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  • Resare, Fabian,1998Department of Physics, Chalmers University of Technology, 41296 Gothenburg, Sweden,Kvantteknologi,Institutionen för mikroteknologi och nanovetenskap,Chalmers tekniska högskola,Quantum Technology,Department of Microtechnology and Nanoscience,Chalmers University of Technology (författare)

Few-to-many-particle crossover of pair excitations in a superfluid

  • Artikel/kapitelEngelska2024

Förlag, utgivningsår, omfång ...

  • 2024-12-03
  • American Physical Society (APS),2024
  • printrdacarrier

Nummerbeteckningar

  • LIBRIS-ID:oai:DiVA.org:kth-357925
  • https://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-357925URI
  • https://doi.org/10.1103/PhysRevA.110.L061302DOI
  • https://urn.kb.se/resolve?urn=urn:nbn:se:su:diva-240716URI
  • https://research.chalmers.se/publication/544283URI

Kompletterande språkuppgifter

  • Språk:engelska
  • Sammanfattning på:engelska

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  • Ämneskategori:ref swepub-contenttype
  • Ämneskategori:art swepub-publicationtype

Anmärkningar

  • QC 20241230
  • Motivated by recent advances in the creation of few-body atomic Fermi gases with attractive interactions, we study theoretically the few-to-many-particle crossover of pair excitations, which for large particle numbers evolve into a mode that describes amplitude fluctuations of the superfluid order parameter (the "Higgs"mode). Our analysis is based on the hypothesis that salient aspects of the excitation spectrum are captured by interactions between time-reversed pair states in a harmonic oscillator potential. Microscopically, this assumption leads to a Richardson-type pairing model, which is integrable and thus allows a systematic quantitative study of the few-to-many-particle crossover with only minor numerical effort. We first establish a parity effect in the ground-state energy, i.e., a spectral convexity in the energy of open-shell configurations compared to their closed-shell neighbors, which is quantified by a so-called Matveev-Larkin parameter discussed for mesoscopic superconductors, which generalizes the pairing gap to mesoscopic ensembles and which behaves quantitatively differently in a few-body and a many-body regime. The crossover point for this quantity is widely tunable as a function of interaction strength. We then compute the excitation spectrum and demonstrate that the pair excitation energy shows a minimum that deepens with increasing particle number and shifts to smaller interaction strengths, consistent with the finite-size precursor of a quantum phase transition to a superfluid state. We extract a critical finite-size scaling exponent that characterizes the decrease of the gap with increasing particle number.

Ämnesord och genrebeteckningar

Biuppslag (personer, institutioner, konferenser, titlar ...)

  • Hofmann, JohannesStockholms universitet,Nordiska institutet för teoretisk fysik (Nordita),Nordita SU; Department of Physics, Gothenburg University, 41296 Gothenburg, Sweden,Stockholm University,Göteborgs universitet,University of Gothenburg,Chalmers tekniska högskola,Chalmers University of Technology(Swepub:cth)hofmannj (författare)
  • Department of Physics, Chalmers University of Technology, 41296 Gothenburg, SwedenKvantteknologi (creator_code:org_t)

Sammanhörande titlar

  • Ingår i:Physical Review A: covering atomic, molecular, and optical physics and quantum information: American Physical Society (APS)110:62469-99262469-9934

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