Scientific Results

Quantum criticality in a bosonic Josephson junction

Year: 2012

Authors: Buonsante P., Burioni R., Vescovi E., Vezzani A

Autors Affiliation: Dipartimento di Fisica, Università degli Studi di Parma, Viale G.P. Usberti n.7/A, 43100 Parma, Italy;
Istituto Nazionale di Ottica-CNR (INO-CNR) and European Laboratory for Non-Linear Spectroscopy (LENS) Via N. Carrara 1,I-50019 Sesto Fiorentino, Italy;
INFN, Gruppo Collegato di Parma, Viale G.P. Usberti n.7/A, 43100 Parma, Italy;
Centro S3, CNR Istituto di Nanoscienze, via Campi 213/a, 41100 Modena, Italy

Abstract: In this paper we consider a bosonic Josephson junction described by a two-mode Bose-Hubbard model, and we thoroughly analyze a quantum phase transition occurring in the system in the limit of infinite bosonic population. We discuss the relation between this quantum phase transition and the dynamical bifurcation occurring in the spectrum of the discrete self-trapping equations describing the system at the semiclassical level. In particular, we identify five regimes depending on the strength of the effective interaction among bosons, and study the finite-size effects arising from the finiteness of the bosonic population. We devote special attention to the critical regime which reduces to the dynamical bifurcation point in the thermodynamic limit of infinite bosonic population. Specifically, we highlight an anomalous scaling in the population imbalance between the two wells of the trapping potential, as well as in two quantities borrowed from quantum information theory, i.e., the entropy of entanglement and the ground-state fidelity. Our analysis is not limited to the zero-temperature case, but considers thermal effects as well.

Journal/Review: PHYSICAL REVIEW A

Volume: 85 (4)      Pages from: 043625  to: 043625

KeyWords: double well; ultracold atoms; attractive; bifurcation; transition
DOI: 10.1103/PhysRevA.85.043625

Citations: 25
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English