What was shown
The authors worked out, on paper, what a quantum computer would need to calculate how a molecule vibrates. The molecule is a polyyne, a chain of carbon atoms with 80 triple bonds. The computer imitates the molecule's motion in many small time steps, like a flip-book that approximates a smooth movement. The authors estimate the number of steps more accurately and report significant savings that seem to grow with problem size rather than stay a fixed share. For the large chain they count 4810 logical qubits in one encoding and 1598 in the other. A logical qubit is one dependable unit of computing, assembled from many fragile ones. No machine ran this.
“As expected there are significant savings in estimating the Trotter number more accurately. What is more important is that the growth of the green curve in Figure 2 seems to be of lower-order, suggesting that the savings are more than just a constant factor.”
— Section 4.4 Trotterization cost (Figure 2), in: Refining resource estimation for the quantum computation of vibrational molecular spectra through Trotter error analysis1
- How it was done: a calculation on paper, not run on any machine
- Qubits: 4810 dependable qubits in one encoding or 1598 in another, for a chain with 80 triple bonds and 10 modals per mode.
- Error correction: It assumes machines with built-in error protection that do not exist yet, and counts only the protected qubits, not the hardware beneath them.
- Compared against classical computing: no comparison stated in the paper
Who it affects
This concerns chemistry and materials work, specifically predicting how large molecules vibrate. The molecules studied are intermediates in turning light gases into carbon nanotubes and carbon fibers. For someone in that field today, nothing changes: no machine can run this calculation. The paper is a sizing exercise that shows what a future machine would have to offer.
Chemicals and materials: McKinsey & Company estimates $450B to $800B by 2035 — value at stake for the industry, not vendor revenue (Quantum Technology Monitor, April 2026, p. 22).
This figure is an estimate, not a measurement: McKinsey & Company is a consultancy with its own quantum advisory business. It covers a whole use case, not the result of this paper.
What is still missing
The paper counts only logical qubits. It gives no count of the physical hardware beneath them and no error-correction overhead, and it states the number of time steps only in a figure and as upper bounds. It makes no comparison with the best classical method, so whether this calculation would beat a conventional computer for these molecules stays open. The machines it needs, with 4810 or 1598 protected qubits, do not exist yet.
Against published roadmaps: the task needs 4,810 logical qubits. One announcement we have on file covers that:
No second source on file covers it. The year in the verdict is therefore this vendor’s own announcement, not a judgement by this site, and an announcement is not a delivered machine.
Who is working on it
The paper (November 2023) lists its authors' affiliations as: ExxonMobil Technology and Engineering Company, Annandale, NJ 08801, USA; IBM Quantum, IBM Research Zurich, Säumerstrasse 4, 8803 Rüschlikon, Switzerland; IBM Quantum, IBM Research Almaden, San Jose, CA 95120, USA; IBM Quantum, IBM T.J. Watson Research Center, Yorktown Heights, NY 10598, USA. That is who signed this work — it is not a ranking of who is ahead.
It strengthens the step-by-step simulation route, in which a future error-protected quantum computer imitates a molecule's motion in small time steps, regardless of the type of hardware it is built on.
How this brief was made
This brief was written by software, not by a person: a language model read the full text of the paper, and code then checked every quotation, number and name in this brief against that text before it was published. The rules are set out under Method. Responsible for the rules and for this page: Georg Singer. The paper is peer-reviewed, published in Quantum 9, 1630 (2025). Georg Singer holds no shares in any company or institution named in this brief (as of October 2026).