Microwave quantum communication over thermal channels

Quantum information processing with superconducting circuits is expected to advance from individual processors to distributed quantum computing systems. It is hence important to realize quantum local area networks (QLANs) compatible with superconducting technology. Here, we present a microwave QLAN platform operable in a wide temperature range, based on a cryogenic link connecting two separate dilution refrigerators over a distance of 6.6 m. We demonstrate the continuous-variable entanglement distribution between the remote cryostats in the form of two-mode squeezed states. We find that entanglement is preserved at channel temperatures up to 4 K. As a benchmark, we show that microwave quantum teleportation is also robust against ambient thermal noise in the communication channels, thus paving the way towards microwave quantum networks at elevated temperatures.