Spin and Charge Resolved Quantum Gas Microscopy of Antiferromagnetic   Order in Hubbard Chains
  The repulsive Hubbard Hamiltonian is one of the foundational models describing strongly correlated electrons and is believed to capture essential aspects of high temperature superconductivity. Ultracold fermions in optical lattices allow for the simulation of the Hubbard Hamiltonian with a unique control over kinetic energy, interactions and doping. A great challenge is to reach the required low entropy and to observe antiferromagnetic spin correlations beyond nearest neighbors, for which quantum gas microscopes are ideal. Here we report on the direct, single-site resolved detection of antiferromagnetic correlations extending up to three sites in spin-$1/2$ Hubbard chains, which requires an entropy well below $s^*=\ln(2)$. Finally, the simultaneous detection of spin and density opens the route towards the study of the interplay between magnetic ordering and doping in various dimensions. 
Martin Boll, Timon A. Hilker, Guillaume Salomon, Ahmed Omran, Jacopo   Nespolo, Lode Pollet, Immanuel Bloch, Christian Gross
cond-mat.quant-gas