Excitation Spectrum of a Supersolid

Saccani, Sebastiano; Moroni, Saverio; Boninsegni, Massimo

doi:10.1103/physrevlett.108.175301

Cited by 144 publications

(153 citation statements)

References 26 publications

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“…In quantum physics, a key example is the supersolid phase for bosonic particles [1][2][3], where the rare simultaneous breaking of two symmetries (i.e., continuous translational and global gauge symmetry) leads to the coexistence of both crystalline and superfluid properties [4][5][6][7][8][9][10][11]. Such state of matter may be realized for a monodisperse ensemble of particles with cluster forming interactions, at sufficiently low temperatures [7,9].…”

Section: Introductionmentioning

confidence: 99%

Monodisperse cluster crystals: Classical and quantum dynamics

et al. 2015

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We study the phases and dynamics of a gas of monodisperse particles interacting via soft-core potentials in two spatial dimensions, which is of interest for soft-matter colloidal systems and quantum atomic gases. Using exact theoretical methods, we demonstrate that the equilibrium lowtemperature classical phase simultaneously breaks continuous translational symmetry and dynamic space-time homogeneity, whose absence is usually associated with out-of-equilibrium glassy phenomena. This results in an exotic self-assembled cluster crystal with coexisting liquid-like long-time dynamical properties, which corresponds to a classical analog of supersolid behavior. We demonstrate that the effects of quantum fluctuations and bosonic statistics on cluster-glassy crystals are separate and competing: zero-point motion tends to destabilize crystalline order, which can be restored by bosonic statistics.

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Section: Introductionmentioning

confidence: 99%

Monodisperse cluster crystals: Classical and quantum dynamics

et al. 2015

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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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“…These functions are obtained from analytic continuation of the imaginary-time Green's functions and density-density or spin-spin correlation functions, using the Genetic Inversion via Falsification of Theories (GIFT) method [47][48][49][50][51][52][53]. Figure 1 shows the computed pairing gap across different interaction strengths.…”

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confidence: 99%

Visualizing the BEC-BCS crossover in a two-dimensional Fermi gas: Pairing gaps and dynamical response functions from ab initio computations

et al. 2017

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Experiments with ultracold atoms provide a highly controllable laboratory setting with many unique opportunities for precision exploration of quantum many-body phenomena. The nature of such systems, with strong interaction and quantum entanglement, makes reliable theoretical calculations challenging. Especially difficult are excitation and dynamical properties, which are often the most directly relevant to experiment. We carry out exact numerical calculations, by Monte Carlo sampling of imaginary-time propagation of Slater determinants, to compute the pairing gap in the two-dimensional Fermi gas from first principles. Applying state-of-art analytic continuation techniques, we obtain the spectral function, and the density and spin structure factors providing unique tools to visualize the BEC-BCS crossover. These quantities will allow for a direct comparison with experiments.It is truly unusual when, starting from a microscopic Hamiltonian, theory can achieve an exact description of a strongly correlated fermionic system which, at the same time, can be realized in a laboratory with great precision and control. Experiments with ultracold atoms [1,2] have provided a possibility to realize such a scenario. The accuracy that can be reached in experiments with Fermi atomic gases and optical lattices is exceptional, thus offering a unique setting to explore highly correlated quantum fermion systems. In this paper, we demonstrate that, from the theoretical side, advances in computational methods now make it feasible to obtain numerically exact results for not only equilibrium properties, but also excited states. We compute the pairing gap, spectral functions and dynamical response functions in the two-dimensional Fermi gas across the range of interactions, which will allow direct comparisons with spectroscopy or scattering experiments. The dynamical properties provide a powerful tool to probe the behavior of the system and to visualize the crossover from a gas of molecules to a BCS superfluid.We study the Fermi gas with a zero-range attractive interaction, which has generated a great deal of research activity [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15]. The interest of the system is very wide, ranging from condensed matter physics [6,16] to nuclear physics, with possible important applications also in the study of neutron stars [17,18]. This system describes experiments with a collection of atoms, for example 6 Li, which are cooled to degeneracy in an equal mixture of two hyperfine ground states, labeled | ↑ and | ↓ . Feshbach resonances allow the tuning of the interactions by varying an external magnetic field, making the system a unique laboratory to explore many-body physics [19,20]. Starting from a weakly interacting BCS regime, where the attraction between particles induces a pairing similar to the one observed in ordinary superconductors, a crossover is observed as the interaction strength is increased, leading to a BEC regime where the Cooper pairs are tightly bound such that the system behaves as a gas of...

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Excitation Spectrum of a Supersolid

Cited by 144 publications

References 26 publications

Monodisperse cluster crystals: Classical and quantum dynamics

Monodisperse cluster crystals: Classical and quantum dynamics

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

Visualizing the BEC-BCS crossover in a two-dimensional Fermi gas: Pairing gaps and dynamical response functions from ab initio computations

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