Essay: Semiconductor Sources of Large-Scale Photonic Entanglement for Science and Technology

Over the past twenty-five years, intensive research on epitaxial semiconductor quantum dots (QDs) has transformed these systems from random quantum emitters embedded in a noisy solid-state environment into one of the most efficient platforms for generating not only single photons but also multiple entangled photons in highly pure quantum states. Today, QD-photon interfaces often outperform their natural-atom counterparts in both quantum-state purity and photon-generation rates while also offering a clear route toward scalable integration and industrial deployment. Building on these remarkable achievements, this Essay outlines a path toward a not-so-distant future in which large numbers of quantum-dot spins are entangled to generate quantum states of light with unprecedented numbers of entangled photons. Just as lasers evolved from laboratory curiosities into ubiquitous enabling technologies, semiconductor sources of large-scale photonic entanglement could become indispensable resources for both emerging quantum technologies and fundamental research. Part of a series of Essays in Physical Review Letters which concisely present author visions for the future of their field.