arXiv subjects

Edmond Orignac

Publications and source records attributed to Edmond Orignac.

At least 19 recordsLinked to original sources

arXiv2026

Sound attenuation and velocity shift in antiferromagnetic spin-1/2 chains

We investigate ultrasound attenuation and sound velocity shift in antiferromagnetic spin-1/2 XXZ chains in magnetic field. We relate the sound velocity shift to derivatives of the free energy with respect to exchange interactions, permitting its calculation with integrability techniques at any temperature. Using bosonization, we predict the sound velocity shift exhibits a quadratic temperature correction at low temperatures in the Tomonaga-Luttinger liquid phase. Close to the fully polarized phase, a universal behavior associated with z=2 quantum criticality is found. In the Tomonaga-Luttinger liquid phase, ultrasound attenuation obeys a scaling law as a function of wavelength and temperature. An enhancement of attenuation is obtained near the fully polarized phase.

cond-mat.str-el↗

arXiv2026

Hall effect in multi-leg bosonic ladders

We use bosonization to analyze the ground state Hall response of interacting bosonic N-leg ladders threaded by a flux. We derive an explicit expression of the Hall imbalance in a perturbative expansion in the band curvature, retaining fully the interactions. For small magnetic field the Hall resistance is proportional to the derivative of the logarithm of the charge stiffness with respect to density, generalizing the result obtained in the two leg case. We also consider the effect of temperature, and establish that at low temperature, corrections to the Hall resistance are exponentially small in the Meissner phase.

cond-mat.quant-gas↗

arXiv2025

Critical Berezinskii-Kosterlitz-Thouless dynamics in the archetypal two-dimensional spin system Ba$_2$CuSi$_2$O$_6$Cl$_2$

We study the spin dynamics in the quasi-2D spin-$1/2$ dimer compound Ba$_2$CuSi$_2$O$_6$Cl$_2$, which exhibits a magnetic field-induced Bose-Einstein condensate (BEC) of triplons. Using nuclear magnetic resonance spin-lattice relaxation rate ($T_1^{-1}$) measurements combined with large-scale quantum Monte Carlo (QMC) simulations, we investigate critical fluctuations across the field-temperature phase diagram. Bridging the behavior observed in 1D and 3D systems, the $T_1^{-1}$ relaxation rate shows a pronounced peak extending well above the N\'eel temperature $T_N$, indicating strong two-dimensional Berezinskii-Kosterlitz-Thouless (BKT)-type fluctuations. A quantitative match between experimental and theoretical BEC phase boundaries validates an effective XXZ model. The study determines the intrinsic BKT transition temperature $T_{\mathrm{BKT}}$ from QMC, revealing a nearly field-independent $T_{\mathrm{BKT}}/T_N \approx 0.74$. Scaling analysis of the relaxation rate shows critical exponents consistent with 2D universality, and a narrow temperature window is identified where 2D physics dominates. These findings establish Ba$_2$CuSi$_2$O$_6$Cl$_2$ as a model system for exploring BKT dynamics in quantum magnets.

cond-mat.str-el↗

arXiv2025

Superconductivity in the repulsive Hubbard model on different geometries induced by density-assisted hopping

We study the effect of density-assisted hopping on different dimerized lattice geometries, such as bilayers and ladder structures. We show analytically that the density-assisted hopping induces an attractive interaction in the lower (bonding) band of the dimer structure and a repulsion in the upper (anti-bonding) band. Overcoming the onsite repulsion, this can lead to the appearance of superconductivity with a pairing structure more complex than s-wave pairing. Combining numerical and analytical methods such as the matrix product states ansatz, bosonization and perturbative calculations we map out the phase diagram of the two-leg ladder system and identify its superconducting phase. We characterize the transition from the non-density-assisted repulsive regime to the spin-gapped superconducting regime as a Berezinskii-Kosterlitz-Thouless transition.

