Fig. 4: Electron temperature and density contour for isochorically heated matter using an intense short-pulse laser.

The temperature and density map is divided using the coupling constant, \({\Gamma }_{{{{\rm{e}}}}}\), and the degree of degeneracy, \(\Theta\), both of which are defined in the text. The shading indicates that matter at high temperatures and low densities with \({\Gamma }_{{{{\rm{e}}}}}\)<< 1 and \(\Theta\) > 1 is treated as classical plasmas, while cold, dense matter (\({\Gamma }_{{{{\rm{e}}}}}\,\)> 1 and \(\Theta\) < 1) is considered to be strongly coupled and Fermi degenerate matter. The warm dense matter regime is loosely defined in the vicinity of \({\Gamma }_{{{{\rm{e}}}}} \sim 1\) and \(\Theta \sim 1\). The experimentally deduced conditions are depicted with a white box. Trajectories represented by red and purple lines correspond to PIC simulations at different distances from the laser interaction region, aligning with the axes in Fig. 3a and b. The evolving conditions at Y = 0 µm and Y = 60 µm are presented as representatives of conditions near the laser interaction in Region 1 and further from the center in Region 2. Filled circles on the solid lines indicate the simulation time of 0.15 ps.