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Single-click protocols for remote state preparation using weak coherent pulses

Janice van Dam1,2,3,*,†, Emil R. Hellebek4,*,‡, Tzula B. Propp1,2,3, Junior R. Gonzales-Ureta5, Anders S. Sørensen4, and Stephanie D. C. Wehner1,2,3

  • *These authors contributed equally to this work.
  • †Contact author: j.vandam-3@tudelft.nl
  • ‡Contact author: emil.hellebek@nbi.ku.dk
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Phys. Rev. Research 8, 033272 – Published 3 September, 2026

DOI: https://doi.org/10.1103/x1nr-qbz7

Abstract

Remote state preparation (RSP) allows one party to remotely prepare a known quantum state on another party's qubit using entanglement. This can be used in quantum networks to perform applications such as blind quantum computing or long-distance quantum key distribution (QKD) with quantum repeaters. Devices to perform RSP, referred to as a client, ideally have low hardware requirements, such as only sending photonic qubits. A weak coherent pulse source offers a practical alternative to true single-photon sources and is already widely used in QKD. Here, we introduce two protocols to the previously known protocol for RSP with a weak-coherent-pulse-based device. The known technique uses a double-click (DC) protocol, where a photon from both the server and the client needs to reach an intermediate Bell state measurement. Here, we add to that a single-click (SC) RSP protocol, which requires only one photon to reach the Bell state measurement, allowing for better performance in certain regimes. In addition, we introduce a double-single-click (DSC) protocol, where the SC protocol is repeated twice, and a cnot gate is applied between the resulting qubits. DSC mitigates the need for phase stabilization in certain regimes, lowering technical complexity while still improving performance compared to DC in some regimes. We compare these protocols in terms of fidelity and rate, finding that SC consistently achieves higher rates than DC and, interestingly, does not suffer from an inherently lower fidelity than DC, as is the case for entanglement generation. Although SC provides stronger performance, DSC can still show performance improvements over DC, and it may have reduced technical complexity compared to SC. Finally, we show how these protocols can be used in long-distance QKD using quantum repeaters.

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Phys. Rev. Research 8, 033272– Published 3 September, 2026
  • Received 16 February 2026
  • Accepted 24 July 2026
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Published by the American Physical Society under the terms of the Creative Commons Attribution 4.0 International license. Further distribution of this work must maintain attribution to the author(s) and the published article's title, journal citation, and DOI.

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