1,112 research outputs found
Quark-hadron phase transition with surface fluctuation
The effect of surface fluctuation on the observables of quark-hadron phase
transition is studied. The Ginzburg-Landau formalism is extended by the
inclusion of an extra term in the free energy that depends on the vertical
displacements from a flat surface. The probability that a bin has a particular
net displacement is determined by lattice simulation, where the physics input
is color confinement. The surface fluctuation from bin to bin is related to
multiplicity fluctuation, which in turn is measured by the factorial moments.
It is found that both the F-scaling behavior and the scaling exponent are
essentially unaffected by the inclusion of surface fluctuation.Comment: 9 pages, LaTex, 7 figures in a single postscript file, submitted to
Phys. Rev.
Effect of electron-nuclear spin interactions on electron-spin qubits localized in self-assembled quantum dots
The effect of electron-nuclear spin interactions on qubit operations is
investigated for a qubit represented by the spin of an electron localized in a
self-assembled quantum dot. The localized electron wave function is evaluated
within the atomistic tight-binding model. The magnetic field generated by the
nuclear spins is estimated in the presence of an inhomogeneous environment
characterized by a random nuclear spin configuration, by the dot-size
distribution, by alloy disorder, and by interface disorder. Due to these
inhomogeneities, the magnitude of the nuclear magnetic field varies from one
qubit to another by the order of 100 G, 100 G, 10 G, and 0.1 G, respectively.
The fluctuation of the magnetic field causes errors in exchange operations due
to the inequality of the Zeeman splitting between two qubits. We show that the
errors can be made lower than the quantum error threshold if an exchange energy
larger than 0.1 meV is used for the operation.Comment: 15 pages, 2 figure
Plasma Wave Instabilities in Non-Equilibrium Graphene
We study two-stream instabilities in a non-equilibrium system in which a
stream of electrons is injected into doped graphene. As with equivalent
non-equilibrium parabolic band systems, we find that the graphene systems can
support unstable charge-density waves whose amplitudes grow with time. We
determine the range of wavevector that are unstable, and their
growth rates. We find no instability for waves with wavevectors parallel or
perpendicular to the direction of the injected carriers. We find that, within
the small wavevector approximation, the angle between and the
direction of the injected electrons that maximizes the growth rate increases
with increasing . We compare the range and strength of the
instability in graphene to that of two and three dimensional parabolic band
systems.Comment: 21 pages, 7 figure
Finite-size scaling in complex networks
A finite-size-scaling (FSS) theory is proposed for various models in complex
networks. In particular, we focus on the FSS exponent, which plays a crucial
role in analyzing numerical data for finite-size systems. Based on the
droplet-excitation (hyperscaling) argument, we conjecture the values of the FSS
exponents for the Ising model, the susceptible-infected-susceptible model, and
the contact process, all of which are confirmed reasonably well in numerical
simulations
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