We report on the experimental realization of a robust and efficient magneto-optical trap for erbium atoms, based on a narrow cooling transition at 583 nm. We observe up to N = 2 × 10 8 atoms at a temperature of about T = 15 µK. This simple scheme provides better starting conditions for direct loading of dipole traps as compared to approaches based on the strong cooling transition alone, or on a combination of a strong and a narrow kHz transition. Our results on Er point to a general, simple and efficient approach to laser cool samples of other lanthanide atoms (Ho, Dy, and Tm) for the production of quantum-degenerate samples.PACS numbers: 37.10. De, 37.10.Vz Laser cooling of non-alkali atoms has become a very active and challenging field of research. The great appeal of unconventional atomic systems for experiments on ultracold atomic quantum gases stems from the possibility of engineering complex interactions and of accessing rich atomic energy spectra. Both features are at the foundation of a number of novel fascinating phenomena. For instance the energy spectra of two-valence-electron species, as alkaline earth and alkalineearth-like atoms, feature narrow and ultra-narrow optical transitions, which are key ingredients for ultra-precise atomic clocks [1], efficient quantum computation schemes [2], and novel laser cooling approaches as beautifully demonstrated in experiments with Sr, Yb,.As a next step in complexity, multi-valence-electron atoms with non-S electronic ground state such as lanthanides are currently attracting an increasing experimental and theoretical interest. Among many, one of the special features of lanthanides is the exceptionally large magnetic dipole moment of atoms in the electronic ground state (e. g. 7 µ B for Er and 10 µ B for both Dy and Tb), which provides a unique chance to study strongly dipolar phenomena with atoms. Highly magnetic atoms interact with each other not only via the usual contact interaction but also via an anisotropic and long-range interaction, known as the dipole-dipole interaction [6]. Chromium was the first atomic species used for experiments on atomic dipolar quantum gases [7,8], and the even more magnetic lanthanides are nowadays in the limelight thanks to laser cooling experiments on Er and Tm [9,10] and to the recent realization of quantumdegenerate Dy gases [11,12].Similarly to Yb and the alkaline earth atoms, the atomic energy spectra of magnetic lanthanides include broad, narrow, and ultra-narrow optical transitions. This collection of lines is reflected in a wide choice of possible schemes for laser cooling experiments. However, all experiments on Zeeman slowing and cooling in a magneto-optical trap (MOT) with magnetic lanthanides so far relied on an approach, essentially based on the strongest cycling transition [9,10,13]. This broad transition typically lies in the blue between 400 and 430 nm and has a linewidth on the order of few tens of MHz. As a consequence, the Doppler temperature is close to a mK. Such a high temperature makes direct loading f...
Mesoscopic irregularly ordered and even amorphous self-assembled electronic structures were recently reported in two-dimensional metallic dichalcogenides (TMDs), created and manipulated with short light pulses or by charge injection. Apart from promising new all-electronic memory devices, such states are of great fundamental importance, since such aperiodic states cannot be described in terms of conventional charge-density-wave (CDW) physics. In this paper, we address the problem of metastable mesoscopic configurational charge ordering in TMDs with a sparsely filled charged lattice gas model in which electrons are subject only to screened Coulomb repulsion. The model correctly predicts commensurate CDW states corresponding to different TMDs at magic filling fractions = / / / / / f 1 3, 1 4, 1 9, 1 13, 1 16.mDoping away from f m results either in multiple neardegenerate configurational states, or an amorphous state at the correct density observed by scanning tunnelling microscopy. Quantum fluctuations between degenerate states predict a quantum charge liquid at low temperatures, revealing a new generalized viewpoint on both regular, irregular and amorphous charge ordering in transition metal dichalcogenides.
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-
Erratum: NbS 3 : A unique quasi-one-dimensional conductor with three charge density wave transitions [Phys. Rev. B 95, 035110 (2017)]
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.