arXiv subjects

Emerson Chiquillo

Publications and source records attributed to Emerson Chiquillo.

8 recordsLinked to original sources

arXiv2025

Nonuniversal equation of state for Rabi-coupled bosonic gases: a droplet phase

Through an effective quantum field theory including zero temperature Gaussian fluctuations we derive analytical and explicit expressions for the equation of state of three-dimensional ultracold Rabi-coupled two-component bosonic gases with nonuniversal corrections to the interactions. At mean-field level the system presents two ground-states, one symmetric and one non-symmetric or unbalanced. For the symmetric ground state, in the regime where inter-species interactions are weakly attractive and subtly higher than repulsive intra-species, the instability by collapse is avoided by the contribution arising from Gaussian fluctuations, driving thus to formation of a liquidlike phase or droplet phase. This self-bound state is crucially affected by the dependence on the nonuniversal corrections to the interactions, which acts controlling the droplet stability. By tuning the ratio between the inter-species scattering length and the intra-species scattering lengths or the nonuniversal contribution to the interactions we address and establish conditions under which the formation and stability of self-bound Rabi-coupled droplets with nonuniversal corrections to the interactions is favorable.

cond-mat.quant-gas↗

arXiv2025

Bose-Bose gases with nonuniversal corrections to the interactions: a droplet phase

Through an effective quantum field theory within Bogoliubov's framework and taking into account nonuniversal effects of the interatomic potential we analytically derive the leading Gaussian zero- and finite-temperature corrections to the equation of state of ultracold interacting Bose-Bose gases. We calculate the ground-state energy per particle at zero and low temperature for three-, two- and one-dimensional two-component bosonic gases. By tuning the nonuniversal contribution to the interactions we address and establish conditions under which the formation and stability of a self-bound liquidlike phase or droplet with nonuniversal corrections to the interactions DNUC) is favorable. At zero temperature in three-dimensions and considering the nonuniversal corrections to the attractive interactions as a fitting parameter the energy per particle for DNUC is in good agreement with some diffusion Monte Carlo results. In two dimensions the DNUC present small deviations regarding conventional droplets. For the one-dimensional DNUC the handling of the nonuniversal effects to the interactions achieves a qualitative agreement with the trend of some available Monte Carlo data in usual droplets. We also introduce some improved Gross-Pitaevskii equations to describe self-trapped DNUC in three, two and one dimension. We briefly discuss some aspects at low temperature regarding nonuniversal corrections to the interactions in Bose-Bose gases. We derive the dependencies on the nonuniversal contribution to the interactions but also on the difference between intra- and inter-species coupling constants. This last dependence crucially affect the three- and the two-dimensional DNUC driving thus to a thermal-induced instability. This thermal instability is also present in one-dimensional Bose-Bose gases, but it is not relevant on the formation of DNUC...

cond-mat.quant-gas↗

arXiv2019

Low-Dimensional Self-Bound Quantum Rabi-Coupled Bosonic Droplets

We analytically calculate the leading quantum corrections of the ground-state energy of two- and one-dimensional weakly interacting Rabi-coupled Bose-Bose mixtures in the frame of the Bogoliubov approximation. We show that to repulsive intraspecies and attractive interspecies interactions, the effect of quantum fluctuations favors the formation of self-bound droplets. These liquidlike states are crucially affected by the Rabi coupling, leading thus to the appearance of a quantum instability. We derive meaningful formulas to describe the droplet phase in the one-dimensional case.

cond-mat.quant-gas↗

arXiv2018

Equation of state of the one- and three-dimensional Bose-Bose gases

We calculate the equation of state of Bose-Bose gases in one and three dimensions in the framework of an effective quantum field theory. The beyond-mean-field approximation at zero-temperature and the one-loop finite-temperature results are obtained performing functional integration on a local effective action. The ultraviolet divergent zero-point quantum fluctuations are removed by means of dimensional regularization. We derive the nonlinear Schrödinger equation to describe one- and three-dimensional Bose-Bose mixtures and solve it analytically in the one-dimensional scenario. This equation supports self-trapped brightlike solitonic-droplets and self-trapped darklike solitons. At low temperature, we also find that the pressure and the number of particles of symmetric quantum droplets have a nontrivial dependence on the chemical potential and the difference between the intra- and the inter-species coupling constants.

