Quantum simulation is one of the most important research fields in quantum information science. There are various experimental platforms used for quantum simulation, such as ultra-cold neutral atom, trapped ion, integrated optical system et al.

GUO Guangcan and his team from University of Science and Technology of China of Chinese Academy of Sciences proposed a new type of platform which allows the simulation of 2D Bosonic system under arbitrary syntheticgauge field. This brand new application of photon’s orbital angular momentum in quantum simulation of topological physics was reported on Nature Communications.

Orbital angular momentum of light is a fundamental optical degree of freedom. It is characterized by unlimited number of available angular momentum states, and has proved invaluable in diverse recent studies ranging from quantum information to optical communication. Researchers designed a special coupled degenerate cavity array in one dimension, which can be used to simulate a variety of two dimensional topological physics by representing the orbital angular momentum states as an extra dimension.

Their basic idea is to design a degenerate cavity supporting photonic modes carrying different orbital angular momentum (i.e. the Laguerre-Gaussian modes), whose resonance frequencies are the same. By coupling photons in different orbital angular momentum states, a single degenerate cavity is equivalent to a 1D coupled-cavity array. Consequently, 1D coupled degenerate cavity array can be used to simulate 2D physics.

In this work, researchers proposed a scheme to realize arbitrary Abelian, SU(2)non-Abelian gauge field, to detect topological invariants such as edge state and Chern number, and to observe topological quantum phase transition. In contrast to other 2D proposals, this 1D structure greatly reduces the complexity of the simulator, and feasible scale of simulation is also increased. For example, to simulate a 10*100 lattice, 1000 cavities are required using other 2D proposals, and only 10 degenerate cavities using this new platform.

This work was funded by National Basic Research Program of China, the Strategic Priority Research Program of the Chinese Academy of Sciences, National Natural Science Foundation of China, and the Fundamental Research Funds for the Central Universities.