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- Smakov, Jurij, et al.
(författare)
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Stripes, topological order, and deconfinement in a planar t-J(z) model
- 2004
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Ingår i: Physical Review Letters. - 0031-9007 .- 1079-7114. ; 93:6, s. 067201-
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Tidskriftsartikel (refereegranskat)abstract
- We determine the quantum phase diagram of a two-dimensional bosonic t-J(z) model as a function of the lattice anisotropy gamma, using a quantum Monte Carlo loop algorithm. We show analytically that the low-energy sectors of the bosonic and the fermionic t-J(z) models become equivalent in the limit of small gamma. In this limit, the ground state represents a static stripe phase characterized by a nonzero value of a topological order parameter. This phase remains up to intermediate values of gamma, where there is a quantum phase transition to a phase-segregated state or a homogeneous superfluid with dynamic stripe fluctuations depending on the ratio J(z)/t.
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- Xu, Huailiang, et al.
(författare)
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Radiative lifetime and transition probabilities in CdI and CdII
- 2004
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Ingår i: Physical Review A (Atomic, Molecular and Optical Physics). - 1050-2947. ; 70:4
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Tidskriftsartikel (refereegranskat)abstract
- Radiative lifetimes of 11 levels belonging to the 5s5p P-1(1)o 5snd D-3(1,2) (n=6-9) and 5sns S-3(1) (n=7,8) series of Cd I, and of 5 levels of Cd II (i.e., 4d(10)5p P-2(1/2.3/2)o, 4d(10)6s S-2(1/2), and 4d(10)5d D-2(3/2,5/2)) have been measured using the time-resolved laser-induced fluorescence technique. Free neutral and singly ionized cadmium atoms have been generated by laser ablation. Single- or two-step excitation processes were considered to populate the levels under study. Branching fractions of Cd II transitions have been measured by laser-induced breakdown spectroscopy. Transition probabilities and oscillator strengths for Cd I and Cd II spectral lines originating from the above states as well as from the 4d(9)5 s(22)D(3/2,5/2) states of Cd II have been deduced by combining the experimental lifetimes and theoretical branching fractions obtained in multiconfigurational relativistic Hartree-Fock calculations taking core-polarization effects into account.
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