Topological phenomena have received great attention as they are closely related to fundamental physics and have great potential in developing new techniques. Also, topological phenomena have been implemented within different systems including condensed matter, ultracold atoms and photonics.
Researchers from Key Lab of Quantum Information at University and Science of Technology of China (USTC) of Chinese Academy of Sciences have proposed a new routine to manipulate topological physics using only a single optical cavity. This new method significantly reduces the practical experimental requirement of simulating such novel physics. The study has been published in Physical Review Letters.
The same group has proposed a new platform several years before which is to simulate 2D topological physics based on degenerate cavity. The cavity is cleverly designed so that it can support various LG modes with different optical angular momenta (OAM), which can be used as a synthetic 1D dimension system without boundaries. Using these settings, 2D physics can then be simulated using 1D cavity arrays.
This time they went a step further by showing that topological phenomena can also be manipulated using only a single cavity, which need the design of sharp boundaries in the synthetic dimension represented by the photonic OAM degree of freedom and the introduction of composite mode structures with modified optical loops inside the cavity.
Using these setting, boundary modes with l=0 can be easily distinguished from other OAM modes with l≠0 due to their different density profiles. Sharp boundaries can then be constructed with the help of hollow beam splitters. Topological features are detectable from the dynamical response of the optical modes at boundaries.
This scheme not only simplifies the simulation of topological physics within a single optical cavity, but also provides new possibilities of dynamically manipulate topological models in much simpler way. For instance, by modulating the phase retardation of the optical loops, Floquet topological phase transitions and edge modes should be observed in such system from the cavity outputs, which currently is still a hot topic and need further investigations.
Figure a. Proposed experimental optical loops inside a single degenerate cavity with composite optical modes to simulate 1D topological physics. Figure b. Optical density profiles with different optical angular momentum at beam splitters (BS1 and BS2) shown in (a). Figure c is the effective finite lattice model with sharp boundaries. (Image file from Physical Review Letters)
Contact: ZHOU Zhengwei zwzhou@ustcnet.
Paper link: http://journals.aps.org/prl/abstract/10.1103/PhysRevLett.118.083603
