Fractional Quantum Hall states in the vicinity of Mott plateaus

We perform variational Monte-Carlo calculations to show that bosons in a rotating optical lattice will form analogs of fractional quantum Hall states when the tunneling is sufficiently weak compared to the interactions and the deviation of density from an integer is commensurate with the effective magnetic field. We compare the energies of superfluid and correlated states to one-another and to the energies found in full configuration-interaction calculations on small systems. We look at overlaps between our variational states and the exact ground-state, characterizing the ways in which fractional quantum Hall effect correlations manifest themselves near the Mott insulating state. We explore the experimental signatures of these states.Comment: 6 pages, 4 figure

Assessment in anatomy

From an educational perspective, a very important problem is that of assessment, for establishing competency and as selection criterion for different professional purposes. Among the issues to be addressed are the methods of assessment and/or the type of tests, the range of scores, or the definition of honour degrees. The methods of assessment comprise such different forms such as the spotter examination, short or long essay questions, short answer questions, true-false questions, single best answer questions, multiple choice questions, extended match questions, or several forms of oral approaches such as viva voce examinations.Knowledge about this is important when assessing different educational objectives; assessing educational objectives from the cognitive domain will need different assessment instruments than assessing educational objectives from the psychomotor domain or even the affective domain.There is no golden rule, which type of assessment instrument or format will be the best in measuring certain educational objectives; but one has to respect that there is no assessment instrument, which is capable to assess educational objectives from all domains of educational objectives.Whereas the first two or three levels of progress can be assessed by well-structured written examinations such as multiple choice questions, or multiple answer questions, other and higher level progresses need other instruments, such as a thesis, or direct observation.This is no issue at all in assessment tools, where the students are required to select the appropriate answer from a given set of choices, as in true false questions, MCQ, EMQ, etc. The standard setting is done in these cases by the selection of the true answer

Stirring trapped atoms into fractional quantum Hall puddles

We theoretically explore the generation of few-body analogs of fractional quantum Hall states. We consider an array of identical few-atom clusters (n=2,3,4), each cluster trapped at the node of an optical lattice. By temporally varying the amplitude and phase of the trapping lasers, one can introduce a rotating deformation at each site. We analyze protocols for coherently transferring ground state clusters into highly correlated states, producing theoretical fidelities in excess of 99%.Comment: 4 pages, 3 figures (13 subfigures) -- v2: published versio

Explanation of 100-fold reduction of spectral shifts for hydrogen on helium films

We show that helium film-mediated hydrogen-hydrogen interactions account for a two orders of magnitude discrepancy between previous theory and recent experiments on cold collision shifts in spin-polarized hydrogen adsorbed on a helium film. These attractive interactions also explain the anomalous dependence of the cold collision frequency shifts on the $^3$He covering of the film. Our findings suggest that the gas will become mechanically unstable before reaching the Kosterlitz-Thouless transition unless the experiment is performed in a drastically different regime, for example with a much different helium film geometry.Comment: 4+ pages, 1 figure (3 subfigures), revtex