Rahman, A.
, Stevens, M.
, Nunn, C.
, Jones, D.
, Kirby, B.
and Lukens, J.
(2026),
A quantum game of telephone, Physical Review Letters (Accessed August 15, 2026)
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A quantum game of telephone
Published
Author(s)
Arefur Rahman, Matthew Stevens, , Daniel Jones, Brian Kirby, Joseph Lukens
Abstract
Characterizing multinode quantum networks without ubiquitous local entanglement sources poses a significant experimental challenge. We introduce "quantum telephone," an iterative ancilla-assisted process tomography protocol that leverages intermediate detection events, effectively treating previously probed network links as ancillae for subsequent links. Implemented on a deployed multinode fiber network, we observe noisy intermediate channels create fundamental parameter degeneracies that compound inference errors under sequential estimation. Counterintuitively, the inclusion of downstream near-unitary channels provides an unambiguous boundary constraint that, when used in tandem with global inference, can resolve ambiguity in channels earlier in the sequence. By effectively compensating for localized information loss, this approach fundamentally obviates the strict full-rank requirements of standard ancilla-assisted process tomography, even when intermediate states become completely depolarized. Quantum telephone offers a scalable path towards characterizing complex quantum networks with limited resources.Citation
Physical Review Letters
Pub Type
Journals
Keywords
quantum networks, quantum measurement, quantum process tomography, bayesian inference
Citation
Issues
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Created August 14, 2026