Scientific Results

Single-particle versus pair superfluidity in a bilayer system of dipolar bosons

Year: 2014

Authors: Macia A., Astrakharchik G.E., Mazzanti F., Giorgini S., Boronat J.

Autors Affiliation: Departament de Física i Enginyeria Nuclear, Universitat Politècnica de Catalunya, Campus Nord B4-B5, E-08034 Barcelona, Spain; Dipartimento di Fisica, Università di Trento and INO-CNR BEC Center, I-38123 Povo, Trento, Italy

Abstract: We consider the ground state of a bilayer system of dipolar bosons, where dipoles are oriented by an external field in the direction perpendicular to the parallel planes. Quantum Monte Carlo methods are used to calculate the ground-state energy, the one-body and two-body density matrix, and the superfluid response as a function of the separation between layers. We find that by decreasing the interlayer distance for fixed value of the strength of the dipolar interaction, the system undergoes a quantum phase transition from a single-particle to a pair superfluid. The single-particle superfluid is characterized by a finite value of both the atomic condensate and the super-counterfluid density. The pair superfluid phase is found to be stable against formation of many-body cluster states and features a gap in the spectrum of elementary excitations.

Journal/Review: PHYSICAL REVIEW A

Volume: 90 (4)      Pages from: 043623  to: 043623

More Information: We acknowledge partial financial support from DGI (Spain) Grant No. FIS2011-25275 and Generalitat de Catalunya Grant No. 2009SGR-1003. G. E. A. acknowledges a fellowship from MEC (Spain) through the Ramon y Cajal program. S. G. acknowledges support from ERC through the QGBE grant and from Provincia Autonoma di Trento. Part of the numerical simulations were carried out at the Barcelona Supercomputing Center (the Spanish National Supercomputing Center-Centro Nacional de Supercomputacion).
DOI: 10.1103/PhysRevA.90.043623

Citations: 20
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