Biomedical subjects

B Douçot

Publications and source records attributed to B Douçot.

14 recordsLinked to original sources

PubMed2004

Fluctuations and vortex-pattern ordering in the fully frustrated XY model on a honeycomb lattice.

The accidental degeneracy of various ground states of a fully frustrated XY model with a honeycomb lattice is shown to survive even when the free energy of the harmonic fluctuations is taken into account. The reason for that consists in the existence of a hidden gauge symmetry between the Hamiltonians describing the harmonic fluctuations in all these ground states. A particular vortex pattern is selected only when anharmonic fluctuations are taken into account. However, the observation of vortex ordering requires relatively large system size L>>Lc > or approximately equal to 10(5).

Journal Article↗

PubMed2003

Topological order in the insulating Josephson junction array.

We propose a Josephson junction array which can be tuned into an unconventional insulating state by varying external magnetic field. This insulating state retains a gap to half-vortices; as a consequence, such an array with nontrivial global geometry exhibits a ground state degeneracy. This degeneracy is protected from the effects of external noise. We compute the gaps, separating higher energy states from the degenerate ground state, and we discuss experiments probing the unusual properties of this insulator.

Journal Article↗

PubMed2001

Nesting induced precursor effects: a renormalization group approach.

We develop a controlled weak coupling renormalization group (RG) approach to itinerant electrons. Within this formalism we rederive the phase diagram for two-dimensional non-nested systems. We then study how nesting modifies this phase diagram. We show that competition between particle-particle and particle-hole channels leads to the manifestation of an unstable precursor fixed point in the RG flow. This effect should be experimentally measurable, and may be relevant for an explanation of pseudogaps in the high temperature superconductors, as a crossover phenomenon.

Journal Article↗

PubMed1993