6,947 research outputs found
Geometric magnetism in open quantum systems
An isolated classical chaotic system, when driven by the slow change of
several parameters, responds with two reaction forces: geometric friction and
geometric magnetism. By using the theory of quantum fluctuation relations we
show that this holds true also for open quantum systems, and provide explicit
expressions for those forces in this case. This extends the concept of Berry
curvature to the realm of open quantum systems. We illustrate our findings by
calculating the geometric magnetism of a damped charged quantum harmonic
oscillator transported along a path in physical space in presence of a magnetic
field and a thermal environment. We find that in this case the geometric
magnetism is unaffected by the presence of the heat bath.Comment: 7 pages. Signs corrected. v3 Accepted in Phys. Rev.
Dynamical heat channels
We consider heat conduction in a 1D dynamical channel. The channel consists
of a group of noninteracting particles, which move between two heat baths
according to some dynamical process. We show that the essential thermodynamic
properties of the heat channel can be evaluated from the diffusion properties
of the underlying particles. Emphasis is put on the conduction under anomalous
diffusion conditions. \\{\bf PACS number}: 05.40.+j, 05.45.ac, 05.60.cdComment: 4 figure
Analytically solvable model of a driven system with quenched dichotomous disorder
We perform a time-dependent study of the driven dynamics of overdamped
particles which are placed in a one-dimensional, piecewise linear random
potential. This set-up of spatially quenched disorder then exerts a dichotomous
varying random force on the particles. We derive the path integral
representation of the resulting probability density function for the position
of the particles and transform this quantity of interest into the form of a
Fourier integral. In doing so, the evolution of the probability density can be
investigated analytically for finite times. It is demonstrated that the
probability density contains both a -singular contribution and a
regular part. While the former part plays a dominant role at short times, the
latter rules the behavior at large evolution times. The slow approach of the
probability density to a limiting Gaussian form as time tends to infinity is
elucidated in detail.Comment: 18 pages, 5 figure
High-performance passive microwave survey on Josephson Junctions
The quasi-optical generations of images of objects with their internal structure in millimeter (MM) and submillimeter (SMM) bands is one of prime problems of modern radioelectronics. The main advantage of passive MM imaging systems in comparison with visible and infrared (IR) systems is small attenuation of signals in fog, cloud, smoke, dust and other obscurants. However, at a panoramic scanning of space the observation time lengthens and thereby the information processing rate becomes restricted so that single-channel system cannot image in real time. Therefore we must use many radiometers in parallel to reduce the observation time. Such system must contain receiving sensors as pixels in multibeam antenna. The use of Josephson Junctions (JJ) for this purpose together with the cryoelectronic devices like GaAs FET (field effect transistors) or SQUIDS for signal amplifications after JJ is of particular interest in this case
Hyper-Raman scattering analysis of the vibrations in vitreous boron oxide
Hyper-Raman scattering has been measured on vitreous boron oxide,
BO. This spectroscopy, complemented with Raman scattering and
infrared absorption, reveals the full set of vibrations that can be observed
with light. A mode analysis is performed based on the local D symmetry
of BO triangles and BO boroxol rings. The results show that in
BO the main spectral components can be succesfully assigned using
this relatively simple model. In particular, it can be shown that the
hyper-Raman boson peak arises from external modes that correspond mainly to
librational motions of rigid boroxol rings.Comment: 13 pages, 11 figures, 2 table
On the theory of the vortex state in the Fulde-Ferrell-Larkin-Ovchinnikov (FFLO) phase
We demonstrate that the vortex state in the Fulde-Ferrell-Larkin-Ovchinnikov
(FFLO) phase may be very different depending on the field orientation relative
to the crystalline axes. We calculate numerically the upper critical field near
the tricritical point taking into account the modulation of the order parameter
along the magnetic field as well as the higher Landau levels. For s-wave
superconductors with the anisotropy described by an elliptical Fermi surface we
propose a general scheme of the analysis of the angular dependence of upper
critical field at all temperatures on the basis of the exact solution for the
order parameter. Our results show that the transitions (with tilting magnetic
field) between different types of mixed states may be a salient feature of the
FFLO phase. Moreover we discuss the reasons for the first-order phase
transition into the FFLO state in the case of CeCoIn5 compound.Comment: 7 figure
Effects of Vacuum Polarization in Strong Magnetic Fields with an Allowance Made for the Anomalous Magnetic Moments of Particles
Given the anomalous magnetic moments of electrons and positrons in the
one-loop approximation, we calculate the exact Lagrangian of an intense
constant magnetic field that replaces the Heisenberg-Euler Lagrangian in
traditional quantum electrodynamics (QED). We have established that the derived
generalization of the Lagrangian is real for arbitrary magnetic fields. In a
weak field, the calculated Lagrangian matches the standard Heisenberg-Euler
formula. In extremely strong fields, the field dependence of the Lagrangian
completely disappears, and the Lagrangian tends to a constant determined by the
anomalous magnetic moments of the particles.Comment: 19 pages, 3 figure
Anomalous diffusion for overdamped particles driven by cross-correlated white noise sources
We study the statistical properties of overdamped particles driven by two
cross-correlated multiplicative Gaussian white noises in a time-dependent
environment. Using the Langevin and Fokker-Planck approaches, we derive the
exact probability distribution function for the particle positions, calculate
its moments and find their corresponding long-time, asymptotic behaviors. The
generally anomalous diffusive regimes of the particles are classified, and
their dependence on the friction coefficient and the characteristics of the
noises is analyzed in detail. The asymptotic predictions are confirmed by exact
solutions for two examples.Comment: 15 page
The arions generation by magnetodipole waves of pulsars and magnetars in a constant magnetic field
The influence of the gravitational fields of pulsars and magnetars on the
arion emission during the propagation of magnetodipole waves in a constant
magnetic field has been evaluated.
The solution of the equation was obtained and the flux of arions emitted by
magnetodipole waves during their propagation in a constant magnetic field was
found. It is shown that the amplitude of the born arion wave at a distance from
the source of magnetodipole radiation of a pulsar or magnetar in
the considered case tends to a constant value. The intensity of the arion
emission in the solid angle element and the amount of arion energy
, emitted in all directions per unit time grow quadratically with
increasing distance, traveled by the magnetodipole radiation of a pulsar or
magnetar in a constant magnetic field.
Such growth of the energy of the born arion wave is due to the fact that in
the considered problem constant magnetic field is defined in the whole space.
In reality, the galactic and intergalactic magnetic fields can be represented
in this form only in regions of space of finite dimensions, outside of which
the force lines of their induction vector are curved. Therefore, it is possible
to apply these results only in a region of space for which , where is the coherence length, the distance at which
the force lines of the induction vector can be considered as straight lines. An
estimate for the value of the coupling constant of photons with arions is
obtained
New limits on di-nucleons decay into invisible channels
Data of the radiochemical experiment [E.L.Fireman, 1978] with 1.7 t of
KC_2H_3O_2, accumulated deep underground during ~1 yr, were reanalyzed to set
limits on di-nucleons (nn and np) decays into invisible channels
(disappearance, decay into neutrinos, etc.). The obtained lifetime bounds
tau_np > 2.1 10^25 yr and tau_nn > 4.2 10^25 yr (at 90% C.L.) are better (or
competitive) than those established in the recent experiments.Comment: 3 pages, accepted in JETP Letter
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