IVADO's Quantum Seminars Winter 2026 - Alexis Morvan, May 8th

About Alexis

Experimental Progress in Scaling Surface Code and Autonomous Calibration

Abstract: The transition of quantum error correction (QEC) from theoretical promise to experimental reality has reached a pivotal turning point. Recently, milestones on 105-qubit processors have demonstrated that logical error rates can be suppressed exponentially, exceeding the "break-even" point where a logical qubit outperforms its physical constituents [Nature 638, 2025]. This progress extends to the realization of distance-preserving logic in the color code, achieving suppressed error rates on a superconducting processor [Nature 645, 2025].

We will discuss the challenges of scaling these results on real-world hardware. We first show how exploiting the "time-dynamics" of QEC circuits allows us to break free from strict gate scheduling and circumvent hardware constraints like reduced connectivity. We explore how these dynamic circuits utilize non-traditional gate sets such as iSWAP and periodically swap the roles of data and measure qubits to mitigate leakage [Nature Physics, 2025]. We then show how error syndromes can be used as a learning signal for Reinforcement Learning (RL) agents to autonomously steer analog control parameters [arXiv:2025]. This allows the system to stabilize against environmental drift in real-time, establishing a path toward self-stabilizing, fault-tolerant quantum processors.

References:

- Quantum error correction below the surface code threshold Google Quantum AI and collaborators Nature volume 638, 920-926 (2025)
- Demonstration of dynamic surface codes, A. Eickbush, Google Quantum AI and collaborators, Nature Physics volume 21, 1994-2001 (2025)
- Scaling and logic in the colour code on a superconducting quantum processor, N. Lacroix, Google Quantum AI and collaborators Nature volume 645, 614-619 (2025)
- Reinforcement Learning Control of Quantum Error Correction, V. Sivak, A. Morvan, Google Quantum AI and collaborators, arXiv:2511.08493 (Dec. 2025)
- Magic state cultivation on a superconducting quantum processor, E. Rosenfeld, Google Quantum AI and collaborators, arXiv:2512.13908 (Dec. 2025)