Perspective on Some Recent and Future Developments in Casimir Interactions

Abstract

Here, we present a critical review of recent developments in Casimir physics motivated by discoveries of novel materials. Specifically, topologically nontrivial properties of the graphene family, Chern and topological insulators, and Weyl semimetals have diverse manifestations in the distance dependence, presence of fundamental constants, magnitude, and sign of the Casimir interaction. Limited studies of the role of nonlinear optical properties in the interaction are also reviewed. We show that, since many new materials have greatly enhanced the nonlinear optical response, new efficient pathways for investigation of the characteristic regimes of the Casimir force need to be explored, which are expected to lead to new discoveries. Recent progress in the dynamical Casimir effect is also reviewed and we argue that nonlinear media can open up new directions in this field as well.

Quantum Vacuum Sagnac Effect

“…Indeed, here the relative motions of the interfering wave packets with respect to the sense of the particle's rotation plays a crucial role in the atom-particle interaction mediated by the quantum vacuum field. While dynamical Casimir photons are too scarce to be measurable [14][15][16] even when considering a cavity resonance [17][18][19][20], we show that the magnitude of the QVSP is close to the sensitivity limit of state-ofthe-art atom interferometers [10,21] when taking into account the record rotation frequencies recently demonstrated with optically levitated nanoparticles [11,22,23].…”

Optical-Cavity-Induced Current

“…Therefore, the increase in current corresponds to an increasingly wide band of suppressed optical modes in the cavity. The source of these optical modes could be the quantum vacuum field, which gives rise to the Casimir force [18][19][20][21], the Lamb shift [22], and other physical effects [23]. It was argued that the use of energy from the vacuum field does not violate fundamental laws of thermodynamics [24].…”

The Casimir Effect in Topological Matter

“…To make our review self-contained, here, we explain how we obtain the conductivity Formula (27). We follow the approach described in Chapter 1 of Ref.…”

“…To the best of the author's knowledge, there have been three reviews on related topics in the past, viz., Refs. [25][26][27]. Reference [25] provides an overview of realizations of the Casimir effect in various materials, e.g., lipid membranes, metamaterials, photonic crystals and plasmonic nanostructures, with a subsection concisely summarising the state of research (as of 2016) on Casimir interaction in topological matter.…”

“…Reference [26] reviews the Casimir effect in two-dimensional Dirac materials, mainly emphasizing graphene systems. Reference [27] is perhaps closest in spirit to the present review, offering a succinct overview of the Casimir effect in electronic topological materials. It is, thus, timely to provide a more detailed and pedagogical review of the Casimir effect in topological matter that is consistent in terms of both approach and notation (e.g., we use Gaussian units throughout).…”