Abstract:We study the quantum melting of stripe phases in models with competing short range and long range interactions decaying with distance as 1/r σ in two space dimensions. At zero temperature we find a two step disordering of the stripe phases with the growth of quantum fluctuations. A quantum critical point separating a phase with long range positional order from a phase with long range orientational order is found when σ ≤ 4/3, which includes the Coulomb interaction case σ = 1. For σ > 4/3 the transition is firs… Show more
“…This effect has been deeply studied in Refs. [42,43] and now our microscopic simulations confirm these predictions. Finally, the last frame corresponds to a temperature where the stripe structure is no more present because it has melted to a (normal) gas.…”
A two-dimensional quantum system of dipoles, with a polarization angle not perpendicular to the plane, shows a transition from a gas to a stripe phase. We have studied the thermal properties of these two phases using the path integral Monte Carlo (PIMC) method. By simulating the thermal density matrix, PIMC provides exact results for magnitudes of interest such as the superfluid fraction and the one-body density matrix. As it is well known, in two dimensions the superfluid-to-normal phase transition follows the Berezinskii-Kosterlitz-Thouless (BKT) scenario. Our results show that both the anisotropic gas and the stripe phases follow the BKT scaling laws. At fixed density and increasing the tilting angle, the transition temperature decreases in going from the gas to the stripe phase. Superfluidity in the perpendicular direction to the stripes is rather small close to the critical temperature but it becomes larger at lower temperatures, mainly close to the transition to the gas. Our results are in qualitative agreement with the supersolidity observed recently in a quasi-onedimensional array of dipolar droplets.
“…This effect has been deeply studied in Refs. [42,43] and now our microscopic simulations confirm these predictions. Finally, the last frame corresponds to a temperature where the stripe structure is no more present because it has melted to a (normal) gas.…”
A two-dimensional quantum system of dipoles, with a polarization angle not perpendicular to the plane, shows a transition from a gas to a stripe phase. We have studied the thermal properties of these two phases using the path integral Monte Carlo (PIMC) method. By simulating the thermal density matrix, PIMC provides exact results for magnitudes of interest such as the superfluid fraction and the one-body density matrix. As it is well known, in two dimensions the superfluid-to-normal phase transition follows the Berezinskii-Kosterlitz-Thouless (BKT) scenario. Our results show that both the anisotropic gas and the stripe phases follow the BKT scaling laws. At fixed density and increasing the tilting angle, the transition temperature decreases in going from the gas to the stripe phase. Superfluidity in the perpendicular direction to the stripes is rather small close to the critical temperature but it becomes larger at lower temperatures, mainly close to the transition to the gas. Our results are in qualitative agreement with the supersolidity observed recently in a quasi-onedimensional array of dipolar droplets.
“…This includes direct evidences for the existence of quantum nematic order in underdoped cuprates, likely related to the original context of fluctuating stripes [12][13][14][15][16][17][18][19]. A similar mechanism could be at hand in so-called pair density waves, which combines charge, spin, and superconducting orderings [20][21][22][23][24][25][26]. This theme later flourished in the context of the iron superconductors where quite some evidence surfaced for the prominent role of orientational symmetry breaking driven by the electron system as being central to their physics [27][28][29].…”
Section: A Quantum Liquid Crystals: the Contextmentioning
The dislocation-mediated quantum melting of solids into quantum liquid crystals is extended from two to three spatial dimensions, using a generalization of boson-vortex or Abelian-Higgs duality. Dislocations are now Burgers-vector-valued strings that trace out worldsheets in space-time while the phonons of the solid dualize into two-form (Kalb-Ramond) gauge fields. We propose an effective dual Higgs potential that allows for restoring translational symmetry in either one, two, or three directions, leading to the quantum analogues of columnar, smectic, or nematic liquid crystals. In these phases, transverse phonons turn into gapped, propagating modes, while compressional stress remains massless. Rotational Goldstone modes emerge whenever translational symmetry is restored. We also consider the effective electromagnetic response of electrically charged quantum liquid crystals, and find among other things that as a hard principle only two out of the possible three rotational Goldstone modes are observable using propagating electromagnetic fields.
“…It is particularly interesting to note that, within the effective field theory approach of Ref. (Mendoza-Coto et al, 2015b), it is possible to show exact correspondence between the universality of the nematic-isotropic transition and the one of homogeneous rotor models at finite temperature with decay exponent α = α + 2 (Mendoza-Coto et al, 2017). Therefore, for modulated phases in d = 2, the relevant regime for long-range interactions is rigidly shifted in such a way that any power law decay α > 2 is always irrelevant, while for α < 2 the interaction energy remains finite also in absence of any rescaling, due to the modulation pattern of the order parameter.…”
Section: Competing Non-local Systemsmentioning
confidence: 99%
“…Another important case is the generalization to the case of multi-scale potential which has been recently studied in the quantum regimes in (Abreu et al, 2020;Cinti and Macrì, 2019;Pupillo et al, 2020) which can for specific values of the parameters of the pairwise potential can support quasicrystalline phases or stripe phases. The corresponding criteria to realize structural phase in these more complex potentials have been investigated (Mendoza-Coto et al, 2017Mendoza-Coto and Stariolo, 2012;Mendoza-Coto et al, 2015a,b).…”
The presence of non-local and long-range interactions in quantum systems induces several peculiar features in their equilibrium and out-of-equilibrium behavior. In current experimental platforms control parameters such as interaction range, temperature, density and dimension can be changed. The existence of universal scaling regimes, where diverse physical systems and observables display quantitative agreement, generates a common framework, where the efforts of different research communities can be -in some cases rigorously -connected. Still, the application of this general framework to particular experimental realisations requires the identification of the regimes where the universality phenomenon is expected to appear. In the present review we summarise the recent investigations of many-body quantum systems with long-range interactions, which are currently realised in Rydberg atom arrays, dipolar systems, trapped ion setups and cold atoms in cavity experiments. Our main aim is to present and identify the common and (mostly) universal features induced by long-range interactions in the behaviour of quantum many-body systems. We will discuss both the case of very strong non-local couplings, i.e. the non-additive regime, and the one in which energy is extensive, but nevertheless low-energy, long wavelength properties are altered with respect to the short-range limit. Cases of competition with other local effects in the above mentioned setups are also reviewed.
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