arXiv:2201.03311 · Nature
Extended Bose–Hubbard model with dipolar excitons
Camille Lagoin, Utso Bhattacharya, Tobias Graß, Ravindra W. Chhajlany, Tymoteusz Salamon, Kirk Baldwin, Loren N. Pfeiffer, Maciej Lewenstein, Markus Holzmann, François Dubin
Abstract
Abstract The Hubbard model constitutes one of the most celebrated theoretical frameworks of condensed-matter physics. It describes strongly correlated phases of interacting quantum particles confined in a lattice potential. For bosons, in the last two decades the Hubbard Hamiltonian has been deeply scrutinised in the regime of short-range on-site interactions. On the other hand, extensions to longer-range off-site couplings between neighbouring lattice sites have remained mostly elusive experimentally. Entering this regime constitutes a well identified research frontier where quantum matter phases can spontaneously break the lattice symmetry. Here we unveil one of such phases, precisely the long-sought-after checkerboard solid. It is accessed by confining semiconductors dipolar excitons in a two-dimensional square lattice. The exciton checkerboard is signalled by a strongly minimised compressibility at half-filling of the lattice sites, in quantitative agreement with theoretical expectations. Our observations thus highlight that dipolar excitons enable controlled implementations of extended Bose-Hubbard Hamiltonians.