Quantum data-center networks must distribute entanglement between QPUs over paths whose length grows with system scale, but each entanglement-swapping step reduces the quality of the raw end-to-end state. Topology, multiplexing, and repeated connection attempts can increase the number of raw end-to-end copies available for a request, yet they do not answer the central resource question: whether those copies are sufficient to remove, via entanglement purification, the fidelity loss caused by multi-hop distribution. We study this question through a topology-independent black-box model of the network. Each elementary link is modeled as a Werner state with parameter $w_0$ , so ideal swapping over an $\ell$ -link path produces equal-quality raw copies with Werner parameter $w_0^\ell$ ; purification succeeds if it outputs at least one state with Werner parameter at least $w_0$ with probability at least $p_{\mathrm{th}}$ . We compare recursive BBPSSW purification with higher-order $r$ -to- $1$ bilocal-Clifford purification protocols of Jansen \emph{et al.}, using an all-in recursive schedule whose success probability is computed by exact dynamic programming. The resulting resource landscapes show a threshold structure governed by the Werner entanglement condition $w_0^\ell>1/3$ and demonstrate that multi-copy purification substantially improves both feasibility and copy efficiency. Across the evaluated grid, the Jansen family requires fewer copies than BBPSSW at more than $96\%$ of shared feasible points; at $p_{\mathrm{th}}=0.70$ , the median copy budget drops from $268$ to $30$ . These results provide a quantitative purification-resource benchmark for assessing whether future quantum data-center architectures can practically support hop-independent end-to-end entanglement quality.Quantum data-center networks must distribute entanglement between QPUs over paths whose length grows with system scale, but each entanglement-swapping step reduces the quality of the raw end-to-end state. Topology, multiplexing, and repeated connection attempts can increase the number of raw end-to-end copies available for a request, yet they do not answer the central resource question: whether those copies are sufficient to remove, via entanglement purification, the fidelity loss caused by multi-hop distribution. We study this question through a topology-independent black-box model of the network. Each elementary link is modeled as a Werner state with parameter $w_0$, so ideal swapping over an $\ell$-link path produces equal-quality raw copies with Werner parameter $w_0^\ell$; purification succeeds if it outputs at least one state with Werner parameter at least $w_0$ with probability at least $p_{\mathrm{th}}$. We compare recursive BBPSSW purification with higher-order $r$-to-$1$ bilocal-Clifford purification protocols of Jansen \emph{et al.}, using an all-in recursive schedule whose success probability is computed by exact dynamic programming. The resulting resource landscapes show a threshold structure governed by the Werner entanglement condition $w_0^\ell>1/3$ and demonstrate that multi-copy purification substantially improves both feasibility and copy efficiency. Across the evaluated grid, the Jansen family requires fewer copies than BBPSSW at more than $96\%$ of shared feasible points; at $p_{\mathrm{th}}=0.70$, the median copy budget drops from $268$ to $30$. These results provide a quantitative purification-resource benchmark for assessing whether future quantum data-center architectures can practically support hop-independent end-to-end entanglement quality.

quant-pharXiv:2605.05369May 8, 20260 citations

A Quantum Repeater Based on Entanglement Purification and Entanglement Swapping

Zhen Zhu Zhou, Wei He, Chun Dan Zhu +1 more

We discuss a long-distance quantum communication system based on entangled photon pairs, which apply entanglement as its fundamental resource. For distances longer than the coherence length of a counterpart noisy quantum channel, the fidelity of transmission is ordinarily so low that standard purification processes are not applicable. The quantum repeater stretches the length of the entangled photon pairs. And the high fidelity entanglement of photons between sender and receiver is obtained by entanglement purification and entanglement swapping. We compare the nested repeater with the common repeater and show that it outperforms the latter, which is built an EPR pair in less time.We discuss a long-distance quantum communication system based on entangled photon pairs, which apply entanglement as its fundamental resource. For distances longer than the coherence length of a counterpart noisy quantum channel, the fidelity of transmission is ordinarily so low that standard purification processes are not applicable. The quantum repeater stretches the length of the entangled photon pairs. And the high fidelity entanglement of photons between sender and receiver is obtained by entanglement purification and entanglement swapping. We compare the nested repeater with the common repeater and show that it outperforms the latter, which is built an EPR pair in less time.

Applied Mechanics and MaterialsFeb 1, 20131 citation

w_0

, so ideal swapping over an

\ell

-link path produces equal-quality raw copies with Werner parameter

w_0^\ell

; purification succeeds if it outputs at least one state with Werner parameter at least

w_0

with probability at least

p_{\mathrm{th}}

. We compare recursive BBPSSW purification with higher-order

r

-to-

1

bilocal-Clifford purification protocols of Jansen \emph{et al.}, using an all-in recursive schedule whose success probability is computed by exact dynamic programming. The resulting resource landscapes show a threshold structure governed by the Werner entanglement condition

w_0^\ell>1/3

and demonstrate that multi-copy purification substantially improves both feasibility and copy efficiency. Across the evaluated grid, the Jansen family requires fewer copies than BBPSSW at more than

96\%

of shared feasible points; at

p_{\mathrm{th}}=0.70

, the median copy budget drops from

268

30

. These results provide a quantitative purification-resource benchmark for assessing whether future quantum data-center architectures can practically support hop-independent end-to-end entanglement quality.