Over the past several decades, quantum information technologies have emerged as a new paradigm that can offer fundamental enhancements in sensing, communications, and computing. By interconnecting quantum sensors and computers at remote locations, quantum communication networks unlock capabilities beyond any isolated device. The long-term vision is a quantum internet: a global network of quantum technologies linked by quantum communication channels capable of distributing quantum resources, such as qubits and entanglement. In parallel, distributed entanglement has emerged as a unifying thread between information science and fundamental physics. In this talk, I present some of the latest advances in quantum communication devices, channels, and networks, both at a technological and fundamental physics level. 

The talk is divided into three parts. Part I focuses on quantum sources and detectors as the building blocks of quantum networks. I present progress in state-of-the-art sources and detectors: photon-number-resolving superconducting nanowire detectors and their application to improving heralded single-photon sources and high-rate photon-number discrimination; a high-rate entangled photon-pair source for quantum key distribution; and high-bandwidth on-chip balanced homodyne detectors for squeezed-light detection.

Part II describes the development of quantum network testbeds at Caltech and Fermi National Accelerator Laboratory (FNAL), with a focus on designing scalable architectures toward the quantum internet. We construct systems capable of high-fidelity quantum teleportation and entanglement swapping over long distances, achieving state-of-the-art teleportation fidelities over 45 km of optical fiber and entanglement swapping visibilities with time-bin qubits. These systems are envisioned to form the backbone of a prototype quantum internet connecting the seventeen national labs of the United States.

Part III explores the intersection of quantum communication and fundamental physics. I describe the experimental implementation of time-bin GHZ states in a quantum network and a traversable wormhole teleportation protocol on a quantum computer. I conclude with an outlook on future directions and opportunities for quantum communication and fundamental physics.