Laser induced transitions between internal states of atoms have been playing a fundamental role to manipulate atomic clouds for many decades. In absence interactions each atom behaves independently and their coherent quantum dynamics is described by the Rabi model. Since experimental observation Bose condensation in dilute gases, static dynamical properties multicomponent gases extensively investigated. Moreover, at very low temperatures fluctuations crucially affect equation state many-body...

We study the collective modes of a binary Bose mixture across soliton to droplet crossover in quasi one dimensional waveguide with beyond-mean-field equation state and variational Gaussian ansatz for scalar bosonic field corresponding effective action. observe sharp difference two regimes. Within regime vary smoothly upon variation particle number or interaction strength. On side are inhibited by emission particles. This mechanism turns out be dominant wide range numbers interactions. In...

We systematically investigate the zero temperature phase diagram of bosons interacting via dipolar interactions in three dimensions free space path integral Monte Carlo simulations with few hundreds particles and periodic boundary conditions based on worm algorithm. Upon increasing strength interaction at sufficiently high densities we find a wide region where filaments are stabilized along direction external field. Most interestingly by computing superfluid fraction conclude that...

Impurity motion in a many-body environment has been central issue the field of low-temperature physics for decades. In bosonic quantum fluids, onset drag force experienced by point-like objects is due to collective excitations, driven exchange linear momentum between impurity and bath. this work we consider rotating impurity, with aim exploring how angular exchanged surrounding environment. order elucidate issues, employ quasiparticle approach based on angulon theory, which allows us...

Impurity motion in a many-body environment has been central issue the field of low-temperature physics for decades. In bosonic quantum fluids, onset drag force experienced by point-like objects is due to collective excitations, driven exchange linear momentum between impurity and bath. this work we consider rotating impurity, with aim exploring how angular exchanged surrounding environment. order elucidate these issues, employ quasiparticle approach based on angulon theory, which allows us...

We investigate an ultracold and dilute Bose gas by taking into account a finite-range two-body interaction. The coupling constants of the resulting Lagrangian density are related to measurable scattering parameters following effective-field-theory approach. A perturbative scheme is then developed up Gaussian level, where both quantum thermal fluctuations crucially affected corrections. In particular, relation between spontaneous symmetry breaking onset superfluidity emphasized recovering...

We study the dynamics of dilute and ultracold bosonic gases in a quasi two-dimensional (2D) configuration collisionless regime. adopt 2D Landau-Vlasov equation to describe three-dimensional gas under very strong harmonic confinement along one direction. use this effective investigate speed sound gases, i.e. propagation around Bose-Einstein distribution gases. derive coupled algebraic equations for real imaginary parts velocity, which are then solved taking also into account state system....

Brownian motion of a mobile impurity in bath is affected by spin-orbit coupling (SOC). Here, we discuss Caldeira-Leggett-type model that can be used to propose and interpret quantum simulators this problem cold Bose gases. First, derive master equation describes the explore it one-dimensional (1D) setting. To validate standard assumptions needed for our derivation, analyze available experimental data without SOC; as byproduct, analysis suggests quench dynamics beyond 1D Bose-polaron approach...

We study a dilute and ultracold Bose gas of interacting atoms by using an effective field theory which takes into account the finite-range effects interatomic potential. Within formalism functional integration from grand canonical partition function, we derive beyond-mean-field analytical results depend on both scattering length range interaction. In particular, calculate equation state bosonic system as function these interaction parameters at zero finite temperature including one-loop...

Sound propagation is a macroscopic manifestation of the interplay between equilibrium thermodynamics and dynamical transport properties fluids. Here, for two-dimensional system ultracold fermions, we calculate first second sound velocities across whole BCS-BEC crossover, analyze response to an external perturbation. In low-temperature regime reproduce recent measurements [Phys. Rev. Lett. 124, 240403 (2020)] velocity, which, due decoupling density entropy fluctuations, sole mode excited by...

The Lieb-Liniger equation of state accurately describes the zero-temperature universal properties a dilute one-dimensional Bose gas in terms s-wave scattering length. For weakly-interacting bosons we derive non-universal corrections to this taking into account finite-range effects inter-atomic potential. Within finite-temperature formalism functional integration find beyond-mean-field which depends on length and effective range interaction Our analytical results, are obtained performing...

