A Perspective on Synthetic Dimensions in Photonics

Abstract

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.

Topological Hong-Ou-Mandel interference

“…Our findings pave the way for harnessing topological features in the next generation of quantum photonic architectures with superior stability and resilience against imperfections. We anticipate that photonic devices using photonic degrees of freedom ( 43 ) to introduce topological protection in many-particle dynamics will find use cases in a broad range of new quantum technological applications alongside non-Abelian geometric phases ( 44 ), nonconservative systems ( 45 , 46 ), and many-photon quantum states ( 47 ) with interactions ( 48 , 49 ).…”

Reconfigurable synthetic dimension frequency lattices in an integrated lithium niobate ring cavity

“…Photonic synthetic dimensions [8,9] can be constructed by harnessing various properties of light such as polarization [10], optical angular momentum [11], time bins [12], spatial mode structure [13], and frequency [14]. A well-developed example of the latter approach are the discrete equidistantly spaced frequency modes in a ring resonator, that are conceptually straightforward to couple and partition into lattices by dynamically modulating the cavity [15].…”

On-Chip Topological Photonic Crystal Nanobeam Filters

“…However, the realization of topological nanophotonic crystal devices remains challenging, primarily due to material constraints and the complexity of their design. Recent advancements in the field have introduced the concept of synthetic dimensions, which allows for the exploration of topological physics in higher-dimensional spaces beyond the traditional geometrical dimensionality of the structures. − This innovative approach simplifies the design of on-chip TPC devices by eliminating the reliance on specific symmetry protection or stringent material requirements. − By incorporating synthetic dimensions, researchers have opened up new possibilities for realizing practical topological nanophotonic crystal devices.…”