Response of the polaron system consisting of an impurity in a Bose-Einstein condensate to Bragg spectroscopy

Journal Article · Tue Mar 15 04:00:00 EDT 2011 · Physical Review. A

DOI:https://doi.org/10.1103/PHYSREVA.83.033631· OSTI ID:21541357

Casteels, W; Devreese, J T ^[1]; Tempere, J ^[1]

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1. TQC, Universiteit Antwerpen, Groenenborgerlaan 171, B-2020 Antwerpen (Belgium)

We expand the existing polaron response theory, expressed within the Mori-Zwanzig projection operator formalism applicable for the transfer of arbitrary energy and zero momentum, for the case of finite momentum exchange. A general formula is then derived that can be used to calculate the response of a system to a probe that transfers both momentum and energy to the system. The main extension of the existing polaron response theory is the finite momentum exchange, which was not needed until now, since it is negligible for optical absorption. However, this formalism is needed to calculate the response of the polaronic system consisting of an impurity in a Bose-Einstein condensate (BEC) to Bragg spectroscopy. We show that the well-known features that appear in the optical absorption of the solid-state Froehlich polaron are also present in the Bragg response of the BEC-impurity polaron. The f-sum rule is written in a form suitable to provide an independent consistency test for our results. The effect of lifetime broadening on the BEC-impurity spectrum is examined. The results derived here are discussed in the framework of an experimental realization consisting of a lithium impurity in a sodium condensate.

• OSTI ID: 21541357
• Journal Information: Physical Review. A, Journal Name: Physical Review. A Journal Issue: 3 Vol. 83; ISSN 1050-2947; ISSN PLRAAN
• Country of Publication: United States
• Language: English

Related Subjects

71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
74 ATOMIC AND MOLECULAR PHYSICS
75 CONDENSED MATTER PHYSICS
SUPERCONDUCTIVITY AND SUPERFLUIDITY
ABSORPTION
ALKALI METALS
BOSE-EINSTEIN CONDENSATION
BRAGG REFLECTION
ELEMENTS
EQUATIONS
IMPURITIES
LITHIUM
MATHEMATICAL OPERATORS
METALS
PROJECTION OPERATORS
REFLECTION
SODIUM
SOLIDS
SORPTION
SPECTRA
SPECTROSCOPY
SUM RULES