Unified view on linear response of interacting identical and distinguishable particles from multiconfigurational time-dependent Hartree methods

In this work, we study many-body excitations of Bose-Einstein condensates (BECs) trapped in periodic one-dimensional optical lattices. In particular, we investigate the impact of quantum depletion onto the structure of the low-energy spectrum and contrast the findings to the mean-field predictions of the Bogoliubov-de Gennes (BdG) equations. Accurate results for the many-body excited states are obtained by applying a linear-response theory atop the MCTDHB (multiconfigurational time-dependent Hartree method for bosons) equations of motion, termed LR-MCTDHB.We demonstrate for condensates in a triple well that even weak ground-state depletion of around 1% leads to visible many-body effects in the low-energy spectrum which deviate substantially from the corresponding BdG spectrum. We further show that these effects also appear in larger systems with more lattice sites and particles, indicating the general necessity of a full many-body treatment.

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“…The lengthy but straightforward derivation of the linear-response equations is described in Refs. [41,42].…”

Section: B Methodologymentioning

confidence: 99%

Many-body effects in the excitation spectrum of weakly interacting Bose-Einstein condensates in one-dimensional optical lattices

et al. 2017

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“…A complicating feature of the non-equilibrium dynamics is the presence of interactions at a level that often precludes the use of a perturbative analysis and/or mean-field (MF) approximation. Specifically, the dynamics beyond the paradigm of linear response has been a subject of growing theoretical interest [16][17][18][19][20][21][22][23][24] triggered by the recent progress in ultracold atom experiments particularly in one spatial dimension [25][26][27][28].…”

Section: Introductionmentioning

confidence: 99%

Quantum dynamical response of ultracold few-boson ensembles in finite optical lattices to multiple interaction quenches

2017

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The correlated non-equilibrium quantum dynamics following a multiple interaction quench protocol for few-bosonic ensembles confined in finite optical lattices is investigated. The quenches give rise to an interwell tunneling and excite the cradle and a breathing mode. Several tunneling pathways open during the time interval of increased interactions, while only a few occur when the system is quenched back to its original interaction strength. The cradle mode, however, persists during and in between the quenches, while the breathing mode possesses dinstinct frequencies. The occupation of excited bands is explored in detail revealing a monotonic behavior with increasing quench amplitude and a non-linear dependence on the duration of the application of the quenched interaction strength. Finally, a periodic population transfer between momenta for quenches of increasing interaction is observed, with a power-law frequency dependence on the quench amplitude. Our results open the possibility to dynamically manipulate various excited modes of the bosonic system.

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“…The derivation of the linear-response (LR) theory atop the wavefunction (4) is rather lengthly but otherwise straightforward [11,14]. We will not repeat it here and begin from the final result for the resulting LR-MCTDHB theory, which takes on the form of the eigenvalue equation [11,14] …”

Section: Many-body Theorymentioning

confidence: 99%

“…We will not repeat it here and begin from the final result for the resulting LR-MCTDHB theory, which takes on the form of the eigenvalue equation [11,14] …”

Section: Many-body Theorymentioning

confidence: 99%

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Many-body excitation spectra of trapped bosons with general interaction by linear response

Alon

2015

J. Phys.: Conf. Ser.

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The linear-response theory of the multiconfigurational time-dependent Hartree for bosons method for computing many-body excitations of trapped Bose-Einstein condensates [Phys. Rev. A 88, 023606 (2013)] is implemented for systems with general interparticle interaction. Illustrative numerical examples for repulsive and attractive bosons are provided. The many-body linear-response theory identifies the excitations not unraveled within Bogoliubov-de Gennes equations. The theory is herewith benchmarked against the exactly-solvable one-dimensional harmonic-interaction model. As a complementary result, we represent the theory in a compact block-diagonal form, opening up thereby an avenue for treating larger systems.

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Unified view on linear response of interacting identical and distinguishable particles from multiconfigurational time-dependent Hartree methods

Cited by 15 publications

References 89 publications

Many-body effects in the excitation spectrum of weakly interacting Bose-Einstein condensates in one-dimensional optical lattices

Many-body effects in the excitation spectrum of weakly interacting Bose-Einstein condensates in one-dimensional optical lattices

Quantum dynamical response of ultracold few-boson ensembles in finite optical lattices to multiple interaction quenches

Many-body excitation spectra of trapped bosons with general interaction by linear response

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