On the uniqueness of positive semidefinite matrix solution under compressed observations

In this paper, we investigate the uniqueness of positive semidefinite matrix solution to compressed linear observations. We show that under a necessary and sufficient condition for the linear compressed observations operator, there will be a unique positive semidefinite matrix solution to the compressed linear observations. It is further shown, through concentration of measure phenomenon and sphere covering arguments, that a randomly generated Gaussian linear compressed observations operator will satisfy this necessary and sufficient condition with overwhelmingly large probability.