Allen Zhang

Entanglement distillation and entanglement swapping have been extensively researched in the context of perfect quantum memories. However, near-term quantum networks will be fundamentally limited by quantum memories with finite coherence time, resulting in complex choices for the timing and ordering of these operations. In this work, we study entanglement distillation and entanglement swapping at the level of the elementary building blocks of noisy quantum repeater networks, with the goal of isolating the basic tradeoffs induced by memory decoherence. First, we focus on a minimal single-hop setting, where we analytically compare "distill-as-soon-as-possible" and "distill-as-late-as-possible" strategies against a benchmark protocol that simply discards the older entangled state. We find that delaying distillation until the end consistently outperforms the other two strategies. We then extend our analysis to two-hop repeater chains using Monte Carlo simulation. In this setting, we find that entanglement swapping should be performed as soon as possible, while distillation should again be delayed to the end. Together, these results clarify how decoherence reshapes optimal operation timing in quantum networks and provide insight into the basic repeater-level rules that govern larger-scale architectures.