54,084 research outputs found
A large-scale one-way quantum computer in an array of coupled cavities
We propose an efficient method to realize a large-scale one-way quantum
computer in a two-dimensional (2D) array of coupled cavities, based on coherent
displacements of an arbitrary state of cavity fields in a closed phase space.
Due to the nontrivial geometric phase shifts accumulating only between the
qubits in nearest-neighbor cavities, a large-scale 2D cluster state can be
created within a short time. We discuss the feasibility of our method for scale
solid-state quantum computationComment: 5 pages, 3 figure
Delocalization and scaling properties of low-dimensional quasiperiodic systems
In this paper, we explore the localization transition and the scaling
properties of both quasi-one-dimensional and two-dimensional quasiperiodic
systems, which are constituted from coupling several Aubry-Andr\'{e} (AA)
chains along the transverse direction, in the presence of next-nearest-neighbor
(NNN) hopping. The localization length, two-terminal conductance, and
participation ratio are calculated within the tight-binding Hamiltonian. Our
results reveal that a metal-insulator transition could be driven in these
systems not only by changing the NNN hopping integral but also by the
dimensionality effects. These results are general and hold by coupling distinct
AA chains with various model parameters. Furthermore, we show from finite-size
scaling that the transport properties of the two-dimensional quasiperiodic
system can be described by a single parameter and the scaling function can
reach the value 1, contrary to the scaling theory of localization of disordered
systems. The underlying physical mechanism is discussed.Comment: 9 pages, 8 figure
Observation of an in-plane magnetic-field-driven phase transition in a quantum Hall system with SU(4) symmetry
In condensed matter physics, the study of electronic states with SU(N)
symmetry has attracted considerable and growing attention in recent years, as
systems with such a symmetry can often have a spontaneous symmetry-breaking
effect giving rise to a novel ground state. For example, pseudospin quantum
Hall ferromagnet of broken SU(2) symmetry has been realized by bringing two
Landau levels close to degeneracy in a bilayer quantum Hall system. In the past
several years, the exploration of collective states in other multi-component
quantum Hall systems has emerged. Here we show the conventional pseudospin
quantum Hall ferromagnetic states with broken SU(2) symmetry collapsed rapidly
into an unexpected state with broken SU(4) symmetry, by in-plane magnetic field
in a two-subband GaAs/AlGaAs two-dimensional electron system at filling factor
around . Within a narrow tilting range angle of 0.5 degrees, the
activation energy increases as much as 12 K. While the origin of this puzzling
observation remains to be exploited, we discuss the possibility of a
long-sought pairing state of electrons with a four-fold degeneracy.Comment: 13 pages, 4 figure
Spectra of Baryons Containing Two Heavy Quarks in Potential Model
In this work, we employ the effective vertices for interaction between
diquarks (scalar or axial-vector) and gluon where the form factors are derived
in terms of the B-S equation, to obtain the potential for baryons including a
light quark and a heavy diquark. The concerned phenomenological parameters are
obtained by fitting data of mesons instead of the heavy quarkonia.
The operator ordering problem in quantum mechanics is discussed. Our numerical
results indicate that the mass splitting between and
is very small and it is consistent with the heavy quark effective
theory (HQET).Comment: 16 page
On the Cauchy problem for the magnetic Zakharov system
In this paper, we study the Cauchy problem of the magnetic type Zakharov
system which describes the pondermotive force and magnetic field generation
effects resulting from the non-linear interaction between plasma-wave and
particles. By using the energy method to derive a priori bounds and an
approximation argument for the construction of solutions, we obtain local
existence and uniqueness results for the magnetic Zakharov system in the case
of
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