Quantum phase transition in a three-level atom-molecule system

We adopt a three-level bosonic model to investigate the quantum phase transition in an ultracold atom-molecule conversion system which includes one atomic mode and two molecular modes. Through thoroughly exploring the properties of energy level structure, fidelity, and adiabatical geometric phase, we confirm that the system exists a second-order phase transition from an atommolecule mixture phase to a pure molecule phase. We give the explicit expression of the critical point and obtain two scaling laws to characterize this transition. In particular we find that both the critical exponents and the behaviors of ground-state geometric phase change obviously in contrast to a similar two-level model. Our analytical calculations show that the ground-state geometric phase jumps from zero to ?pi/3 at the critical point. This discontinuous behavior has been checked by numerical simulations and it can be used to identify the phase transition in the system.Comment: 8 pages,8 figure

Some Aspects of the Ecology of Elaeidobius Kamerunicus Faust, The Pollinating Weevil of Oil Palm, With Emphasis on Developing Sampling Techniques

Some aspects of the ecology of the pollinating weevil of oil palm, Elaeidobius kamerunicus Faust - an exotic insect to Malaysia imported from Cameroon, West Africa, three years ago - were studied in 1983 and 1984. In particular, sampling techniques for estimating the weevil population were developed and the effect of rat predation on the immature weevils was studied. In the course of these studies, certain aspects of the weevil's behaviour and activity were investigated. Field studies concerning the ecology of the weevil requires a satisfactory method for estimating the weevil population. Three sampling methods were compared: petridish traps set on receptive female inflorescences, sticky traps incorporating anthesising male flowers as bait, and sampling the weevil-covered spikelets of the anthesising male inflorescence. The last method was found to be superior it was more reliable and the data could be converted to an absolute estimate. To be reliable, the method must consider the time of sampling, stage of anthesis of the male inflorescence, and position of spikelet on the male inflorescence. Taking samples after 5 pm, separating the anthesising male inflorescences into three stages, and stratified sampling from six sections of the male inflorescence were found to be optimal for a reliable estimation