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arXiv · 2409.20082

Local contextuality-based self-tests are sufficient for randomness expansion secure against quantum adversaries

Jaskaran Singh·Cameron Foreman·Kishor Bharti·Adán Cabello
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Abstract

In quantum cryptography, secure randomness expansion involves using a short private string of random bits to generate a longer one, even in the presence of an adversary who may have access to quantum resources. In this work, we demonstrate that local contextuality-based self-tests are sufficient to construct a randomness expansion protocol that is secure against computationally unbounded quantum adversaries. Our protocol is based on self-testing from non-contextuality inequalities and we prove that our scheme asymptotically produces secure random numbers which are $\mathcal{O}(m\sqrt{\epsilon})$-close to uniformly distributed and private, where $\epsilon$ is the robustness parameter of the self-test and $m$ is the length of the generated random bit string. Our protocol is semi-device-independent in the sense that it inherits any assumptions necessary for the underlying self-test.

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Jaskaran Singh, Cameron Foreman, Kishor Bharti, Adán Cabello. 2024-09-30. Local contextuality-based self-tests are sufficient for randomness expansion secure against quantum adversaries. https://arxiv.org/abs/2409.20082

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