Dynamical excitation of maxon and roton modes in a Rydberg-dressed Bose-Einstein condensate

Abstract

We investigate the dynamics of a three-dimensional Bose-Einstein condensate of ultracold atomic gases with a soft-core shape long-range interaction, which is induced by laser dressing the atoms to a highly excited Rydberg state. For a homogeneous condensate, the long-range interaction drastically alters the dispersion relation of the excitation, supporting both roton and maxon modes. Rotons are typically responsible for the creation of supersolids, while maxons are normally dynamically unstable in BECs with dipolar interactions. We show that maxon modes in the Rydberg-dressed condensate, on the contrary, are dynamically stable. We find that the maxon modes can be excited through an interaction quench, i.e. turning on the soft-core interaction instantaneously. The emergence of the maxon modes is accompanied by oscillations at high frequencies in the quantum depletion, while rotons lead to much slower oscillations. The dynamically stable excitation of the roton and maxon modes leads to persistent oscillations in the quantum depletion. Through a self-consistent Bogoliubov approach, we identify the dependence of the maxon mode on the soft-core interaction.Our study shows that maxon and roton modes can be excited dynamically and simultaneously by quenching Rydberg-dressed long-range interactions. This is relevant to current studies in creating and probing exotic states of matter with ultracold atomic gases.

Dispersion relation of Landau elementary excitations and thermodynamic properties of superfluid He4

“…The results on pure superfluid 4 He have analogs in other systems. Rotons and maxons are studied in 4 He in reduced dimensions, confined geometries, droplets spectrometry [25,[96][97][98][99][100], but also in 3 He [101,102], in cold atomic gases 104516-30 [103][104][105], classical liquids [106,107], etc. : They are a general feature of many-body interacting systems.…”

Phonon and maxon instability in Bose–Einstein condensates with parity-time symmetric spin–orbit coupling

“…Besides the phonon instability [26], there also emerges a roton instability, which can lead to the formation of supersolid states [27][28][29][30]. The maxon excitation can either rapidly decay through Beliaev damping [31,32], or otherwise induce high frequency oscillations of the quantum depletion [33]. So far, whether the maxon excitation would lead to instability of BECs is yet pending for investigation.…”

Hyperchaos in a Bose-Hubbard Chain with Rydberg-Dressed Interactions

“…For r > R, the interaction decreases rapidly as r −6 , shown in Figure 1a. Various theoretical studies on the static and dynamical properties of Rydberg-dressed atoms confined in harmonic traps [55][56][57][58] and optical lattices [59][60][61][62][63][64][65] have been conducted in the past decade. Rydberg-dressed interactions have been experimentally demonstrated in optical tweezers [66], optical lattices [67][68][69], and harmonic traps [70], using various atomic species such as Rb [67,68], Cs [66,70], and Li [69] atoms.…”