cond-mat.str-el↗

arXiv2025

One dimensional Bose-Hubbard model with long range hopping

Interacting one-dimensional bosons with long range hopping decaying as a power law $r^{-\alpha}$ with distance $r$ are considered with the renormalization group and the self-consistent harmonic approximation. For $\alpha\ge 3$, the ground state is always a Tomonaga-Luttinger liquid, whereas for $\alpha <3$, a ground state with long range order breaking the continuous global gauge symmetry becomes possible for sufficiently weak repulsion. At positive temperature, continuous symmetry breaking becomes restricted to $\alpha<2$, and for $2<\alpha<3$, a Tomonaga-Luttinger liquid with the Tomonaga-Luttinger exponent diverging at low temperature is found.

cond-mat.quant-gas↗

arXiv2025

Platforms for the realization and characterization of Tomonaga-Luttinger liquids

The concept of a Tomonaga-Luttinger liquid (TLL) has been established as a fundamental theory for the understanding of one-dimensional quantum systems. Originally formulated as a replacement for Landau's Fermi-liquid theory, which accurately predicts the behaviour of most 3D metals but fails dramatically in 1D, the TLL description applies to a even broader class of 1D systems,including bosons and anyons. After a certain number of theoretical breakthroughs, its descriptive power has now been confirmed experimentally in different experimental platforms. They extend from organic conductors, carbon nanotubes, quantum wires, topological edge states of quantum spin Hall insulators to cold atoms, Josephson junctions, Bose liquids confined within 1D nanocapillaries and spin chains. In the ground state of such systems, quantum fluctuations become correlated on all length scales, but, counter-intuitively, no long-range order exists. In this respect, this review will illustrate the validity of conformal field theory for describing real-world systems, establishing the boundaries for its application and, on the other side will discuss the spectacular demonstration of how the quantum-critical TLL state governs the properties of many-body systems in one dimension.

cond-mat.str-el↗

arXiv2024

Emergent SU(3) symmetry in a four leg spin tube

We consider an antiferromagnetic four leg spin-1/2 tube using abelian and non-abelian bosonization. We show that in the limit of weak interchain coupling, the most relevant interaction gives rise to an emergent SU(3)} symmetry, broken only by marginal interactions that can be canceled by diagonal interchain couplings. We discuss the low energy spectrum in the semiclassical limit and using a mapping to a trimerized SU(3) spin chain. We establish that the correlation functions of ferroquadrupolar operators can be used to reveal the emergent symmetry.

cond-mat.str-el↗

arXiv2024

Breathing mode of a quantum droplet in a quasi-one-dimensional dipolar Bose gas

We investigate the breathing mode and the stability of a quantum droplet in a tightly trapped one-dimensional dipolar gas of bosonic atoms. When the droplet with a flat-top density profile is formed, the breathing mode frequency scales as the inverse of the number of atoms in the cloud. This is straightforwardly derived within a phenomenological hydrodynamical approach and confirmed using both a variational method based on a generalized Gross-Pitaevskii action functional and the sum-rule approach. We extend our analysis also to the presence of axial confinement showing the effect of the trap on the density profile and therefore on the breathing mode frequency scaling. Our analysis confirms the stability of the quantum droplet against the particles emission when the flat-top density profile is observed. Our results can be used as a guide to the experimental investigations of collective modes to detect the formation of quantum droplets in quasi-one-dimensional dipolar gases.

cond-mat.quant-gas↗

arXiv2023

Effect of transverse confinement on a quasi-one dimensional dipolar Bose gas

We study a gas of bosonic dipolar atoms in the presence of a transverse harmonic trapping potential by using an improved variational Bethe ansatz, which includes the transverse width of the atomic cloud as a variational parameter. Our calculations show that the system behavior evolves from quasi-one dimensional to a strictly one-dimensional one by changing the atom-atom interaction, or the axial density, or the frequency of the transverse confinement. Quite remarkably, in the droplet phase induced by the attractive dipolar interaction the system becomes sub-one dimensional when the transverse width is smaller than the characteristic length of the transverse harmonic confinement.

