A research team led by Prof. LI Chuanfeng from the University of Science and Technology of China (USTC) of the Chinese Academy of Sciences developed an on-chip photonic simulator capable of simulating arbitrary-range coupled frequency lattices with gauge potential. This study was published in Physical Review Letters.

The quest for effective simulators that can replicate the dynamics of real systems has been a driving force in quantum physics. Photonic systems have emerged as versatile candidates for quantum simulation. However, the challenge lies in creating frequency lattices that can simulate complex structures like atom chains and nanotubes, which are crucial for understanding low-dimensional materials.

To address this challenge, researchers developed a novel approach involves the use of thin-film lithium niobate chips, which are particularly suited for creating lattices in the frequency domain due to their high electro-optic coefficient. They observed band structures by periodically modulating an on-chip resonator, which allows for the simulation of structures with arbitrary-range coupling. 

This approach enabled coupling up to eight and nine times the lattice constant, while reducing the required modulation frequency by over five orders of magnitude. This was achieved by including multiple lattice points within one resonant peak, reducing the difficulty of applying and detecting multiharmonic signals conventionally of ultrahigh frequency on chips.

The special focus of this study on low-frequency radio-frequency modulation offers a high degree of flexibility in choosing lattice points and regulating compound interaction, which significantly reduces the required frequencies by more than three orders of magnitude, translating to a reduction from near 100 GHz to around 10 MHz in their examples. This reduces the requirement on source and measurement equipment.

This work achieves high-dimensional and complex frequency synthetic dimensions on thin-film lithium niobate optical chips, which opens a new avenue to study synthetic dimensions on photonic chips.