  Owing to the ubiquity of synchronization in the classical world, it is
interesting to study its behavior in quantum systems. Though quantum
synchronisation has been investigated in many systems, a clear connection to
quantum technology applications is lacking. We bridge this gap and show that
nanoscale heat engines are a natural platform to study quantum synchronization
and always possess a stable limit cycle. Furthermore, we demonstrate an
intimate relationship between the power of a heat engine and its phase-locking
properties by proving that synchronization places an upper bound on the
achievable steady-state power of the engine. Finally, we show that the
efficiency of the engine sets a point in terms of the bath temperatures where
synchronization vanishes. We link the physical phenomenon of synchronization
with the emerging field of quantum thermodynamics by establishing quantum
synchronization as a mechanism of stable phase coherence.
