Simulating the vibrational quantum dynamics of molecules using photonics

Advances in control techniques for vibrational quantum states in molecules present new challenges for modelling such systems, which could be amenable to quantum simulation methods. Here, by exploiting a natural mapping between vibrations in molecules and photons in waveguides, we demonstrate a reprogrammable photonic chip as a versatile simulation platform for a range of quantum dynamic behaviour in different molecules. We begin by simulating the time evolution of vibrational excitations in the harmonic approximation for several four-atom molecules, including H ₂ CS, SO ₃ , HNCO, HFHF, N ₄ and P ₄ . We then simulate coherent and dephased energy transport in the simplest model of the peptide bond in proteins - N-methylacetamide - and simulate thermal relaxation and the effect of anharmonicities in H ₂ O. Finally, we use multi-photon statistics with a feedback control algorithm to iteratively identify quantum states that increase a particular dissociation pathway of NH ₃ . These methods point to powerful new simulation tools for molecular quantum dynamics and the field of femtochemistry.