1,904,516 research outputs found
Superconductivity and superconducting order parameter phase fluctuations in a weakly doped antiferromagnet
The superconducting properties of a recently proposed phenomenological model
for a weakly doped antiferromagnet are analyzed, taking into account
fluctuations of the phase of the order parameter. In this model, we assume that
the doped charge carriers can't move out of the antiferromagnetic sublattice
they were introduced. This case corresponds to the free carrier spectra with
the maximum at , as it was observed in ARPES
experiments in some of the cuprates in the insulating state [1]. The doping
dependence of the superconducting gap and the temperature-carrier density phase
diagram of the model are studied in the case of the pairing
symmetry and different values of the effective coupling. A possible relevance
of the results to the experiments on high-temperature superconductors is
discussed.Comment: 16 pages, 4 figure
Magnetotransport in dilute 2D Si-MOSFET system
The beating pattern of Shubnikov-de Haas oscillations is reproduced in both
the crossed and tilted magnetic field configuration and in presence of
zero-field valley splitting in Si-MOSFET system. The consequences of IQHE in
extremely dilute 2DEG are discussed.Comment: 4 pages, 4 figure
The Schmidt modes of biphoton qutrits: Poincare-sphere representation
For a general-form polarization biphoton qutrit, physically corresponding to
a pair of arbitrarily polarized photons in a single frequency and wavevector
mode, we explicitly find polarization Schmidt modes. A simple method is
suggested for factorizing the state vector and the explicit expressions for the
factorizing photon creation operators are found. The degrees of entanglement
and polarization of a qutrit are shown to depend directly on the commutation
features of the factorizing operators. Clear graphic representations for the
Stokes vectors of the qutrit state as a whole, its Schmidt modes, and
factorizing single-photon creation operators are given, based on the Poincar\'e
sphere. An experimental scheme is proposed for measuring the parameters of the
Schmidt decomposition as well as for demonstrating the operational meaning of
qutrit entanglement.Comment: 20 pages, 3 figure
Classical electrodynamics in a space with spin noncommutativity of coordinates
We propose a new relativistic Lorentz-invariant spin-noncommutative algebra.
Using the Weyl ordering of noncommutative position operators, we build an
analogue of the Moyal-Groenewald product for the proposed algebra. The Lagrange
function of an electromagnetic field in the space with spin noncommutativity is
constructed. In such a space electromagnetic field becomes non-abelian. A gauge
transformation law of this field is also obtained. Exact nonlinear field
equations of noncommutative electromagnetic field are derived from the least
action principle. Within the perturbative approach we consider field of a point
charge in a constant magnetic field and interaction of two plane waves. An
exact solution of a plane wave propagation in a constant magnetic and electric
fields is found.Comment: 15 page
On temperature versus doping phase diagram of high critiical temperature superconductors
The attempt to describe the bell-shape dependence of the critical temperature
of high- superconductors on charge carriers density is made. Its linear
increase in the region of small densities (underdoped regime) is proposed to
explain by the role of the order parameter phase 2D fluctuations which become
less at this density growth. The critical temperature suppression in the region
of large carrier densities (overdoped regime) is connected with the appearance
(because of doping) of the essential damping of long-wave bosons which in the
frame of the model proposed define the mechanism of indirect inter-fermion
attraction.Comment: 15 pages, 3 figures, EMTE
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