  High-fidelity quantum entanglement is a key resource for quantum
communication and distributed quantum computing, enabling quantum state
teleportation, dense coding, and quantum encryption. Any sources of decoherence
in the communication channel however degrade entanglement fidelity, thereby
increasing the error rates of entangled state protocols. Entanglement
purification provides a method to alleviate these non-idealities, by distilling
impure states into higher-fidelity entangled states. Here we demonstrate the
entanglement purification of Bell pairs shared between two remote
superconducting quantum nodes connected by a moderately lossy, 1-meter long
superconducting communication cable. We use a purification process to correct
the dominant amplitude damping errors caused by transmission through the cable,
with fractional increases in fidelity as large as $25\%$, achieved for higher
damping errors. The best final fidelity the purification achieves is $94.09\pm
0.98\%$. In addition, we use both dynamical decoupling and Rabi driving to
protect the entangled states from local noise, increasing the effective qubit
dephasing time by a factor of 4, from $3~\rm \mu s$ to $12~\rm\mu s$. These
methods demonstrate the potential for the generation and preservation of very
high-fidelity entanglement in a superconducting quantum communication network.
