  Entanglement underpins a variety of quantum-enhanced communication, sensing,
and computing capabilities. Entanglement-assisted communication (EACOMM)
leverages entanglement pre-shared by communication parties to boost the rate of
classical information transmission. Pioneering theory works showed that EACOMM
can enable a communication rate well beyond the ultimate classical capacity of
optical communications, but an experimental demonstration of any EACOMM
advantage remains elusive. Here, we report the implementation of EACOMM
surpassing the classical capacity over lossy and noisy bosonic channels. We
construct a high-efficiency entanglement source and a phase-conjugate quantum
receiver to reap the benefit of pre-shared entanglement, despite entanglement
being broken by channel loss and noise. We show that EACOMM beats the
Holevo-Schumacher-Westmoreland capacity of classical communication by up to
14.6%, when both protocols are subject to the same power constraint at the
transmitter. As a practical performance benchmark, a classical communication
protocol without entanglement assistance is implemented, showing that EACOMM
can reduce the bit-error rate by up to 69% over the same bosonic channel. Our
work opens a route to provable quantum advantages in a wide range of quantum
information processing tasks.
