A new study demonstrates that the use of shared classical randomness, combined with buffer memories, can significantly enhance quantum entanglement purification. This technique is particularly useful when entanglement sources are heterogeneous and their source labels are unavailable at the entanglement purification protocol (EPP) layer. EPPs are crucial for increasing entanglement fidelity, a fundamental requirement for the development of fault-tolerant distributed quantum information processing.

The proposed strategy involves accumulating multiple rounds of entanglement distribution and then using shared randomness to shuffle all stored entangled states before packaging them as inputs to the EPP. This method does not require state characterization or EPP circuit optimization, making it applicable in practical scenarios where information about the sources is limited. The improvement has been demonstrated for any number of Werner sources and for any fixed $n$-to-1 bilocal Clifford EPP.

The researchers have proven that this accumulation and shuffling improves the expected success probability and the success-weighted output Bell fidelity, compared to the baseline without accumulation. This improvement is observed for any finite number of accumulation rounds and in the asymptotic limit, and it increases monotonically with the number of accumulation rounds. This advance is key for building robust and scalable quantum networks, where entanglement quality is a critical bottleneck.