"Cherenkov radiation" of a sound in a Bose-condensed gas

We develop a microscopic theory of sound damping due to Landau mechanism in dilute gas with Bose condensate. It is based on the coupled evolution equations of the parameters describing the system. These equations have been derived in earlier works within a microscopic approach which employs the Peletminskii-Yatsenko reduced description method for quantum many-particle systems and Bogoliubov model for a weakly nonideal Bose gas with a separated condensate. The dispersion equat...

Bose-Einstein condensation (BEC) and evaporation of transverse photons from the Bose condensate is studied in the case when the density of plasma does not change. The generation of the longitudinal photons (photonikos) by the transverse photons (photons) in terms of the Cherenkov type of radiation in a uniform plasma is demonstrated. The Bogoliubov energy spectrum is derived for photonikos. A new physical phenomena of the "Compton" scattering type in nonlinear photon gas is d...

The equations of massive electrodynamics are derived and the power spectrum formula for the Cherenkov radiation of massive photons is found. The Cherenkov power spectrum is determined also for the two-charge system. It is argued that the massive Cherenkov effect can be observed in superconductive media, ionosphere plasma, waveguides and in particle laboratories.

Above a critical velocity, the dominant mechanism of energy transfer between a moving object and a dilute Bose-Einstein condensate is vortex formation. In this paper, we discuss the critical velocity for vortex formation and the link between vortex shedding and drag in both homogeneous and inhomogeneous condensates. We find that at supersonic velocities sound radiation also contributes significantly to the drag force.

Emission process of a charged particle propagating in a medium with a curved magnetic field is considered. This mechanism combines features of conventional Cherenkov and curvature emission. Thus, presence of a medium with the index of refraction larger than the unity is essential for the emission. In the present paper the generation of high frequency radiation by the mentioned mechanism is considered. The generated waves are vacuum-like electromagnetic waves and may leave the...

Based on the new quantum Vavilov-Cherenkov,s radiation(VCR) theory (PRL,2004),it is stated the possibility of threshold realization in the modern epoch of the novel VCR effect by the relict photon gas, when it is traversed by relativistic particles of the cosmic rays with \gamma \geq \gamma_th \cong 2 \cdot 10^10, where \gamma^2 = 1 - \frac{V^2}{C^2}, v is the speed of particles, and c is the speed of the light in vacuum.

The paper is devoted to the study of the influence of crystalline lattice distortions due to external excitations (acoustic vibrations, temperature gradient, etc.) on the Quasicerenkov radiation. Equations describing Quasicerenkov radiation of charged particles in distorted crystals are derived. These equations are solved numerically. It is shown that certain types of lattice deformations may intensify the Quasicerenkov radiation by several times.

This chapter is an introduction to the Bogoliubov theory of dilute Bose condensates as applied to the study of the spontaneous emission of phonons in a stationary condensate flowing at supersonic speeds. This emission process is a condensed-matter analog of Hawking radiation from astrophysical black holes but is derived here from a microscopic quantum theory of the condensate without any use of the analogy with gravitational systems. To facilitate physical understanding of th...

We study numerically the reconnection of quantized vortices and the concurrent acoustic emission by the analysis of the Gross-Pitaevskii equation. Two quantized vortices reconnect following the process similar to classical vortices; they approach, twist themselves locally so that they become anti-parallel at the closest place, reconnect and leave separately.The investigation of the motion of the singular lines where the amplitude of the wave function vanishes in the vortex co...

We have created an analogue of a black hole in a Bose-Einstein condensate. In this sonic black hole, sound waves, rather than light waves, cannot escape the event horizon. A step-like potential accelerates the flow of the condensate to velocities which cross and exceed the speed of sound by an order of magnitude. The Landau critical velocity is therefore surpassed. The point where the flow velocity equals the speed of sound is the sonic event horizon. The effective gravity is...