Certifying delivered entanglement
Independent Study, Information Networking Institute, CMU — with Prof. Michael Mattarock
I study what a quantum network can promise about the entanglement it delivers. A model-based guard supports per-user risk bounds; hidden random tests certify the average fidelity of kept pairs.
Retrospective test splits; no certificate for an individual pair.
Updated November 2026
Read more: methods, evidence & limitations
What can a quantum network promise about the entangled pairs it delivers?
Per-pair promises need a model; hidden random tests can certify an average.
I separate two guarantees for delivered entanglement: a model-based guard bounds a user's risk of ever receiving a below-threshold pair under adaptive routing, while hidden random tests certify the average fidelity of the pairs kept. The guard needs a model and declared margins that cover the actual noise. The certificate needs trustworthy measurements and a fresh, hidden test choice; it does not certify any individual kept pair.
- 7 + 2
- experimental-data re-analyses and local runs on one IBM processor
- 0.818
- IonQ median certificate, compared with 0.817 predicted before reading the data
- 0 / 8.8M
- bad guarded deliveries in topology simulations; descriptive count
The seven re-analyses cover ICFO, USTC, Innsbruck, Delft, Oxford, Harvard, and IonQ. On IonQ's ion–silicon-vacancy link, a 3,000-pair record—about three seconds at 1.03 kHz—gave the predicted certificate. The test-or-keep splits were drawn retrospectively and the measurement settings were collected in blocks, so this did not test an online, time-ordered protocol. On Oxford's randomised test-or-keep record, the trusted-settings certificate ended at 0.917 and stayed above 0.9 after about 220,000 kept pairs; the separate device-independent bound was 0.837.
The topology simulations cover cubes up to 1,000 nodes, square grids up to 37 × 37, and a grid with diagonal links. No guarded delivery was bad across 36 conditions with 32 simulated networks each; networks, rather than individual deliveries, are the independent replication units. These are simulations with simplified physics, not physical network trials. The two IBM runs tested local components on one processor. An alarm cannot undo earlier deliveries, and protection against arbitrary model drift is not established.
The manuscript is complete and under review by the authors before submission.