Phase Diagram of a Polarized Fermi Gas Across a Feshbach Resonance

We investigate a Fermi gas of $^6$Li atoms with unbalanced populations in two spin states, whose interactions are tuned by a Feshbach resonance. At the unitarity limit, we observe three distinct phases connected by a tricritical point on a polarization vs. temperature (\textit{P}-\textit{T}) phase diagram: a phase-separated state at low \textit{T}, a polarized superfluid and a polarized normal gas at higher \textit{T}. \footnote{G.B. Partridge {\it et al.}, {\it Science} {\bf 311}, 503 (2006).}$^,$\footnote{G.B. Partridge {\it et al.}, {\it Phys. Rev. Lett.} {\bf 97}, 190407 (2006).} We are currently mapping out the phase diagram as a function of \textit{P}, \textit{T} and interaction. At \textit{T} = 0, as the interaction strength is tuned toward the BEC side of the resonance, we expect to encounter a phase boundary between the phase-separated state and the polarized superfluid. Conversely, on the BCS side, for finite \textit{P}, a transition to the polarized normal gas is expected. We will present our latest results.