Cesium bright matter-wave solitons and soliton trains

Abstract

A study of bright matter-wave solitons of a cesium Bose-Einstein condensate (BEC) is presented. Production of a single soliton is demonstrated and dependence of soliton atom number on the interatomic interaction is investigated. Formation of soliton trains in the quasi one-dimensional confinement is shown. Additionally, fragmentation of a BEC has been observed outside confinement, in free space. In the end a double BEC production setup for studying soliton collisions is described. PACS numbers: 03.75.Lm, 67.85.Hj I. INTRODUCTION Non-dispersing wavepackets called solitons appear in many non-linear physical systems. Examples of solitons can be found in water waves [1], acoustic waves [2], light propagating through non-linear materials [3], plasmas [4], energy propagation along proteins [5], and many other systems including Bose-Einstein condensates (BECs) of cold atoms. Experimental research on solitons in BECs began with creation of a dark soliton [6, 7], followed by a bright soliton [8] and bright soliton trains [9]. Observation of more exotic gap solitons [10], decay of dark solitons into vortex rings [11], interactions between solitons [12-14], their interactions with impurities [15], optical potential barriers [16], speckle potentials [17] and demonstration of a matter-wave interferometer [18] show that a cold-atom BEC is an excellent and versatile system for studying solitons.Formation of solitons in a BEC depends on the twobody interaction between the atoms and the geometry of the trap used to confine the BEC. A quasi-onedimensional (quasi-1D) confinement is needed, which can be achieved in either magnetic or optical dipole traps. In such traps a dark soliton forms as a trough of lower density within a BEC with repulsive interatomic interaction while a bright soliton is a wavepacket comprising the whole BEC with attractive interatomic interaction that can move over macroscopic distances in a vacuum. So-called dark-bright solitons can be supported in twocomponent BECs, where atoms with one spin component fill the dark soliton within the BEC of the other spin component [13,19,20].Usually, only unchanging waves in one-dimensional integrable systems are called solitons. In quasi-1D harmonically confined geometry integrability is broken, but only slightly so. The solitary waves that form from BECs are three-dimensional objects, not one-dimensional, but their propagation is limited to one-dimension. The name soliton in this paper is used in its broader meaning com-

Collisionally Inhomogeneous Bose-Einstein Condensates with a Linear Interaction Gradient

“…2(e), hatched areas). Bright matter-wave solitons have been created by seeding modulational instabilities in a dense background gas with noise or interferences [21][22][23], and by shaping the density profile with an external potential before an interaction quench [18,[24][25][26]. Here, in contrast, the single soliton-like peak emerges due to the propagation of the matter wave in the linear interaction gradient and without the need of additional seedings or quenches.…”

Splitting and recombination of bright-solitary-matter waves

“…Our apparatus also lends itself to soliton-soliton collision experiments. As the relative phase of the daughter solitons is expected to be well-defined and controllable, the outcome of soliton-soliton collisions could be controlled completely deterministically, unlike in other reported experiments 10,11 . The ability to manipulate the daughter solitons' relative velocity and population fractions also allows us to access a wide parameter range of interest 12,13 .…”

Soliton Dimer-soliton scattering in coupled Quasi-one-dimensional Dipolar Bose-Einstein Condensates

“…In condensates, strictly speaking, we do not deal with solitons but solitary waves due to both the external confinement and their quasi-onedimensional (Q1D) nature and thus can experience in-elastic collisions [15]. The collisional dynamics between bright solitons is studied in condensates with both contact interactions [6,13,[15][16][17][18][19][20][21][22][23][24][25][26][27][28] and dipoledipole interactions (DDIs) [29,[31][32][33][34][35][36][37][38][39][40], which have been exploited to generate entangled soliton pairs [17,18] and design interferometers [19,22,28,41,42]. Contrary to the short-range condensates, in dipolar BECs, the long range and anisotropic nature of DDI lead to novel scenarios such as the multi-dimensional solitons [43][44][45][46][47][48] and interlayer effects [49][50][51][52]…”