We show that qubits traveling along closed timelike curves are a resource that a party can exploit to distinguish perfectly any set of quantum states. As a result, an adversary with access to closed timelike curves can break any prepare-and-measure quantum key distribution protocol. Our result also implies that a party with access to closed timelike curves can violate the Holevo bound. © 2009 The American Physical Society.
Publication Source (Journal or Book title)
Physical Review Letters
Brun, T., Harrington, J., & Wilde, M. (2009). Localized closed timelike curves can perfectly distinguish quantum states. Physical Review Letters, 102 (21) https://doi.org/10.1103/PhysRevLett.102.210402