Quasiparticles and their interactions are a key part of our understanding quantum many-body systems. Quantum simulation experiments with cold atoms have in recent years advanced isolated quasiparticles, but so far they provided limited information regarding possible bound states. Here, we show how exploring mobile impurities immersed Bose-Einstein condensate (BEC) two-dimensional lattice can ad...

We consider perfect matchings of the square-octagon lattice, also known as “fortresses” [16]. There is a natural local Markov chain on the set of perfect matchings that is known to be ergodic. However, unlike Markov chains for sampling perfect matchings on the square and hexagonal lattices, corresponding to domino and lozenge tilings, respectively, the seemingly related Markov chain on the squa...

Let γm,n denote the size of a minimum dominating set in the m× n grid graph. For the square grid graph, exact values for γn,n have earlier been published for n 6 19. By using a dynamic programming algorithm, the values of γm,n for m,n 6 29 are here obtained. Minimum dominating sets for square grid graphs up to size 29× 29 are depicted. ∗Supported by the Academy of Finland, Grant No. 132122 and ...

We report FePd3 as a material for studying thermally active artificial spin ice (ASI) systems and use it to investigate both the square and kagome ice geometries. We readily achieve perfect ground state ordering in the square lattice and demonstrate the highest yet degree of monopole charge ordering in the kagome lattice. We find that smaller lattice constants in the kagome system generally pro...

We propose an efficient variational method for Z2 lattice gauge theory based on the matrix product ansatz. The method is applied to ladder and square lattices. The Gauss law needs to be imposed on quantum states to guarantee gauge invariance when one studies gauge theory in hamiltonian formalism. On the ladder lattice, we identify gauge invariant low-lying states by evaluating expectation value...

We report here on the first direct observations of the vortex lattice in the bulk of electron-doped Nd1.85Ce0.15CuO4 single crystals. Using small-angle neutron scattering, we have observed a square vortex lattice with the nearest neighbors oriented at 45 degrees from the Cu-O bond direction, which is consistent with theories based on the d-wave superconducting gap. However, the square symmetry ...