3,081 research outputs found
A String Approximation for Cooper Pair in High-T superconductivity
It is assumed that in some sense the High-T superconductivity is similar
to the quantum chromodynamics (QCD). This means that the phonons in High-T
superconductor have the strong interaction between themselves like to gluons in
the QCD. At the experimental level this means that in High-T superconductor
exists the nonlinear sound waves. It is possible that the existence of the
strong phonon-phonon interaction leads to the confinement of phonons into a
phonon tube (PT) stretched between two Cooper electrons like a hypothesized
flux tube between quark and antiquark in the QCD. The flux tube in the QCD
brings to a very strong interaction between quark-antiquark, the similar
situation can be in the High-T superconductor: the presence of the PT can
essentially increase the binding energy for the Cooper pair. In the first rough
approximation the PT can be approximated as a nonrelativistic string with
Cooper electrons at the ends. The BCS theory with such potential term is
considered. It is shown that Green's function method in the superconductivity
theory is a realization of discussed Heisenberg idea proposed by him for the
quantization of nonlinear spinor field. A possible experimental testing for the
string approximation of the Cooper pair is offered.Comment: Essential changes: (a) the section is added in which it is shown that
Green's function method in the superconductivity theory is a realization of
discussed Heisenberg quantization method; (b) Veneziano amplitude is
discussed as an approximation for the 4-point Green's function in High-T_c;
(c) it is shown that Eq.(53) has more natural solution on the layer rather
than on 3 dimensional spac
The actual content of quantum theoretical kinematics and mechanics
First, exact definitions are supplied for the terms: position, velocity, energy, etc. (of the electron, for instance), such that they are valid also in quantum mechanics. Canonically conjugated variables are determined simultaneously only with a characteristic uncertainty. This uncertainty is the intrinsic reason for the occurrence of statistical relations in quantum mechanics. Mathematical formulation is made possible by the Dirac-Jordan theory. Beginning from the basic principles thus obtained, macroscopic processes are understood from the viewpoint of quantum mechanics. Several imaginary experiments are discussed to elucidate the theory
Entanglement condition via su(2) and su(1,1) algebra using Schr{\"o}dinger-Robertson uncertainty relation
The Schr{\"o}dinger-Robertson inequality generally provides a stronger bound
on the product of uncertainties for two noncommuting observables than the
Heisenberg uncertainty relation, and as such, it can yield a stricter
separability condition in conjunction with partial transposition. In this
paper, using the Schr{\"o}dinger-Robertson uncertainty relation, the
separability condition previously derived from the su(2) and the su(1,1)
algebra is made stricter and refined to a form invariant with respect to local
phase shifts. Furthermore, a linear optical scheme is proposed to test this
invariant separability condition.Comment: published version, 3.5 pages, 1 figur
Two-dimensional anyons and the temperature dependence of commutator anomalies
The temperature dependence of commutator anomalies is discussed on the
explicit example of particular (anyonic) field operators in two dimensions. The
correlation functions obtained show that effects of the non-zero temperature
might manifest themselves not only globally but also locally.Comment: 11 pages, LaTe
Introduction to Quantum Thermodynamics: History and Prospects
Quantum Thermodynamics is a continuous dialogue between two independent
theories: Thermodynamics and Quantum Mechanics. Whenever the two theories
addressed the same phenomena new insight has emerged. We follow the dialogue
from equilibrium Quantum Thermodynamics and the notion of entropy and entropy
inequalities which are the base of the II-law. Dynamical considerations lead to
non-equilibrium thermodynamics of quantum Open Systems. The central part played
by completely positive maps is discussed leading to the
Gorini-Kossakowski-Lindblad-Sudarshan GKLS equation. We address the connection
to thermodynamics through the system-bath weak-coupling-limit WCL leading to
dynamical versions of the I-law. The dialogue has developed through the
analysis of quantum engines and refrigerators. Reciprocating and continuous
engines are discussed. The autonomous quantum absorption refrigerator is
employed to illustrate the III-law. Finally, we describe some open questions
and perspectives
Dynamical gravities
It is offered that modified gravities can be considered as
nonperturbative quantum effects arising from Einstein gravity. It is assumed
that nonperturbative quantum effects gives rise to the fact that the connection
becomes incompatible with the metric, the metric factors and the square of the
connection in Einstein - Hilbert Lagrangian have nonperturbative additions. In
the simplest approximation both additions can be considered as functions of one
scalar field. The scalar field can be excluded from the Lagrangian obtaining
gravity. The essence of quantum correction to the affine connection as a
torsion is discussed.Comment: discussion on quantum corrections is adde
Unitary equivalence between ordinary intelligent states and generalized intelligent states
Ordinary intelligent states (OIS) hold equality in the Heisenberg uncertainty
relation involving two noncommuting observables {A, B}, whereas generalized
intelligent states (GIS) do so in the more generalized uncertainty relation,
the Schrodinger-Robertson inequality. In general, OISs form a subset of GISs.
However, if there exists a unitary evolution U that transforms the operators
{A, B} to a new pair of operators in a rotation form, it is shown that an
arbitrary GIS can be generated by applying the rotation operator U to a certain
OIS. In this sense, the set of OISs is unitarily equivalent to the set of GISs.
It is the case, for example, with the su(2) and the su(1,1) algebra that have
been extensively studied particularly in quantum optics. When these algebras
are represented by two bosonic operators (nondegenerate case), or by a single
bosonic operator (degenerate case), the rotation, or pseudo-rotation, operator
U corresponds to phase shift, beam splitting, or parametric amplification,
depending on two observables {A, B}.Comment: published version, 4 page
Formulation of the Spinor Field in the Presence of a Minimal Length Based on the Quesne-Tkachuk Algebra
In 2006 Quesne and Tkachuk (J. Phys. A: Math. Gen. {\bf 39}, 10909, 2006)
introduced a (D+1)-dimensional -two-parameter Lorentz-covariant
deformed algebra which leads to a nonzero minimal length. In this work, the
Lagrangian formulation of the spinor field in a (3+1)-dimensional space-time
described by Quesne-Tkachuk Lorentz-covariant deformed algebra is studied in
the case where up to first order over deformation parameter
. It is shown that the modified Dirac equation which contains higher
order derivative of the wave function describes two massive particles with
different masses. We show that physically acceptable mass states can only exist
for . Applying the condition
to an electron, the upper bound for the isotropic
minimal length becomes about . This value is near to the
reduced Compton wavelength of the electron and is not incompatible with the results obtained for
the minimal length in previous investigations.Comment: 11 pages, no figur
Cosmological constant and Euclidean space from nonperturbative quantum torsion
Heisenberg's nonperturbative quantization technique is applied to the
nonpertrubative quantization of gravity. An infinite set of equations for all
Green's functions is obtained. An approximation is considered where: (a) the
metric remains as a classical field; (b) the affine connection can be
decomposed into classical and quantum parts; (c) the classical part of the
affine connection are the Christoffel symbols; (d) the quantum part is the
torsion. Using a scalar and vector fields approximation it is shown that
nonperturbative quantum effects gives rise to a cosmological constant and an
Euclidean solution.Comment: title is changed. arXiv admin note: text overlap with arXiv:1201.106
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