18,918 research outputs found
Nuclear /EC decays in covariant density functional theory and the impact of isoscalar proton-neutron pairing
Self-consistent proton-neutron quasiparticle random phase approximation based
on the spherical nonlinear point-coupling relativistic Hartree-Bogoliubov
theory is established and used to investigate the /EC-decay half-lives
of neutron-deficient Ar, Ca, Ti, Fe, Ni, Zn, Cd, and Sn isotopes. The isoscalar
proton-neutron pairing is found to play an important role in reducing the decay
half-lives, which is consistent with the same mechanism in the decays
of neutron-rich nuclei. The experimental /EC-decay half-lives can be
well reproduced by a universal isoscalar proton-neutron pairing strength.Comment: 12 pages, 4 figure
Vacuum induced Berry phases in single-mode Jaynes-Cummings models
Motivated by the work [Phys. Rev. Lett. 89, 220404 (2002)] for detecting the
vacuum-induced Berry phases with two-mode Jaynes-Cummings models (JCMs), we
show here that, for a parameter-dependent single-mode JCM, certain atom-field
states also acquire the photon-number-dependent Berry phases after the
parameter slowly changed and eventually returned to its initial value. This
geometric effect related to the field quantization still exists, even the filed
is kept in its vacuum state. Specifically, a feasible Ramsey interference
experiment with cavity quantum electrodynamics (QED) system is designed to
detect the vacuum-induced Berry phase.Comment: 10 pages, 4 figures
Exotic quantum phase transitions in a Bose-Einstein condensate coupled to an optical cavity
A new extended Dicke model, which includes atom-atom interactions and a
driving classical laser field, is established for a Bose-Einstein condensate
inside an ultrahigh-finesse optical cavity. A feasible experimental setup with
a strong atom-field coupling is proposed, where most parameters are easily
controllable and thus the predicted second-order superradiant-normal phase
transition may be detected by measuring the ground-state atomic population.
More intriguingly, a novel second-order phase transition from the superradiant
phase to the \textquotedblleft Mott" phase is also revealed. In addition, a
rich and exotic phase diagram is presented.Comment: 4 pages; figures 1 and 3 are modified; topos are correcte
Dynamics and Berry phase of two-species Bose-Einstein condensates
In terms of exact solutions of the time-dependent Schrodinger equation for an
effective giant spin modeled from a coupled two-mode Bose-Einstein condensate
(BEC) with adiabatic and cyclic time-varying Raman coupling between two
hyperfine states of the BEC, we obtain analytic time-evolution formulas of the
population imbalance and relative phase between two components with various
initial states, especially the SU(2)coherent state. We find the Berry phase
depending on the number parity of atoms, and particle number dependence of the
collapse revival of population-imbalance oscillation. It is shown that
self-trapping and phase locking can be achieved from initial SU(2) coherent
states with proper parameters.Comment: 18 pages,5 figure
Implementing topological quantum manipulation with superconducting circuits
A two-component fermion model with conventional two-body interactions was
recently shown to have anyonic excitations. We here propose a scheme to
physically implement this model by transforming each chain of two two-component
fermions to the two capacitively coupled chains of superconducting devices. In
particular, we elaborate how to achieve the wanted operations to create and
manipulate the topological quantum states, providing an experimentally feasible
scenario to access the topological memory and to build the anyonic
interferometry.Comment: 4 pages with 3 figures; V2: published version with minor updation
Magnetic Soliton and Soliton Collisions of Spinor Bose-Einstein Condensates in an Optical Lattice
We study the magnetic soliton dynamics of spinor Bose-Einstein condensates in
an optical lattice which results in an effective Hamiltonian of anisotropic
pseudospin chain. A modified Landau-Lifshitz equation is derived and exact
magnetic soliton solutions are obtained analytically. Our results show that the
time-oscillation of the soliton size can be controlled in practical experiment
by adjusting of the light-induced dipole-dipole interaction. Moreover, the
elastic collision of two solitons is investigated.Comment: 16 pages, 5 figure
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