13,105 research outputs found
Fermion condensation: a strange idea successfully explaining behavior of numerous objects in Nature
Strongly correlated Fermi systems are among the most intriguing, best
experimentally studied and fundamental systems in physics. These are, however,
in defiance of theoretical understanding. The ideas based on the concepts like
Kondo lattice and involving quantum and thermal fluctuations at a quantum
critical point have been used to explain the unusual physics. Alas, being
suggested to describe one property, these approaches fail to explain the
others. This means a real crisis in theory suggesting that there is a hidden
fundamental law of nature, which remains to be recognized. A theory of fermion
condensation quantum phase transition, preserving the extended quasiparticles
paradigm and intimately related to unlimited growth of the effective mass as a
function of temperature, magnetic field etc, is capable to resolve the problem.
We discuss the construction of the theory and show that it delivers theoretical
explanations of vast majority of experimental results in strongly correlated
systems such as heavy-fermion metals and quasi-two-dimensional Fermi systems.Comment: 12 pages, 14 figures, Invited talk at Bogolyubov Kyiv Conference,
Modern Problems of Theoretical and Mathematical Physics, 2009, Kyiv, Ukrain
Mirrorless Negative-index Parametric Micro-oscillator
The feasibility and extraordinary properties of mirrorless parametric
oscillations in strongly absorbing negative-index metamaterials are shown. They
stem from the backwardness of electromagnetic waves inherent to this type of
metamaterials.Comment: 4 pages, 2 figure
Enhanced four-wave mixing via elimination of inhomogeneous broadening by coherent driving of quantum transition with control fields
We show that atoms from wide velocity interval can be concurrently involved
in Doppler-free two-photon resonant far from frequency degenerate four-wave
mixing with the aid of auxiliary electromagnetic field. This gives rise to
substantial enhancement of the output radiation generated in optically thick
medium. Numerical illustrations addressed to typical experimental conditions
are given.Comment: LaTeX2e, hyperref, 7 pages, 5 figures, to appear in PRA 1 august 200
Scaling Behavior of Heavy Fermion Metals
Strongly correlated Fermi systems are fundamental systems in physics that are
best studied experimentally, which until very recently have lacked theoretical
explanations. This review discusses the construction of a theory and the
analysis of phenomena occurring in strongly correlated Fermi systems such as
heavy-fermion (HF) metals and two-dimensional (2D) Fermi systems. It is shown
that the basic properties and the scaling behavior of HF metals can be
described within the framework of a fermion condensation quantum phase
transition (FCQPT) and extended quasiparticle paradigm that allow us to explain
the non-Fermi liquid behavior observed in strongly correlated Fermi systems. In
contrast to the Landau paradigm stating that the quasiparticle effective mass
is a constant, the effective mass of new quasiparticles strongly depends on
temperature, magnetic field, pressure, and other parameters. Having analyzed
collected facts on strongly correlated Fermi systems with quite different
microscopic nature, we find these to exhibit the same non-Fermi liquid behavior
at FCQPT. We show both analytically and using arguments based entirely on the
experimental grounds that the data collected on very different strongly
correlated Fermi systems have a universal scaling behavior, and materials with
strongly correlated fermions can unexpectedly be uniform in their diversity.
Our analysis of strongly correlated systems such as HF metals and 2D Fermi
systems is in the context of salient experimental results. Our calculations of
the non-Fermi liquid behavior, the scales and thermodynamic, relaxation and
transport properties are in good agreement with experimental facts.Comment: 100 pages, 66 figures, to appear in Physics Report
Damping of electromagnetic waves due to electron-positron pair production
The problem of the backreaction during the process of electron-positron pair
production by a circularly polarized electromagnetic wave propagating in a
plasma is investigated. A model based on the relativistic Boltzmann-Vlasov
equation with a source term corresponding to the Schwinger formula for the pair
creation rate is used. The damping of the wave, the nonlinear up-shift of its
frequency due to the plasma density increase and the effect of the damping on
the wave polarization and on the background plasma acceleration are
investigated as a function of the wave amplitude.Comment: 11 pages, 5 figures; revtex
Four-wave mixing, quantum control and compensating losses in doped negative-index photonic metamaterials
The possibility of compensating absorption in negative-index metatamterials
(NIMs) doped by resonant nonlinear-optical centers is shown. The role of
quantum interference and extraordinary properties of four-wave parametric
amplification of counter-propagating electromagnetic waves in NIMs are
discussed.Comment: 3 pages, 3 figures, LaTeX, corrected typos in eqs. (1) and (2
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