Entanglement-Assisted Communication Surpassing the Ultimate Classical Capacity.

Area of Science:

• Quantum Information Science
• Quantum Communication
• Optical Communications

Background:

• Entanglement is fundamental to quantum-enhanced technologies like communication, sensing, and computing.
• Entanglement-assisted communication (EACOMM) theoretically promises higher classical information transmission rates beyond classical limits.
• Experimental validation of EACOMM advantages, especially over realistic channels, has been a significant challenge.

Purpose of the Study:

• To experimentally demonstrate entanglement-assisted communication (EACOMM) surpassing the classical capacity over lossy and noisy bosonic channels.
• To quantify the performance improvement of EACOMM compared to classical communication under identical channel conditions and power constraints.

Main Methods:

• Implementation of a high-efficiency entanglement source and a phase-conjugate quantum receiver.
• Transmission of classical information via EACOMM over simulated lossy and noisy bosonic channels.
• Comparison of EACOMM performance against the Holevo-Schumacher-Westmoreland classical capacity and a benchmark classical protocol.

Main Results:

• EACOMM demonstrated a communication rate exceeding the classical capacity by up to 16.3% under the same transmitter power constraint.
• EACOMM achieved a reduction in bit-error rate by up to 69% compared to a classical protocol over the identical bosonic channel.
• The implemented system effectively leveraged preshared entanglement despite channel-induced decoherence.

Conclusions:

• This work provides the first experimental proof of EACOMM outperforming classical communication capacity in realistic, noisy environments.
• The results highlight the practical viability of using entanglement to enhance classical communication rates and reliability.
• This research opens a pathway for realizing provable quantum advantages in diverse quantum information processing applications.