Superfluid Bloch dynamics in an incommensurate optical lattice

Reeves, Jeremy; Gadway, Bryce; Bergeman, T.; Danshita, Ippei; Schneble, Dominik

doi:10.1088/1367-2630/16/6/065011

Cited by 7 publications

(4 citation statements)

References 49 publications

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“…A quick large space spreading has also observed in experiments with 7 Li atoms where the lattice amplitude is modulated in the presence of a static trap with displaced origin [36]. Here, we find that opposite to a modulation of the lattice, the modulation of the force provides an easy visualization of the modulation effects on wavepacket dynamics by monitoring the dynamics in k-space.…”

Section: Introductionsupporting

confidence: 74%

“…Improved measurement techniques opens doors to new perspectives, effects, and applications [1]. One of the most significant example are Bloch oscillations (BO) which are largely explored in various ultracold atomic ensembles, such as degenerate Bose/Fermi gases [2,3], strongly correlated atoms [4,5], and Bose-Einstein condensates [6][7][8][9]. In BOs the width or mean position of a localized wave interacting with a periodic lattice and a linear potential oscillates periodically due to periodic oscillations of the quasimomentum [10][11][12][13][14][15].…”

Section: Introductionmentioning

confidence: 99%

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Super-Bloch oscillations with parametric modulation of a parabolic trap

Ali¹,

Meier²

2022

Preprint

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Super-Bloch oscillations are the outcome of a relative phase between Bloch oscillations and modulations of the periodic lattice. We analyze the dynamics for a model system in which such a relative phase is intrinsically present due to the position-dependent force provided by a parabolic trap and therefore an external detuning is not required. The relative phase is not unique and the realized dynamics depends on the initial phase of the modulated parabolic potential. We provide accurate explanations for the different obtained oscillatory transport and spreading regimes by analyzing the spatio-temporal dynamics in real space and by visualizing the relative phase in the k-space dynamics. We also compare our numerical results to an approximate semiclassical analytical expression for the group velocity for a modulated constant force system and find good agreement for coherent oscillations but deviations for oscillations with spreading dynamics which altogether supports the interpretations of our findings.

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Section: Introductionsupporting

confidence: 74%

Section: Introductionmentioning

confidence: 99%

Super-Bloch oscillations with parametric modulation of a parabolic trap

Ali¹,

Meier²

2022

Preprint

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“…In contrast, in physics of ultracold atomic and molecular gases [3], the studies of transport, unlike those performed in solid state settings, are hindered by the difficulty of having continuous and durable flow of atoms; for this reason they have been very limited so far. Among others they included: the investigations of Bloch oscillations (from the early studies with cold atoms [4] to the recent experiments with disordered gases [5]), the extensive work on transport and diffusion in disordered gases [6,7,8,9,10], and the very recent experiments on quantized conductivity [11,12,13,14,15].…”

Section: Introductionmentioning

confidence: 99%

Quantum simulation of conductivity plateaux and fractional quantum Hall effect using ultracold atoms

et al. 2015

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Keywords: fractional quantum Hall effect, transport phenomena in ultracold quantum gases, impurities in ultracold quantum gases, quantum simulators AbstractWe analyze the role of impurities in the fractional quantum Hall effect using a highly controllable system of ultracold atoms. We investigate the mechanism responsible for the formation of plateaux in the resistivity/conductivity as a function of the applied magnetic field in the lowest Landau level regime. To this aim, we consider an impurity immersed in a small cloud of an ultracold quantum Bose gas subjected to an artificial magnetic field. We consider scenarios corresponding to experimentally realistic systems with gauge fields induced by rotation of the trapping parabolic potential. Systems of this kind are adequate to simulate quantum Hall effects in ultracold atom setups. We use exact diagonalization for few atoms and to emulate transport equations, we analyze the time evolution of the system under a periodic perturbation. We provide a theoretical proposal to detect the up-to-now elusive presence of strongly correlated states related to fractional filling factors in the context of ultracold atoms. We analyze the conditions under which these strongly correlated states are associated with the presence of the resistivity/conductivity plateaux. Our main result is the presence of a plateau in a region, where the transfer between localized and non-localized particles takes place, as a necessary condition to maintain a constant value of the resistivity/conductivity as the magnetic field increases.

