  Effective quantum communication between remote quantum nodes requires high
fidelity quantum state transfer and remote entanglement generation. Recent
experiments have demonstrated that microwave photons, as well as phonons, can
be used to couple superconducting qubits, with a fidelity limited primarily by
loss in the communication channel. Adiabatic protocols can overcome channel
loss by transferring quantum states without populating the lossy communication
channel. Here we present a unique superconducting quantum communication system,
comprising two superconducting qubits connected by a 0.73 m-long communication
channel. Significantly, we can introduce large tunable loss to the channel,
allowing exploration of different entanglement protocols in the presence of
dissipation. When set for minimum loss in the channel, we demonstrate an
adiabatic quantum state transfer protocol that achieves 99% transfer efficiency
as well as the deterministic generation of entangled Bell states with a
fidelity of 96%, all without populating the intervening communication channel,
and competitive with a qubit-resonant mode-qubit relay method. We also explore
the performance of the adiabatic protocol in the presence of significant
channel loss, and show that the adiabatic protocol protects against loss in the
channel, achieving higher state transfer and entanglement fidelities than the
relay method.
