Bouncing motion and penetration dynamics in multicomponent Bose-Einstein condensates

Abstract

We investigate dynamic properties of bouncing and penetration in colliding binary and ternary Bose-Einstein condensates comprised of different Zeeman or hyperfine states of 87 Rb. Through the application of magnetic field gradient pulses, two-or three-component condensates in an optical trap are spatially separated and then made to collide. The subsequent evolutions are classified into two categories: repeated bouncing motion and mutual penetration after damped bounces. We experimentally observed mutual penetration for immiscible condensates, bouncing between miscible condensates, and domain formation for miscible condensates. From numerical simulations of the Gross-Pitaevskii equation, we find that the penetration time can be tuned by slightly changing the atomic interaction strengths. Multicomponent Bose-Einstein condensates (BECs) in dilute atomic gases are an attractive system for studying hydrodynamics of multicomponent quantum fluids owing to their unprecedented controllability. One of the significant properties characterizing multicomponent fluid systems is their miscibility; different fluids are either mutually miscible or phase separation occurs. In multicomponent BECs, the miscibility is determined by inter-and intra-species atomic interaction strengths [1] and, importantly, they can be experimentally controlled using Feshbach resonances [2,3] and Rabi coupling [4,5]. Multicomponent BECs with various degrees of miscibility are also available by choosing the internal states [6] or atomic species [7]. Employing such adjustability and selectability, intriguing phenomena that depend on the degree of miscibility have been experimentally observed, e.g., soliton generation in a counterflow of miscible fluids [8,9] The condition for miscibility in multicomponent BECs is determined by linear stability analysis of a static or steady state, and is not naively applicable to dynamical situations. Let us consider a situation in which two wave packets of different BECs collide with each other. One may think that the two wave packets pass through each other without much reflection for miscible BECs, while for immiscible BECs they do not. However, we will show that these simple predictions from the miscibility do not apply to a highly dynamic situation.In this Rapid Communication, we generate multicomponent BECs with various degrees of miscibility by utilizing the rich spin degrees of freedom of the 87 Rb atom, and investigate the dynamical properties of bouncing and penetration in colliding binary and ternary BECs in an optical trap. We observed various dynamics, including bouncing between miscible BECs and mutual penetration of immiscible BECs, which seems counterintuitive at first glance. In miscible and weakly immiscible binary and ternary systems, after a few bounces, BECs mutually penetrate and create the domain structure. In contrast, in the case of a relatively strongly immiscible system, binary BECs continue to bounce. Such repetitive bouncing motion between atoms has been observed only in a Tonks-Girardeau ga...

Correlation effects in the quench-induced phase separation dynamics of a two species ultracold quantum gas

“…two hyperfine states of 23 Na [8] and of 87 Rb [9]. Progress of the experimental control over the relevant multi-component settings enabled detailed observations of phase separation phenomena and related dynamical manifestations [10][11][12][13][14][15][16][17][18]. In recent years, external coupling fields have been utilized to control and modify the thresholds for mixing-demixing dynamics in pseudo-spinor (two-component) [19,20] and even in spinor systems [21].…”

Magnetic-field-induced dynamical instabilities in an antiferromagnetic spin-1 Bose-Einstein condensate

“…The fine tunability and the wonderful controllability in BEC experiments provide an excellent testbed for many theoretical predictions [11][12][13][14][15][16][17][18]. In fact, the DIs exist not only in scalar (single-component) BECs, such as solitons [19] and vortices [20], but also in spinor BECs, including the two-component and threecomponent spinor BECs, where vector solitons [21], Skyrmion vortices [22,23], and spin domains/textures are explored [24][25][26][27][28][29][30]. These DI types belong to either III O or I O .…”

Nonequilibrium dynamics induced by miscible–immiscible transition in binary Bose–Einstein condensates

“…To create the stable magnetic field environment, the entire experimental setup is installed inside a magnetically shielded room. The bias magnetic field along the z-direction is created using a low noise current source (Newport, LDX-3232-100V), and has a magnitude = B 11.599 z G. The immiscible system comprising | -ñ 1, 1 and | ñ 1, 0 is generated by the application of a microwave (mw) π pulse and radio-frequency (rf) p 2 pulse, which are resonant to the transition between | -ñ 2, 2 and | -ñ 1, 1 , and the transition between | -ñ 1, 1 and | ñ 1, 0 , respectively [14]. The mw π pulse transfer 99 1% atoms to | -ñ 1, 1 , and the rf p 2 pulse transfer 50 3% atoms to | ñ 1, 0 .…”

“…A widely used method in binary systems is to generate twocomponent BECs by application of a π/2 pulse to a single-component BEC. The experimental realization of various degrees of miscibility, which is enabled by the rich internal degrees of freedom [12][13][14] and the control of atomic interactions [3][4][5], has provided the various pattern formation dynamics [15][16][17][18][19][20][21]. The two-component BECs produced from a single condensate by the application of a π/2 pulse are in nonequilibrium superposition states that are different from the ground state, and the oscillations of the wave function of two components causes collective pattern oscillations that are very sensitive to the small difference in the s-wave scattering length [22][23][24][25][26].…”