Photonic Molecules Unlock Exotic Quantum Simulations

Engineering the topological properties of physical systems is a major goal in modern physics. A new study proposes a scheme to simulate these properties using 'photonic molecules'—coupled optical structures—subjected to dynamic modulations.

The researchers utilise synthetic space-frequency dimensions, where frequency-split supermodes serve as a 'pseudospin' degree of freedom. This setup allows for the independent connection of these modes, leading to a complex generalisation of standard quantum fields known as an SL(2,C) non-Abelian gauge field. In simple terms, this is a field where the sequence of physical interactions dictates the outcome.

By theoretically varying the interactions between these spin states (specifically the spin-flipped hopping terms), the team demonstrated the existence of Dirac semimetal transitions and specific rotations of edge states. The authors state that this proposal is experimentally feasible, offering a versatile new platform for studying complex topological physics using photonics.