arXiv subjects

Julio Barreiro

Publications and source records attributed to Julio Barreiro.

3 recordsLinked to original sources

arXiv2018

An energy-resolved atomic scanning probe

We propose a method to probe the local density of states (LDOS) of atomic systems that provides both spatial and energy resolution. The method combines atomic and tunneling techniques to supply a simple, yet quantitative and operational, definition of the LDOS for both interacting and non-interacting systems: It is the rate at which particles can be siphoned from the system of interest by a narrow energy band of non-interacting states contacted locally to the many-body system of interest. Ultracold atoms in optical lattices are a natural platform for implementing this broad concept to visualize the energy and spatial dependence of the atom density in interacting, inhomogeneous lattices. This includes models of strongly correlated condensed matter systems, as well as ones with non-trivial topologies.

cond-mat.mes-hall↗

arXiv2018

Interaction effects with varying $N$ in SU($N$) symmetric fermion lattice systems

The interaction effects in ultracold Fermi gases with SU($N$) symmetry are studied non-perturbatively in half-filled one-dimensional lattices by employing quantum Monte Carlo simulations.We find that as $N$ increases, weak and strong interacting systems are driven to a crossover region, but from opposite directions as a convergence of itinerancy and Mottness.In the weak interaction region, particles are nearly itinerant,and inter-particle collisions are enhanced by $N$, resulting in the amplification of interaction effects. In contrast, in the strong coupling region, increasing $N$ softens the Mott-insulating background through the enhanced virtual hopping processes.The crossover region exhibits nearly $N$-independent physical quantities, including the relative bandwidth, Fermi distribution, and the spin structure factor.The difference between even-$N$ and odd-$N$ systems is most prominent at small $N$'s with strong interactions, since the odd case allows local real hopping with an energy scale much larger than the virtual one.The above effects can be experimentally tested in ultracold atom experiments with alkaline-earth (-like) fermions such as $^{87}$Sr ($^{173}$Yb).

cond-mat.str-el↗

arXiv1999

Density and expansion effects on pion spectra in relativistic heavy-ion collisions

We compute the pion inclusive momentum distribution in heavy-ion collisions at AGS energies, assuming thermal equilibrium and accounting for density and expansion effects at the time of decoupling. We compare to data on mid rapidity charged pions produced in central Au + Au collisions and find a very good agreement. The shape of the distribution at low $m_t-m$ is explained in part as an effect arising from the high mean pion density achieved in these reactions. The difference between the positive and negative pion distributions in the same region is attributed in part to the different average yields of each kind of charged pions.

nucl-th↗