Hardware‐Intrinsic Encryption Using Spectrally Multiplexed Nitrogen Vacancy Spin Ensembles in Nanodiamonds

ABSTRACT Secure encryption lies at the heart of data protection across virtually every sector of modern society. Physical unclonable functions (PUFs) provide an indispensable root of trust for ensuring this security. However, existing PUFs remain limited by two key constraints: a trade‐off between cryptographic capacity and physical footprint, and architectural vulnerabilities to both key‐centric interception and machine‐learning (ML) cloning attacks. Here, we introduce a hardware‐intrinsic, coherent‐spin‐mediated encryption architecture based on nanodiamonds (NDs) containing nitrogen‐vacancy (NV) centers. Spectral multiplexing of spin‐resonance channels directly transduces microwave‐programmed plaintext into the frequency and phase of coherent Rabi oscillations, yielding hardware‐specific temporal waveforms as physical ciphertext. Operating within a sub‐wavelength footprint, this process supports over 10 45 addressable encryption states, corresponding to an encoding density of approximately 721 bits µm – 2 , which represents the highest value reported for a physical‐security platform. The coherent quantum evolution of the NV spin ensembles, together with ND‐specific disorder, produces a complex, channel‐dependent plaintext‐to‐waveform transformation that proved difficult for the evaluated ML models to reconstruct, with predictive accuracy approaching the random‐guessing baseline. These results establish a new encryption paradigm, delivering an ultra‐dense, intrinsically unclonable encryption foundation for next‐generation secure devices.