Simulating ultrastrong-coupling processes breaking parity conservation in Jaynes-Cummings systems

Journal article, 2020

We propose the effective simulation of light-matter ultrastrong-coupling phenomena with strong-coupling systems. Recent theory and experiments have shown that the quantum Rabi Hamiltonian can be simulated by a Jaynes-Cummings system with the addition of two classical drives. This allows one to implement nonlinear processes that do not conserve the total number of excitations. However, parity is still a conserved quantity in the quantum Rabi Hamiltonian, which forbids a wide family of processes involving virtual transitions that break this conservation. Here, we show that these parity-nonconserving processes can be simulated and that this can be done in an even simpler setup: A Jaynes-Cummings-type system with the addition of a single classical drive. By shifting the paradigm from simulating a particular model to simulating a particular process, we are able to implement a much wider family of nonlinear coherent protocols than in previous simulation approaches, doing so with fewer resources and constraints. We focus our analysis on three particular examples: A single atom exciting two photons, frequency conversion, and a single photon exciting two atoms.