think of Classical bits as vectors in a two dimensional space. (0,1) and (1,0) would represent 0 and 1 as we normally think about them. So then think about Quantum bits (qubits) as (a,b) which is just a superposition of the two classical bits with amplitudes a and b which are complex scalars. The only condition is that the qubit is a unit vector in two dimensional complex vector space, or in short |a|^2 + |b|^2 = 1. Now more to the point of this thread, if you go to section 1..62 you can see that n qubits make up a computational basis (or classical basis). So, the answer is, there's not really anything like simple 0,1 states for qubits. The truth is more complicated but once you start looking at how to take advantage of qubits, a lot more beautiful in my oppinion.

Re:Que?

[tendays]

I was also wondering where this idea that a qubit has four states was coming from. It would be like saying there are four directions on a plane (north west south east) while of course there are an infinite number of them.

Actually I think the confusion comes from the fact that quantum cryptography (key exchange) is only using those four different states mentionned by L0phtpDK (btw that looks more like a password than a username are you sure you didn't swap them? :-)

Re:no word in the article

[mikael]

Have a look at the tutorials at QuBit.org [qubit.org]. The general principle is that the QuBit computer uses constructive interference between the qubits to generate a new state that is closer towards a solution, and eventually reaches a final state. This article describes how to implement Quantum Cryptoanalysis [qubit.org] using a Quantum Fourier Transform.

As an example, imaging the qubits were discs of polarizing glass being rapidly spun by electric motors. You could test the state of each bit by having a set of lasers on one side to a beam of light through the discs to a bunch of light sensors on the other side. Depending on the states detected by the light sensors, the motors are used to adjust the rotation or position the discs. If you get the right feedback system, you will iterate towards whatever solution needed.

The only difference is that the quantum computer would be instantanous.

Re:Why eight?

[cev]

The work presented in the Nature article represents an incremental step towards applied quantum computing. There is no mention of "byte" in the Nature article. I suspect that the use of "byte" in the linked article is an abstraction created by a semi-technical promotional writer.

The primary interest of the result is demonstration of the fidelity of 6, 7, and 8 particle entanglements. No applied computing is done, nor is there any particular reason why they stopped at eight particles except that it appears to be the practical limit of the current engineering.

CV