Reduced-state embedding for quantum cryptography
Amit Kam, Kfir Sulimany, Shai Tsesses +1 more
Encoding in a high-dimensional Hilbert space improves noise resilience in quantum information processing. This approach, however, may result in cross-mode coupling and detection complexities, thereby reducing quantum cryptography performance. This fundamental trade-off between correctness and secrecy motivates the search for quantum high-dimensional encoding approaches for cryptography. Here, we introduce state embeddings that use a k -symbol subset within a d -dimensional Hilbert space, tailored to the channel's error structure. We demonstrate the advantage of our scheme in realistic quantum channels, producing a higher secure key rate. We validate our approach using d = 25 quantum key distribution (QKD) experimental data, derive closed-form expressions for the key rate and threshold, and determine the optimum at k = 5 . These findings advance high-dimensional QKD and pave the way for error correction and modulation for quantum cryptography.
arXiv:2510.19989•Newton•Jul 1, 2026•0 citations