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“…This is responsible for effects like the Anderson localization of otherwise superfluid extended states. The engineering of random optical potentials [167,168] or additional incommensurate ones [139,169] allows one to explore the transitions between the localized states originated from Anderson localization, and those expected in the Mott insulating phase as the trapping depth increases [170].…”

Section: Generalized Bose-hubbard Modelsmentioning

confidence: 99%

Synthetic quantum matter using atoms and light

Argüello Luengo

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Atomic and optical physics are two fields closely connected by a shared range of energy scales, and the interactions between them. Atoms represent the most fundamental components of matter, and interactions with electromagnetic fields are responsible for many properties used to characterize a material, like the emission and absorption of radiation by these systems. Over the last decades, this has allowed us to use light as a tool to access and manipulate the internal states of atomic systems. Such a quantum control has transformed atoms into one of the preferred platforms to explore fundamental science, including applications in quantum information, quantum metrology or, more recently, the realization of synthetic materials where light can induce interactions that would be difficult to find intrinsically in real materials. In the first part of this Thesis, we show how single atoms coupled to a cavity field can offer unique opportunities as quantum optomechanical devices because of their small mass and strong interaction with light. In particular, we focus on the "single-photon strong coupling" regime, where motional displacements on the order of the zero-point uncertainty are sufficient to shift the cavity resonance frequency by more than its linewidth. By coupling atomic motion to the narrow cavity-dressed atomic resonance, we theoretically observe that the scattering properties of single photons can become highly entangled with the atomic wavefunction, even if the cavity linewidth is large. This leads to a per-photon motional heating that is significantly larger than the single-photon recoil energy, as well as mechanically-induced oscillations that could be observed in the correlations of state-of-the-art cavity systems. In the second part of the Thesis, we investigate how synthetic materials built using light can be harnessed as quantum simulators, defeating the limitations that classical computers face in the exploration of quantum phenomena. We particularly focus on ultracold atomic mixtures trapped in optical lattices, where atom-mediated long-range interactions can provide an enabling tool in the simulation of relevant problems in condensed matter or quantum chemistry. First, we show that fermionic atoms in an ultracold gas can act as a mediator, giving rise to effective long-range RKKY interactions among other neutral atoms trapped in an optical lattice. We further propose several experimental knobs to tune these interactions, which are characterized by the density and dimensionality of the gas and are accessible in current experimental platforms. We also show that these knobs open up the exploration of new frustrated regimes where symmetry-protected topological phases and chiral spin liquids emerge. Second, we introduce a set of experimental schemes where long-range interactions are mediated by an additional bosonic species trapped in a commensurate optical lattice, both in 2D and 3D. In particular, we show that the interplay with cavity QED can lead to effective Coulomb-like repulsion, which opens the door to the analog simulation of quantum chemistry problems using ultracold fermionic atoms as simulated electrons. Apart from explaining the emergent mechanism, we provide operational conditions for the simulator, benchmark it with simple atoms and molecules, and analyze how the continuous limit is approached for increasing optical lattice sizes. Finally, we compare our results with those of the continuum limit, where conventional quantum chemistry methods can be evaluated and tested. In summary, our results show connections between different areas of theoretical and experimental physics where light-matter interaction can play a dominant role, and suggest how this can be harnessed to further advance our understanding of stronglycorrelated quantum matter. La física óptica y atómica son dos