Scientists from the U.S. Department of Energy’s Brookhaven National Laboratory, Stony Brook University, and DOEs Energy Sciences Network (ESnet)are collaborating on an experiment that puts U.S. quantum networking research on the international map. Researchers have built a quantum network testbed that connects several buildings on the Brookhaven Lab campus using unique portable quantum entanglement sources and an existing DOE ESnet communications fiber network—a significant step in building a large-scale quantum network that can transmit information over long distances.