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Researchers Create Silicon-Based Quantum Bit

samzenpus posted about 2 years ago | from the size-matters-not dept.

Hardware 46

angry tapir writes "Researchers at the University of New South Wales in Australia have created the world's first working quantum bit based on a single atom in silicon. The research team was able to both read and write information using the spin, or magnetic orientation, of an electron bound to a single phosphorous atom embedded in a silicon chip. In February, UNSW researchers revealed they had successfully created a single-atom transistor using a single phosphorous atom in a silicon crystal."

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ONLY A BIT ?? (1, Funny)

Anonymous Coward | about 2 years ago | (#41396911)

Seems like a bit of waste !!

Re:ONLY A BIT ?? (3, Insightful)

Anonymous Coward | about 2 years ago | (#41396975)

so did a single vacuum tube when that was first invented...

Re:ONLY A BIT ?? (1)

mcgrew (92797) | about 2 years ago | (#41398705)

The difference being that you can't do anything with a single bit, although this will of course lead to better things, but a single vaccuum tube, a diode, wire, and a speaker will make a radio (without the tube you need headphones). A single vaccuum tube is an amplifier..

Re:ONLY A BIT ?? (2)

Chris Burke (6130) | about 2 years ago | (#41402335)

A single vaccuum tube is an amplifier.

So's a single transistor.

Both become "bits" only when you choose to interpret their outputs as binary.

Re:ONLY A BIT ?? (1)

mcgrew (92797) | more than 2 years ago | (#41410415)

I'm not talking about bits, I'm talking about sound amplification. You can hook an input to a tube's cathode, a speaker to its anode, a power source to its heater, and it will amplify the input. You need at least two transistors to do that.

Re:ONLY A BIT ?? (1)

Chris Burke (6130) | more than 2 years ago | (#41415021)

Ah, so saying "bit" was a typo. Okay. Anyway, you only need one transistor to make a linear amplifier.

Re:ONLY A BIT ?? (1)

slashmydots (2189826) | about 2 years ago | (#41398107)

Not necessarily but it begs the question, has anyone gotten one of these to "go fast" yet? They're supposed to be some kind of magical unlimited 2-state ultimate binary data processing device. I think I heard that got one to add like 1 + 1 or something but has anyone else gotten one to run at like an equivilant of 1GHz yet?

Re:ONLY A BIT ?? (0)

Anonymous Coward | about 2 years ago | (#41399865)

Quantum computers aren't intended for general purpose computing or math operations (in fact, they need classical computers to complete many of their algorithms). There are a few specific algorithms where they are in a whole different complexity class than classical computers. In many of those cases, they could run at 1 Hz and still be faster than some future 10 GHz classical cpu, although only for specific algorithms. What is needed is not speed, but ability to handle enough bits to work with real world data.

Re:ONLY A BIT ?? (1)

stairmaster (2652939) | about 2 years ago | (#41403363)

Quantum computers aren't intended for general purpose computing or math operations

Not entirely true. There is a lot of work being done on general purpose quantum computing architectures at the moment. In fact there are already some quantum compilers out there such as http://tph.tuwien.ac.at/~oemer/qcl.html [tuwien.ac.at] . Also, a number of algorithms do actually require math operations to be performed by the quantum processor. Remember that measuring a qubit collapses its wavefunction so it is often important to do math operations on qubits before they are measured.

hmmmm.... (-1)

Anonymous Coward | about 2 years ago | (#41396925)

Thinking Breasts !

Spin direction (0)

Anonymous Coward | about 2 years ago | (#41396957)

Was it spinning counter-clockwise?

Bit not a Qubit (4, Informative)

Big Hairy Ian (1155547) | about 2 years ago | (#41396973)

All this demonstrates is the ability to store 1 bit of information at the atomic level not a Qubit which can be in multiple states at once due to quantum entanglement. This is like heralding the dawn of the computer age by promoting a mechanical calculator.

Re:Bit not a Qubit (5, Informative)

hweimer (709734) | about 2 years ago | (#41397001)

They show relatively clear Rabi oscillations [wikipedia.org] , which are a definite proof of the quantumness of the evolution of their system (which has nothing to do with entanglement). So, yes, this is a genuine qubit, albeit not a perfect one.

Re:Bit not a Qubit (0)

Anonymous Coward | about 2 years ago | (#41397093)

Oh, if only thee were a smidgen more evolved. Mayhaps the emergence of mechanical calculation would have then heralded the dawn of the mental age -- instead it heralded the computer age. Ye I'll visit again, when 'tis realized that a sufficiently complex calculation is indistinguishable from sentience. Until then you're all still as primitive as your hairier ape brethren.

Re:Bit not a Qubit (5, Funny)

Anonymous Coward | about 2 years ago | (#41397121)

No, they've demonstrated a single Qubit.

TFS makes things mucky by mentioning single electron transistors too, which are a completely different beast.

The problem with quantum computing isn't demonstrating single qubits though. The problem is in getting a reasonable number in a superposition. Most I've ever seen in a QC that actually does computations is 7 qubits.

