119,434 research outputs found
Quantum phase transition in a three-level atom-molecule system
We adopt a three-level bosonic model to investigate the quantum phase
transition in an ultracold atom-molecule conversion system which includes one
atomic mode and two molecular modes. Through thoroughly exploring the
properties of energy level structure, fidelity, and adiabatical geometric
phase, we confirm that the system exists a second-order phase transition from
an atommolecule mixture phase to a pure molecule phase. We give the explicit
expression of the critical point and obtain two scaling laws to characterize
this transition. In particular we find that both the critical exponents and the
behaviors of ground-state geometric phase change obviously in contrast to a
similar two-level model. Our analytical calculations show that the ground-state
geometric phase jumps from zero to ?pi/3 at the critical point. This
discontinuous behavior has been checked by numerical simulations and it can be
used to identify the phase transition in the system.Comment: 8 pages,8 figure
Energy dependent kinetic freeze-out temperature and transverse flow velocity in high energy collisions
Transverse momentum spectra of negative and positive pions produced at
mid-(pseudo)rapidity in inelastic or non-single-diffractive proton-proton
collisions and in central nucleus-nucleus collisions over an energy range from
a few GeV to above 10 TeV are analyzed by a (two-component) blast-wave model
with Boltzmann-Gibbs statistics and with Tsallis statistics respectively. The
model results are in similarly well agreement with the experimental data
measured by a few productive collaborations who work at the Heavy Ion
Synchrotron (SIS), Super Proton Synchrotron (SPS), Relativistic Heavy Ion
Collider (RHIC), and Large Hadron Collider (LHC), respectively. The energy
dependent kinetic freeze-out temperature and transverse flow velocity are
obtained and analyzed. Both the quantities have quick increase from the SIS to
SPS, and slight increase or approximate invariability from the top RHIC to LHC.
Around the energy bridge from the SPS to RHIC, the considered quantities in
proton-proton collisions obtained by the blast-wave model with Boltzmann-Gibbs
statistics show more complex energy dependent behavior comparing with the
results in other three cases.Comment: 16 pages, 4 figures. The European Physical Journal A, accepted. arXiv
admin note: text overlap with arXiv:1805.0334
General correlation functions of the Clauser-Horne-Shimony-Holt inequality for arbitrarily high-dimensional systems
We generalize the correlation functions of the Clauser-Horne-Shimony-Holt
(CHSH) inequality to arbitrarily high-dimensional systems. Based on this
generalization, we construct the general CHSH inequality for bipartite quantum
systems of arbitrarily high dimensionality, which takes the same simple form as
CHSH inequality for two-dimension. This inequality is optimal in the same sense
as the CHSH inequality for two dimensional systems, namely, the maximal amount
by which the inequality is violated consists with the maximal resistance to
noise. We also discuss the physical meaning and general definition of the
correlation functions. Furthermore, by giving another specific set of the
correlation functions with the same physical meaning, we realize the inequality
presented in [Phys. Rev. Lett. {\bf 88,}040404 (2002)].Comment: 4 pages, accepted by Phys. Rev. Let
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