Observation of Dipole-Dipole Interaction in a Degenerate Quantum Gas

Stühler, J.; Griesmaier, Axel; Koch, Tobias; Fattori, M.; Pfau, Tilman; Giovanazzi, S.; Pedri, P.; Santos, Luís

doi:10.1103/physrevlett.95.150406

Cited by 458 publications

(415 citation statements)

References 34 publications

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“…The good tunability of optical lattices enables us to experimentally elucidate the subtleties of 1D quantum many-body systems, for example, the physical properties in the strongly interacting limit. Due to recent experimental progress on chromium atoms [10,11] and heteronuclear polar molecule produced by stimulated Raman adiabatic passage technique [12,13], dipolar atomic systems with strong long-range dipole-dipole interaction (DDI) have also attracted intensive studies [14][15][16][17][18][19]. In addition, schemes of creating * Electronic address: xuzhihao@outlook.com Coulomb-like interaction in cold atom systems have also been proposed [20,21].…”

Section: Introductionmentioning

confidence: 99%

Wigner crystal versus fermionization for one-dimensional Hubbard models with and without long-range interactions

Xu¹,

Li²,

Xianlong³

et al. 2012

J. Phys.: Condens. Matter

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The ground state properties of Hubbard model with or without long-range interactions in the regime with strongly repulsive on-site interaction are investigated by means of the exact diagonalization method. We show that the appearance of N -crests in the density profile of a trapped N-fermion system is a natural result of "fermionization" between antiparallel-spin fermions in the strongly repulsive limit and can not be taken as the only signature of Wigner crystal phase, as the static structure factor does not show any signature of crystallization. On the contrary, both the density distribution and static structure factor of Hubbard model with strong long-range interactions display clear signature of Wigner crystal. Our results indicate the important role of long-range interaction in the formation of Wigner crystal.

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Section: Introductionmentioning

confidence: 99%

Wigner crystal versus fermionization for one-dimensional Hubbard models with and without long-range interactions

Xu¹,

Li²,

Xianlong³

et al. 2012

J. Phys.: Condens. Matter

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“…Following this simple argument one expects that in the prolate case a positive scattering length a is needed to stabilize the BEC, whilst in the oblate case one can even afford a slightly negative a. The dependance of the stability of a dipolar BEC on the trap aspect ratio λ and scattering length a has been extensively studied theoretically [12,13,14], and is experimentally investigated in this paper.Our measurements are performed with a BEC of 52 Cr [15] which is to date the only experimentally accessible quantum gas with observable dipole-dipole interaction [16,17]. To compare contact and dipolar interactions we introduce the length scale of the magnetic DDI a dd = µ 0 µ 2 m 12πh 2 .…”

mentioning

confidence: 99%

“…Our measurements are performed with a BEC of 52 Cr [15] which is to date the only experimentally accessible quantum gas with observable dipole-dipole interaction [16,17]. To compare contact and dipolar interactions we introduce the length scale of the magnetic DDI a dd = µ 0 µ 2 m 12πh 2 .…”

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confidence: 99%

Stabilization of a purely dipolar quantum gas against collapse

et al. 2008

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We report on the experimental observation of the dipolar collapse of a quantum gas which sets in when we reduce the contact interaction below some critical value using a Feshbach resonance. Due to the anisotropy of the dipole-dipole interaction, the stability of a dipolar Bose-Einstein condensate depends not only on the strength of the contact interaction, but also on the trapping geometry. We investigate the stability diagram and find good agreement with a universal stability threshold arising from a simple theoretical model. Using a pancake-shaped trap with the dipoles oriented along the short axis of the trap, we are able to tune the scattering length to zero, stabilizing a purely dipolar quantum gas.Interactions between atoms dominate most of the properties of quantum degenerate gases [1]. In the ultracold regime these interactions are usually well described by an effective isotropic zero-range potential. The strength and sign of this contact interaction is determined by a single parameter, the scattering length a. The contact interaction is responsible for a variety of striking properties of quantum gases. Strongly influencing the excitation spectrum of the condensate it gives rise to e.g. the superfluidity of Bose-Einstein condensates (BEC) or the existence of vortex lattices. The contact interaction also plays a crucial role in the physics of strongly correlated systems like in the BEC-BCS crossover [2] or in quantum phase transitions like the Mott insulator transition [3].Another fundamental topic is the question of the existence of a stable ground state depending on the modulus and sign of the contact interaction. In the homogeneous case repulsive contact interaction (a > 0) is necessary for the stability of the BEC. In contrast, if the contact interaction is attractive (a < 0), the BEC is unstable. This instability can be prevented by an external trapping potential. The tendency to shrink towards the center of the trap is in that case counteracted by the repulsive quantum pressure arising from the Heisenberg uncertainty relation. Detailed analysis [4] yields that a condensate is stable as long as the number of atoms N in the condensate stays below a critical value N crit given bywhere a ho is the harmonic oscillator length and k is a constant on the order of 1/2. This scaling, as well as the collapse dynamics for N > N crit , have been studied experimentally with condensates of 7 Li [5, 6] and 85 Rb [7,8]. In [9, 10] the atom number dependance of the collapse of mixtures of bosonic 87 Rb and fermionic 40 K quantum gases has been investigated. Being anisotropic and long-range, the dipole-dipole interaction (DDI) differs fundamentally from the contact interaction. Besides many other properties, the stability condition therefore changes in a system with a DDI present. Considering the case of a purely dipolar condensate with homogeneous density polarized by an external field, one finds that due to the anisotropy of the DDI, the BEC is unstable, independent of how small the dipole moment is [11]. As in the ...

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“…From these considerations as well as from the study of the effects induced by the algebra (1) on other physical systems one can speculate about the order of magnitude of θ. For example, the present approach could be connected to recent experiments carried out using 52 Cr condensates [9,10,12] where one uses the fact that, at large distances, the spins interact via the potential…”

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confidence: 99%

Aharonov-Bohm effect in a class of noncommutative theories

et al. 2011

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The Aharonov-Bohm effect including spin-noncommutative effects is considered. At linear order in θ, the magnetic field is gauge invariant although spatially strongly anisotropic. Despite this anisotropy, the Schrödinger-Pauli equation is separable through successive unitary transformations and the exact solution is found. The scattering amplitude is calculated and compared with the usual case. In the noncommutative Aharonov-Bohm case the differential cross section is independent of θ.

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Observation of Dipole-Dipole Interaction in a Degenerate Quantum Gas

Cited by 458 publications

References 34 publications

Wigner crystal versus fermionization for one-dimensional Hubbard models with and without long-range interactions

Wigner crystal versus fermionization for one-dimensional Hubbard models with and without long-range interactions

Stabilization of a purely dipolar quantum gas against collapse

Aharonov-Bohm effect in a class of noncommutative theories

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