Connection of surface code patches based on entanglement distillation without postselection

Abstract

Distributed quantum computing is a promising approach for overcoming the scalability limitations of fault-tolerant quantum computing. Entanglement distillation, a process that extracts higher-fidelity entangled states from noisy ones, plays a key role in distributed quantum computing. However, simple distillation protocols typically rely on postselection, which poses practical challenges for implementation. Here, we propose a scheme for distributed surface-code quantum computing that benefits from entanglement distillation even without postselection. Numerical simulations show that the logical error rates in the proposed scheme are lower than those in the setting without distillation. Additionally, we demonstrate that the logical error rates can be suppressed further by exploiting the asymmetry between spacelike and timelike errors in the surface code. The proposed scheme offers a practical and simple approach to distributed quantum computing with surface codes.