  The coherent nonlinear process where a single photon simultaneously excites
two or more two-level systems (qubits) in a single-mode resonator has recently
been theoretically predicted. Here we explore the case where the two qubits are
placed in different resonators in an array of two or three weakly coupled
resonators. Investigating different setups and excitation schemes, we show that
this process can still occur with a probability approaching one under specific
conditions. The obtained results provide interesting insights into subtle
causality issues underlying the simultaneous excitation processes of qubits
placed in different resonators.
