Quantum-enabled communication without a phase reference

Abstract

A phase reference has been a standard requirement in continuous-variable quantum sensing and communication protocols. However, maintaining a phase reference is challenging due to environmental fluctuations, preventing quantum phenomena such as entanglement and coherence from being utilized in many scenarios. We show that quantum communication and entanglement-assisted communication without a phase reference are possible, when a short-time memory effect is present. The degradation in the communication rate of classical or quantum information transmission decreases inversely with the correlation time. An exact solution of the quantum capacity and entanglement-assisted classical/quantum capacity for pure dephasing channels is derived, where non-Gaussian multipartite-entangled states show strict advantages over usual Gaussian sources. For thermal-loss dephasing channels, lower bounds of the capacities are derived. The lower bounds also extend to scenarios with fading effect in the channel. In addition, for entanglement-assisted communication, the lower bounds can be achieved by a simple phase-encoding scheme on two-mode squeezed vacuum sources, when the noise is large.

5+11 pages, 3+4 figures

References in corpus (4)

• Quantum Communication With Zero-Capacity Channels
• Coding Theorem for a Class of Quantum Channels with Long-Term Memory
• Quantum illumination for enhanced detection of Rayleigh-fading targets
• Information trade-offs for optical quantum communication

Cited by in corpus (8)

• Entanglement-Based Quantum Information Technology
• Entanglement-Assisted Communication Surpassing the Ultimate Classical Capacity
• Exact solution for the quantum and private capacities of bosonic dephasing channels
• Entanglement-assisted capacity regions and protocol designs for quantum multiple-access channels
• Exact quantum sensing limits for bosonic dephasing channels
• Discrimination of dephasing channels
• Entanglement-assisted detection of fading targets via correlation-to-coherence conversion
• Linear-optical protocols for mitigating and suppressing noise in bosonic systems