On Purification Strategies for Teleportation Fidelity for Quantum Communication Applications

Given a quantum communication system that offers a service to a distributed quantum application, we consider the problem of optimizing purification strategies for link-level entanglements with respect to the offered teleportation fidelity. We study the trade-off between the entanglement generation and purification process, which may probabilistically fail, and the fidelity decay of application qubits due to waiting in memory for ready entanglements. Given application requests for entanglements that arrive at random time points, we devise a purification strategy that takes into account the current system state and a probabilistic notion of time-dependent risk to gauge the impact on the average teleportation fidelity. Numerical results show that the optimized purification strategy performs better when compared to always pumping across a number of different regimes and that always pumping is only optimal for certain intermediate decoherence time values.