N. B. Narozhny

Radiation friction versus ponderomotive effect

The concept of ponderomotive potential is upgraded to a regime in which radiation friction becomes dominant. The radiation friction manifests itself in novel features of long-term capturing of the particles released at the focus and impenetrability of the focus from the exterior. We apply time scales separation to the Landau-Lifshitz equation splitting the particle motion into quivering and slow drift of a guiding center. The drift equation is deduced by averaging over fast motion.

On the incompleteness of the Unruh fermion modes in the Minkowski space

It has been shown that boost modes of two-dimensional fermions on a light cone are expressed in terms of the Dirac delta function of a complex argument. Therefore, the decomposition of integrals over the entire range of the boost parameter into parts is inapplicable and the Unruh quantization is valid only in the double Rindler wedge, rather than in the entire Minkowski space. This means that the Unruh “effect” is absent for any statistics of particles. Thus, both the theoretical predictions and numerous proposals of experiments based on the assumption of the existence of this effect are unfounded.

Quantum dot version of topological phase: Half-integer orbital angular momenta

We show that there exists a topological phase equal to π for circular quantum dots with an odd number of electrons. The non-zero value of the topological phase is explained by axial symmetry and two-dimensionality of the system. Its particular value (π) is fixed by the Pauli exclusion principle and leads to half-integer values for the eigenvalues of the orbital angular momentum. Our conclusions agree with the experimental results of T. Schmidt et al., Phys. Rev. B 51, 5570 (1995), which can be considered as the first experimental evidence for the existence of the new topological phase and half-integer quantization of the orbital angular momentum in a system of an odd number of electrons in circular quantum dots.

On the dynamical Casimir effect in a one-dimensional contracting cavity

The dynamical Casimir effect is analyzed in the framework of the S-matrix formulation for a one-dimensional cavity that exhibits contraction at a constant rate over a finite time interval. The exact solution to the problem is presented. It is demonstrated that the efficiency of the creation of pairs nonmonotonically depends on the contraction time. This is due to the fact that the particles are only created at the moments corresponding to the acceleration and stopping of the moving boundary, so that the contributions of these processes on the number of the created particles interfere with each other. The parameters that correspond to the optimal creation of pairs and the stability of a vacuum are presented. The effect of the finiteness of the cavity-boundary acceleration on the results obtained is studied.