arXiv subjects

S. Sivasubramanian

Publications and source records attributed to S. Sivasubramanian.

26 records · Page 2Linked to original sources

arXiv2002

Landau Ghosts and Anti-Ghosts in Condensed Matter and High Density Hadronic Matter

It is observed that the ``ghost'' (originally discovered by Landau in quantum electro-dynamics) and its counterparts in other theories are indeed ubiquitous as they occur in a one-loop approximation to any conventional (unbroken) gauge theory. The mechanism is first exposed in its generality via the Dyson equation and a simple but explicit example in condensed matter is provided through the static Clausius-Mossotti and its dynamic counterpart the Lorenz-Lorentz equation. The physical phase transition phenomenon associated with it is found to be super-radiance. We verify quantitatively that water (and many other polar liquids) are indeed super-radiant at room temperature. In quantum chromo-dynamics on the other hand, we encounter, thanks to asymptotic freedom, an ``anti-ghost'' which is closely associated with color confinement. Thus, in QCD, free quarks and glue exist in a super-radiant phase and hadronic matter in the normal one.

hep-ph↗

arXiv2002

Thermodynamic QED Coherence in Condensed Matter: Microscopic Basis of Thermal Superradiance

Electromagnetic superradiant field coherence exists in a condensed matter system if the electromagnetic field oscillators undergo a mean displacement. Transitions into thermal states with ordered superradiant phases have been shown to theoretically exist in Dicke-Preparata models. The theoretical validity of these models for condensed matter has been called into question due to non-relativistic diamagnetic terms in the electronic Hamiltonian. The microscopic bases of Dicke-Preparata thermal superradiance for realistic macroscopic systems are explored in this work. The impossibility of diaelectric correlations in condensed matter systems (via the Landau-Lifshitz theorem) provides a strong theoretical basis for understanding the physical reality of condensed matter thermodynamic superradiant phases.

cond-mat.stat-mech↗

arXiv2002

Thermal Superradiance and the Clausius-Mossotti Lorentz-Lorenz Equations

Electric polarization phenomena in insulating systems have long been described in mean field theory by the (static) Clausius-Mossotti or (dynamic) Lorentz-Lorenz polarizabilities. It is here shown, in the strong coupling regime, that a thermodynamic phase instability exists in these models. The resulting thermodynamic phase diagram coincides with that obtained from Dicke-Preparata model of thermal superradiance.

cond-mat.stat-mech↗

arXiv2002

Temperature of a Compressed Bubble with Application to Sonoluminescence

The rise in temperature from the adiabatic compression of a bubble is computed in thermodynamic mean field (van der Waals) theory. It is shown that the temperature rise is higher for the noble gas atoms than for more complex gas molecules. The adiabatic temperature rise is shown to be sufficient for producing sonoluminescence via the excited electronic states of the atoms.

cond-mat↗

arXiv2002

Radiation Induced Landau-Lifshitz-Gilbert Damping in Ferromagnets

The Landau-Lifshitz-Gilbert damping coefficient employed in the analysis of spin wave ferromagnetic resonance is related to the electrical conductivity of the sample. The changing magnetization (with time) radiates electromagnetic fields. The electromagnetic energy is then absorbed by the sample and the resulting heating effect describes magnetic dissipative damping. The ferromagnetic resonance relaxation rate theoretically depends on the geometry (shape and size) of the sample as well as temperature in agreement with experiment.

cond-mat.stat-mech↗

arXiv2001

Landau-Khalatnikov Circuit model for Ferroelectric Hysteresis

We present the circuit equivalent of the Landau-Khalatnikov dynamical ferroelectric model. The differential equation for hysteretic behavior is subject to numerical computer simulations. The size and shape of the simulated hysteretic loops depends strongly on the frequency and the amplitude of the driving electric field. This dependence makes the experimental extraction of the coercive electric field difficult. The bifurcation of the driven Landau-Khalatnikov model is explained in detail.

cond-mat.stat-mech↗

arXiv2001

Physical Kinetics of Ferroelectric Hysteresis

The physical kinetics of single domain ferroelectric materials are studied using Landau-Khalatnikov equation. The hysteretic curves are obtained numerically. The effective coercive electric field theoretically varies with the driving amplitude and frequency. The effects of thermal noise are explored using the Fokker-Planck kinetic equation. The ferroelectric switching times are discussed and Quantum effects are briefly explored.

cond-mat.stat-mech↗

arXiv2000

Super-Radiance and the Unstable Photon Oscillator

If the damping of a simple harmonic oscillator from a thermally random force is sufficiently strong, then the oscillator may become unstable. For a photon oscillator (radiatively damped by electric dipole moments), the instability leads to a low temperature Hepp-Lieb-Preparata super-radiant phase transition. The stable oscillator regime is described by the free energy of the conventional Casimir effect. The unstable (strongly damped) oscillator has a free energy corresponding to Dicke super-radiance.

cond-mat.stat-mech↗