Geol Moon

Analytic solutions for the saturated absorption spectra

We present analytic solutions for saturated absorption spectra. The analytic forms of all the ground- and excited-state populations were obtained, and the absorption of a counterpropagating probe beam was calculated by solving the rate equations in the presence of a pump laser beam. The analytic solutions were compared with the numerical, experimental results, and Nakayamas model and good agreement was found between them. We found that the analytic theory could provide accurate spectra at an arbitrary pump beam intensity and diameter.

Relaxation of superfluid turbulence in highly oblate Bose-Einstein condensates

We investigate thermal relaxation of superfluid turbulence in a highly oblate Bose-Einstein condensate. We generate turbulent flow in the condensate by sweeping the center region of the condensate with a repulsive optical potential. The turbulent condensate shows a spatially disordered distribution of quantized vortices and the vortex number of the condensate exhibits nonexponential decay behavior which we attribute to the vortex pair annihilation. The vortex-antivortex collisions in the condensate are identified with crescent-shaped, coalesced vortex cores. We observe that the nonexponential decay of the vortex number is quantitatively well described by a rate equation consisting of one-body and two-body decay terms. In our measurement, we find that the local two-body decay rate is closely proportional to

Thermal friction on quantum vortices in a Bose-Einstein condensate

T^2/\mu

Ideal mean-field transition in a modulated cold atom system.

, where

Critical velocity for vortex shedding in a Bose-Einstein condensate

T

A comparison of the dependence of saturated absorption signals on pump beam diameter and intensity

is the temperature and

Effect of Laser Beam Diameter Variation in Saturated Absorption Spectra

\mu

Bifurcation-enhanced ultrahigh sensitivity of a buckled cantilever

is the chemical potential.

Nonlinear, nonequilibrium and collective dynamics in a periodically modulated cold atom system

We investigate the dissipative dynamics of a corotating vortex pair in a highly oblate axisymmetric Bose-Einstein condensate trapped in a harmonic potential. The initial vortex state is prepared by creating a doubly charged vortex at the center of the condensate and letting it dissociate into two singly charged vortices. The separation of the vortex pair gradually increases over time and its increasing rate becomes higher with increasing the sample temperature

Buckling-Based Non-Linear Mechanical Sensor

T