  We show that molecular spin qudits provide an ideal platform to simulate the
quantum dynamics of photon fields strongly interacting with matter. The basic
unit of the proposed molecular quantum simulator can be realized by a simple
dimer of a spin 1/2 and a spin $S$ transition metal ion, solely controlled by
microwave pulses. The spin $S$ ion is exploited to encode the photon field in a
flexible architecture, which enables the digital simulation of a wide range of
spin-boson models much more efficiently than by using a multi-qubit register.
The effectiveness of our proposal is demonstrated by numerical simulations
using realistic molecular parameters, whose prerequisites delineating possible
chemical approaches are also discussed.
