A dimensionless Hamiltonian of an N-spin Ising model without an external magnetic field (Fig. 1a) is given by Figure 1: Ising model and set-up for generating artificial Ising spins based on DOPOs.

By extending a proof of a physically important behavior in one-dimensional quantum spin systems to higher dimensions, a RIKEN physicist has shown in a new study that the model lacks exact solutions.

Zebras and tigers have stripes, cheetahs and leopards have spots, and the ocellated lizard (Timon lepidus) boasts a labyrinthine pattern of black-and-green chains of scales. Now researchers from the ...