  Integrated photonics is at the heart of many classical technologies, from
optical communications to biosensors, LIDAR, and data center fiber
interconnects. There is strong evidence that these integrated technologies will
play a key role in quantum systems as they grow from few-qubit prototypes to
tens of thousands of qubits. The underlying laser and optical quantum
technologies, with the required functionality and performance, can only be
realized through the integration of these components onto quantum photonic
integrated circuits (QPICs) with accompanying electronics. In the last decade,
remarkable advances in quantum photonic integration and a dramatic reduction in
optical losses have enabled benchtop experiments to be scaled down to prototype
chips with improvements in efficiency, robustness, and key performance metrics.
The reduction in size, weight, power, and improvement in stability that will be
enabled by QPICs will play a key role in increasing the degree of complexity
and scale in quantum demonstrations. In the next decade, with sustained
research, development, and investment in the quantum photonic ecosystem (i.e.
PIC-based platforms, devices and circuits, fabrication and integration
processes, packaging, and testing and benchmarking), we will witness the
transition from single- and few-function prototypes to the large-scale
integration of multi-functional and reconfigurable QPICs that will define how
information is processed, stored, transmitted, and utilized for quantum
computing, communications, metrology, and sensing. This roadmap highlights the
current progress in the field of integrated quantum photonics, future
challenges, and advances in science and technology needed to meet these
challenges.
