  We study source compression with a helper in the fully quantum regime,
extending our earlier result on classical source compression with a quantum
helper [arXiv:1501.04366, 2015]. We characterise the quantum resources involved
in this problem, and derive a single-letter expression of the achievable rate
region when entanglement assistance is available. The direct coding proof is
based on a combination of two fundamental protocols, namely the quantum state
merging protocol and the quantum reverse Shannon theorem (QRST). This result
demonstrates an unexpected connection between distributed source compression
with the QRST protocol, a quantum protocol that consumes noiseless resources to
simulate a noisy quantum channel.
