Interband Heating Processes in a Periodically Driven Optical Lattice

Sträter, Christoph; Eckardt, André

doi:10.1515/zna-2016-0129

Cited by 27 publications

(30 citation statements)

References 54 publications

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“…. These latter peaks are significantly broader than the initial condensate peaks, which is indicative of an effective increase of the temperature as a consequence of the dynamical instability mechanism [14,19,32,33]. As shown in figure 2(a), this is also observed in the TW simulations, which also reveal that many-body coherence is lost in those side peaks (see appendix A).…”

Section: Experimental Findings and Comparison With Numerical Simulationssupporting

confidence: 52%

Phase transition kinetics for a Bose Einstein condensate in a periodically driven band system

et al. 2018

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The dynamical transition of an atomic Bose-Einstein condensate from a spatially periodic state to a staggered state with alternating sign in its wavefunction is experimentally studied using a onedimensional phase modulated optical lattice. We observe the crossover from quantum to thermal fluctuations as the triggering mechanism for the nucleation of staggered states. In good quantitative agreement with numerical simulations based on the truncated Wigner method, we experimentally investigate how the nucleation time varies with the renormalized tunneling rate, the atomic density, and the driving frequency. The effective inverted energy band in the driven lattice is identified as the key ingredient which explains the emergence of gap solitons as observed in numerics and the possibility to nucleate staggered states from interband excitations as reported experimentally.

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Section: Experimental Findings and Comparison With Numerical Simulationssupporting

confidence: 52%

Phase transition kinetics for a Bose Einstein condensate in a periodically driven band system

et al. 2018

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“…Then, independently from the driving scheme itself and the obtained stability properties, a central question is that of the preparation of the initial state, as loading the system into a desired eigenstate with highest fidelity is far from being trivial: one solution could be to apply adiabatic perturbation theory in the presence of the periodic drive [56,57], but there might exist other alternatives and their impact on the stability properties of the prepared state remains uncharacterized. Finally, the interplay between parametric instabilities and other instability mechanisms neglected in our approach, especially inter-band transitions [39,51,52], is expected to lead to rich behaviors that still remain to be studied.…”

Section: Discussionmentioning

confidence: 99%

Parametric instabilities in resonantly-driven Bose–Einstein condensates

Lellouch

Goldman

2018

Quantum Sci. Technol.

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Shaking optical lattices in a resonant manner offers an efficient and versatile method to devise artificial gauge fields and topological band structures for ultracold atomic gases. This was recently demonstrated through the experimental realization of the Harper-Hofstadter model, which combined optical superlattices and resonant time-modulations. Adding inter-particle interactions to these engineered band systems is expected to lead to strongly-correlated states with topological features, such as fractional Chern insulators. However, the interplay between interactions and external timeperiodic drives typically triggers violent instabilities and uncontrollable heating, hence potentially ruling out the possibility of accessing such intriguing states of matter in experiments. In this work, we study the early-stage parametric instabilities that occur in systems of resonantly-driven Bose-Einstein condensates in optical lattices. We apply and extend an approach based on Bogoliubov theory [PRX 7, 021015 (2017)] to a variety of resonantly-driven band models, from a simple shaken Wannier-Stark ladder to the more intriguing driven-induced Harper-Hofstadter model. In particular, we provide ab initio numerical and analytical predictions for the stability properties of these topical models. This work sheds light on general features that could guide current experiments to stable regimes of operation. * samuel.lellouch@univ-lille1.fr † ngoldman@ulb.ac.be arXiv:1711.08832v1 [cond-mat.quant-gas]

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“…and driving amplitudes K that remaining below a threshold value K th below which multi-photon transitions are expected to be suppressed exponentially with the photon number ∆/ ω [34]. It leads to a description of the system in terms of a tight-binding model with a single orbital state per lattice site, which in our case is given by the single-band model…”

Section: Single-band and High-frequency Approximationmentioning

confidence: 97%

“…While in a non-driven system, a description in the lowenergy subspace of the s band is well justified, this assumption is not as clear in a system that is driven periodically. Even if the driving frequency is small compared to the band gap separating the s band from the first excited p band, states of excited bands might still be populated via multiphoton excitations corresponding to either single-particle processes [29,34] or two-particle scattering [35]. If periodic driving is used to control the physics of the lowest band, such excitation processes must be viewed as unwanted heating.…”

Section: System and Modelmentioning

confidence: 99%

Optimal frequency window for Floquet engineering in optical lattices

Sun

Eckardt

2020

Phys. Rev. Research

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The concept of Floquet engineering is to subject a quantum system to time-periodic driving in such a way that it acquires interesting novel properties. It has successfully been employed in atomic quantum gases in driven optical lattices. Typically, Floquet engineering is based on two approximations. On the one hand, it is assuming that resonant excitations to high-lying states above some energy gap are suppressed for sufficiently low driving frequencies, so that the system can be described within some low-energy subspace (e.g. spanned by the lowest Bloch band of a lattice). On the other hand, the driving frequency is also assumed to still be large compared to the typical energy scale of this low-energy subspace, so that it does not resonantly create excitations within this space. Eventually, on some time scale τ , deviations from these approximations will make themselves felt as unwanted heating. Floquet engineering, thus, requires a window of driving frequencies, where both types of heating processes are suppressed on the experimentally relevant time scale. In this paper, we theoretically investigate the existence of such an optimal frequency window, using the example of interacting bosons in a shaken optical lattice. We find that the maximum value of τ , measured in the experimentally relevant unit of the tunneling time, increases with the lattice depth.

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Interband Heating Processes in a Periodically Driven Optical Lattice

Cited by 27 publications

References 54 publications

Phase transition kinetics for a Bose Einstein condensate in a periodically driven band system

Phase transition kinetics for a Bose Einstein condensate in a periodically driven band system

Parametric instabilities in resonantly-driven Bose–Einstein condensates

Optimal frequency window for Floquet engineering in optical lattices

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