arXiv subjects

David Laroze

Publications and source records attributed to David Laroze.

39 records · Page 3Linked to original sources

arXiv2015

Correlations and synchronization in a Bose-Fermi mixture

We study a Bose-Fermi mixture within the framework of the mean-field theory, including three possible regimes for the fermionic species: fully polarized, BCS, and unitarity. Starting from the 3D description and using the variational approximation (VA), we derive 1D and 2D systems of equations, under the corresponding confining potentials. This method produces a pair of nonlinear Schrödinger (NLS) equations coupled to algebraic equations for the transverse widths of the confined state. The equations incorporate interactions between atoms of the same species and between the species, assuming that the latter can be manipulated by means of the Feshbach resonance (FR). As an application, we explore spatial density correlations in the ground state (GS) between the species, concluding that they strongly depend on the sign and strength of the inter-species interaction. Also studied are the dynamics of the mixture in a vicinity of the GS and the corresponding spatiotemporal inter-species correlation. The correlations are strongly affected by the fermionic component, featuring the greatest variation in the unitary regime. Results produced by the VA are verified by comparison with full numerical solutions.

cond-mat.quant-gas↗

arXiv2012

One- and two-dimensional reductions of the mean-field description of degenerate Fermi gases

We study collective behavior of Fermi gases trapped in various external potentials, including optical lattices (OLs), in the framework of the mean-field (hydrodynamic) description. Using the variational method, we derive effective dynamical equations for the one- and two-dimensional (1D and 2D) settings from the general 3D mean-field equation. The respective confinement is provided by trapping potentials with the cylindrical and planar symmetry, respectively. The resulting equations are nonpolynomial Schr% ödinger equations (NPSEs) coupled to equations for the local transverse size of the trapped states. Numerical simulations demonstrate close agreement of results produced by the underlying 3D equation and the effective low-dimensional ones. We consider the ground state in these settings. In particular, analytical solutions are obtained for the effectively 2D non-interacting Fermi gas. Differences between the 1D and 2D configurations are highlighted. Finally, we analyze the dependence of the 1D and 2D density patterns of the trapped gas, in the presence of the OL, on the strengths of the confining and OL potentials, and on the scattering length which determines the strength of interactions between non-identical fermions.

cond-mat.quant-gas↗

arXiv2009

Quantum circuits under magnetic field

We consider a quantum $LC$ circuit under a constant magnetic flux $f$, and derive a discretized form of the Schrödinger equation, which is equivalent to introducing a {\em potential} $V(ϕ,f)$ in the pseudo-flux $ϕ$-representation, which is different from that found previously by Li and Chen \cite{LI-CHEN}. Firts, we discuss the physical assumptions leading to these different results, and then study the energy spectrum of the $LC$ quantum circuit as a function of a constant external magnetic flux, using a direct numerical approach. The results are compared with the spectrum obtained using the Li-Chen potential. Our results indicate that the energy spectra from both models are quite different numerically, and as a function of $f$, so that they may be clearly distinguished under appropiate experimental conditions.

cond-mat.mes-hall↗