# Can Error Mitigation Make NISQ Hardware Useful for Quantum Chemistry Today?

Qedma's QESEM software achieved a **30–50× accuracy improvement** over raw, unmitigated results when calculating the potential energy surface of a water molecule on [IBM Quantum](https://quantumintel.tech/companies/ibm)'s Aachen quantum processor — a result published today by Qedma and the HQC2 consortium, a collaboration spanning the University of Copenhagen (KU), the Technical University of Denmark (DTU), and the University of Southern Denmark (SDU).

The study, conducted under Q-CHEMION — a project within the Eureka open call for applied quantum technologies — used an orbital-optimized variational ansatz to map the water molecule's potential energy surface on current noisy hardware. The improvement figure is significant: quantum chemistry is notoriously intolerant of accumulated gate errors, because small deviations in calculated molecular energies can cascade into unreliable predictions of molecular properties. Getting a 30–50× noise reduction without waiting for [fault-tolerant quantum computing](https://quantumintel.tech/glossary/fault-tolerant-quantum-computing) changes the calculus for near-term quantum chemistry workloads.

The findings were announced September 9, 2026, with Qedma researchers presenting at Q2B Copenhagen, running September 9–10, 2026.

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## What QESEM Does — and What It Doesn't

QESEM (Qedma's patented error mitigation software) sits in the error mitigation tier of the quantum stack, below full quantum error correction (QEC) and above doing nothing. It does not encode [logical qubits](https://quantumintel.tech/glossary/logical-qubit) or suppress errors at the physical level through redundancy; instead, it characterizes and mitigates the noise present in a given circuit execution, producing more accurate expectation values from the same noisy physical hardware.

This distinction matters for enterprise and research buyers evaluating near-term quantum computing options. Error mitigation cannot make a 100-qubit [NISQ](https://quantumintel.tech/glossary/nisq) device perform like a fault-tolerant machine — it has known overhead costs in circuit runs and classical post-processing, and its effectiveness degrades as circuit depth increases. The water molecule study represents a tractable, well-defined chemistry problem; scaling the same approach to industrially relevant molecules (larger active spaces, deeper circuits) will stress-test these limits.

That said, the result is not trivial. Potential energy surface calculations require consistent accuracy across multiple geometric configurations of a molecule, not just a single ground-state energy snapshot. Sustaining a 30–50× mitigation factor across that sweep is a more demanding demonstration than a single-point energy estimate.

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## Who Led the Research

The HQC2 side of the collaboration was led by **Prof. Stephan P. A. Sauer** and postdoctoral researcher **Renato Olarte Hernandez** at the University of Copenhagen, alongside **Prof. Sonia Coriani** and postdoctoral researcher **Emanuele Rossi** at DTU.

Qedma was co-founded by **Dr. Asif Sinay** (CEO), Dorit Aharonov of the Hebrew University, and Nathaniel Lindner of the Technion. The company is headquartered in Israel and employs between 11 and 50 people, per its company profile.

"The work shows a strong proof of concept for applying quantum computing to quantum chemistry on current hardware, demonstrating improved accuracy as higher levels of precision were required," said Sinay in the release.

Prof. Sauer added: "Accuracy is particularly important in quantum chemistry, where even relatively small errors can affect the reliability of calculated molecular properties and energies."

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## Context: Qedma's Broader Quantum Advantage Claim

The paper arrives shortly after Qedma and IBM jointly claimed [quantum advantage](https://quantumintel.tech/glossary/quantum-advantage) in modeling quantum materials dynamics — a result Qedma describes as the first quantum advantage demonstration using commercially available hardware and software, in a regime where multiple state-of-the-art classical simulation methods reportedly failed to provide consistent answers. That claim has not yet been independently adjudicated by the broader community, and the details of which classical methods were benchmarked will matter significantly for how the field receives it.

The water molecule chemistry result is more modest in framing — explicitly presented as a proof of concept rather than a quantum advantage claim — which is the appropriate posture given the system size and the maturity of classical quantum chemistry solvers for molecules of this scale. Classical methods like CCSD(T) remain highly competitive for small molecules; the value proposition for QESEM here is methodology validation, not classical displacement.

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## Industry Trajectory

The study reinforces a practical near-term strategy that several software-layer quantum companies are pursuing: extract useful signal from today's noisy hardware through aggressive error mitigation, rather than waiting for fault-tolerant systems that remain years away at scale. Q-CHEMION's Eureka funding structure also signals continued European institutional investment in applied quantum software — an area where Israel-based companies like Qedma have found effective collaborative footing with Nordic academic groups.

For enterprise buyers in pharma, materials science, or specialty chemicals evaluating quantum chemistry platforms, this result provides one data point in favor of pairing IBM superconducting hardware with a dedicated error mitigation software layer. The key open question is [circuit depth](https://quantumintel.tech/glossary/circuit-depth) scaling: at what point does QESEM's overhead outpace its mitigation benefit for larger, more industrially relevant molecular systems? That answer will define the commercial ceiling for this approach in the pre-fault-tolerant era.

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## Key Takeaways

- **30–50× accuracy improvement** over raw results reported by Qedma and HQC2 for quantum chemistry on IBM's Aachen processor — these figures come directly from the published study.
- The calculation targeted the **potential energy surface of a water molecule** using an orbital-optimized variational ansatz — a methodologically rigorous test requiring consistent accuracy across multiple geometric configurations.
- **QESEM is error mitigation, not QEC** — it improves results on noisy hardware without encoding logical qubits; its scalability to deeper circuits remains an open question.
- The collaboration spans three Danish universities (KU, DTU, SDU) under the **Q-CHEMION project**, funded through the Eureka open call for applied quantum technologies.
- Qedma presentations at **Q2B Copenhagen, September 9–10, 2026** will cover both this study and the company's broader quantum advantage claims.

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## Frequently Asked Questions

**What is Qedma's QESEM software?**
QESEM is Qedma's patented error mitigation software designed to reduce the impact of noise on quantum computations run on current, noisy quantum hardware. Unlike full quantum error correction, it does not require encoding logical qubits — instead, it characterizes hardware noise and post-processes results to produce more accurate expectation values.

**What quantum processor was used in the Qedma and HQC2 study?**
The study ran on IBM's Aachen quantum processor, using an orbital-optimized variational ansatz to calculate the potential energy surface of a water molecule.

**What does 30–50× improvement mean in quantum chemistry terms?**
It means the error-mitigated results were between 30 and 50 times closer to the accurate target values than raw, unmitigated results from the same hardware. In quantum chemistry, where small energy errors can invalidate molecular property predictions, this is a material improvement — though the absolute accuracy relative to classical benchmark methods was not detailed in the source material reviewed.

**Is this a quantum advantage demonstration?**
No. The researchers explicitly frame this as a proof of concept for error mitigation in quantum chemistry, not a quantum advantage claim. Classical solvers remain competitive for molecules at this scale. Qedma's separate quantum advantage claim — involving quantum materials dynamics — is a distinct result under separate scrutiny.

**What is the HQC2 consortium?**
HQC2 is a research collaboration spanning the University of Copenhagen (KU), the Technical University of Denmark (DTU), and the University of Southern Denmark (SDU). The quantum chemistry study was carried out as part of Q-CHEMION, a project under the Eureka open call for applied quantum technologies.