arXiv subjects

Wonho Jhe

Publications and source records attributed to Wonho Jhe.

24 records · Page 2Linked to original sources

arXiv2005

Spontaneous Symmetry Breaking of Population between Two Dynamic Attractors in a Driven Atomic Trap: Ising-class Phase Transition

We have observed spontaneous symmetry breaking of atomic populations in the dynamic phase-space double-potential system, which is produced in the parametrically driven magneto-optical trap of atoms. We find that the system exhibits similar characteristics of the Ising-class phase transition and the critical value of the control parameter, which is the total atomic number, can be calculated. In particular, the collective effect of the laser shadow becomes dominant at large atomic number, which is responsible for the population asymmetry of the dynamic two-state system. This study may be useful for investigation of dynamic phase transition and temporal behaviour of critical phenomena.

physics.atom-ph↗

arXiv2005

Near-field spectroscopy of bimodal size distribution of InAs/AlGaAs quantum dots

We report on high-resolution photoluminescence (PL) spectroscopy of spatial structure of InAs/AlGaAs quantum dots (QDs) by using a near-field scanning optical microscope (NSOM). The double-peaked distribution of PL spectra is clearly observed, which is associated with the bimodal size distribution of single QDs. In particular, the size difference of single QDs, represented by the doublet spectral distribution, can be directly observed by the NSOM images of PL.

physics.optics↗

arXiv2005

Near-field photoluminescence study of InAs/AlGaAs quantum-dot-based nanoclusters: band filling effect

We have performed near-field spectroscopy and microscopy of the InAs/AlGaAs quantum-dot-based nanoclusters. It is observed that the photoluminescence spectra of spatially confined excitons in the nanoclusters is blue-shifted up to 20 meV as the power density is increased. In particular, the near-field photoluminescence images have shown that excitons became spatially confined gradually from lower energy state (1.4150 eV) to higher energy state (1.4392 eV) as the excitation power is increased, which is indicative of the band-filling effect of semiconductor nanostructures.

physics.optics↗

arXiv2005

Noise-induced Transition between Dynamic Attractors in the Parametrically Excited Magneto-optical Trap

We have investigated noise-induced transition of atoms between double or triple phase-space attractors that are produced in the parametrically driven magneto-optical trap. The transition rates between two or three dynamic attractors, measured for various modulation frequencies and amplitudes, are in good agreement with theoretical calculations and Monte-Carlo simulations based on the Langevin equations. Our experiment may be useful to study nonlinear dynamic problems involving transitions between states far from equilibrium.

physics.atom-ph↗

arXiv2000

Bose-Einstein condensation in a two-dimensional trap

The theory of Bose-Einstein condensation in a two-dimensional(2D) harmonic trap is developed from 2D Gross-Pitaevskii equation. The 2D interaction strength is obtained from a 2D collision theory. We show the realization of 2D condensation of trapped Bose atoms directly by obtaining the stable solutions for the condensate wave function from the 2D Gross-Pitaevskii equation. We calculate the ground-state energy of the 2D system, and also the wave function of the 2D vortex state. In particular, the 2D energy state becomes less stable than the 3D case with the number of trapped atoms. The results of the 2D Bose condensation are also compared with those of the well-known 3D case.

cond-mat.stat-mech↗

arXiv1999

Two-Dimensional Gross-Pitaevskii Equation: Theory of Bose-Einstein Condensation and the Vortex State

We derive the Gross-Pitaevskii equation in two-dimension from the first principles of two-dimensional scattering theory. Numerical calculation of the condensate wave function shows that atoms in a two-dimensional harmonic trap can be condensed into its ground state. Moreover, the ground state energy and the wave function of two-dimensional vortex state are also obtained. Quantitative comparisons between 2D results and 3D ones are made in detail.

cond-mat↗