Curator's Take
This research tackles one of quantum computing's most pressing security challenges: how to run private quantum computations on untrusted quantum hardware without revealing sensitive data to the service provider. The team's quantum homomorphic encryption framework builds on the well-established Quantum One-Time Pad to enable secure computation across the full Clifford+T gate set, which is sufficient for universal quantum computation. What makes this particularly significant is their demonstration on real quantum processors, showing the approach works despite current hardware noise limitations. As quantum cloud services become more prevalent, this type of encryption could be essential for enabling businesses and researchers to leverage powerful quantum computers while maintaining complete data privacy.
— Mark Eatherly
Summary
As quantum computing matures into a practical paradigm, the need for secure and private quantum computation on untrusted hardware becomes increasingly urgent. While classical fully homomorphic encryption has enabled computation over encrypted data in untrusted environments, a fully homomorphic and practically implementable quantum counterpart remains elusive. In this work, we propose a universal quantum homomorphic encryption (QHE) framework developed from the Quantum One-Time Pad (QOTP) scheme. Our approach (QOTPH) maintains information-theoretic security and supports a broad class of quantum operations on encrypted quantum states through a systematic set of homomorphic gate decompositions and key update rules. By leveraging the symmetric structure of QOTP and exploiting the transformation properties of quantum gates under Pauli encryption, we enable non-interactive homomorphic evaluation of arbitrary circuits expressible in the Clifford+T gate set, as well as controlled and parameterized operations relevant to variational quantum algorithms and delegated computation. We provide a formal specification of the proposed encryption model, detail its implementation procedure, and report the results obtained from both simulated environments and real quantum processors. Experimental validation demonstrates the correctness of the homomorphic operations and the preservation of key secrecy under circuit-level noise and real-device constraints. This work takes a step toward bridging the gap between theoretical quantum homomorphic encryption and practical realization on near-term quantum hardware, offering a scalable and symmetric cryptographic primitive for privacy-preserving quantum computation.