42,929 research outputs found
Expanding the thermodynamical potential and the analysis of the possible phase diagram of deconfinement in FL model
The deconfinement phase transition is studied in the FL model at finite
temperature and chemical potential. At MFT approximation, the phase transition
can only be the first order in the whole phase plane. By a Landau
expansion we further study the phase transition order and the possible phase
diagram of deconfinement. We discuss the possibilities of second order phase
transitions in FL model. By our analysis the cubic term in the Landau expansion
could be cancelled by the high order fluctuations. By an ansatz of the Landau
parameters, we obtain the possible phase diagram with both first and second
order phase transition including the tricritical point which is similar to that
of the chiral phase transition.Comment: 7 pages, 8 figures, submitted to Chinese Physics
Monolithic arrays of surface emitting laser NOR logic devices
Monolithic, cascadable, laser-logic-device arrays have been realized and characterized. The monolithic surface-emitting laser logic (SELL) device consists of an AlGaAs superlattice lasing around 780 nm connected to a heterojunction phototransistor (HPT) in parallel and a resistor in series. Arrays up to 8×8 have been fabricated, and 2×2 arrays show uniform characteristics. The optical logic output is switched off with 40 μW incident optical input
Monolithic arrays of surface emitting laser NOR logic devices
Monolithic, cascadable, laser-logic-device arrays have been realized and characterized. The monolithic surface-emitting laser logic (SELL) device consists of an AlGaAs superlattice lasing around 780 nm connected to a heterojunction phototransistor (HPT) in parallel and a resistor in series. Arrays up to 8×8 have been fabricated, and 2×2 arrays show uniform characteristics. The optical logic output is switched off with 40 μW incident optical input
Schwinger-Boson Mean-Field Theory of Mixed-Spin Antiferromagnet
The Schwinger-boson mean-field theory is used to study the three-dimensional
antiferromagnetic ordering and excitations in compounds , a large
family of quasi-one-dimensional mixed-spin antiferromagnet. To investigate
magnetic properties of these compounds, we introduce a three-dimensional
mixed-spin antiferromagnetic Heisenberg model based on experimental results for
the crystal structure of . This model can explain the experimental
discovery of coexistence of Haldane gap and antiferromagnetic long-range order
below N\'{e}el temperature. Properties such as the low-lying excitations,
magnetizations of and rare-earth ions, N\'{e}el temperatures of different
compounds, and the behavior of Haldane gap below the N\'{e}el temperature are
investigated within this model, and the results are in good agreement with
neutron scattering experiments.Comment: 12 pages, 6 figure
Interaction between a fast rotating sunspot and ephemeral regions as the origin of the major solar event on 2006 December 13
The major solar event on 2006 December 13 is characterized by the
approximately simultaneous occurrence of a heap of hot ejecta, a great
two-ribbon flare and an extended Earth-directed coronal mass ejection. We
examine the magnetic field and sunspot evolution in active region NOAA AR
10930, the source region of the event, while it transited the solar disk centre
from Dec. 10 to Dec. 13. We find that the obvious changes in the active region
associated with the event are the development of magnetic shear, the appearance
of ephemeral regions and fast rotation of a smaller sunspot. Around the area of
the magnetic neutral line of the active region, interaction between the fast
rotating sunspot and the ephemeral regions triggers continual brightening and
finally the major flare. It is indicative that only after the sunspot rotates
up to 200 does the major event take place. The sunspot rotates at
least 240 about its centre, the largest sunspot rotation angle which
has been reported.Comment: 4 pages, 6 figures, ApJ Letters inpres
Anomalous Dimers in Quantum Mixtures near Broad Resonances: Pauli Blocking, Fermi Surface Dynamics and Implications
We study the energetics and dispersion of anomalous dimers that are induced
by the Pauli blocking effect in a quantum Fermi gas of majority atoms near
interspecies resonances. Unlike in vacuum, we find that both the sign and
magnitude of the dimer masses are tunable via Feshbach resonances. We also
investigate the effects of particle-hole fluctuations on the dispersion of
dimers and demonstrate that the particle-hole fluctuations near a Fermi surface
(with Fermi momentum ) generally reduce the effective two-body
interactions and the binding energy of dimers. Furthermore, in the limit of
light minority atoms the particle-hole fluctuations disfavor the formation of
dimers with a total momentum , because near the modes
where the dominating particle-hole fluctuations appear are the softest. Our
calculation suggests that near broad interspecies resonances when the
minority-majority mass ratio is smaller than a critical value
(estimated to be 0.136), dimers in a finite-momentum channel are energetically
favored over dimers in the zero-momentum channel. We apply our theory to
quantum gases of LiK, LiRb, KRb and
LiNa near broad interspecies resonances, and discuss the
limitations of our calculations and implications.Comment: 15 pages, 10 figures, published versio
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