A neutron imaging technique aimed at certifying the authenticity of nuclear warheads without revealing their underlying details is demonstrated in Nature Communications.
Future arms control agreements may require trusted verification mechanisms aimed at confirming the authenticity of items presented as nuclear warheads. However, security and proliferation concerns require that verifications reveal no information about the composition or design of the warheads. Zero-knowledge proofs are mathematical cryptographic methods that allow us to do just that, but translating these abstract concepts into real physical imaging techniques remains a challenge.
Sebastien Philippe and colleagues demonstrate a protocol that provides an inspector with a verification tool that contains no information about the imaged object. By placing a test object between a neutron source and an emulsion detector, a “fingerprint” of the object gets imprinted by the bubbles appearing in the emulsion. Host detectors are pre-loaded with a complementary bubble distribution generated by a reference sample. In this way, a positive match is represented by a completely levelled signal, yielding no usable information to the inspector, but still confirming that the test object is identical to the reference sample.