Recent years have witnessed significant progress in quantum communication and quantum internet with the emerging quantum photonic chips, whose characteristics of scalability, stability, and low cost, flourish and open up new possibilities in miniaturized footprints. Here, we provide an overview of the advances in quantum photonic chips for quantum communication, beginning with a summary of the prevalent photonic integrated fabrication platforms and key components for integrated quantum communication systems. We then discuss a range of quantum communication applications, such as quantum key distribution and quantum teleportation. Finally, the review culminates with a perspective on challenges towards high-performance chip-based quantum communication, as well as a glimpse into future opportunities for integrated quantum networks.

Optical tweezers employing forces produced by light underpin important manipulation tools employed in numerous areas of applied and biological physics. Conventional optical tweezers are widely based on refractive optics, and they require excessive auxiliary optical elements to reshape both amplitude and phase, as well as wavevector and angular momentum of light, and thus impose limitations on the overall cost and integration of optical systems. Metamaterials can provide both electric and optically induced magnetic responses in subwavelength optical structures, and they are highly beneficial to achieve unprecedented control of light required for many applications and can open new opportunities for optical manipulation. Here, we review the recent advances in the field of optical manipulation employing the physics and concepts of metamaterials and demonstrate that metamaterial structures could not only help to advance classical operations such as trapping, transporting, and sorting of particles, but they can uncover exotic optical forces such as pulling and lateral forces. In addition, apart from optical manipulation of particles (that can also be called “meta-tweezers”), metamaterials can be powered dynamically by light to realize ingenious “meta-robots.” This review culminates with an outlook discussing future novel opportunities in this recently emerged field ranging from enhanced particle manipulation to meta-robot actuation.

Harnessing linear and angular momenta of light is one of the cornerstones in modern optics and has found tremendous applications in optical circuits, particle manipulation, metrology, quantum information processing, etc. Emerging theoretical protocols and experimental explorations have created a surge of interest in light lateral momenta and forces, which are perpendicular to the light wave propagation direction. However, there is yet a lack of a comprehensive and holistic overview of transverse momenta (both linear and angular) as well as of optical lateral forces (OLFs). In this article, we first review the most recent transverse momenta including the transverse spin angular momentum, optical skyrmions, as well as lateral momenta from directional side scattering, spin–orbit interaction, and surface plasmon polaritons. Since optical forces result from the momentum exchange between light and matter, the transverse momentum consequently gives rise to intriguing OLFs, which is the second topic of this article. Additional non-trivial lateral forces that combine optics with other effects from thermodynamics, electricity, and microfluidics, are also discussed. It should be emphasized that these momenta and forces ubiquitously exist in a broad range of optical phenomena and have often been neglected due to their unpredicted underlying physics and shortage of experimental means, especially prior to the last decade.

Optical sorting combines optical tweezers with diverse techniques, including optical spectrum, artificial intelligence (AI) and immunoassay, to endow unprecedented capabilities in particle sorting. In comparison to other methods such as microfluidics, acoustics and electrophoresis, optical sorting offers appreciable advantages in nanoscale precision, high resolution, non-invasiveness, and is becoming increasingly indispensable in fields of biophysics, chemistry, and materials science. This review aims to offer a comprehensive overview of the history, development, and perspectives of various optical sorting techniques, categorised as passive and active sorting methods. To begin, we elucidate the fundamental physics and attributes of both conventional and exotic optical forces. We then explore sorting capabilities of active optical sorting, which fuses optical tweezers with a diversity of techniques, including Raman spectroscopy and machine learning. Afterwards, we reveal the essential roles played by deterministic light fields, configured with lens systems or metasurfaces, in the passive sorting of particles based on their varying sizes and shapes, sorting resolutions and speeds. We conclude with our vision of the most promising and futuristic directions, including AI-facilitated ultrafast and bio-morphology-selective sorting. It can be envisioned that optical sorting will inevitably become a revolutionary tool in scientific research and practical biomedical applications.