Commercial quantum computer identifies molecular candidate for better solar cell

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.

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.."

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.

1: https://pubs.acs.org/doi/10.1021/acsenergylett.1c00972

Probably a couple points to note

-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.

As always, any press release about "quantum" is fake.

What is "H-4"? How could this be used in solar panels? Did they use quantum computers for anything other than to spice up the press release?

There are no answers.

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

> from months to a few weeks

So a 4x speedup? A completely irrelevant performance improvement for a "quantum computer".

Quantinuum H1-1 quantum computer

https://www.quantinuum.com/hardware/h1

huh, ok. discuss?

How can there be a 4 atom hydrogen molecule?

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.

Imagine deploying a 12 inch by 12 inch solar panel someday and powering your entire home.

What will the world look like in 50 years with constant advances in quantum computing and AI.