Exact ground states and correlation functions of chain and ladder models of interacting hardcore bosons or spinless fermions

Physical Review B - Condensed Matter and Materials Physics

Volumn 80, Issue 16, 2009, Pages

  Cheong, Siew Ann ^a,b,c   Henley, Christopher L ^a  

^a Laboratory of Atomic and Solid State Physics and Sibley School of Mechanical and Aerospace Engineering   (United States)

^b Department of Obstetrics Gynecology   (United States)

^c NANYANG TECHNOLOGICAL UNIVERSITY   (Singapore)

Author keywords

[No Author keywords available]

Indexed keywords

EID: 72449122949     PISSN: 10980121     EISSN: 1550235X     Source Type: Journal    
DOI: 10.1103/PhysRevB.80.165124     Document Type: Article

References (39)

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25. As we expect from having two flavors of bound pairs, the many-bound-pair ground state is twofold degenerate for ladders of even length L subject to periodic boundary conditions. For ladders of odd length L subject to periodic boundary conditions, the flavor of a bound pair changes as it goes around the boundary of the ladder, and so the conserved quantum numbers are not the even and odd flavors but are instead the symmetric and antisymmetric combinations of the two flavors. This mixing between even and odd flavors lifts the ground-state degeneracy giving a nondegenerate many-bound-pair ground state whose quantum number is the antisymmetric combination of flavors. In this paper we consider only ladders of even length L because we want to work with ground states containing bound pairs with a definite flavor.
26. More quantitatively, every sector maps to an ordinary fermion chain such that each change in flavor (between successive pairs) diminishes the effective length L′ by 1, thereby increasing the particle density (and hence the energy of that sector's ground state).
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