This paper aims to review the measure synchronization observed in coupled
Hamiltonian systems briefly. The word `measure' implies the Lebesgue measure,
which generalizes the notion of length, area, and volume in Euclidean space.
During the measure synchronized state, each system shares a phase space domain
with an identical invariant measure. Measure synchronization is characterized
by a Hamiltonian system that displays either quasiperiodic or chaotic dynamics.
This synchronization has been observed in various physical systems, such as
coupled pendula, Josephson junctions, and lasers.Comment: 9 pages, 3 figure