Light-cone effect and supersonic correlations in one- and two-dimensional bosonic superfluids

Giuseppe Carleo (1) , Federico Becca (2) , Laurent Sanchez-Palencia (1) , Sandro Sorella (2) , Michele Fabrizio (2)

1 Laboratoire Charles Fabry / Optique atomique
2 SISSA / ISAS - Scuola Internazionale Superiore di Studi Avanzati / International School for Advanced Studies

We study the spreading of density-density correlations in Bose-Hubbard models after a quench of the interaction strength, using time-dependent variational Monte Carlo simulations. It gives access to unprecedented long propagation times and to dimensions higher than one. In both one and two dimensions, we find ballistic light-cone spreading of correlations and extract accurate values of the light-cone velocity in the superfluid regime. We show that the spreading of correlations is generally supersonic, with a light-cone propagating faster than sound modes but slower than the maximum group velocity of density excitations, except at the Mott transition, where all the characteristic velocities are equal. Further, we show that in two dimensions the correlation spreading is highly anisotropic and presents nontrivial interference effects.

Domaines: Physique Quantique [quant-ph]; Optique [physics.optics]

Giuseppe Carleo, Federico Becca, Laurent Sanchez-Palencia, Sandro Sorella, Michele Fabrizio. Light-cone effect and supersonic correlations in one- and two-dimensional bosonic superfluids. Physical Review A : Atomic, molecular, and optical physics [1990-2015], 2014, 89, pp.031602(R). ⟨10.1103/PhysRevA.89.031602⟩. ⟨hal-00871090v2⟩