English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Global: Zendy Plus annual

Presents the access of premium content as premium feature

Premium Content

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Global: Zendy Tools annual

Global: Zendy Free Plan

Global: Zendy Tools monthly

Global: Zendy Plus monthly

Quantum-field-theoretic descriptions of interacting condensed bosons havesuffered from the lack of self-consistent approximation schemes satisfyingGoldstone's theorem and dynamical conservation laws simultaneously. We presenta procedure to construct such approximations systematically by using either anexact relation for the interaction energy or the Hugenholtz-Pines relation toexpress the thermodynamic potential in a Luttinger-Ward form. Inspection of theself-consistent perturbation expansion up to the third order with respect tothe interaction shows that the two relations yield a unique identical result ateach order, reproducing the conserving-gapless mean-field theory [T. Kita, J.Phys. Soc. Jpn. 74, 1891 (2005)] as the lowest-order approximation. Theuniqueness implies that the series becomes exact when infinite terms areretained. We also derive useful expressions for the entropy and superfluiddensity in terms of Green's function and a set of real-time dynamical equationsto describe thermalization of the condensate.

Self-consistent perturbation expansion for Bose-Einstein condensates satisfying Goldstone's theorem and conservation laws