Collectively induced many-vortices topology via rotatory Dicke quantum phase transition

Abstract

We examine the superradiance of a Bose-Einstein condensate pumped with a Laguerre-Gaussian laser of high winding number, e.g., = ℓ 7. The laser beam transfers its orbital angular momentum (OAM) to the condensate at once due to the collectivity of the superradiance. An ℓ-fold rotational symmetric structure emerges with the rotatory superradiance. ℓ number of single-charge vortices appear at the arms of this structure. Even though the pump and the condensate profiles initially have cylindrical symmetry, we observe that it is broken to ℓ-fold rotational symmetry at the superradiance. Breaking of the cylindrical symmetry into the ℓ-fold symmetry and OAM transfer to the condensate become significant after the same critical pump strength. Reorganization of the condensate resembles the ordering in the experiment by Esslinger and colleagues (2010 Nature 264 1301). We numerically verify that the critical point for the onset of the reorganization, as well as the properties of the emitted pulse, conform to the characteristics of superradiant quantum phase transition.

Superradiant atomic recoil lasing with orbital angular momentum light

“…This would allow study of interactions involving exchange of both OAM and SAM. Additionally, extension from cold, thermal gases to quantum degenerate gases opens up possibilities for new methods for creation of vortices and persistent currents in BECs, in addition to those described in [11,12]. with g = g k (Ω 0 /2∆ 0 ).…”

Light-matter interaction and Bose-Einstein condensation of light

“…This phenomenon of enhancement of spontaneous emission rate of a collection of N two level atoms is called Dicke superradiance, and the atomic states with j = N/2, m ∼ 0 are often called the Dicke (superradiant) states [16,19]. This phenomenon has been experimentally observed in many different systems [22,23,19,24] and lately has been a subject of interest [25,26,7,27].…”

Many-Particle Entanglement Criterion for Superradiantlike States

“…Experiments on BECs [42][43][44][45][46] show that a condensate reacts to an excitation collectively unless the energy of the excitationhω exc exceeds the interaction en- (a) Wave-function operator, describing indistinguishable atoms in a BEC, is bunched in the superradiant phase. g (3) and g (4) display behavior similar to g (2) .…”

“…When Uint/N > hωexc, the ground state of the BEC becomes many-particle entangled (ξnew < 0) as well as atoms are bunched (g (2) > 1). Incidentally, experiments with BECs [42][43][44][45][46] show that BEC responses the external excitations collectively unless an hωexc > Uint/N is transferred to a single atom. the single-photon superradiance of 2000 atoms randomly placed at positions r j .…”

“…5. Incidentally, in experiments with BECs [42][43][44][45][46] we observe that BEC cannot recoil partially unless the excitation energy exceeds U int /N .…”