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PT Leung

Publications and source records attributed to PT Leung.

At least 19 recordsLinked to original sources
PubMed2000

Motional dressed states in a bose-einstein condensate: superfluidity at supersonic speed

We present an exact analytic solution of a nonlinear Schrodinger field interacting with a moving potential (obstacle) at supersonic speed. We discover conditions under which the field can form a stable shape-invariant structure localized around the obstacle-a dressing effect that protects the field against excitations by the obstacle. Such an effect demonstrates the existence of frictionless motion beyond the conventionally defined critical velocity.

Journal Article↗
PubMed2000

Optical emissions in a sonoluminescing bubble

We study how the mechanism of spontaneous decay of atoms (or molecules) in a sonoluminescing bubble (SLB) can be affected by the high density and high temperature environment resulting from the rapid collapse of the gas bubble immediately prior to light emission. We present a detailed study of the density of states of photons in multiple-layered spheres, which mimic various stages of a SLB. In particular, we found that the spontaneous decay rate could be strongly enhanced in the presence of a thin plasma shell inside the bubble, which was predicted recently in numerical hydrodynamic simulations of a SLB.

Journal Article↗
PubMed2000

Molecular fluorescence in the vicinity of a gradient-index medium

The problem of molecular fluorescence in the vicinity of a gradient-index medium is studied theoretically through classical modeling of a radiating dipole. A previously developed formulation involving the Green dyadic for an inhomogeneous medium is applied to the present problem. Normalized lifetimes for the admolecules are calculated and compared with those for a homogeneous medium. The results are illustrated by numerical examples assuming certain simple forms for the index profile.

Journal Article↗