Bragg scattering and the spin structure factor of two-component atomic gases

Carusotto, Iacopo

doi:10.1088/0953-4075/39/10/s20

Cited by 22 publications

(30 citation statements)

References 31 publications

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“…This can be measured via, for example, Bragg spectroscopy [49]. To compare finite-temperature and ground state correlations (obtained from DMRG), we define an appropriate distance measure that accounts also for the overall magnitude of the ground state correlations [38], This quantity is sensitive to both long range and short range magnetic correlations [50,51].…”

Section: One-dimensional Su(n) Alkaline Earth Fermions In Optical Latmentioning

confidence: 99%

Adiabatic Loading of One-DimensionalSU(N)Alkaline-Earth-Atom Fermions in Optical Lattices

et al. 2012

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Ultracold fermionic alkaline earth atoms confined in optical lattices realize Hubbard models with internal SU(N ) symmetries, where N can be as large as ten. Such systems are expected to harbor exotic magnetic physics at temperatures below the superexchange energy scale. Employing quantum Monte Carlo simulations to access the low-temperature regime of one-dimensional chains, we show that after adiabatically loading a weakly interacting gas into the strongly interacting regime of an optical lattice, the final temperature decreases with increasing N . Furthermore, we estimate the temperature scale required to probe correlations associated with low-temperature SU(N ) magnetism. Our findings are encouraging for the exploration of exotic large-N magnetic states in ongoing experiments.

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Section: One-dimensional Su(n) Alkaline Earth Fermions In Optical Latmentioning

confidence: 99%

Adiabatic Loading of One-DimensionalSU(N)Alkaline-Earth-Atom Fermions in Optical Lattices

et al. 2012

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“…Scattering of light has been suggested theoretically and used experimentally in a number of contexts to probe the spin distribution of ultracold atoms [28][29][30][31][32][33][34][35][36][37][38][39]. Here we wish to determine if light scattering is a useful probe of the many-body states described above.…”

Section: Light Scattering From Multicomponent Statesmentioning

confidence: 99%

Imaging of quantum Hall states in ultracold atomic gases

Douglas

Burnett

2011

Phys. Rev. A

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We examine off-resonant light scattering from ultracold atoms in the quantum Hall regime. When the light scattering is spin dependent, we show that images formed in the far field can be used to distinguish states of the system. The spatial dependence of the far-field images is determined by the two-particle spin-correlation functions, which the images are related to by a transformation. Quasiholes in the system appear in images of the density formed by collecting the scattered light with a microscope, where the quasihole statistics are revealed by the reduction in density at the quasihole position

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“…The spin response is suppressed at low energies due to pairing and displays a universal high frequency tail, decaying as ω −5/2 , where ω is the probe energy (Bragg frequency) [13].The key to accessing the spin response in two-photon scattering experiments is to use Bragg lasers with a different coupling to each of the two spin states in the mixture. This can be achieved using spin-flip Bragg spectroscopy [22,28], polarisation sensitive coupling [29] or by detuning the Bragg lasers close to resonance. In our experiments with 6 Li, the first two methods prove challenging because of the atomic state configuration at high magnetic fields, and therefore we use the third method.To understand our measurements we first review the atomic level structure of 6 Li atoms.…”

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confidence: 99%

Dynamic Spin Response of a Strongly Interacting Fermi Gas

et al. 2012

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We present an experimental investigation of the dynamic spin response of a strongly interacting Fermi gas using Bragg spectroscopy. By varying the detuning of the Bragg lasers, we show that it is possible to measure the response in the spin and density channels separately. At low Bragg energies, the spin response is suppressed due to pairing, whereas the density response is enhanced. These experiments provide the first independent measurements of the spin-parallel and spin-antiparallel dynamic and static structure factors which provide insight into the different features of density and spin response functions. At high momentum the spin-antiparallel dynamic structure factor displays a universal high frequency tail, proportional to ω −5/2 , where ω is the probe energy. Two-component Fermi gases near Feshbach resonances provide a well controlled setting to explore many-body phenomena in highly correlated quantum systems [1,2]. When the interparticle interactions are sufficiently strong, ultracold atomic gases display universal features, where macroscopic parameters become independent of the microscopic details of the interatomic potential [3][4][5]. Most studies to date have focussed on static aspects of universality [6][7][8][9][10]; however, certain dynamical properties can also become universal. Key among these are dynamic susceptibilities which describe the way a system responds to a perturbation. Recent theoretical work has shown that the dynamic structure factor, which is connected to the imaginary part of susceptibility through the fluctuation-dissipation theorem, shows a universal high frequency tail both at high momentum [11][12][13] and low momentum where it depends on the frequency dependent shear viscosity [14,15].Bragg spectroscopy is a well established tool to measure dynamic and static density response functions [16][17][18][19]. Previous work on Fermi gases has shown that the static structure factor follows a universal law which arises from Tan's relation for the density-density correlator [20]. Several theoretical studies have also investigated the dynamic spin response [12,13,[21][22][23]] and a recent study of universal spin transport examined the static spin susceptibility [24,25], yet the dynamic spin susceptibility has not been studied experimentally.In this letter we present the first measurements of the dynamic spin response of a strongly interacting Fermi gas. Two-photon Bragg scattering is used to probe either the spin or density response by appropriate choice of the Bragg laser detuning. This allows full characterisation of the spin-parallel and spin-antiparallel components of the dynamic and static structure factors through the application of the f -sum rule [26,27]. The spin response is suppressed at low energies due to pairing and displays a universal high frequency tail, decaying as ω −5/2 , where ω is the probe energy (Bragg frequency) [13].The key to accessing the spin response in two-photon scattering experiments is to use Bragg lasers with a different coupling to each of the two s...

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Bragg scattering and the spin structure factor of two-component atomic gases

Cited by 22 publications

References 31 publications

Adiabatic Loading of One-DimensionalSU(N)Alkaline-Earth-Atom Fermions in Optical Lattices

Adiabatic Loading of One-DimensionalSU(N)Alkaline-Earth-Atom Fermions in Optical Lattices

Imaging of quantum Hall states in ultracold atomic gases

Dynamic Spin Response of a Strongly Interacting Fermi Gas

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