UCSB and UCLA researchers propose faster unclonable quantum encryption scheme

Researchers Prabhanjan Ananth at UC Santa Barbara and Amit Sahai at UCLA describe a quantum encryption method that aims to make unclonable protection faster and more practical, Phys.org reported, citing work posted as arXiv DOI: 10.48550/arxiv.2607.21551. The approach uses the no-cloning theorem, which says it is physically impossible to create an identical copy of an unknown quantum state. The authors encrypt a one-bit message into a quantum ciphertext by scrambling the hidden bit across a row of quantum states that the intended receiver can measure with a secret digital key. The design targets an attack in which an interceptor splits data between two accomplices. Attempting to split the quantum data disturbs the information so both parties cannot reliably read the secret; even if they later receive the key, both sides' chances of correctly identifying the bit approach 50/50 odds of random guessing as more quantum states are used. The authors write that they show one-time, information-theoretically secure, efficient unclonable encryption exists and that the scheme is exponentially secure.