A Deployed Quantum Local Area Network with Flex-Grid Technology

The development of quantum communications networks is crucial for advancing quantum information science, including the highly anticipated Quantum Internet. Nevertheless, quantum network testbeds have so far not fully utilized modern lightwave communications technologies, such as flexible-grid bandwidth distribution. Here we summarize recent work [M. Alshowkan et al., PRX Quantum 2, 040304 (2021)] demonstrating flex-grid entanglement distribution in a quantum local area network (QLAN), connecting nodes in three campus buildings that are time-synchronized by the Global Positioning System (GPS). The network enables both adaptive bandwidth provisioning and simultaneous distributed remote detection with off-the-shelf control systems. We use log-negativity to measure the quality of the distributed polarization entanglement, which provides a general metric of link performance in terms of entangled bits per second. After demonstrating successful entanglement distribution for two allocations of our eight dynamically reconfigurable channels, we realize the first deployed fiber network demonstration of remote state preparation (RSP). Our results highlight an advanced paradigm for managing entanglement resources in quantum networks of ever-increasing complexity and service demands.