  One key issue of the foundation of statistical mechanics is the emergence of
equilibrium ensembles in isolated and closed quantum systems. Recently, it was
predicted that in the thermodynamic ($N \rightarrow \infty$) limit the
canonical density matrix emerges for small subsystems from almost all pure
states of large quantum many-body systems. This notion of "canonical
typicality" is assumed to originate from the entanglement between subsystem and
environment and the resulting intrinsic quantum complexity of the many-body
state. We show that quantum chaos plays a crucial role in the emergence of
canonical typicality for large but finite quantum systems. We demonstrate that
the degree of canonical typicality can be quantitatively controlled and tuned
by the degree of quantum chaoticity present in the many-body system.
