IBM’s “Loon” Chip: A Landmark Step Toward a Fully Fault‑Tolerant Quantum Computer by 2029

On 12 November 2025, IBM introduced its latest experimental quantum computing chip, named Loon, signaling a major step toward building a practical, large-scale quantum computer by 2029. This announcement has sparked excitement and discussions in the scientific community, highlighting IBM’s progress in overcoming one of quantum computing’s biggest challenges: error correction.

The Loon chip incorporates a fault-tolerant system for the first time in IBM’s publicly described roadmap. It uses qLDPC (low-density parity-check) codes to automatically detect and correct errors during quantum processing. Additionally, the chip is equipped with advanced c-couplers, which connect multiple qubits more efficiently, enabling stronger computational interactions and improving overall performance.

Scaling up quantum computers introduces new challenges. Each additional qubit or processing layer increases the potential for noise and errors, making it difficult to achieve accurate results. The Loon chip represents a significant milestone in addressing these challenges, offering a pathway to operate thousands of qubits stably and simultaneously, with minimal data corruption.

IBM’s roadmap outlines ambitious goals: achieving quantum advantage, the stage at which quantum computers outperform classical computers for certain tasks, and ultimately creating a fully fault-tolerant quantum computer by 2029. This machine would not only advance scientific research but could also solve complex real-world problems in pharmaceuticals, climate modeling, and economic simulations.

The company also announced that its next chip, “Nighthawk,” will launch by the end of 2025. Expected to be a successor to Loon, Nighthawk is anticipated to surpass classical computers in specific computational experiments by mid-2026. This demonstrates IBM’s commitment to steadily increasing the scale and reliability of quantum computing systems.

Despite these breakthroughs, several challenges remain. Experts highlight the need to generate large numbers of high-fidelity qubits, maintain stable long-range connections between them, and develop software algorithms capable of leveraging these complex architectures. Additional technical hurdles include energy consumption and temperature stability, both critical for sustained quantum operations.

Even with these challenges, the release of Loon marks a historic step in quantum computing. The chip not only exemplifies a scientific achievement but also points toward a future where computers operate in ways closer to human-like thinking, capable of solving problems once considered beyond reach.

The 12 November 2025 announcement confirms that humanity is approaching the era of practical quantum computing, and IBM’s Loon chip is a tangible representation of the progress made toward that vision.