cond-mat.quant-gas↗

arXiv2018

Matter-waves in Bose-Einstein condensates with spin-orbit and Rabi couplings

We investigate the one-dimensional (1D) and two-dimensional (2D)reduction of a quantum field theory starting from the three-dimensional (3D) many-body Hamiltonian of interacting bosons with spin-orbit (SO) and Rabi couplings. We obtain the effective time-dependent 1D and 2D nonpolynomial Heisenberg equations for both repulsive and attractive signs of the inter-atomic interaction. Our findings show that in case in which the many-body state coincides with the Glauber coherent state,the 1D and 2D Heisenberg equations become 1D and 2D nonpolynomial Schrödinger equations (NPSEs). These models were derived in a mean-field approximation from 3D Gross-Pitaevskii equation (GPE), describing a Bose-Einstein condensate (BEC)with SO and Rabi couplings. In the present work self-repulsive and self-attractive localized solutions of the 1D NPSE and the 1D GPE are obtained in a numerical form. The combined action of SO and Rabi couplings produces conspicuous sidelobes on the density profile, for both signs of the interaction. In the case of the attractive nonlinearity, an essential result is the possibility of getting an unstable condensate by increasing of SO coupling.

cond-mat.quant-gas↗

arXiv2018

Harmonically trapped attractive and repulsive spin-orbit and Rabi coupled Bose-Einstein condensates

Numerically we investigate the ground state of effective one-dimensional spin-orbit (SO) and Rabi coupled two pseudo-spinor Bose-Einstein condensates (BECs) under the effect of harmonic traps. For both signs of the interaction, density profiles of SO and Rabi coupled BECs in harmonic potentials, which simulate a real experimental situation are obtained. The harmonic trap causes a strong reduction of the multi-peak nature of the condensate and it increases its density. For repulsive interactions, the increase of SO coupling results in an uncompressed less dense condensate and with increased multi-peak nature of the density. The increase of Rabi coupling leads to a density increase with an almost constant number of multi-peaks. For both signs of the interaction and negative values of Rabi coupling, the condensate develops a notch in the central point and it seems to a dark-in-bright soliton. In the case of the attractive nonlinearity, an interesting result is the increase of the collapse threshold under the action of the SO and Rabi couplings.

cond-mat.quant-gas↗

arXiv2018

Quasi-one-dimensional spin-orbit- and Rabi-coupled bright dipolar Bose-Einstein-condensate solitons

We study the formation of stable bright solitons in quasi-one-dimensional (quasi-1D) spin-orbit- (SO-) and Rabi-coupled two pseudospinor dipolar Bose-Einstein condensates (BECs) of 164 Dy atoms in the presence of repulsive contact interactions. As a result of the combined attraction-repulsion effect of both interactions and the addition of SO and Rabi couplings, two kinds of ground states in the form of self-trapped bright solitons can be formed, a plane-wave soliton (PWS) and a stripe soliton (SS). These quasi-1D solitons cannot exist in a condensate with purely repulsive contact interactions and SO and Rabi couplings (no dipole). Neglecting the repulsive contact interactions, our findings also show the possibility of creating PWSs and SSs. When the strengths of the two interactions are close to each other, the SS develops an oscillatory instability indicating a possibility of a breather solution, eventually leading to its destruction. We also obtain a phase diagram showing regions where the solution is a PWS or SS.

cond-mat.quant-gas↗

arXiv2014

Bright solitons in a quasi-one-dimensional reduced model of a dipolar Bose-Einstein condensate with repulsive short-range interactions

We study the formation and dynamics of bright solitons in a quasi-one-dimensional reduced mean-field Gross-Pitaevskii equation of a dipolar Bose-Einstein condensate with repulsive short-range interactions. The study is carried out using a variational approximation and a numerical solution. Plots of chemical potential and root mean square (rms) size of solitons are obtained for the quasi-one-dimensional model of three different dipolar condensates of 52Cr, 168Er and 164Dy atoms. The results achieved are in good agreement with those produced by the full three-dimensional mean-field model of the condensate. We also study the dynamics of the collision of a train of two solitons in the quasi-one-dimensional model of every condensate above. At small velocities (zero or close to zero) the dynamics is attractive for a phase difference δ = 0, the solitons coalesce and these oscillate forming a bound soliton molecule. For a phase difference δ = π the effect is repulsive. At large velocities the collision is independent of the initial phase difference δ. This is quasi-elastic and the result is two quasi-solitons.

cond-mat.quant-gas↗