Measuring Entropy and Short-Range Correlations in the Two-Dimensional Hubbard Model (B4)

E. Cocchi, L.A. Miller, J.H. Drewes, C.F. Chan, D. Pertot, F. Brennecke, and M. Köhl:

🔓 Phys. Rev. X 7, 031025 (2017)

We measure entropy and short-range correlations of ultracold fermionic atoms in an optical lattice for a range of interaction strengths, temperatures, and fillings. In particular, we extract the mutual information between a single lattice site and the rest of the system from a comparison between the reduced density matrix of a single lattice site and the thermodynamic entropy. Moreover, we determine the single-particle density matrix between nearest neighbors from thermodynamic observables and show that even in a strongly interacting Mott insulator fermions are significantly delocalized over short distances in the lattice.