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Single-particle versus pair condensation of hard-core bosons with correlated hopping

K. P. Schmidt·J. Dorier·A. Laeuchli·F. Mila
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Abstract

We investigate the consequences of correlated hopping on the ground state properties of hard-core bosons on a square lattice as revealed by extensive exact diagonalizations and quantum Monte Carlo simulations. While for non interacting hard-core bosons the effective attraction induced by the correlated hopping leads to phase separation at low density, we show that a modest nearest-neighbor repulsion suppresses phase separation, leading to a remarkable low-density pairing phase with no single particle Bose-Einstein condensation but long-range two-particle correlations, signaling a condensation of pairs. We also explain why the unusual properties of the pairing phase are a real challenge for standard one-worm quantum Monte Carlo simulations.

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K. P. Schmidt, J. Dorier, A. Laeuchli, F. Mila. 2006-11-20. Single-particle versus pair condensation of hard-core bosons with correlated hopping. https://doi.org/10.1103/physrevb.74.174508

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