Polaronic effects in one- and two-band quantum systems

Yin, Tao, Cocks, Daniel, and Hofstetter, Walter (2015) Polaronic effects in one- and two-band quantum systems. Physical Review A (Atomic, Molecular and Optical Physics), 92 (6). 063635. pp. 1-20.

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Abstract

In this work, we study the formation and dynamics of polarons in a system with a few impurities in a lattice immersed in a Bose-Einstein condensate (BEC). This system has been experimentally realized using ultracold atoms and optical lattices. Here, we consider a two-band model for the impurity atoms, along with a Bogoliubov approximation for the BEC, with phonons coupled to impurities via both intraband and interband transitions. We decouple this Fröhlich-type term by an extended two-band Lang-Firsov polaron transformation using a variational method. The new effective Hamiltonian with two (polaron) bands differs from the original Hamiltonian by modified coherent transport, polaron energy shifts, and induced long-range interaction. A Lindblad master-equation approach is used to take into account residual incoherent coupling between polaron and bath. This polaronic treatment yields a renormalized interband relaxation rate compared to Fermi's golden rule. For a strongly coupled two-band Fröhlich Hamiltonian, the polaron is tightly dressed in each band and can not tunnel between them, leading to an interband self-trapping effect.

Item ID: 42452
Item Type: Article (Research - C1)
ISSN: 1094-1622
Date Deposited: 03 Feb 2016 14:55
FoR Codes: 02 PHYSICAL SCIENCES > 0202 Atomic, Molecular, Nuclear, Particle and Plasma Physics > 020201 Atomic and Molecular Physics @ 50%
02 PHYSICAL SCIENCES > 0204 Condensed Matter Physics > 020403 Condensed Matter Modelling and Density Functional Theory @ 50%
SEO Codes: 97 EXPANDING KNOWLEDGE > 970102 Expanding Knowledge in the Physical Sciences @ 100%
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