Casimir Forces and Quantum Friction from Ginzburg Radiation in Atomic Bose-Einstein Condensates

We theoretically propose an experimentally viable scheme to use an impurity atom in an atomic Bose-Einstein condensate, in order to realize condensed-matter analogs of quantum vacuum effects. In a suitable atomic level configuration, the collisional interaction between the impurity atom and the density fluctuations in the condensate can be tailored to closely reproduce the electric-dipole coupling of quantum electrodynamics. By virtue of this analogy, we recover and extend the paradigm of electromagnetic vacuum forces to the domain of cold atoms, showing in particular the emergence, at supersonic atomic speeds, of a novel power-law scaling of the Casimir force felt by the atomic impurity, as well as the occurrence of a quantum frictional force, accompanied by the Ginzburg emission of Bogoliubov quanta. Observable consequences of these quantum vacuum effects in realistic spectroscopic experiments are discussed.

Figure 1

Schematic representation of the moving impurity with internal frequency ${\omega }_0$ and the plate on the $z=0$ plane, confining the condensate (in blue).

Figure 2

Numerical evaluation of Eq. (3) (left panel, blue line) versus Eq. (4) (left panel, red line) in units of ${\mathrm{\Gamma }}_e$, for $\mathrm{\Omega }={10}^{-3}$. The right panel shows the transition rate [Eq. (3)] for $\mathrm{\Omega }=1$.