Piecemaker

Abstract

We introduce entanglement distribution protocols that use a quantum switch to deliver stabilizer states to remote end users. As in existing schemes, the first step in our protocols involves Bell pair generation between the switch and each end user. However, unlike existing schemes that wait for all Bell pairs to be established before distributing the desired state, our approach stores only a minimal subset of Bell pairs while processing every subsequent Bell pair immediately. In doing so, our protocols reduce the average Bell pair storage time compared to existing schemes, resulting in less cumulative quantum storage noise as a direct consequence. On the theoretical side, our protocol design is grounded in the structure of vertex covers in graph states up to local complementation. Through a comprehensive numerical evaluation, we compare the fidelities of delivered states with those of a baseline scheme, for state sizes up to n=50 qubits. Simulations show that our protocols can achieve the critical fidelity threshold of 12 for multipartite entanglement in a wider range of depolarization rates and success probabilities of Bell-pair generation. Overall, our protocols achieve higher fidelity of the distributed state than the baseline in most considered parameter regimes, and can reduce infidelity by up to 45%.