Impurity dephasing in a Bose–Hubbard model. (15th March 2021)

• Record Type: Journal Article
• Authors: Caleffi, Fabio; Capone, Massimo; de Vega, Inés; Recati, Alessio
• Is Part Of: New journal of physics. Volume 23:Number 3(2021)
• Publication Date: 2021-03-15
• Subjects: open quantum systems -- pure dephasing -- cold gases in optical lattices -- Bose–Hubbard model -- quasiparticles and collective excitations; Physics -- Periodicals; Physics; Periodicals; 530.05
• DOI: 10.1088/1367-2630/abe080
• Languages: English
• ISSNs: 1367-2630

Abstract

Abstract: We study the dynamics of a two-level impurity embedded in a two-dimensional Bose–Hubbard (BH) model at zero temperature from an open quantum system perspective. Results for the decoherence across the whole phase diagram are presented, with a focus on the critical region close to the transition between superfluid and Mott insulator. In particular we show how the decoherence and the deviation from a Markovian behaviour are sensitive to whether the transition is crossed at commensurate or incommensurate densities. The role of the spectrum of the BH environment and its non-Gaussian statistics, beyond the standard independent boson model, is highlighted. Our analysis resorts on a recently developed method (2020 Phys. Rev. Res. 2 033276) – closely related to slave boson approaches – that enables us to capture the correlations across the whole phase diagram. This semi-analytical method provides us with a deep insight into the physics of the spin decoherence in the superfluid and Mott phases as well as close to the phase transitions.