  Scalable quantum information processing with superconducting circuits is
expected to advance from individual processors located in single dilution
refrigerators to more powerful distributed quantum computing systems. The
realization of hardware platforms for quantum local area networks (QLANs)
compatible with superconducting technology is of high importance in order to
achieve a practical quantum advantage. Here, we present a fundamental prototype
platform for a microwave QLAN based on a cryogenic link connecting two separate
dilution cryostats over a distance of $6.6$ m with a base temperature of $52$
mK in the center. Superconducting microwave coaxial cables are employed to form
a quantum communication channel between the distributed network nodes. We
demonstrate the continuous-variable entanglement distribution between the
remote dilution refrigerators in the form of two-mode squeezed microwave
states, reaching squeezing of $2.10 \pm 0.02$ dB and negativity of $0.501 \pm
0.011$. Furthermore, we show that quantum entanglement is preserved at channel
center temperatures up to $1$ K, paving the way towards microwave quantum
communication at elevated temperatures. Consequently, such a QLAN system can
form the backbone for future distributed quantum computing with superconducting
circuits.
