Superradiance for lattice model with lee interaction

Phonons and rotons of trapped atoms in a gravitational field

“…The conclusions on the equations (4)- (9) are as follows: a) for a given G 0 the inequality (8) can be satisfied for large | | y 0 , so the presence of rotons diminishes the BEC density; b) the less amount of BEC bosons | | y 0 2 we have, the larger will be a rotational momentum of atom for a given trap. These conclusions seems to be in accordance with the prioriting Popov [1] result, that the zero points of boson trajectory y = 0 are starting points for a vortexes in superfluid 4 He. As to the influence of gravity, we note here the point (c) as follows: c) the gravitational field diminishes the BEC density in a trap.…”

“…The particular time-independent ( ) * * y y (4)- (6) is similar to «slow» trajectories in superfluid 4 He theory [1], associated with the Bose-Einstein condensation (BEC) in quantum liquid. In the same way y y 0 0 * , trajectories correspond BEC of atoms in a trap, observed experimentally during the last years [6].…”

“…If we rotate a trap, the new form of atomic motion-rotons-may be expected. In 4 He the same maxon-roton excitations are followed by vortexes. They are defined as a singularity points of a velocity field rot V r ( ) = 0, connected to the condition for an amplitude y to become zero y( ) r = 0 [1,2].…”

“…The calculation of Sp in (4)- (6) is carried out following [4,5] both in the matrix and Path Integral sense…”

Single-bubble sonoluminescence as Dicke superradiance at finite temperature

“…In the case of g 1 = 0 and g 2 = 0, and also in the case of g 1 = 0 and g 2 = 0, the maximum points are a continuous set of values given by the expression b 0 = ρ e i φ and b * 0 = ρ e −i φ with φ ∈ [0, 2π) and ρ = |b 0 |, with |b 0 | defined by Eq. (24). In the case of g 1 = 0 and g 2 = 0, we have two maximum points, which are given by b * 0 = b 0 = ±|b 0 |, with |b 0 | defined by Eq.…”