111,278 research outputs found
Unified description of pairing, trionic and quarteting states for one-dimensional SU(4) attractive fermions
Paired states, trions and quarteting states in one-dimensional SU(4)
attractive fermions are investigated via exact Bethe ansatz calculations. In
particular, quantum phase transitions are identified and calculated from the
quarteting phase into normal Fermi liquid, trionic states and spin-2 paired
states which belong to the universality class of linear field-dependent
magnetization in the vicinity of critical points. Moreover, unified exact
results for the ground state energy, chemical potentials and complete phase
diagrams for isospin attractive fermions with external fields
are presented. Also identified are the magnetization plateaux of
and , where is the magnetization saturation value. The
universality of finite-size corrections and collective dispersion relations
provides a further test ground for low energy effective field theory.Comment: 13 pages, 4 figure
Phase Transitions and Pairing Signature in Strongly Attractive Fermi Atomic Gases
We investigate pairing and quantum phase transitions in the one-dimensional
two-component Fermi atomic gas in an external field. The phase diagram,
critical fields, magnetization and local pairing correlation are obtained
analytically via the exact thermodynamic Bethe ansatz solution. At zero
temperature, bound pairs of fermions with opposite spin states form a singlet
ground state when the external field . A completely ferromagnetic
phase without pairing occurs when the external field . In the
region we observe a mixed phase of matter in which paired
and unpaired atoms coexist. The phase diagram is reminiscent of that of type II
superconductors. For temperatures below the degenerate temperature and in the
absence of an external field, the bound pairs of fermions form hard-core bosons
obeying generalized exclusion statistics.Comment: 9 pages, 5 figures, expanded version with additional text, references
and figure
The 1D interacting Bose gas in a hard wall box
We consider the integrable one-dimensional delta-function interacting Bose
gas in a hard wall box which is exactly solved via the coordinate Bethe Ansatz.
The ground state energy, including the surface energy, is derived from the
Lieb-Liniger type integral equations. The leading and correction terms are
obtained in the weak coupling and strong coupling regimes from both the
discrete Bethe equations and the integral equations. This allows the
investigation of both finite-size and boundary effects in the integrable model.
We also study the Luttinger liquid behaviour by calculating Luttinger
parameters and correlations. The hard wall boundary conditions are seen to have
a strong effect on the ground state energy and phase correlations in the weak
coupling regime. Enhancement of the local two-body correlations is shown by
application of the Hellmann-Feynman theorem.Comment: 23 pages, 7 figures. Improved version. Extra figure added for the
weak coupling regime. New expression for the interaction-dependent cloud size
and additional reference
Wilson ratio of Fermi gases in one dimension
We calculate the Wilson ratio of the one-dimensional Fermi gas with spin
imbalance. The Wilson ratio of attractively interacting fermions is solely
determined by the density stiffness and sound velocity of pairs and of excess
fermions for the two-component Tomonaga-Luttinger liquid (TLL) phase. The ratio
exhibits anomalous enhancement at the two critical points due to the sudden
change in the density of states. Despite a breakdown of the quasiparticle
description in one dimension, two important features of the Fermi liquid are
retained, namely the specific heat is linearly proportional to temperature
whereas the susceptibility is independent of temperature. In contrast to the
phenomenological TLL parameter, the Wilson ratio provides a powerful parameter
for testing universal quantum liquids of interacting fermions in one, two and
three dimensions.Comment: 5+2 pages, 4+1 figures, Eq. (4) is proved, figures were refine
Universal local pair correlations of Lieb-Liniger bosons at quantum criticality
The one-dimensional Lieb-Liniger Bose gas is a prototypical many-body system
featuring universal Tomonaga-Luttinger liquid (TLL) physics and free fermion
quantum criticality. We analytically calculate finite temperature local pair
correlations for the strong coupling Bose gas at quantum criticality using the
polylog function in the framework of the Yang-Yang thermodynamic equations. We
show that the local pair correlation has the universal value in the quantum critical regime, the TLL phase and the
quasi-classical region, where is the pressure per unit length rescaled by
the interaction energy with interaction
strength and linear density . This suggests the possibility to test
finite temperature local pair correlations for the TLL in the relativistic
dispersion regime and to probe quantum criticality with the local correlations
beyond the TLL phase. Furthermore, thermodynamic properties at high
temperatures are obtained by both high temperature and virial expansion of the
Yang-Yang thermodynamic equation.Comment: 8 pages, 6 figures, additional text and reference
Magnetic Phase Transitions in One-dimensional Strongly Attractive Three-Component Ultracold Fermions
We investigate the nature of trions, pairing and quantum phase transitions in
one-dimensional strongly attractive three-component ultracold fermions in
external fields. Exact results for the groundstate energy, critical fields,
magnetization and phase diagrams are obtained analytically from the Bethe
ansatz solutions. Driven by Zeeman splitting, the system shows exotic phases of
trions, bound pairs, a normal Fermi liquid and four mixtures of these states.
Particularly, a smooth phase transition from a trionic phase into a pairing
phase occurs as the highest hyperfine level separates from the two lower energy
levels. In contrast, there is a smooth phase transition from the trionic phase
into a normal Fermi liquid as the lowest level separates from the two higher
levels.Comment: 4 pages, 3 figures, minor revisions to text, replacement figure, refs
added and update
Coulomb Driven New Bound States at the Integer Quantum Hall States in GaAs/Al(0.3)Ga(0.7)As Single Heterojunctions
Coulomb driven, magneto-optically induced electron and hole bound states from
a series of heavily doped GaAs/Al(0.3)Ga(0.7)As single heterojunctions (SHJ)
are revealed in high magnetic fields. At low magnetic fields (nu > 2), the
photoluminescence spectra display Shubnikov de-Haas type oscillations
associated with the empty second subband transition. In the regime of the
Landau filling factor nu < 1 and 1 < nu <2, we found strong bound states due to
Mott type localizations. Since a SHJ has an open valence band structure, these
bound states are a unique property of the dynamic movement of the valence holes
in strong magnetic fields
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