  (Abridged) Stellar mass black hole X-ray binaries exhibit X-ray spectral
states which also have distinct and characteristic temporal properties. These
states are believed to correspond to different accretion disk geometries. We
present analysis of two long XMM-Newton observations of the Ultra-Luminous
X-ray source (ULX) NGC 1313 X-1, which reveal that the system was in two
different spectral/temporal states. With a count rate of 1.5 counts/s and a
fractional variability amplitude of ~15%, the ULX was in a high flux and
strongly variable state in March 2006. In October 2006, the count rate of the
ULX had reduced by a factor of ~2 and the spectral shape was distinctly
different with the presence of a soft component. No strong variability was
detected during this low flux state with an upper limit on the amplitude < 3%.
Moreover, the spectral properties of the two states implies that the accretion
disk geometry was different for them. The low flux state is consistent with a
model where a standard accretion disk is truncated at a radius of ~17
Schwarzschild radius around a ~200 Msun black hole. The inner hot region
Comptonizes photons from the outer disk to give the primary spectral component.
The spectrum of the high flux state is not compatible with such a geometry.
Instead, it is consistent with a model where a hot corona covers a cold
accretion disk and Comptonizes the disk photons. The variability as a function
of energy is also shown to be consistent with the corona model. Despite these
broad analogies with Galactic black hole systems, the spectral nature of the
ULX is distinct in having a colder Comptonizing temperature (~2 keV) and higher
optical depth (~15) than what is observed for the Galactic ones.
