  We report the observation of a temperature-controlled synchronization of two
Brownian-particles in a binary mixture close to the critical point of the
demixing transition. The two beads are trapped by two optical tweezers whose
distance is periodically modulated. We notice that the motion synchronization
of the two beads appears when the critical temperature is approached. In
contrast, when the fluid is far from its critical temperature, the
displacements of the two beads are uncorrelated. Small changes in temperature
can radically change the global dynamics of the system. We show that the
synchronisation is induced by the critical Casimir forces. Finally, we present
the measure of the energy transfers inside the system produced by the critical
interaction.
