Semiconductor qubits scale in two dimensions:
The heart of any computer, its central processing unit, is built using semiconductor technology, which is capable of putting billions of transistors onto a single chip. Now, researchers from the group of Menno Veldhorst at QuTech, a collaboration between TU Delft and TNO, have shown that this technology can be used to build a two-dimensional array of qubits to function as a quantum processor. Their work, a crucial milestone for scalable quantum technology, was published today in Nature.
[...] Electrons trapped in quantum dots, semiconductor structures of only a few tens of nanometres in size, have been studied for more than two decades as a platform for quantum information. Despite all promises, scaling beyond two-qubit logic has remained elusive. To break this barrier, the groups of Menno Veldhorst and Giordano Scappucci decided to take an entirely different approach and started to work with holes (i.e. missing electrons) in germanium. Using this approach, the same electrodes needed to define the qubits could also be used to control and entangle them. 'No large additional structures have to be added next to each qubit such that our qubits are almost identical to the transistors in a computer chip,' says Nico Hendrickx, graduate student in the group of Menno Veldhorst and first author of the article. 'Furthermore, we have obtained excellent control and can couple qubits at will, allowing us to program one, two, three, and four-qubit gates, promising highly compact quantum circuits.'
After successfully creating the first germanium quantum dot qubit in 2019, the number of qubits on their chips has doubled every year. 'Four qubits by no means makes a universal quantum computer, of course,' Veldhorst says. 'But by putting the qubits in a two-by-two grid we now know how to control and couple qubits along different directions.' Any realistic architecture for integrating large numbers of qubits requires them to be interconnected along two dimensions.
Journal Reference:
Nico W. Hendrickx, William I. L. Lawrie, Maximilian Russ, et al. A four-qubit germanium quantum processor, Nature (DOI: 10.1038/s41586-021-03332-6)
(Score: 2) by Snotnose on Thursday March 25 2021, @11:19PM (2 children)
Does anyone even think this probability based, problem structured "theory" will ever have any more than a niche application?
I just passed a drug test. My dealer has some explaining to do.
(Score: 2) by takyon on Thursday March 25 2021, @11:32PM
What theory? The theory that quantum computing is useful?
If it is, we'll never hear the end of it, and if they can get it to work at room temperature, it will eventually be in our phones or ocular devices.
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(Score: 2) by Mojibake Tengu on Thursday March 25 2021, @11:36PM
Only probably, in this niche part of Universe...
The edge of 太玄 cannot be defined, for it is beyond every aspect of design
(Score: 2) by KilroySmith on Friday March 26 2021, @04:28AM
and NVidia will build a reticle-limited Q100 chip with 10 billion qubits.
All your RSA belongs to us.
(Score: 2) by HiThere on Friday March 26 2021, @02:24PM
How much heat does this kind of activity generate? Is it low enough to allow 3-d chips? If so, they may have a real winner.
FWIW, I haven't been that impressed by quantum computers. They should excel in certain problems, but in most problems they don't have much advantage over standard computers. But if they could build 3-d chips, that would change things a LOT. Standard computers can't scale in that direction because of thermal problems, but if quantum computers can, it may justify the cost of the refrigerator you need to run the thing. Otherwise I want to hold out for the optical version that can run at room temperature. (Of course, I'm not the person who could afford to buy one anyway, but you know what I mean.)
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