Supersolid formation in a quantum gas breaking a continuous translational symmetry

Léonard, Julian; Morales, Andrea; Zupancic, Philip; Esslinger, Tilman; Donner, Tobias

doi:10.1038/nature21067

Cited by 477 publications

(468 citation statements)

References 34 publications

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“…These interactions may be sufficiently strong to create novel quantum phases of matter [4]. Indeed, single-and few-mode cavity QED in the optical domain have already provided demonstrations of supersolidity [5,6] and exotic Mott physics [7,8], in addition to supermode-density-wave-polariton condensation [9]. Moreover, the driven-dissipative, openquantum-system nature of cavity QED can change the character of quantum phase transitions, providing a new window into quantum nonequilibrium physics [10,11].…”

Section: Introductionmentioning

confidence: 99%

“…[9] in the regime of a few degenerate modes. Two crossed single-mode cavities with a BEC coupled to both was shown to exhibit a Uð1Þ symmetry in the superradiant, self-organization phase as well as a Higgs mode [5,6]. Though BECs were employed in the latter two experiments, the number of modes was insufficient to mediate short-range interactions.…”

Section: Introductionmentioning

confidence: 99%

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Tunable-Range, Photon-Mediated Atomic Interactions in Multimode Cavity QED

et al. 2018

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Optical cavity QED provides a platform with which to explore quantum many-body physics in drivendissipative systems. Single-mode cavities provide strong, infinite-range photon-mediated interactions among intracavity atoms. However, these global all-to-all couplings are limiting from the perspective of exploring quantum many-body physics beyond the mean-field approximation. The present work demonstrates that local couplings can be created using multimode cavity QED. This is established through measurements of the threshold of a superradiant, self-organization phase transition versus atomic position. Specifically, we experimentally show that the interference of near-degenerate cavity modes leads to both a strong and tunable-range interaction between Bose-Einstein condensates (BECs) trapped within the cavity. We exploit the symmetry of a confocal cavity to measure the interaction between real BECs and their virtual images without unwanted contributions arising from the merger of real BECs. Atom-atom coupling may be tuned from short range to long range. This capability paves the way toward future explorations of exotic, strongly correlated systems such as quantum liquid crystals and driven-dissipative spin glasses.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Tunable-Range, Photon-Mediated Atomic Interactions in Multimode Cavity QED

et al. 2018

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“…A number of theoretical suggestions have been made of specific cold atom systems and settings, wherein this elusive phase of matter may be unambiguously observed, for example with Rydberg atoms [27][28][29][30][31][32][33]; experimentally, evidence of novel phases displaying density ordering and superfluidity has been recently reported for atomic BECs featuring spin-orbit interactions [34], or coupled to the modes of optical cavities [35].…”

Section: Introductionmentioning

confidence: 99%

Classical and quantum filaments in the ground state of trapped dipolar Bose gases

Cinti

2017

Phys. Rev. A

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We study by quantum Monte Carlo simulations the ground state of a harmonically confined dipolar Bose gas with aligned dipole moments, and with the inclusion of a repulsive two-body potential of varying range. Two different limits can be clearly identified, namely a classical one in which the attractive part of the dipolar interaction dominates and the system forms an ordered array of parallel filaments, and a quantum-mechanical one, wherein filaments are destabilized by zero-point motion, and eventually the ground state becomes a uniform cloud. The physical character of the system smoothly evolves from classical to quantum mechanical as the range of the repulsive twobody potential increases. An intermediate regime is observed, in which ordered filaments are still present, albeit forming different structures from the ones predicted classically; quantum-mechanical exchanges of indistinguishable particles across different filaments allow phase coherence to be established, underlying a global superfluid response.

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“…In a narrow range ∆λ 0.1 ω R around λ c , a bifurcation of the decay rate can be observed, whereas the lowest excitation frequency is constantly zero. Such a behavior is well known from atomic ensembles with long-range interactions [34,35,41,42] which, in the present case, are mediated by the membrane. Indeed, adiabatically eliminating the membrane mode introduces a long-range interaction potential that takes the form G(z, z ) = G 0 sin(2z) sin(2z ) with G 0 = −2λ 2 /Ω m .…”

Section: Collective Excitation Modesmentioning

confidence: 76%

“…A Dicke quantum phase transition between a normal phase and a self-organized superradiant phase occurs [26][27][28][29][30]. Moreover, optical bistability [31,32], a roton-type softening in the atomic dispersion relation [26,[33][34][35] and optomechanical Bloch oscillations [36] were uncovered. Similar effects occur also for polarizable and thermal particles in a cavity at finite temperature [37][38][39].…”

mentioning

confidence: 97%

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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Supersolid formation in a quantum gas breaking a continuous translational symmetry

Cited by 477 publications

References 34 publications

Tunable-Range, Photon-Mediated Atomic Interactions in Multimode Cavity QED

Tunable-Range, Photon-Mediated Atomic Interactions in Multimode Cavity QED

Classical and quantum filaments in the ground state of trapped dipolar Bose gases

Nonequilibrium Quantum Phase Transition in a Hybrid Atom-Optomechanical System

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