In a paper published today in Nature Communications, UNSW quantum computing researchers describe how they created artificial atoms in a silicon 'quantum dot', a tiny space in a quantum circuit where electrons are used as qubits (or quantum bits), the basic units of quantum information.
Scientia Professor Andrew Dzurak explains that unlike a real atom, an artificial atom has no nucleus, but it still has shells of electrons whizzing around the centre of the device, rather than around the atom's nucleus.
[...] [Ph.D. student Ross] Leon, who ran the experiments, says the researchers were interested in what happened when an extra electron began to populate a new outer shell. In the periodic table, the elements with just one electron in their outer shells include Hydrogen and the metals Lithium, Sodium and Potassium.
"When we create the equivalent of Hydrogen, Lithium and Sodium in the quantum dot, we are basically able to use that lone electron on the outer shell as a qubit," Ross says.
"Up until now, imperfections in silicon devices at the atomic level have disrupted the way qubits behave, leading to unreliable operation and errors. But it seems that the extra electrons in the inner shells act like a 'primer' on the imperfect surface of the quantum dot, smoothing things out and giving stability to the electron in the outer shell."
[...] It is the spin of an electron that we use to encode the value of the qubit, explains Professor Dzurak.
[...] "When the electrons in either a real atom, or our artificial atoms, form a complete shell, they align their poles in opposite directions so that the total spin of the system is zero, making them useless as a qubit. But when we add one more electron to start a new shell, this extra electron has a spin that we can now use as a qubit again.
"Our new work shows that we can control the spin of electrons in the outer shells of these artificial atoms to give us reliable and stable qubits.
Journal Reference:
Leon, R.C.C., Yang, C.H., Hwang, J.C.C. et al. "Coherent spin control of s-, p-, d- and f-electrons in a silicon quantum dot." Nat Commun 11, 797 (2020). DOI: 10.1038/s41467-019-14053-w
(Score: 1, Informative) by Anonymous Coward on Thursday February 13 2020, @03:26PM (1 child)
Pretty cool idea to have an atom with no nucleus. Apparently the electrons orbit on a flat disc.
Here is the paper for anyone that wants to take a look
(Score: 4, Informative) by maxwell demon on Thursday February 13 2020, @06:11PM
I didn't check your link, but note that the link at the end of the summary goes directly to the paper, which is Open Access (no paywall, Creative Commons Attribution 4.0 International). If it is about your link being in PDF form, a link for that is also on the linked journal page.
When the journal offers free direct access to the article, I don't see the point of loading it from a third-party link.
The Tao of math: The numbers you can count are not the real numbers.
(Score: 0) by Anonymous Coward on Thursday February 13 2020, @04:56PM
Why do i smell super fast and pervasive and long lasting cheap memory chips incomming?
(Score: 0) by Anonymous Coward on Thursday February 13 2020, @06:20PM (1 child)
bohrs orbital type electrons v superposition
(Score: 3, Informative) by maxwell demon on Friday February 14 2020, @12:16PM
Bohr's model had orbits, not orbitals. Orbitals are the single-electron quantum eigenstates predicted by quantum mechanics. Orbital states are still an approximation (because they neglect electron correlations and treat the electromagnetic field classically) but a much better one than Bohr's orbits. Since orbitals are genuine quantum states, deviations from the orbital model can usually be calculated using perturbation theory. And of course, superpositions of them are well-defined (and actually are quite common in chemistry, known there as hybridization).
The Tao of math: The numbers you can count are not the real numbers.
(Score: 0) by Anonymous Coward on Thursday February 13 2020, @06:55PM (1 child)
I would have to spend more time actually reading and researching this (time I don't have right now) but this does look interesting and more promising than most of the other stuff that comes out on quantum computations. It's probably still at least ten years into the future before any of this manifests (but tech always seems to progress much faster than my expectations so who knows).
(Score: 3, Interesting) by maxwell demon on Friday February 14 2020, @12:28PM
It certainly looks interesting, however note that up to now they only did single-qubit operations. While those are of course important, the true power of quantum computation comes with two-qubit operations. Before they did that, I'd be careful about judging the promise.
For example, with photons we can do single-qubit operations almost perfectly (they are just the standard linear optics operations, with the only genuine quantum devices involved being the single-photon sources and detectors). However to my knowledge, no one has yet managed to build a scalable general quantum computer from photonics.
The Tao of math: The numbers you can count are not the real numbers.