We study cold dilute gases made of bosonic atoms, showing that in the mean-field one-dimensional regime they support stable out-of-equilibrium states. Starting from 3D Boltzmann-Vlasov equation with contact interaction, we derive an effective 1D Landau-Vlasov under condition a strong transverse harmonic confinement. investigate existence states, obtaining stability criteria similar to those classical plasmas.

We demonstrate the possibility of a coupling between magnetization direction ferromagnet and tilting angle adsorbed achiral molecules. To illustrate mechanism coupling, we analyze minimal Stoner model that includes Rashba spin–orbit due to electric field on surface ferromagnet. The proposed allows us study magnetic anisotropy system with an extended Stoner–Wohlfarth argue molecules can change magnetocrystalline substrate. Our research aims motivate further experimental studies current-free...

We study the quantum tunneling of two one-dimensional quasi-condensates made alkali-metal atoms, considering different configurations: side-by-side and head-to-tail. After deriving quasiparticle excitation spectrum, we discuss dynamics relative phase following a sudden coupling independent subsystems. In particular, calculate coherence factor system, which, due to nonzero amplitude, it exhibits dephasing-rephasing oscillations instead pure dephasing. These are enhanced by higher energy,...

We present a field-theory description of ultracold bosonic atoms in the presence disordered external potential. By means functional integration techniques, we aim to investigate and review interplay between energy landscapes fluctuations, both thermal quantum ones. Within broken-symmetry phase, up Gaussian level approximation, disorder contribution crucially modifies condensate depletion superfluid response. Remarkably, it is found that ordered (i.e., superfluid) phase can be destroyed also...

We compare recent experimental results [Science 375, 528 (2022)] of the superfluid unitary Fermi gas near critical temperature with a thermodynamic model based on elementary excitations system. find very good agreement between data and our theory for several quantities such as first sound, second fraction. also show that mode mixing sound occurs. Finally, we characterize response amplitude to density perturbation: close both can be excited through perturbation, whereas at lower temperatures...

We investigate the low-temperature properties of an ultracold gas made bosonic alkali-metal atoms with finite-range interaction under effect a disordered environment. The statistical characterization disorder is investigated within effective-field-theory formalism for generic spatial dimension $d$. Moving to $d=3$, where all arising divergences are properly regularized, we focus on depletion both condensate and superfluid densities. At zero temperature obtain meaningful analytical formulas...

Abstract Within the Ginzburg-Landau functional framework for superconducting transition, we analyze fluctuation-driven shift of critical temperature. In addition to order parameter fluctuations, also take into account fluctuations vector potential above its vacuum. We detail approximation scheme include fluctuating fields contribution, based on Hartree-Fock-Bogoliubov-Popov framework. give explicit results d = 2 and 3 spatial dimensions, in terms easily accessible experimental parameters...

In this brief report we discuss the action functional of a particle with damping, showing that it can be obtained from dissipative equation motion through modification which makes new invariant for time reversal symmetry. This is exactly effective Caldeira-Leggett model but, in our approach, derived without assumption weakly coupled to bath infinite harmonic oscillators.

We review our theoretical results about the sound propagation in two-dimensional (2D) systems of ultracold fermionic and bosonic atoms. In superfluid phase, characterized by spontaneous symmetry breaking $U(1)$ symmetry, there is coexistence first second sound. case weakly-interacting repulsive bosons, we model recent measurements velocities 39K atoms 2D obtained regime around Berezinskii-Kosterlitz-Thouless (BKT) superfluid-to-normal transition temperature. particular, perform a quite...

We demonstrate the possibility of a coupling between magnetization direction ferromagnet and tilting angle adsorbed achiral molecules. To illustrate mechanism coupling, we analyze minimal Stoner model that includes Rashba spin-orbit due to electric field on surface ferromagnet. The proposed allows us study magnetic anisotropy system with an extended Stoner-Wohlfarth model, argue molecules can change magnetocrystalline substrate. Our research's aim is motivate further experimental studies...

Brownian motion of a mobile impurity in bath is affected by spin-orbit coupling (SOC). Here, we discuss Caldeira-Leggett-type model that can be used to propose and interpret quantum simulators this problem cold Bose gases. First, derive master equation describes the explore it one-dimensional (1D) setting. To validate standard assumptions needed for our derivation, analyze available experimental data without SOC; as byproduct, analysis suggests quench dynamics beyond 1D Bose-polaron approach...