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

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

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

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, Dimitri M. Gangardt, Maxim Arzamasov, K. V. Kheruntsyan. Two-body momentum correlations in a weakly interacting one-dimensional Bose gas. 2012. ⟨hal-00719723v1⟩