Just to get an idea of the scale we need, Shor's algorithm, the one which we could use to crack RSA encryption in polynomial time, needs 2*N qubits minimum. So to crack RSA1024 we'd need 2048 qubits all in a state of superposition.

I'm of the opinion adding more qubits to a superposition is going to be an exponentially hard problem.

Re:Bit not a Qubit (1, Interesting)

hweimer (709734) | about 2 years ago | (#41402667)

I'm of the opinion adding more qubits to a superposition is going to be an exponentially hard problem.

History tells otherwise. [quantenblog.net]

Re:Bit not a Qubit (2)

js33 (1077193) | about 2 years ago | (#41403951)

... based on a grand total of seven data points, and not controlled for the amount of resources that went into achieving an ever-so-brief superposition of, so far, no more than 14 or 15 qubits. The article you linked is very appropriately and clearly not much more than a scientifically excited suggestion that the growing number of qubits is in an exponential trend, and a guess at what might happen if the assumed trend should continue. You've got nerve to say "History tells otherwise." "History" also tells us that AAPL's stock price has reached escape velocity, and it will never return to earth, because all the analysts tell us that soon we'll all be incredibly wealthy and lining up around the block to spend 30% of our income on a mortgage for our next iPhone. Not saying it's impossible, but in either case, past performance in no guarantee of future returns, as that author was careful to note.

Re:Bit not a Qubit (1)

gruntkowski (1743014) | about 2 years ago | (#41397189)

quantum entanglement != superposition

Re:Bit not a Qubit (1)

Shavano (2541114) | about 2 years ago | (#41397863)

But representing n bit numbers is.

Re:Bit not a Qubit (0)

Anonymous Coward | about 2 years ago | (#41401845)

Entanglement does involve superposition of states. If you are doing the basic Alice gets either state X or state Y, and Bob gets the opposite, then entanglement is the superposition of Alice:X & Bob:Y with Alice:Y & Bob:X.

But they are not synonymous, as there superposition is a much broader category of effects than just quantum entanglement. The original poster probably did mean superposition of states, although to be a useful to quantum computing, it needs quantum entanglement of more than one bit too.

Re:Bit not a Qubit (1)

Bigby (659157) | about 2 years ago | (#41397961)

So at some level we will be able to store more than off/on information? How many states can we expect? 3? 10?

Re:Bit not a Qubit (1)

jbo5112 (154963) | about 2 years ago | (#41398273)

A qbit is a quantum binary digit, so there will only two states by definition. Otherwise, it's not a binary digit. Eventually, we might find a way to pack more than 1 qbit per physical device, but we're having enough trouble just getting a usable number of qbits.

On the other hand, regular transistors are a technology that is quite mature, and most people don't realize they're actually analog devices. We just pick a threshold current, where anything above is on and anything below is off, in order to make them binary, but it can be divided into more categories. Flash memory is currently storing 2, 4 or 8 different values per transistor to get 1 (SLC), 2 (MLC) or 3 (TLC) bits per transistor.

Re:Bit not a Qubit (1)

mcgrew (92797) | about 2 years ago | (#41398925)

So at some level we will be able to store more than off/on information?

You could do that now, but you would need a completely new archetecture. You could have a three state machine, positive, negative, and off. It would work in trinary rather than binary (000 001 002 010 011 012 020 021...)

back in the fifties through seventies they had "infinite state" analog computers in many universities. I built a primitive one when I was 12 (more of an electric slide rule than a computer). But the big fancy ones did real math for real scientific research.

Re:Bit not a Qubit (1)

Bigby (659157) | about 2 years ago | (#41400197)

I have often thought of the ternary/trinary architecture with the positive/negative/off or a no charge, half charge, full charge type of breakdown.

An infinite state medium of storage increases chances for corruption. I was wondering if there are multi-state quantum particles at the atomic or subatomic level. That would make for REALLY small mediums of storage. A 100-state subatomic particle would result in TBs of storage in the smallest imaginable locations.

Re:Bit not a Qubit (1)

Chris Burke (6130) | about 2 years ago | (#41402501)

I have often thought of the ternary/trinary architecture with the positive/negative/off or a no charge, half charge, full charge type of breakdown.

That makes the circuits much harder to design.

For traces that are short enough that you can just treat them as capacitive/resistive loads rather than transmission lines, the nice thing about a binary circuit is that you just drive the output towards one of the two voltage rails. Driving it harder just gives you the result you want faster, or drive it slower if that's okay.

With a 3-rail circuit there would be plenty of situations where driving too fast towards the middle rail would result in reading '0' or '2' when you wanted to read '1', or where transitioning from 0 to 2 could result in a circuit reading a 1.

These issues can come up with binary circuits (e.g. not meeting hold time requirements for a flip-flop, and metastable states), but are easier to deal with.

Trinary computers have been built -- in the USSR I believe -- and I don't know what circuit issues they ran into specifically. But I think there's a reason it was just a blip in the history of computing. The hypothetical 50% increase in information density is more than offset by increased circuit complexity and reduced speed.

