Deterministic Nonlocal Quantum Gate with Room-Temperature Memory Modules

Scaling quantum computation is a crucial challenge for practical applications, hindered by the inherent errors and noises in real-world quantum systems. The quantum modular architecture offers a possible solution, where smaller quantum modules are individually constructed and assembled into a larger architecture. In this architecture, the nonlocal quantum gates are the building blocks; until now, it has remained challenging for practical applications to implement a nonlocal quantum gate with the memory modules under deterministic and room-temperature conditions, due to intrinsic probability and hardware complexity. Here, we propose and demonstrate a scheme to deterministically implement a nonlocal quantum gate between the room-temperature memory modules. The key technologies include cavity-enhanced atomic modules, two of which are connected by a single pair of distributed entangled optical modes and real-time mutual feedforward controls. The nonlocal quantum nondemolition gate between two room-temperature memory modules is deterministically demonstrated with different input coherent states, and the quantum nature is confirmed by outputting entangled atomic modules. Our results illustrate the functionality and feasibility of nonlocal quantum gate and may have potential applications in modular quantum information processing.