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Encrypted Qubits Can Be Cloned

Koji Yamaguchi1,2,*,† and Achim Kempf1,3,4,5,‡

  • *Present address: Department of Informatics, Faculty of Information Science and Electrical Engineering, Kyushu University, 744 Motooka, Nishi-ku, Fukuoka, 819-0395, Japan.
  • †Contact author: koji.yamaguchi@inf.kyushu-u.ac.jp
  • ‡Contact author: akempf@uwaterloo.ca
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Phys. Rev. Lett. 136, 010801 – Published 6 January, 2026

DOI: https://doi.org/10.1103/y4y1-1ll6

Abstract

We show that encrypted cloning of unknown quantum states is possible. Any number of encrypted clones of a qubit can be created through a unitary transformation, and each of the encrypted clones can be decrypted through a unitary transformation. The decryption of an encrypted clone consumes the decryption key; i.e., only one decryption is possible, in agreement with the no-cloning theorem. Encrypted cloning represents a new paradigm that provides a form of redundancy, parallelism, or scalability where direct duplication is forbidden by the no-cloning theorem. For example, a possible application of encrypted cloning is to enable encrypted quantum multicloud storage.

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Phys. Rev. Lett. 136, 010801– Published 6 January, 2026
  • Received 14 January 2025
  • Revised 21 May 2025
  • Accepted 14 November 2025
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