Motion induced radiation and quantum friction for a moving atom

Abstract

We study quantum dissipative effects that result from the non-relativistic motion of an atom, coupled to a quantum real scalar field, in the presence of a static imperfect mirror. Our study consists of two parts: in the first, we consider accelerated motion in free space, namely, switching off the coupling to the mirror. This results in motion induced radiation, which we quantify via the vacuum persistence amplitude. In the model we use, the atom is described by a quantum harmonic oscillator (QHO). We show that its natural frequency poses a threshold which separates different regimes, involving or not the internal excitation of the oscillator, with the ulterior emission of a photon. At higher orders in the coupling to the field, pairs of photons may be created by virtue of the Dynamical Casimir Effect (DCE). In the second part, we switch on the coupling to the mirror, which we describe by localized microscopic degrees of freedom. We show that this leads to the existence of quantum contactless friction as well as to corrections to the free space emission considered in the first part. The latter are similar to the effect of a dielectric on the spontaneous emission of an excited atom. We have found that, when the atom is accelerated and close to the plate, it is crucial to take into account the losses in the dielectric in order to obtain finite results for the vacuum persistence amplitude. a mbelfarias@df.uba.ar b fosco@cab.cnea.gov.ar c lombardo@df.uba.ar d fdmazzi@cab.cnea.gov.ar arXiv:1907.02128v2 [quant-ph] 15 Aug 2019 2

Motion-Induced Radiation Due to an Atom in the Presence of a Graphene Plane

“…Aside from this contribution, the second, finite one, may be conveniently studied in Fourier space, where it can be related to our previous results on the scalar model [27]. Introducing…”

“…Due to dimensional reasons, the spectrum has a different power law than that of the scalar counterpart of this model [27], as well as different coefficient and factor of 2 (due to the polarizations of the EM field).…”

“…The DCE has been investigated in different models and physical setups, starting from the simplest case of a one-dimensional field theory in a cavity with a moving boundary [24], then a single accelerated mirror [25], and more recent calculations which focus on resonant effects [12][13][14][15]. The microscopic origin of the DCE [26,27] can be traced back to photon emission processes in accelerated atoms: indeed, even when the oscillation frequency is not sufficient to excite the atom, the coupling to the quantum electromagnetic field allows for the emission of photon pairs. Production of photons out of the vacuum can also occur in situations where the electromagnetic properties of a media change with time [28,29].…”

“…We also previously studied the microscopic DCE due to an atom, with an internal structure modelled by a quantum harmonic oscillator, coupled to a scalar field, in the presence of an imperfect mirror [27]. The internal degrees of freedom of the mirror were described in terms of a set of harmonic oscillators.…”

Unruh-DeWitt detector responses for complex scalar fields in de Sitter spacetime

“…This analysis was later extended in various directions, including scalar fields without conformal symmetry, in the static de Sitter coordinate and also quite extensively in the context of quantum entanglement and decoherence, e.g. [13][14][15][16][17][18][19][20][21][22][23][24][25][26][27][28][29][30][31][32] and references therein.…”