Emerging DeepTech Startup Executes World's First 108-Qubit Calculation of FeMoCo Molecule on IBM Quantum Computer: Paving the Way for Chemical Accuracy Once Deemed Solvable Only by Quantum Computers
DeepTech company H.I.Council has achieved the world's first 108-qubit scale execution of the FeMoCo molecule on an IBM quantum computer. The research validated the path to chemical accuracy while defining the 'coherence wall', the current quantitative limit of quantum hardware.
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- 📰 Published: April 14, 2026 at 02:22
- 🔍 Collected: April 13, 2026 at 18:01
- 🤖 AI Analyzed: April 19, 2026 at 19:20 (145h 18m after Collected)
H.I.Council (Shibuya, Tokyo; CEO: Futoshi Hamanoue), a deep tech company, executed the world's first 108-qubit scale electronic structure calculation of the FeMoCo molecule—the active center of the nitrogen-fixing enzyme—on IBM's quantum computer ibm_pittsburgh (Heron r2, 156 qubits), and published the results as a research paper. This research demonstrates that the chemical accuracy calculation of FeMoCo, long targeted as the "killer application" for quantum computers, can be achieved in a 48-qubit system using a classical DMRG-AFQMC pipeline leveraging quantum chemistry insights. Simultaneously, it clearly defined the quantitative limits (the coherence wall) of current quantum computers for the first time. The paper has already been published on ChemRxiv, a preprint server co-operated by major chemical societies including the Chemical Society of Japan, and the open-access repository Zenodo. ChemRxiv (DOI: 10.26434/chemrxiv.15001770/v2), Zenodo (DOI: 10.5281/zenodo.19463795). Patents for the related technology are pending (Patent Application 2025-182361).
[Background of the Research]
FeMoCo (iron-molybdenum cofactor, MoFe7S9C) is the active center of nitrogenase, the enzyme responsible for biological nitrogen fixation. Accurate calculation of its electronic structure holds the key to designing novel catalysts in the agrochemical and fertilizer industries. In 2017, Reiher et al. estimated the computational scale required for the electronic structure calculation of FeMoCo to be "108 qubits," positioning it as the "killer application" for quantum computers. Since then, FeMoCo has been recognized as a long-standing goal in the quantum computing industry.
However, current NISQ quantum computers have their accuracy of many-body correlations limited by noise, and until now, there had been no study that successfully completed a FeMoCo-scale calculation on real hardware while quantifying the validity of the results.
[Results of This Study]
H.I.Council executed FeMoCo electronic structure calculations across four scales—48, 56, 80, and 108 qubits—on IBM's latest quantum processor, ibm_pittsburgh (Heron r2, 156 qubits). There are four main achievements:
First, they performed the world's first 108-qubit scale FeMoCo calculation on real hardware, reaching a statistical error of ±0.67 mHa (milliHartree) via the phaseless auxiliary-field quantum Monte Carlo (ph-AFQMC) method. This is an unprecedented level of accuracy achieved for a calculation of this scale on quantum hardware. However, further improvement of systematic errors (phaseless bias) is required to achieve absolute chemical accuracy, which was explicitly defined as the next research challenge.
Second, through spatial correlation measurements across multiple scales, they quantified the systematic decay of correlation amplitudes as circuit depth increased. They showed that even after exhausting roughly 20 Bayesian estimation methods, the extractable correlation signal at the 108-qubit scale hits an upper bound of r ≈ 0.03, which they termed the "coherence wall." This marks the first systematic measurement of the quantitative limits inherent in current quantum computers.
Third, using a classical computational approach deeply rooted in quantum chemistry (DMRG multi-determinant trial wave functions + ph-AFQMC), they achieved chemical accuracy (+1.07 mHa) in the 48-qubit FeMoCo electronic structure calculation. This result proves that the chemical accuracy calculation of FeMoCo—long believed by the quantum computing industry to be solvable "only by quantum computation"—can be achieved by applying quantum mechanical insights through an alternative route (classical quantum chemistry methods). This does not negate quantum computers; rather, it implies that "broad quantum supremacy"—translating the understanding of quantum mechanics into practical use—has borne fruit through one of multiple pathways.
Fourth, based on these findings, they constructively proposed three specific directions for improving next-generation quantum hardware: moving away from isotropic thermal equilibration, prioritizing connectivity quality over the sheer number of qubits, and implementing hardware bias design to preserve the information backbone. These serve as testable hypotheses and a direct call to action for the quantum hardware community.
[Background of the Research]
FeMoCo (iron-molybdenum cofactor, MoFe7S9C) is the active center of nitrogenase, the enzyme responsible for biological nitrogen fixation. Accurate calculation of its electronic structure holds the key to designing novel catalysts in the agrochemical and fertilizer industries. In 2017, Reiher et al. estimated the computational scale required for the electronic structure calculation of FeMoCo to be "108 qubits," positioning it as the "killer application" for quantum computers. Since then, FeMoCo has been recognized as a long-standing goal in the quantum computing industry.
However, current NISQ quantum computers have their accuracy of many-body correlations limited by noise, and until now, there had been no study that successfully completed a FeMoCo-scale calculation on real hardware while quantifying the validity of the results.
[Results of This Study]
H.I.Council executed FeMoCo electronic structure calculations across four scales—48, 56, 80, and 108 qubits—on IBM's latest quantum processor, ibm_pittsburgh (Heron r2, 156 qubits). There are four main achievements:
First, they performed the world's first 108-qubit scale FeMoCo calculation on real hardware, reaching a statistical error of ±0.67 mHa (milliHartree) via the phaseless auxiliary-field quantum Monte Carlo (ph-AFQMC) method. This is an unprecedented level of accuracy achieved for a calculation of this scale on quantum hardware. However, further improvement of systematic errors (phaseless bias) is required to achieve absolute chemical accuracy, which was explicitly defined as the next research challenge.
Second, through spatial correlation measurements across multiple scales, they quantified the systematic decay of correlation amplitudes as circuit depth increased. They showed that even after exhausting roughly 20 Bayesian estimation methods, the extractable correlation signal at the 108-qubit scale hits an upper bound of r ≈ 0.03, which they termed the "coherence wall." This marks the first systematic measurement of the quantitative limits inherent in current quantum computers.
Third, using a classical computational approach deeply rooted in quantum chemistry (DMRG multi-determinant trial wave functions + ph-AFQMC), they achieved chemical accuracy (+1.07 mHa) in the 48-qubit FeMoCo electronic structure calculation. This result proves that the chemical accuracy calculation of FeMoCo—long believed by the quantum computing industry to be solvable "only by quantum computation"—can be achieved by applying quantum mechanical insights through an alternative route (classical quantum chemistry methods). This does not negate quantum computers; rather, it implies that "broad quantum supremacy"—translating the understanding of quantum mechanics into practical use—has borne fruit through one of multiple pathways.
Fourth, based on these findings, they constructively proposed three specific directions for improving next-generation quantum hardware: moving away from isotropic thermal equilibration, prioritizing connectivity quality over the sheer number of qubits, and implementing hardware bias design to preserve the information backbone. These serve as testable hypotheses and a direct call to action for the quantum hardware community.