Re:Bit not a Qubit (0)

Anonymous Coward | about 2 years ago | (#41403199)

All this demonstrates is the ability to store 1 bit of information at the atomic level not a Qubit which can be in multiple states at once due to quantum entanglement. This is like heralding the dawn of the computer age by promoting a mechanical calculator.

...or saying that full 4G is now out and available, but it's nowhere near the speed of 4G, nor does it have the same specifications. :)

payback (0)

gedw99 (1597337) | about 2 years ago | (#41397005)

i imagine someone will scan the physical book and combine it with the pictures online and put it on pirate bay, and then email all the students.

Re:payback (1)

SuricouRaven (1897204) | about 2 years ago | (#41397127)

Wrong article.

Re:payback (5, Funny)

wonkey_monkey (2592601) | about 2 years ago | (#41397181)

First Evidence of Quantum Tunnelling Slashdot Post Dismissed as Human Error.

It's called PHOSPHORUS (1)

Anonymous Coward | about 2 years ago | (#41397041)

...not phosphorous. That's something different.

Geez. For a geek site, I'd expect better. Just look up in Wikipedia if unsure.

Re:It's called PHOSPHORUS (0)

Anonymous Coward | about 2 years ago | (#41397287)

Thanks. Now go put back the aluminum rod into the nucular reactor, will ya?

Dr. Morello comes off as a great marketer but (1)

divisionbyzero (300681) | about 2 years ago | (#41397099)

provides little details on how it was done. I suspect an incremental but important improvement being hyped as revolutionary.

Re:Dr. Morello comes off as a great marketer but (0)

Anonymous Coward | more than 2 years ago | (#41406815)

The video linked to the article in GIO actually contains a fairly accurate explanation of how the experiment was done. Anything beyond that level of detail would be only for quantum physics specialists - who will read about it in the Nature article.
The revolutionary aspect of the work is in the combination of atomic-scale quantum physics, with every-day silicon nanoelectronics. We really do expect this will make a big impact.
  Andrea Morello.

I have a question: (2)

mister.woody (2712229) | about 2 years ago | (#41397125)

can you run linux on it?

Re:I have a question: (5, Funny)

jamesh (87723) | about 2 years ago | (#41397153)

can you run linux on it?

Nope. Linux requires at least a two bit computer to run.

Re:I have a question: (1)

gruntkowski (1743014) | about 2 years ago | (#41397185)

lemme see:

|linux> = kernel|1> + distro|2> + windowmanager|3> + shell|4>

So it seems to be in a superposition of 4 qubits (and I'm sure I'm forgetting a few), so: Yes it can run linux, or better: linux IS quantum computing.

Re:I have a question: (1)

gruntkowski (1743014) | about 2 years ago | (#41397199)

uh should be 4 quantum states instead of 4 qubits.
*note to myself: use preview funtion*

Re:I have a question: (1)

Chris Burke (6130) | about 2 years ago | (#41402579)

Yeah, that just ruined the joke. ;)

Re:I have a question: (0)

Anonymous Coward | more than 2 years ago | (#41406841)

No, and you don't want to.
(rest reassured: Windows and MacOS won't run on it either...)
A quantum computer gets is computational advantage not from running a higher clock speed, but from using radically different codes and algorithms. You need to write a totally different OS.
  Andrea Morello

Great News (-1)

Anonymous Coward | about 2 years ago | (#41397193)

Wow, it's great....

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Time for us all to learn QCL, Q-Lisp... (1, Funny)

QilessQi (2044624) | about 2 years ago | (#41397713)

...or some other quantum computer programming language.

(Of course, I suppose that to really do quantum software development correctly, you have to learn to be great at it and totally suck at the same time. Well, at least while no one's watching...)

I wouldn't want to be a Quantum Software Engineer. (-1)

Anonymous Coward | about 2 years ago | (#41398003)

...because the first time their manager pesters them with "Is it done yet?", the entire dev team will vanish before his eyes.

Impressive when you consider... (2)

sykobabul (1835784) | about 2 years ago | (#41398397)

... that the Core i7 processor containing 731,000,000 transistors weighs approximately 386 g. 731,000,000 Silicon atoms weighs roughly 34 fg (femtograms) - using Avogadro's Constant and assuming I did my calculation correctly. That's a pretty huge space savings, even if you were only using binary computation.

Re:Impressive when you consider... (1)

poofmeisterp (650750) | about 2 years ago | (#41403233)

... that the Core i7 processor containing 731,000,000 transistors weighs approximately 386 g. 731,000,000 Silicon atoms weighs roughly 34 fg (femtograms) - using Avogadro's Constant and assuming I did my calculation correctly. That's a pretty huge space savings, even if you were only using binary computation.

...and then it got hot and separated the atoms too far from each other to interact. D'oh!

Lucifer, the quantum bit bringer. (0)

Anonymous Coward | more than 2 years ago | (#41425333)

Funny how phosphorus is synonymous with "Lucifer" or otherwise "the light bringer." :)

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