Multi-band spectroscopy of inhomogeneous Mott-insulator states of ultracold bosons

Clément, David; Fabbri, Nicole; Fallani, Leonardo; Fort, C.; Inguscio, M.

doi:10.1088/1367-2630/11/10/103030

Cited by 24 publications

(23 citation statements)

References 53 publications

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“…We have verified the increase of σ 2 due to Bragg excitation, compared to the squared width σ 2 0 measured in the case of the unperturbed system, to be proportional to the increase of total energy [18,33], and thus we can write…”

Section: Experimental Bragg Spectrasupporting

confidence: 66%

Dynamical structure factor of one-dimensional Bose gases: Experimental signatures of beyond-Luttinger-liquid physics

et al. 2015

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Interactions are known to have dramatic effects on bosonic gases in one dimension (1D). Not only does the ground state transform from a condensate like state to an effective Fermi sea, but new fundamental excitations, which do not have any higher-dimensional equivalents, are predicted to appear. In this work, we trace these elusive excitations via their effects on the dynamical structure factor of 1D strongly interacting Bose gases at low temperature. An array of 1D Bose gases is obtained by loading a 87 Rb condensate in a two-dimensional lattice potential. The dynamical structure factor of the system is probed by energy deposition through low-momentum Bragg excitations. The experimental signals are compared to recent theoretical predictions for the dynamical structure factor of the Lieb-Liniger model at T > 0. Our results demonstrate that the main contribution to the spectral widths stems from the dynamics of the interaction-induced excitations in the gas, which cannot be described by the Luttinger liquid theory.

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Section: Experimental Bragg Spectrasupporting

confidence: 66%

Dynamical structure factor of one-dimensional Bose gases: Experimental signatures of beyond-Luttinger-liquid physics

et al. 2015

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“…Therefore we can simplify the numerics by using the noninteracting eigenfunctions of the Duffing potential to approximate ψ j (z) and to calculate the coefficients (6)- (9). The four-mode approach permits a simplified study of systems in which the two ground-state modes coexist with a significant depletion cloud or, more realistically, where a large part of the gas is intentionally excited to the first excited level [1][2][3][4][5][6]53,54].…”

Section: Semiclassical Approximationmentioning

confidence: 99%

“…Recent experimental realizations of systems of ultracold atoms prepared in excited Bloch bands in optical lattices have opened new prospects in ultracold atomic science [1][2][3][4][5][6]. This access to the orbital degree of freedom allows observation of new exotic physics by playing with the anisotropy of the Wannier functions from which the Bloch states of the excited bands are built.…”

Section: Introductionmentioning

confidence: 99%

Tunneling, self-trapping, and manipulation of higher modes of a Bose-Einstein condensate in a double well

et al. 2014

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We consider an atomic Bose-Einstein condensate trapped in a symmetric one-dimensional double-well potential in the four-mode approximation and show that the semiclassical dynamics of the two ground-state modes can be strongly influenced by a macroscopic occupation of the two excited modes. In particular, the addition of the two excited modes already unveils features related to the effect of dissipation on the condensate. In general, we find a rich dynamics that includes Rabi oscillations, a mixed Josephson-Rabi regime, self-trapping, chaotic behavior, and the existence of fixed points. We investigate how the dynamics of the atoms in the excited modes can be manipulated by controlling the atomic populations of the ground states.

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Section: Fig 1 (Color Online)mentioning

confidence: 99%

“…Therefore, the measured spectrum describes a convolution (without vertex corrections) of the density of states of the lower occupied with the upper unoccupied band. From this convolution the spectral function of the lower strong-correlated bands can be extracted [39].In the present paper we study in detail the spectral properties of bosonic atoms in a disordered optical lattice, modeled by the one-dimensional BH model in which, for simplicity, the harmonic trap potential has been neglected. We focus on the strongly correlated regime and…”

mentioning

confidence: 99%

Excitations in disordered bosonic optical lattices

2010

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Spectral excitations of ultracold gases of bosonic atoms trapped in one-dimensional optical lattices with disorder are investigated by means of the variational cluster approach applied to the BoseHubbard model. Qualitatively different disorder distributions typically employed in experiments are considered. The computed spectra exhibit a strong dependence on the shape of the disorder distribution and the disorder strength. We compare alternative results for the Mott gap obtained from its formal definition and from the minimum peak distance, which is the quantity available from experiments.PACS numbers: 64.70. Tg, 73.43.Nq, 67.85.De, 03.75.Kk Interacting many-body systems with disorder are fascinating and challenging from both the experimental as well as the theoretical point of view. Understanding disordered bosonic systems has been of great interest ever since the pioneering works on the Bose-Hubbard (BH) model [1], which describes strongly interacting lattice bosons. Originally, the disordered BH model has been used to approximately describe various condensed matter systems, such as superfluid helium absorbed in porous media [2,3], superfluid films on substrates [4], and Josephson junction arrays [5]. However, seminal experiments on ultracold gases of atoms trapped in optical lattices shed new light on interacting bosonic many-body systems, as these systems provide a direct experimental realization of the BH model [6,7]. Intriguingly, these experiments allow to observe quantum many-body phenomena, such as the quantum phase transition from a superfluid to a Mott state [8]. The condensate of atoms can be driven across this phase transition by gradually increasing the laser beam intensity, which is directly related to the depth of the potential wells. There is a large experimental control over the system parameters such as the particle number or lattice depth, and in addition the parameters are tuneable over a wide range. While optical lattices provide a very clean experimental realization of strongly correlated lattice bosons, they can be used to study disordered systems on a very high level of control as well. Disorder can be added to the regular optical lattice by several techniques, such as by superposing additional optical lattices with shifted wavelength and beam angles [9][10][11][12][13][14], laser speckle fields [15][16][17][18], or including atoms of a different species acting as impurities [19].The disordered BH model has been widely investigated in the literature. Most of the work has been devoted to study the phase transitions occurring in the disordered BH model [20][21][22][23][24][25][26][27][28][29][30][31][32][33][34][35]. At zero temperature the ground-state phase diagram depending on the chemical potential, the tunneling probability of the particles and the disorder * michael.knap@tugraz.at FIG. 1. (Color online)The periodic optical lattice potential is locally modified by disorder. In the illustration the disorder is bounded by ǫ * corresponding to a situation obtained by the superposition ...

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Multi-band spectroscopy of inhomogeneous Mott-insulator states of ultracold bosons

Cited by 24 publications

References 53 publications

Dynamical structure factor of one-dimensional Bose gases: Experimental signatures of beyond-Luttinger-liquid physics

Dynamical structure factor of one-dimensional Bose gases: Experimental signatures of beyond-Luttinger-liquid physics

Tunneling, self-trapping, and manipulation of higher modes of a Bose-Einstein condensate in a double well

Excitations in disordered bosonic optical lattices

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