campos de investigación conectados por un rango de energías común. El átomo representa el componente más fundamental de la materia, y su interacción con campos electromagnéticos es responsable de muchas de las propiedades utilizadas para caracterizar materiales, como por ejemplo la emisión y absorción de radiación por estos sistemas. Este control a nivel cuántico ha erigido los átomos como una de las plataformas preferidas para explorar ciencia fundamental, incluyendo aplicaciones en información cuántica, metrología o, más recientemente, la fabricación de materiales sintéticos en que la luz es capaz de inducir interacciones que serían difíciles de encontrar intrínsecamente en materiales convencionales. En la primera parte de esta Tesis mostramos cómo un átomo individual acoplado a una cavidad puede manifestar propiedades optomecánicas a nivel cuántico únicas, debido a su baja masa y fuerte interacción con la luz. En particular, nos centramos en el límite de acoplamiento fuerte al nivel de un único fotón, donde un desplazamiento en el orden de la incertidumbre del punto cero es suficiente para cambiar la frecuencia de resonancia de la cavidad más allá de su ancho de línea. Al acoplar este movimiento del átomo a su estrecha resonancia, observamos teóricamente que la dispersión de fotones individuales queda fuertemente entrelazada con la función de onda del átomo, incluso cuando la resonancia de la cavidad es ancha. Esto conlleva que cada fotón caliente el átomo significativamente más de lo que se esperaría de su energía de retroceso, y podría manifestarse en dispositivos actuales en forma de oscilaciones dictadas por el movimiento del átomo. En la segunda parte de la Tesis investigamos cómo algunos materiales sintéticos fabricados con luz pueden utilizarse como simuladores cuánticos, desafiando así las limitaciones que los ordenadores clásicos enfrentan actualmente a la hora de explorar fenómenos cuánticos. En particular, nos centramos en el estudio de mezclas de átomos ultrafríos atrapados en redes ópticas, donde interacciones de largo alcance mediadas por estos átomos pueden jugar un papel fundamental en la simulación de problemas relevantes en materia condensada o química cuántica. Primero, mostramos que átomos fermiónicos en un gas ultrafrío pueden actuar como mediadores, dando lugar a interacciones efectivas de largo alcance tipo RKKY entre átomos neutros atrapados. Asimismo, proponemos diferentes estrategias para modular estas interacciones a través de la densidad y dimensión del gas, lo que es experimentalmente accesible en plataformas actuales. Mostramos también que esta versatilidad permite la exploración de sistemas frustrados, donde aparecen fases topológicas protegidas por simetría y líquidos quirales de espín. En segundo lugar, introducimos un conjunto de esquemas experimentales donde las interacciones de largo alcance son mediadas por una especie bosónica adicional atrapada en una red óptica, tanto en 2D como en 3D. En particular, mostramos que la interacción adicional con una cavidad puede dar lugar a una repulsión efectiva del tipo Coulomb, lo que abre la puerta a simular de manera analógica problemas de química cuántica, tomando átomos fermiónicos ultrafríos como electrones simulados. Además de explicar estos mecanismos, derivamos las condiciones operacionales para el simulador, lo probamos para átomos y moléculas sencillas, y analizamos cómo se aproxima el límite en el continuo a medida que la red óptica aumenta. Finalmente, comparamos nuestros resultados con los esperados en el continuo, donde los métodos utilizados en química cuántica pueden ser evaluados y puestos a prueba. En resumen, nuestros resultados dibujan conexiones entre diferentes áreas de la física teórica y experimental donde la interacción entre la luz y la materia puede jugar un papel fundamental, y sugerimos cómo se puede aprovechar esto para avanzar aún más en nuestra comprensión de la materia cuántica fuertemente correlacionada.

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Superfluid Bloch dynamics in an incommensurate optical lattice

Cited by 7 publications

References 49 publications

Super-Bloch oscillations with parametric modulation of a parabolic trap

Super-Bloch oscillations with parametric modulation of a parabolic trap

Quantum simulation of conductivity plateaux and fractional quantum Hall effect using ultracold atoms

Synthetic quantum matter using atoms and light

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