Southwest Quantum Information and Technology

Tamper-Resistant Cryptographic Hardware in the Isolated Qubits Model

Yi-Kai Liu, National Institute of Standards and Technology (NIST)

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Using quantum information, one can perform certain cryptographic tasks, such as quantum key distribution, with information-theoretic security. But other tasks, such as quantum bit-commitment and oblivious transfer, are provably impossible. We show how a special class of quantum devices -- "isolated qubits" -- can circumvent these limitations. Isolated qubits are qubits that have long coherence times, but can only be accessed using single-qubit gates and measurements; entangling operations are not allowed. (This definition is motivated by the properties of solid-state nuclear spins.) We show how isolated qubits can be used to construct "one-time memories," a kind of non-interactive oblivious transfer, as well as "one-time programs," programs that can only be run once, and reveal nothing about their internal structure.