Manufacturing qubits that can move
- Thread starter JournalBot
- Start date
This is the first quantum computing article in a year and a half that explains error correction or other technical quantum computing factors.
All the recent articles have been about it's theoretical effect on cracking passwords.
Thanks, these types of articles are appreciated.
All the recent articles have been about it's theoretical effect on cracking passwords.
Thanks, these types of articles are appreciated.
Upvote
41
(41
/
0)
Dr Jay, I always appreciate your forays into this field...so thank you. It confounds me to no end however that despite knowing all the words in the articles I can't wrap my head around these concepts. This is, of course, a me problem*. I have no doubt people with more math skills and a better grounding in QCD have no difficulty parsing your articles. I will keep reading them and maybe some quantum of understanding will break through my dense skull...or maybe simultaneously break through and not break through.
A s the saying goes "A man's just got to know his limitations"
A s the saying goes "A man's just got to know his limitations"
Upvote
21
(21
/
0)
J.C. Helios
Ars Scholae Palatinae
Whenever I hear about quantum dots, I'm reminded that they get sold in barrels. Imagine how many qubits you could (notionally) make out of each of these!
https://www.cnet.com/pictures/touring-a-quantum-dot-factory/
Upvote
15
(15
/
0)
It might be a canister packed in vermiculite inside the barrels but it does look like you can just pour/pump it out directly... Must be pretty robust stuff if that's the case
Upvote
3
(3
/
0)
I would hate to be the Amazon COO, pumping a quarter of a trillion dollars into data centers, and worrying about the potential of “quantum dots” to do the same for a million.
Upvote
6
(6
/
0)
Small nitpicking detail, but the image at the top of the article is depicting a different type of quantum dot than the one in the paper. Quantum dots like in the image are nano particles that are used in displays among other things as very efficient color filters. The ones in the paper are spots on a 2D electron gas defined by electrodes which can trap single electrons. They are used for very different applications, but share the fact that they are essentially zero dimensional systems. Other than that, great article as always!
Upvote
13
(13
/
0)
As the previous comment says, these are not the free-standing nanoparticle "quantum dot" things that are used in TVs and so forth. Here's a picture from the paper:
You're looking at a lithographic construct (the scale bar is 100 nm), where metal electrodes are used to create small confinement regions in the semiconducting substrate. They can in principle be made in bulk, for CMOS fabrication definitions of "bulk", which is one advantage of this particular platform for qubits. Another nice feature, on paper anyway, is that because they're compatible with CMOS fab, you can integrate conventional logic onto the same die to handle at least some of the control and readout processes, which should help a lot in scaling. I say "on paper" because it's a bear to get working in reality; the heat from even a tiny handful of conventional transistors is a real problem for delicate states like the ones being studied here.
You're looking at a lithographic construct (the scale bar is 100 nm), where metal electrodes are used to create small confinement regions in the semiconducting substrate. They can in principle be made in bulk, for CMOS fabrication definitions of "bulk", which is one advantage of this particular platform for qubits. Another nice feature, on paper anyway, is that because they're compatible with CMOS fab, you can integrate conventional logic onto the same die to handle at least some of the control and readout processes, which should help a lot in scaling. I say "on paper" because it's a bear to get working in reality; the heat from even a tiny handful of conventional transistors is a real problem for delicate states like the ones being studied here.
Upvote
17
(17
/
0)
Less than a year, to be accurate.
But there's a simple rule: general quantum computing advances are in the science section. Security related quantum computing is in security. So just watch whichever section(s) interest you.
Upvote
9
(9
/
0)
jonbob_newcastle
Ars Praetorian
You can make them in a shed (using olive oil). I think I’ve linked this video before.
ed: removed the video because these are a different kind of quantum dots.
Whatever became of spintronics?
Last edited:
Upvote
2
(2
/
0)
This isn't really an accurate characterization. QuTech is a research center at the Delft University of Technology (TU Delft). It's not a private company or startup, it's an academic department. Also, since it's part of TU Delft, it doesn't make any sense to describe this research as "in collaboration" with TU Delft as they're fundamentally the same entity.
Upvote
9
(9
/
0)
I believe the collaboration was with the Department of Quantum Nanoscience at TU Delft. QuTech calls this out sometimes, but the professors that they collaborate with are ALSO declare that they are part of QuTech in their research papers, but I've found it is like this. In the Math field, we prefer to just collaborate with only people of a different continent from yourself while we think about odd sets of numbers.
Upvote
2
(2
/
0)
They're definitely barrels of dots, noone knows if they're quantum or not until they open the barrel.
