Quantum age edges closer

Jan 05, 2010
Quantum age edges closer
A colour-enhanced Scanning Electron Microscope image of a quantum dot and (below) a graphic explaining the image.

(PhysOrg.com) -- The arrival of superfast quantum computing is closer following recent breakthroughs by an international team led by UNSW researchers.

Superfast is closer than ever following recent breakthroughs by an international team led by researchers from the University of New South Wales.

Quantum computing relies on controlling and observing the behaviour of quantum particles - for instance individual electrons - to deliver enormous processing power.

In the two breakthroughs, written up in the international journals Nano Letters and Applied Physics Letters, researchers have for the first time demonstrated two ways to deliberately place an electron in a nano-sized device on a .

Quantum age edges closer

The achievements set the stage for the next crucial steps of being able to observe and then control the electron’s or "spin", to create
a .

Multiple quantum bits coupled together make up the processor of a quantum computer.

Professor Andrew Dzurak, the NSW Node Director of the Australian National Fabrication Facility at UNSW and Dr Andrea Morello, Manager of the Quantum Measurement and Control Chip Program at the ARC Centre of Excellence for Quantum Computer Technology, were leaders in the breakthrough work.

In research just published in , the team, including PhD student Wee Han Lim, were able to accurately localise a single electron in silicon without it being attached to an atom. This “artificial atom” is known as a “quantum dot”.

Dr Morello said the quantum dot avoided the difficulty of having to introduce single atoms in precise positions in a silicon chip.

In a separate project, published in the journal Nano Letters, the researchers, including PhD student Kuan Yen Tan, used "nature’s own way" to localise electrons, by binding them to single atoms.

Quantum computing’s power comes from the fact that electrons can have a "spin" pointing in one of two directions. The spin position can be used in the same way that zeroes and ones represent data in today’s computers.

However electrons can also hold intermediate spin positions, or quantum states, which is what gives quantum computing its power.

While today's computers increase their power linearly with the number of bits added, quantum bits, when coupled together, can deliver an exponential increase in their ability to represent data.

The other leaders of the research team are Professor David Jamieson at the University of Melbourne, and Dr Mikko Möttönen at the Helsinki University of Technology. Students Wee Han Lim and Kuan Yen Tan have just completed their PhD degrees in the UNSW School of Electrical Engineering and Telecommunications.

Explore further: X-ray powder diffraction beamline at NSLS-II takes first beam and first data

More information: -- Applied Physics Letters paper: scitation.aip.org/getabs/servl… dtype=cvips&gifs=yes

-- Nano Letters paper: pubs.acs.org/doi/abs/10.1021/n… ak&searchHistoryKey=

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User comments : 8

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El_Nose
5 / 5 (1) Jan 05, 2010
While today's computers increase their power linearly with the number of bits added, quantum bits, when coupled together, can deliver an exponential increase in their ability to represent data.


Wait a second thats not true todays computers increase there memory exponentially as well when a new bit is added on. If you add a new bit onto an array you increase it by a factor of 2. Then another thats 2^2 and another is 2^3 -- an exponential increase.

The difference is the base changes and that is a huge change. 2^30 is a hell of a lot smaller than 3^30 and that isn't where the real performance increase lies, the real power is in the operations. if you had 2^3 different pieces of memory(lets keep it small) and you needed to do an operation on all of them you would have to do them one at a time so it takes a minimum of 2^8 operations but in a QC you can do the operation once across all 2^3 at one time.
Rynox77
not rated yet Jan 05, 2010
Any inaccuracies aside, I found this to be a very good article for explaining quantum computing. Electrons are probably pretty fast... much faster than any of the modern metal oxide semiconductors.
El_Nose
not rated yet Jan 05, 2010
I cannot edit my comment ----

In the last sentance I said it would take 2^8 operations -- I meant 2^3 --- sorry combination of a fuzzy monitor and the fact 2^3 = 8
de_la_meu
not rated yet Jan 05, 2010
@El_Nose
i think the author is right if you look at it this way:

if you double your x bit memory you now have twice as much storage space, 2x bits -- which is a linear increase.

but if you double x quantum bits you now have a 2^2x bit storage space -- which is an exponential growth.

de_la_meu
not rated yet Jan 05, 2010
@Rynox77
the power of the quantum computer is in the superposition of its states rather than the speed of its particles.

you are right, electrons travel extremely slowly in conductors, the current can be calculated in cm/hr.
but its actually the electromagnetic waves that carry the information...

and these waves travel close to the speed of light depending on the medium (air, copper, etc.)
tkjtkj
not rated yet Jan 06, 2010

the real power is in the operations. if you had 2^3 different pieces of memory(lets keep it small) and you needed to do an operation on all of them you would have to do them one at a time so it takes a minimum of 2^8 operations but in a QC you can do the operation once across all 2^3 at one time.


so, you are saying that a QC does all op's in one cycle?

so, would a QC being used to break an AES256 have to be constructed of at least 256 dots?
Walid
not rated yet Jan 06, 2010
The author was correct in saying that quantum computers give exponential power gains per qubit. He/She was not talking about memory size per added bit nor was the subject the number of permutations using n bits. Quantum dots carry out computations themselves, this is different from what people perceive information storage to do today. Unlike my computer's bits and bytes, quantum dots actually do computations which is what we are used to have the CPU of our computers do. Quantum dots also acts as memory at the same time. It is a little complicated but to understand it you have to read an article about how quantum dots or quantum computers are theorized to be used (search for it, lots of stuff online). This article is a breakthrough announcement, not a tutorial.
El_Nose
not rated yet Jan 13, 2010
@tkjtkj

so, would a QC being used to break an AES256 have to be constructed of at least 256 dots?


depends on what the base is. In normal computers we take for granted its in base 2. A quantum computer could have a base of 3 - off/on/maybe . If memory is restricted to base 2 then yes it would need 256 bits of memory and would perform the operations in a big O of c.

Not necessarily one operation but definitely a fixed number.

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