Robust self-test of the maximally entangled state of two-qubits without assuming unitary observables

Abstract:Standard device-independent self-testing uses Naimark dilation to assume projective measurements, masking the operational limitations of realistic non-unitary observables. We establish a robust pure self-test for the singlet and Pauli observables that entirely circumvents dilation of the measurement apparatus. Assuming a pure state to model an untrusted source, we regularize the physical non-projective operators and derive an analytic $\mathcal{O}(\sqrt{\epsilon})$ robustness bound. Our results suggest that device-independent certification of real implementations is significantly more demanding than standard projective models imply.

5 pages + supplemental material. New version with corrected Eq. (13). Final result remains unaltered

arXiv:2607.04035 [quant-ph]

(or arXiv:2607.04035v2 [quant-ph] for this version)

https://doi.org/10.48550/arXiv.2607.04035 Focus to learn more arXiv-issued DOI via DataCite

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