I'm here all weekend. Try the fish…
Upvote
12
(12
/
0)
- Add bookmark
- Featured
- #17
They’re two different things. The QDs in displays are free standing particles a few nm in size; by carefully choosing the composition, shape, and size, they can be engineered to emit photons at a specific color, great for display purposes. The QDs in this article are made in a manner similar to transistors on a silicon wafer, using lithography to define patterns. In this case, the patterns are metal electrodes surrounding a small area of semiconductor. Putting the right voltages on those electrodes can confine a single electron in that 'dot' region and then manipulate and sense its state.
The similarity which underlies both things having the same name is the use of small size scales to confine things like electrons, which then limits them to a few discrete states because of the rules of quantum mechanics (without going into the math, roughly speaking, the bigger the confinement region, the more states an electron or whatever can have, and the closer together in energy they can be. Once the gap between state energies gets small compared to things like the temperature, it’s effectively a continuous range of energies).
Upvote
14
(14
/
0)
The illustration of this article seems to reference a different kind of object which is also called a quantum dot: semiconductor nano crystals which confine electron-hole pairs and emit light at wavelengths that are related to the physical size of the quantum dots. These are the quantum dots which are used in some TV displays.
That's an unfortunate consequence of us Physicists calling very different things by the same name, because in the end they have the same underlying property of behaving as a nearly 0D object. In this paper, however, the authors are working with gate defined quantum dots, which are completely different from the nano crystals and also from the self-assembled quantum dots which are nano islands of a semiconductor material embedded inside another.
Gate defined quantum dots are made with electrodes, which confine single electrons in a very small region of the device. That electron can then be precisely manipulated to act as a quantum bit for quantum information protocols.
This confusion even affects researchers at conferences! Oh, and to make things worse for everyone not in the field, the word gate in this paper means two things. There are the electric gates, used in the sense which is common when talking about transistors, for instance, and there are the quantum gates, meaning logical operations acting on the quantum bits.
That's an unfortunate consequence of us Physicists calling very different things by the same name, because in the end they have the same underlying property of behaving as a nearly 0D object. In this paper, however, the authors are working with gate defined quantum dots, which are completely different from the nano crystals and also from the self-assembled quantum dots which are nano islands of a semiconductor material embedded inside another.
Gate defined quantum dots are made with electrodes, which confine single electrons in a very small region of the device. That electron can then be precisely manipulated to act as a quantum bit for quantum information protocols.
This confusion even affects researchers at conferences! Oh, and to make things worse for everyone not in the field, the word gate in this paper means two things. There are the electric gates, used in the sense which is common when talking about transistors, for instance, and there are the quantum gates, meaning logical operations acting on the quantum bits.
Upvote
7
(7
/
0)
Now I feel justified for being confused...though I confess I am still WAY out of my depth here. Give me biology and immune system complexity and perplexity any day.
Upvote
2
(2
/
0)
This is actually a very big disadvantage: moving atoms or ions around physically is a mechanical process that is much, much slower than electronic or optical processes. Such systems can reach at most MHz clock speeds.
If we want to build quantum computers that outperform classical computers we need to approach GHz clock speeds, otherwise large classical computer systems (think data centre size) will still be faster than quantum computers for the forseeable future. The exponential speed up of quantum algorithms will kick in at some point, but not until we have overcome errors and hardware overheads. This will require the type of scalability that can come only with chip-scale integration.
Upvote
-6
(0
/
-6)
Here's QuTech's own press release on this work: https://qutech.nl/2026/05/07/the-qubit-there-and-back-again/
They don't describe it as being any sort of collaboration. They describe the authors as "Maxim De Smet, first author of the paper and PhD candidate at QuTech, part of TU Delft" and "Senior author Lieven Vandersypen, chief scientist at QuTech and professor at TU Delft".
Can you really call it a "collaboration" just because you're cross affiliated with different departments? On the actual paper all the authors list QuTech as their affiliation. Vandersypen lists both QuTech and the Kavli Institute of Nanoscience at TU Delft as his affiliation. It's weird to call it a "collaboration" since it's the same guy representing both places (or rather representing the same place twice). There's no meaningful distinction between them. As far as I can tell, nobody uniquely affiliated with the Department of Quantum Nanoscience was involved in this work (which still wouldn't be a meaningfully distinct entity).
Upvote
2
(2
/
0)
I'm afraid you'll have to ask marketing. They're currently stuck between "schrödibits" and "superposies," but the CMO's Alabaman girlfriend still wants "qThangs."
Upvote
2
(2
/
0)
They're still for sale: https://upperstory.com/en/spintronics/
Upvote
0
(0
/
0)