Enhancing vibrationally assisted energy transfer via vibrational cooperativity and interference*

Vibrationally assisted energy transfer has recently been engineered in a trapped-ion quantum simulator [Gorman el al., Phys. Rev. X 8, 011038 (2018)]. Motivated by this demonstration, we investigate how cooperativity and interference of multiple vibrations enhance energy transfer. This is a step in the quest to reveal the extent of vibrational or vibronic mechanisms behind the phenomenon of long-time coherences in photosynthetic light harvesting systems. By analyzing a donor-bridge-acceptor trimeric chromophore system coupled to two vibrations, we identify features of one-, two-, and even four-phonon transfer processes and signatures of cooperativity and interference that provide maximum enhancement of energy transfer. Our findings of vibrational cooperativity and interference in excited state energy transfer are verifiable in trapped-ion quantum simulators.