cond-mat.quant-gas↗

arXiv2022

Many-body parametric resonances in the driven sine-Gordon model

We study a quantum many-body variant of the parametric oscillator, by investigating the driven sine-Gordon model with a modulated tunnel coupling via a semi-classical Truncated Wigner Approximation (TWA). We first analyze the parametric resonant regime for driving protocols that retain our model gapped, and compare the TWA to a Time-Dependent Gaussian Variational Ansatz (TGVA). We then turn to a drive which closes the gap, resulting in an enhanced energy absorption. While the TGVA approach breaks down in this regime, we can apply TWA to explore the dynamics of the mode-resolved energy density, and the higher-order correlations between modes in the prethermal heating regime. For weak driving amplitude, we find an exponentially fast energy absorption in the main resonant mode, while the heating of all remaining modes is almost perfectly suppressed on short time scales. At later times, the highly excited main resonance provides effective resonant driving terms for its higher harmonics through the non-linearities in the Hamiltonian, and gives rise to an exponentially fast heating in these particular modes. We capture the strong correlations induced by these resonant processes by evaluating higher order connected correlation functions. Our results can be experimentally probed in ultracold atomic settings, with parallel one-dimensional quasi-condensates in the presence of a modulated tunnel coupling.

cond-mat.quant-gas↗

arXiv2020

Direct determination of the Tomonaga-Luttinger parameter $K$ in quasi-one-dimensional spin systems

We test the analytical formula for the enhancement of the nuclear magnetic resonance rate $T_1^{-1}$ by the critical spin fluctuations, over the simple power-law dependence predicted for a purely one-dimensional spin system, recently derived in the random phase approximation [M. Dupont et al., Phys. Rev. B 98, 094403 (2018)]. This prediction is experimentally confirmed by excellent fits to the published temperature dependence of $T_1^{-1}$ data in the two representative spin compounds, (C$_7$H$_{10}$N)$_2$CuBr$_4$ (DIMPY) and BaCo$_2$V$_2$O$_8$, providing at the same time a direct and convenient experimental determination of the Tomonaga-Luttinger-liquid parameter $K$, very well in agreement with theoretical predictions.

cond-mat.str-el↗

arXiv2020

Lattice modulation spectroscopy of one-dimensional quantum gases:Universal scaling of the absorbed energy

Lattice modulation spectroscopy is a powerful tool for probing low-energy excitations of interacting many-body systems. By means of bosonization we analyze the absorbed power in a one dimensional interacting quantum gas of bosons or fermions, subjected to a periodic drive of the optical lattice. For these Tomonaga Luttinger liquids we find a universal $\omega^3$ scaling of the absorbed power, that at very low-frequency turns into an $\omega^2$ scaling when scattering processes at the boundary of the system are taken into account. We confirm this behavior numerically by simulations based on time-dependent matrix product states. Furthermore, in the presence of impurities, the theory predicts an $\omega^2$ bulk scaling. While typical response functions of Tomonaga Luttinger liquids are characterized by exponents that depend on the interaction strength, modulation spectroscopy of cold atoms leads to a universal power-law exponent of the absorbed power. Our findings can be readily demonstrated in ultracold atoms in optical lattices with current experimental technology.

cond-mat.quant-gas↗

arXiv2019

Ground-state properties of the one-dimensional Hubbard model with pairing potential

We consider a modification of the one-dimensional Hubbard model by including an external pairing potential. Guided by analytic bosonization results, we quantitatively determine the grand-canonical zero-temperature phase diagram using both finite and infinite density matrix renormalization group algorithm based on the formalism of matrix product states and matrix product operator, respectively. By computing various local quantities as well as the half-system entanglement, we are able to distinguish between Mott, metallic and superconducting phases. We point out the compressible nature of the Mott phase and the fully gapped nature of the many-body spectrum of the superconducting phase, in the presence of explicit U(1)-charge symmetry breaking.

cond-mat.str-el↗

arXiv2018

Dynamical response and dimensional crossover for spatially anisotropic antiferromagnets

