A Perspective on Synthetic Dimensions in Photonics

The concept of synthetic dimension has recently emerged as a versatile way to overcome limitations in the number of effectively available dimensions by leveraging non-spatial degrees of freedom to mimic additional geometric ones. In particular, the field of photonics offers a plethora of technological possibilities for controlling photons and their degrees of freedom, such as polarization, frequency, or orbital angular momentum. Consequently, a broad range of higher-dimensional physical phenomena is already experimentally accessible in lower-dimensional photonic devices and has been used and celebrated, for instance, for the exploration of topological physics. The field of synthetic dimensions is currently even further boosted due to additional mathematical mapping procedures, which pave the way toward even higher synthetic dimensions or, in the presence of optical nonlinearities, can translate to multi-particle quantum systems, allowing appealing alternatives for quantum simulation. In this perspective, current experimental approaches for harnessing synthetic dimensions to probe higher-dimensional physics on various light-based platforms are summarized and discussed including an outlook on promising future prospects in this field.