We explore a new connection between Seiberg-Witten theory and quantum
statistical systems by relating the dual partition function of SU(2) Super
Yang-Mills theory in a self-dual Omega-background to the spectral determinant
of an ideal Fermi gas. We show that the spectrum of this gas is encoded in the
zeroes of the Painleve III tau function. In addition we find that the Nekrasov
partition function on this background can be expressed as an O(2) matrix model.
Our construction arises as a four-dimensional limit of a recently proposed
conjecture relating topological strings and spectral theory. In this limit, we
provide a mathematical proof of the conjecture for the local P1xP1 geometry.