Casimir repulsion in moving media

Abstract

Casimir-Lifshitz interaction emerging from relative movement of layers in stratified dielectric media (e.g., non-uniformly moving fluids) is considered. It is shown that such movement may result in a repulsive Casimir-Lifshitz force exerted on the layers, with the simplest possible structure consisting of three adjacent layers of the same dielectric medium, where the middle one is stationary and the other two are sliding along a direction parallel to the interfaces of the layers.Comment: 22 pages, 10 figure

Casimir forces at the threshold of the Cherenkov effect

“…From previous studies [7,[13][14][15], it is known that the electromagnetic field in moving media is subject to the canonical quantization; therefore, we may find the zero-point energy of the quantum-electromagnetic fluctuations in the waveguide shown in Fig. 1 (at zero temperature) with the standard summation over the eigenfrequencies of all possible electromagnetic modes in this structure.…”

“…However, we do not consider velocities above the Cherenkov threshold to avoid any potential instabilities related to the appearance of negative quanta [7] in media moving with such high velocities.…”

“…Such nonreciprocity may lead to interesting effects. For instance, it has been recently shown [7] that in a nonuniformly moving fluid the quantum fluctuations of the electromagnetic field may result in both attractive and repulsive interactions between the moving layers, depending on the relative velocities and directions of movement of the layers. Another effectthat we exploit in this paper-is the drag of radiation by moving matter.…”

“…This framework may be generalized to moving media, provided that the essential nonreciprocity of the electromagnetic processes in such media is properly taken into consideration. In a recently published work [7] such generalization has been performed, and, in the rest of the paper, we use this theory to answer the intriguing questions posed above.…”

Quantum friction on monoatomic layers and its classical analog

“…This force acts against the movement of the bodies, and, thus, it is tempting to imagine that there is a certain "viscosity" associated with the fluctuating field 3 that persists even at T = 0 K. It was recently found that the normal Casimir forces are also affected by the shear movement of the bodies. 23 Although this picture is very intuitive, it is not immediately evident how such a nonreversible and nonconservative effect as friction may result out of the mentioned quantummechanical model. Indeed, in quantum electrodynamics it is typically assumed that the fluctuating electromagnetic field, together with the particles that interact with it, is captured within an adiabatically closed cavity.…”