A chess game where pieces move only for castling, and all strikes are delivered from a standstill. That's the strategy physicists at Infleqtion chose for their 114-qubit quantum processor Sqale. Instead of shuttling neutral atoms to a dedicated zone before every operation, they learned to entangle them right on the spot using fine optical tweezers.

At the heart of the approach is the error correction code [[4,2,2]] and its concatenation into [[16,4,4]]. Each logical qubit is assembled from several physical ones, and rare movements are used only for initialization and permutation. On-site entanglement is performed via individual optical addressing, which reduces error accumulation and execution time. In three experiments: Shor's algorithm, constant-depth CX ladders, and preparation of the [[16,4,4]] code, logical performance surpassed physical by up to 8 times.

The results show that combining movement with local addressing can be more efficient than the zone-based approach. This opens the way to scalable fault-tolerant quantum computing, where constant-depth circuits become a working tool for materials science problems such as the Anderson impurity model. Further improvement in gate fidelity and continuous atom reloading will be key steps on this path.