The headline of the article is grossly misleading and has no relation to the paper it is based on. They modeled an extremely simplified toy molecule that doesn't occur in nature (a chain of four hydrogen atoms). Their quantum computer has 20 noisy qubits and can be trivially simulated and outperformed by a laptop. This is solid research, but any practical application is extremely far away, if at all possible.
Why do people continue to lie, or at least irresponsibly overstate, quantum computing results? Is it just a grift for funding? Or are they true believers who think with enough resources, reality will eventually catch up with their hype?
There's a quantum computing "industry". Professors, postdocs, PhD students, courses, conferences, journals, research institutes, government funding agencies, and even startups.
Do you really want all of them to start looking for real jobs just because there are no quantum computers?
We still can't factor all 5-bit numbers (the largest was 15-ish, but even that wasn't general IIRC) on QCs.
Scammy startups are out there claiming all sorts of non-sense; ask them how many
bits (arbitrary) they can run Shor's algorithm on and all their hyperbolic claims
fall flat. Shor's alg. is still the gold-standard when it comes to QC's definitive
advantages on Classical machines (all the ML ones have been disproved IIRC).
All of the words in the above sentence are important, because they'll weasel out and
cheat if you don't include them (even Google/IBM do this).
H4 is impossible under any temperature or pressure. A hydrogen atom has one, count 'em, one electron to bond with. And bonds require, at minimum, two electrons shared between the two atoms. That's why H2 is pretty stable compared to monatomic H1. You'd have to rip up and throw out hundreds of years of chemistry for H4 to be possible.
In other words, the computer spit out nonsense.
This reminds me of the French guy in Holy Grail who giggles with his buddies "I told him we already got one.."
> And bonds require, at minimum, two electrons shared between the two atoms. That's why H2 is pretty stable compared to monatomic H1. You'd have to rip up and throw out hundreds of years of chemistry for H4 to be possible.
Actually, all you have to do is catch up with (checks Wikipedia) 100-year old research. Molecular orbital theory is needed to understand three-center two-electron bonds, and that dates back to the 1920s. However, the concept of "a bond is an electron pair" only predates that discovery by about a decade. It actually turns out that H₃⁺, the classic example of the three-center two-electron bond, predates both of those discoveries.
It's also worth noting that chemistry itself as a recognizable field only dates back to maybe the 1760s, and things like bond structure only really start to be worked on in the mid-19th century, with most of our modern understanding dating from various parts in the 20th century. So that's hardly "hundreds of years of chemistry" that would need to be ripped up and thrown out.
Let me guess, you never took any chemistry classes past gen chem in college? Molecular orbital theory and two-center three-electron bonds is bog standard organic chemistry (might even be first semester orgo, I'm not sure).
And just because it's exotic, that doesn't mean it's not useful to think about. My impression from some rather limited exposure to quantum chemistry is that the molecule hits a sweet spot where it's both not completely trivial to solve, yet within the capabilities of present-day quantum computers, meaning that it becomes a useful benchmark for algorithm development. See e.g. https://arxiv.org/abs/2303.07417 (which covers H₄ and LiH) and the references therein.
H4 certainly sounds strange to me (and as other commenters have pointed out, this is a toy example, not a real molecule), but there are weird bond structures out there in real molecules that violate "at minimum, two electrons shared between the two atoms": https://en.wikipedia.org/wiki/Three-center_two-electron_bond.
(The 3C-2E bonds in diborane are not linear, so that doesn't seem like what could be happening here.)
H4 can transiently exist under some extreme initial conditions, it's just not probable and it wouldn't exist for long as it evolves into molecular hydrogen.
Electrons are fluid. They can agglomerate wherever there's positive charge.
I don't think it's ridiculous that there is an electron configuration that permits H4 to exist.
I'm not really well versed in solar technology, but I found this[1] to maybe explain what this means. It looks like an ~5% overall theoretical efficiency gain might be expected, and if we can achieve the same over 90% of the theoretical maximum we get from silicon processes, that might be ~17% overall efficiency gains over our current silicon processes if some of the best case scenarios line up? (29.4% theoretical max to 34.6%).
Someone that's more knowledgeable about this might completely invalidate my napkin math with actual insight or basic knowledge, so take their opinions over mine, since I'm just lightly scanning random internet info.
-this is intramolecular singlet fission within the H4 molecule.
-The energy requirement (especially for intermolecular singlet fission) can be theoretically derived from the massive Thirring model assuming some degree of strong electron correlation.
Nope. That is discussing "an atom of hydrogen with 1 proton and 3 neutrons". Which kind-of exists, but is too unstable to be meaningful.
The press release says it is a molecule of 4 hydrogen atoms. Neither the press release nor Wikipedia have any further thoughts as to how this is possible.
