科研之友
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摘要
Strongly interacting fermionic atoms on optical lattices are studied through a Hubbard-like model Hamiltonian, in which tunneling rates of atoms and molecules between neighboring sites are assumed to be different. In the limit of large on-site repulsion U, the model is shown to reproduce the t-J Hamiltonian, in which the J coefficient of the Heisenberg term depends on the particle-assisted tunneling rate g: explicitly, J = 4g(2)/U. At half-filling, g drives a crossover from a Brinkman-Rice paramagnetic insulator of fully localized atoms (g = 0) to the antiferromagnetic Mott insulator of the standard Hubbard case (g = t). This is observed already in the number of doubly occupied sites under the intermediate coupling regime, thus providing a criterion for extracting from measurements the effective value of g.
- 出版日期2010-4
