  We computationally study suspensions of slow and fast active Brownian
particles that have undergone motility induced phase separation and are at
steady state. Such mixtures, of varying non-zero activity, remain largely
unexplored even though they are relevant for a plethora of systems and
applications ranging from cellular biophysics to drone swarms. Our mixtures are
modulated by their activity ratios ($\mathrm{Pe}^\mathrm{R}$), which we find to
encode information by giving rise to three regimes, each of which display their
unique emergent behaviors. Specifically, we found non-monotonic behavior of
macroscopic properties, e.g. density and pressure, as a function of activity
ratio, microphase separation of fast and slow particle domains, increased
fluctuations on the interface and severe avalanche events compared to
monodisperse active systems. Our approach of simultaneously varying the two
activities of the particle species allowed us to discover these behaviors and
explain the microscopic physical mechanisms that drive them.
