Ensuring that different clocks are giving the same time is crucial to enable electronic systems to talk to each other. But what is the cost of this synchronisation at the thermodynamic level?

To answer this question, scientists from the East China Normal University in Shanghai studied two tiny resonating membranes inside an optical cavity. Such optomechanical systems can exhibit quantum properties even on a macroscopic scale, and so they’re an ideal platform for studying ultrasensitive metrology and nonequilibrium thermodynamics. Each of the membranes represented a nanomechanical clock, and the two could be synchronised by increasing their coupling strength by adding more light to the cavity. In this way, the team was able to measure the dependence of the degree of synchronisation on the overall entropy cost.

They hope that this experimental investigation will serve as a starting point to explore synchronisation in navigation-satellite and fibre-optic systems with the aim of improving clock performance.