Quantum liquid of repulsively bound pairs of particles in a lattice

Abstract

Repulsively interacting particles in a periodic potential can form bound composite objects, whose dissociation is suppressed by a band gap. Nearly pure samples of such repulsively bound pairs of cold atoms -- "dimers" -- have recently been prepared by Winkler et al. [Nature 441, 853 (2006)]. We here derive an effective Hamiltonian for a lattice loaded with dimers only and discuss its implications to the many-body dynamics of the system. We find that the dimer-dimer interaction includes strong on-site repulsion and nearest-neighbor attraction which always dominates over the dimer kinetic energy at low temperatures. The dimers then form incompressible, minimal-surface "droplets" of a quantum lattice liquid. For low lattice filling, the effective Hamiltonian can be mapped onto the spin-1/2 XXZ model with fixed total magnetization which exhibits a first-order phase transition from the "droplet" to a "gas" phase. This opens the door to studying first order phase transitions using highly controllable ultracold atoms.

Corrected dimer energy & references

References in corpus (2)

• Electron wavepacket propagation and entanglement in a chain of coupled quantum dots
• Tunnelling couplings in discrete lattices, single particle band structure and eigenstates of interacting atom pairs

Cited by in corpus (7)

• Two-particle states in the Hubbard model
• Metastable superfluidity of repulsive fermionic atoms in optical lattices
• Scattering resonances and two-particle bound states of the extended Hubbard model
• Two-channel Feshbach physics in a structured continuum
• Coherent shift of localized bound pair in Bose Hubbard model
• Quantum dynamics of repulsively bound atom pairs in the Bose-Hubbard model
• Quantum dynamics of one and two bosonic atoms in a combined tight-binding periodic and weak parabolic potential