A superradiant clock laser on a magic wavelength optical lattice

Abstract

An ideal superradiant laser on an optical clock transition of noninteracting cold atoms is predicted to exhibit an extreme frequency stability and accuracy far below mHz-linewidth. In any concrete setup sufficiently many atoms have to be confined and pumped within a finite cavity mode volume. Using a magic wavelength lattice minimizes light shifts and allows for almost uniform coupling to the cavity mode. Nevertheless, the atoms are subject to dipole-dipole interaction and collective spontaneous decay which compromises the ultimate frequency stability. In the high density limit the Dicke superradiant linewidth enhancement will broaden the laser line and nearest neighbor couplings will induce shifts and fluctuations of the laser frequency. We estimate the magnitude and scaling of these effects by direct numerical simulations of few atom systems for different geometries and densities. For Strontium in a regularly filled magic wavelength configuration atomic interactions induce small laser frequency shifts only and collective spontaneous emission weakly broadens the laser. These interactions generally enhance the laser sensitivity to cavity length fluctuations but for optimally chosen operating conditions can lead to an improved synchronization of the atomic dipoles.

Laser from a many-body correlated medium

“…It also becomes clear that both hopping and interactions are detrimental to the laser regime when they act individually, as is evident from the two regimes in which either one (U/J 1) or the other (U/J 1) dominates which is in agreement with the analysis in Ref. [50]. We notice that the many-body couplings do not allow for extra stimulated emission of radiation, which would result in an even larger intensity of the cavity output.…”

Generalized mean-field approach to simulate the dynamics of large open spin ensembles with long range interactions

“…For sufficient densities the particles' effective transition frequency and sponta-neous decay is modified by dipole-dipole interaction [20], which in turn will influence the performance of a corresponding clock or super-radiant laser [21]. While the extremely small dipole moment of a clock transition keeps these interactions small, even tiny shifts and broadenings will ultimately influence clock accuracy and precision.…”

Dynamics of bad-cavity-enhanced interaction with cold Sr atoms for laser stabilization

“…By exploiting the high Q factor of the atomic transitions and using cavities with comparatively low Q factors the systems are far less sensitive to thermal fluctuations of the cavity components, and the experimental requirements are simplified. In these approaches active as well as passive atomic systems have been suggested [13][14][15][16][17][18]. The active atomic systems are optical equivalents of the maser, relying on cooperative quantum phenomena such as superradiance or superfluorescence of atoms inside the cavity mode.…”