I have long harbored an ambition of creating a Journal Of Implausible Chemistry, for the publication of research on hydrogen chains and other molecules cruelly disallowed by our impoverished reality.
Okay, the press release here has dumbified the explanation to the point that several commenters are confused as to what it's trying to do, getting hung up on the H₄. The underlying chemistry is somewhat beyond me, and I have not an ACS subscription to speed-read the related research, and this is at the limits of what Wikipedia can describe, so I may be somewhat wrong, but I'm still going to try my best to explain the science being don here nonetheless.
Photon goes bonk on a molecule and it knocks an electron free (we can turn this electron into power in solar cells!). Sometimes, however, this electron knocks a second electron free, which is the "singlet fission" process being described (this means we get more power in our solar cells). We want to model this process in various molecules to be able to make better molecules for solar cells.
There's a problem... this is quantum mechanics, of the "start with Schrödinger's equation" variety, which means it's meaty math that's hard to do without powerful computers, and even then, you either have to make big, (over-)simplifying assumptions or deal with small fry. The systems where singlet fission takes place involve lots of conjugated bonds--a giant line of benzene rings smushed together, or maybe just a line of double bonds (the latter is what our eyes use to see light, FWIW). This provides a simplifying assumption for the math.
Now we come to what this paper is doing. This paper is swapping out one of the subroutines for the math with a quantum computer calculation. It's using a test molecule, and comparing the results of the quantum-based simulation with the purely-classical-based simulation. Note that everything here is pure simulation: there's no real, physical molecules being studied!
Because quantum computers that exist today are weak, they are using the simplest possible system for their work--this is the H₄ system. This H₄ is not a model of any real molecule [1]. Rather, it's a reduction of the behavior of real, interesting systems--linear conjugations of orbits--into the simplest possible model, in order to allow some of the behavior to even be studied in the first place.
So, in short, this is a paper that is concluding that a more powerful quantum computer might be helpful in doing the calculation work needed to evaluate candidate molecules that might make better solar cells. They've done this by showing that a quantum computer can indeed do the calculation on a simple model and that the results track existing classical computations (note there's no actual evaluation of if the quantum computer did it faster).
[1] Offhand, I'd say it's not what a real H₄ would look like. H₄ would likely be a tetrahedral complex. But I also imagine it's thermodynamically unstable and would dissassociate into multiple molecules with any number of electrons: neutral charge would definitely go to 2H₂, +1 charge to H₂ and H₂⁺, +2 charge probably to 2 H₂⁺. I've got no idea how the hell H₄³⁺ would break apart, but I have to imagine that one electron can't keep the protons from flying out of the molecule. In no case would you end up with a linear arrangement of atoms 2Å however
Best comment award!
The point of doing these toy simulations, easily done on classical computers, is to understand the quantum circuits that calculate molecular behavior so that when those circuits are generated for nontrivial molecules the results can be received with confidence.
Well if you ran that on a normal processor it would take you less than 10s and that's including the 9s it takes for python to load and numpy to import.
I don't think so. Isotopes can influence mass and other nuclear characteristics, but it's really the electron configuration that determines the molecular possibilities.
I wonder if LK-99 the new room temp superconductor material would be make solar panels better? I'm not sure where in the design it would be beneficial.
Total solar insolation at peak is under about 400 watts per square meter. A one square foot panel at 100% efficiency is never [1] going to beat 40-50W even in the best circumstances, at the equator, and ignoring weather... and nighttime.
[1] The sun becoming a red giant is hereby defined as an exception to this statement per the follow-up comments.
- "...heating due to gravitational contraction will also lead to hydrogen fusion in a shell just outside the core, where unfused hydrogen remains, contributing to the increased luminosity, which will eventually reach more than 1,000 times its present luminosity...[135]"
1.3 megawatts per square meter! An entire nuclear power plant on your roof, provided the weather allows, provided weather still exists. The future is bright.
Chances are that the expansion of the sun will have stripped away the weather, along with the roof, the house, and any of the lighter elements of the Earth’s surface.
You are forgetting the efficiency gains future homes will make so they require less power. Partly thanks to the rise of room temperature superconducting.
I get annoyed when commenters make back and forth claims without ever providing any citations so I did a Google and found myself on a NASA page. According to that page it's ~1360 W/m^2 at the top of the atmosphere, but by the time it gets to the surface it seems to average out to only about 340 W/m^2[1].
You misread the source. The average is for the entire planet, parts of which are covered by clouds, and half of which is at night. 1 kW/m^2 is a typical value for peak insolations outside extreme latitudes. If the atmosphere absorbed significantly more than that, you could not see very far.
