Thierry Jolicoeur

Quantum Hall fractions for spinless bosons

We study the quantum Hall phases that appear in the fast-rotation limit for Bose-Einstein condensates of spinless bosonic atoms. We use exact diagonalization in a spherical geometry to obtain low-lying states of a small number of bosons as a function of the angular momentum. This allows us to understand or guess the physics at a given filling fraction

The Phase Diagram of the

\ensuremath{\nu}

\nu=5/2

, the ratio of the number of bosons to the number of vortices. This is also the filling factor of the lowest Landau level. In addition to the well-known Bose-Laughlin state at

Fractional Quantum Hall Effect: Effects of Landau Level Mixing and Non-Zero Width

\ensuremath{\nu}=1∕2

Non-Abelian states with negative flux: a new series of quantum Hall states.

, we give evidence for the Jain principal sequence of incompressible states at

Multiparticle Composites in Density-Imbalanced Quantum Fluids

\ensuremath{\nu}=p∕(p\ifmmode\pm\else\textpm\fi{}1)

Generalized helimagnets between two and four dimensions.

for a few values of

Parafermionic states in rotating Bose-Einstein condensates

p

Composite-fermionization of bosons in rapidly rotating atomic traps

. There is a collective mode in these states whose phenomenology is in agreement with standard arguments coming, e.g., from the composite-fermion picture. At filling factor 1, the potential Fermi sea of composite fermions is replaced by a paired state, the Moore-Read state. This is most clearly seen from the half-flux nature of elementary excitations. We find that the hierarchy picture does not extend up to the point of transition towards a vortex lattice. While we cannot come to any definite conclusions, we investigate the clustered Read-Rezayi states and show evidence for incompressible states at the expected ratio of flux versus number of Bose particles.

Field-induced disorder point in noncollinear Ising spin chains

Interesting non-Abelian states, e.g., the Moore-Read Pfaffian and the anti-Pfaffian, offer candidate descriptions of the