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  • Open Access

Quantum-processing-assisted classical communication

Kelly Werker Smith1,2,*, Don Boroson3, Saikat Guha4, and Johannes Borregaard1

  • *Contact author: kwsmith@fas.harvard.edu
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Phys. Rev. Applied 25, 044037 – Published 15 April, 2026

DOI: https://doi.org/10.1103/wp82-718s

Abstract

We describe a general quantum receiver protocol that maps laser-light-modulated classical communications signals into quantum processors for decoding with quantum logic gates. The quantum gates enable joint quantum measurements over a code word to achieve the quantum limit of communication capacity. Our receiver design requires qubit resources that only logarithmically increase with the size of the code word and accommodates practically relevant coherent-state modulation containing multiple photons per pulse. Focusing on classical-quantum polar codes, we outline the necessary quality of quantum operations and code-word lengths to demonstrate a quantum-processing-enhanced communication rate surpassing that of any known classical optical receiver-decoder pair. Specifically, we show that a small quantum receiver of four qubits with operational errors of approximately 0.2% can already provide a 5% gain in the communication rate in the weak-signal limit. Additionally, we outline a possible hardware implementation of the receiver where efficient spin-photon interfaces such as cavity-coupled diamond color centers or atomic qubits are used to input the received photonic signal to a small-scale quantum processor for decoding. Our results outline a promising route for potential quantum advantage in classical communication with near-term, small-scale quantum computers.

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Phys. Rev. Applied 25, 044037– Published 15 April, 2026
  • Received 27 June 2025
  • Revised 14 January 2026
  • Accepted 23 February 2026
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