Breakdown of the Kohn theorem near a Feshbach resonance in a magnetic trap

Al-Jibbouri, Hamid; Pelster, Axel

doi:10.1103/physreva.88.033621

Cited by 10 publications

(3 citation statements)

References 55 publications

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“…According to the theorem BEC in a confining potential must have a mode in which the centre of mass oscillates with the frequency of the confining potential. However, in a magnetic trap in the vicinity of the Feshbach resonance [27] and in fewelectron parabolic quantum dots doped with a single magnetic impurity [28], there are deviations from Kohn's theorem.…”

Section: Resultsmentioning

confidence: 99%

Collective modes in multicomponent condensates with anisotropy

Pal¹,

Roy

Angom³

2018

J. Phys. B: At. Mol. Opt. Phys.

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We report the effects of anisotropy in the confining potential on two component Bose-Einstein condensates (TBECs) through the properties of the low energy quasiparticle excitations. Starting from generalized Gross Pitaevskii equation, we obtain the Bogoliubov de-Gennes (BdG) equation for TBECs using the Hartree-Fock-Bogoliubov (HFB) theory. Based on this theory, we present the influence of radial anisotropy on TBECs in the immiscible or the phase-separated domain. In particular, the TBECs of 85 Rb -87 Rb and 133 Cs -87 Rb TBECs are chosen as specific examples of the two possible interface geometries, shell-structured and side by side, in the immiscible domain. We also show that the dispersion relation for the TBEC shell-structured interface has two branches, and anisotropy modifies the energy scale and structure of the two branches.

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Section: Resultsmentioning

confidence: 99%

Collective modes in multicomponent condensates with anisotropy

Pal¹,

Roy

Angom³

2018

J. Phys. B: At. Mol. Opt. Phys.

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“…To describe a realistic physical set-up, we consider a membrane with Ω m = 100 ω R , which corresponds to a frequency of several hundred kHz. Here, we describe the condensate profile by a Gaussian [40]…”

Section: Modelmentioning

confidence: 99%

Nonequilibrium Quantum Phase Transition in a Hybrid Atom-Optomechanical System

et al. 2018

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We consider a hybrid quantum many-body system formed by a vibrational mode of a nanomembrane, which interacts optomechanically with light in a cavity, and an ultracold atom gas in the optical lattice of the out-coupled light. The adiabatic elimination of the light field yields an effective Hamiltonian which reveals a competition between the force localizing the atoms and the membrane displacement. At a critical atom-membrane interaction, we find a nonequilibrium quantum phase transition from a localized symmetric state of the atom cloud to a shifted symmetry-broken state, the energy of the lowest collective excitation vanishes, and a strong atom-membrane entanglement arises. The effect occurs when the atoms and the membrane are non-resonantly coupled.Hybrid quantum systems combine complementary fields of physics, such as solid-state physics, quantum optics and atom physics, in one set-up. Recently, a hybrid atom-optomechanical system [1] has been realized experimentally [2] in which a single mechanical mode of a nanomembrane in an optical cavity is optically coupled to a far distant cloud of cold 87 Rb atoms residing in the optical potential of the out-coupled standing wave of the cavity light. When displaced, the membrane experiences the radiation pressure force of the cavity light, and in the bad-cavity limit, the field follows the membrane displacement adiabatically. This modulates the light phase which leads to a shaking of the atom gas in the lattice. The nanomechanical motion of the membrane then couples non-resonantly to the collective motion of the atoms. The aim is twofold [1][2][3][4][5][6][7]: The gas can cool the nanomembrane, and, emergent phenomena of the correlated quantum many-body system are of interest [8][9][10][11][12][13][14][15][16][17].State-of-the-art optomechanics [3-6] is nowadays able to realize optical feedback cooling [18,19] of the mechanical oscillator to its quantum-mechanical ground state [20,21]. Yet, the resolved sideband limit allows ground-state cooling only if the oscillator frequency exceeds the photon loss rate in the cavity [22][23][24]. Hence, cooling a macroscopic low-frequency nanomembrane close to its ground state is so far not possible. One promising alternative [1,7] is to utilize an ultracold atom gas, which has been demonstrated recently [2] by sympathetic cooling down to 650 mK. Current investigations aim to a coherent state transfer of robust quantum entanglement [15].Apart from cooling the nanomembrane, an interesting fundamental feature is the collective quantum-many body behavior of the hybrid system. For instance, the atom-atom interaction can in principle be coherently modulated by the back-action of the cavity light on the nanooscillator. By this, a long-range interaction emerges which resembles that of a dipolar Bose-Einstein condensate (BEC) [25]. In fact, a simpler hybrid quantum many-body system has also been implemented in the form of a BEC in an optical lattice inside a transversely pumped optical cavity. A Dicke quantum phase transition between a n...

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“…Therefore, these two phenomena can be easily distinguished, not only by comparing their frequencies, but also the corresponding onset times. We note that resonant behavior can appear not only due to the modulation of the interaction strength or the trapping potential, but also due to its spatial modulation [31][32][33][34][35][36][37][38][39][40].…”

Section: Introductionmentioning

confidence: 99%

Faraday and Resonant Waves in Dipolar Cigar-Shaped Bose-Einstein Condensates

Vudragović

Balaž

2019

Symmetry

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Faraday and resonant density waves emerge in Bose-Einstein condensates as a result of harmonic driving of the system. They represent nonlinear excitations and are generated due to the interaction-induced coupling of collective oscillation modes and the existence of parametric resonances. Using a mean-field variational and a full numerical approach, we studied density waves in dipolar condensates at zero temperature, where breaking of the symmetry due to anisotropy of the dipole-dipole interaction (DDI) plays an important role. We derived variational equations of motion for the dynamics of a driven dipolar system and identify the most unstable modes that correspond to the Faraday and resonant waves. Based on this, we derived the analytical expressions for spatial periods of both types of density waves as functions of the contact and the DDI strength. We compared the obtained variational results with the results of extensive numerical simulations that solve the dipolar Gross-Pitaevskii equation in 3D, and found a very good agreement.

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Breakdown of the Kohn theorem near a Feshbach resonance in a magnetic trap

Cited by 10 publications

References 55 publications

Collective modes in multicomponent condensates with anisotropy

Collective modes in multicomponent condensates with anisotropy

Nonequilibrium Quantum Phase Transition in a Hybrid Atom-Optomechanical System

Faraday and Resonant Waves in Dipolar Cigar-Shaped Bose-Einstein Condensates

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