Two-body momentum correlations in a weakly interacting one-dimensional Bose gas

Isabelle Bouchoule (1) , Maxim Arzamasov (2) , K. V. Kheruntsyan (3) , Dimitri M. Gangardt (4)

1 Laboratoire Charles Fabry / Optique atomique
2 University of Birmingham [Birmingham]
3 ARC - Centre of excellence for quantum atom optics
4 School of Physics and Astronomy [Birmingham]

We analyze the two-body momentum correlation function for a uniform weakly interacting 1D Bose gas. We show that the strong positive correlation between opposite momenta, expected in a Bose-Einstein condensate with a true long-range order, almost vanishes in a phase fluctuating quasicondensate where the long-range order is destroyed. Using the Luttinger liquid approach, we derive an analytic expression for the momentum correlation function in the quasicondensate regime, showing: (i) the reduction and broadening of the opposite-momentum correlations (compared to the singular behaviour in a true condensate), and (ii) an emergence of anti-correlations at small momenta. We also numerically investigate the momentum correlations in the crossover between the quasicondensate and the ideal Bose gas regimes using a classical field approach and show how the anti-correlations gradually disappear in the ideal gas limit.

Domaines: Gaz Quantiques [cond-mat.quant-gas]

Isabelle Bouchoule, Maxim Arzamasov, K. V. Kheruntsyan, Dimitri M. Gangardt. Two-body momentum correlations in a weakly interacting one-dimensional Bose gas. Physical Review A : Atomic, molecular, and optical physics [1990-2015], 2012, 86, pp.033626. ⟨10.1103/PhysRevA.86.033626⟩. ⟨hal-00719723v2⟩