Gaussian quantum fluctuations in the superfluid-Mott-insulator phase transition

Year: 2019

Authors: Faccioli M., Salasnich L.

Autors Affiliation: Univ Padua, Dipartimento Fis & Astron Galileo Galilei, Via Marzolo 8, I-35131 Padua, Italy; CNR, Ist Nazl Ott, Via Nello Carrara 1, I-50019 Sesto Fiorentino, Italy.

Abstract: Recent advances in cooling techniques make possible the experimental study of quantum phase transitions, which are transitions near absolute zero temperature accessed by varying a control parameter. A paradigmatic example is the superfluid-Mott transition of interacting bosons on a periodic lattice. From the relativistic Ginzburg-Landau action of this superfluid-Mott transition we derive the elementary excitations of the bosonic system, which contain in the superfluid phase a gapped Higgs mode and a gapless Goldstone mode. We show that this energy spectrum is in good agreement with the available experimental data and we use it to extract, with the help of dimensional regularization, meaningful analytical formulas for the beyond-mean-field equation of state in two and three spatial dimensions. We find that, while the mean-field equation of state always gives a second-order quantum phase transition, the inclusion of Gaussian quantum fluctuations can induce a first-order quantum phase transition. This prediction is a strong benchmark for future experiments on quantum phase transitions.

Journal/Review: PHYSICAL REVIEW A

Volume: 99 (2)      Pages from: 023614  to: 023614

More Information: The authors thank F. Baldovin, M. Baiesi, G. Gradenigo, P. A. Marchetti, E. Orlandini, A. Stella, F. Toigo, and A. Trovato for fruitful discussions. L.S. acknowledges a FFABR grant from the Italian Ministry of Education, University and Research for partial support.
KeyWords: MODEL; LOCALIZATION
DOI: 10.1103/PhysRevA.99.023614

Citations: 4
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