Dissipative correlated dynamics of a moving impurity immersed in a Bose–Einstein condensate

Abstract

We unravel the nonequilibrium correlated quantum quench dynamics of an impurity traveling through a harmonically confined Bose-Einstein condensate in one-dimension. For weak repulsive interspecies interactions the impurity oscillates within the bosonic gas. At strong repulsions and depending on its prequench position the impurity moves towards an edge of the bosonic medium and subsequently equilibrates. This equilibration being present independently of the initial velocity, the position and the mass of the impurity is inherently related to the generation of entanglement in the many-body system. Focusing on attractive interactions the impurity performs a damped oscillatory motion within the bosonic bath, a behavior that becomes more evident for stronger attractions. To elucidate our understanding of the dynamics an effective potential picture is constructed. The effective mass of the emergent quasiparticle is measured and found to be generically larger than the bare one, especially for strong attractions. In all cases, a transfer of energy from the impurity to the bosonic medium takes place. Finally, by averaging over a sample of simulated in situ single-shot images we expose how the singleparticle density distributions and the two-body interspecies correlations can be probed.

Many-body quantum dynamics and induced correlations of Bose polarons

“…figure 6(f) at t=15). We should also remark that a similar overall dynamical behavior on the single-particle level has been reported in the case of a single spinor impurity and has been also related to an enhanced energy transfer from the impurity to the bosonic bath [35,68,69,75]. Such an energy transfer process takes place also in the present case (results not shown here).…”

“…We note that for values of  g B deeper in R IV a variety of low amplitude but large valued frequency peaks occur in A(ω f ). This fact indicates that the impurities tend to populate a multitude of states indicating the manifestation of the polaron orthogonality catastrophe as discussed in [35,75] (results not shown here).…”

“…The beating pattern can be readily identified e.g. by comparing the maximum height of ( ) as shown by the white colored region in figure 9(a) in the vicinity of x=0 [75]. An almost similar effect to the above-mentioned breathing dynamics is present also for the case of two weakly interacting impurities ( figure 9(c)).…”

“…For instance, when N I =1 mainly three predominant peaks centered at ω f ≈23. 75, ω f ≈25. 13, and ω f ≈26.26 appear in A(ω f ) whilst for N I =2 and g II =0 five dominantly contributing frequencies located at ω f ≈22.…”

“…Moreover, in the present case the impurities which undergo a breathing motion within ( ) V x I eff reside predominantly in its energetically lowest-lying state E 1 , see figure 6(a). It is also important to mention that this effective potential approximation is adequate only for weak interspecies interactions where the impurity-BEC entanglement is small [35,75]. Note also that the inclusion of the Thomas-Fermi approximation in the effective potential of equation (15) can not adequately describe the impurities dynamics when they reach the edges of the bosonic cloud, see [36] for more details.…”