  We formulate the high temperature expansion in supersymmetric matrix quantum
mechanics with 4, 8 and 16 supercharges. The models can be obtained by
dimensionally reducing N=1 U(N) super Yang-Mills theory in D=4,6,10 to 1
dimension, respectively. While the non-zero frequency modes become weakly
coupled at high temperature, the zero modes remain strongly coupled. We find,
however, that the integration over the zero modes that remains after
integrating out all the non-zero modes perturbatively, reduces to the
evaluation of connected Green's functions in the bosonic IKKT model. We perform
Monte Carlo simulation to compute these Green's functions, which are then used
to obtain the coefficients of the high temperature expansion for various
quantities up to the next-leading order. Our results nicely reproduce the
asymptotic behaviors of the recent simulation results at finite temperature. In
particular, the fermionic matrices, which decouple at the leading order, give
rise to substantial effects at the next-leading order, reflecting finite
temperature behaviors qualitatively different from the corresponding models
without fermions.