Theoretically challenging, the understanding of the dynamical response in quantum antiferromagnets is of great interest, in particular for both inelastic neutron scattering (INS) and nuclear magnetic resonance (NMR) experiments. In such a context, we theoretically address this question for quasi-one-dimensional quantum magnets, e.g. weakly coupled spin chains for which many compounds are available in Nature. In this class of systems, the dimensional crossover between a three-dimensional ordered regime at low temperature towards one-dimensional physics at higher temperature is a non-trivial issue, notably difficult concerning dynamical properties. Here we present a comprehensive theoretical study based on both analytical calculations (bosonization + random phase and self-consistent harmonic approximations) and numerical simulations (quantum Monte Carlo + stochastic analytic continuation) which allows us to describe the full temperature crossover for the NMR relaxation rate $1/T_1$, from one-dimensional Tomonaga-Luttinger liquid physics to the three-dimensional ordered regime, as a function of inter-chain couplings. The dynamical structure factor, directly probing the INS intensity, is also computed in the different regimes.

cond-mat.str-el↗

arXiv2018

Accessing finite momentum excitations of the one-dimensional Bose-Hubbard model using superlattice modulation spectroscopy

We investigate the response to superlattice modulation of a bosonic quantum gas confined to arrays of tubes emulating the one-dimensional Bose-Hubbard model. We demonstrate, using both time-dependent density matrix renormalization group and linear response theory, that such a superlattice modulation gives access to the excitation spectrum of the Bose-Hubbard model at finite momenta. Deep in the Mott-insulator, the response is characterized by a narrow energy absorption peak at a frequency approximately corresponding to the onsite interaction strength between bosons. This spectroscopic technique thus allows for an accurate measurement of the effective value of the interaction strength. On the superfluid side, we show that the response depends on the lattice filling. The system can either respond at infinitely small values of the modulation frequency or only above a frequency threshold. We discuss our numerical findings in light of analytical results obtained for the Lieb-Liniger model. In particular, for this continuum model, bosonization predicts power-law onsets for both responses.

cond-mat.quant-gas↗

arXiv2017

Probing the bond order wave phase transitions of the ionic Hubbard model by superlattice modulation spectroscopy

An exotic phase, the bond order wave, characterized by the spontaneous dimerization of the hopping, has been predicted to exist sandwiched between the band and Mott insulators in systems described by the ionic Hubbard model. Despite growing theoretical evidences, this phase still evades experimental detection. Given the recent realization of the ionic Hubbard model in ultracold atomic gases, we propose here to detect the bond order wave using superlattice modulation spectroscopy. We demonstrate, with the help of time-dependent density-matrix renormalization group and bosonization, that this spectroscopic approach reveals characteristics of both the Ising and Kosterlitz-Thouless transitions signaling the presence of the bond order wave phase. This scheme also provides insights into the excitation spectra of both the band and Mott insulators.

cond-mat.quant-gas↗

arXiv2016

Correlation dynamics during a slow interaction quench in a one-dimensional Bose gas

We investigate the response of a one-dimensional Bose gas to a slow increase of its interaction strength. We focus on the rich dynamics of equal-time single-particle correlations treating the Lieb-Liniger model within a bosonization approach and the Bose-Hubbard model using the time-dependent density-matrix renormalization group method. For short distances, correlations follow a power-law with distance with an exponent given by the adiabatic approximation. In contrast, for long distances, correlations decay algebraically with an exponent understood within the sudden quench approximation. This long distance regime is separated from an intermediate distance one by a generalized Lieb-Robinson criterion. At long times, in this intermediate regime, bosonization predicts that single-particle correlations decay following a stretched exponential. This latter regime is unconventional as, for one-dimensional interacting systems, the decay of single-particle correlations is usually algebraic within the Luttinger liquid picture. We develop here an intuitive understanding for the propagation of correlations, in terms of a generalized light-cone, applicable to a large variety of systems and quench forms.

cond-mat.quant-gas↗

arXiv2016

Incommensurate phases of a bosonic two-leg ladder under a flux

A boson two--leg ladder in the presence of a synthetic magnetic flux is investigated by means of bosonization techniques and Density Matrix Renormalization Group (DMRG). We follow the quantum phase transition from the commensurate Meissner to the incommensurate vortex phase with increasing flux at different fillings. When the applied flux is $ρπ$ and close to it, where $ρ$ is the filling per rung, we find a second incommensuration in the vortex state that affects physical observables such as the momentum distribution, the rung-rung correlation function and the spin-spin and charge-charge static structure factors.

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