arXiv subjects

Alberto Brollo

Publications and source records attributed to Alberto Brollo.

7 recordsLinked to original sources

arXiv2026

Thermodynamic Bethe Ansatz for the Toda chain from inverse scattering transform

The Thermodynamic Bethe Ansatz (TBA) procedure developed by Yang-Yang provides the free energy functional to be minimized via a variational problem. Their result not only gives the correct thermodynamics, but it also sets the framework for Generalized Hydrodynamics. Originally developed for quantum systems, this procedure has been recently successfully applied to (integrable) classical particle systems. However, this has never been done for classical field theories: no classical derivation has consistently accounted for solitons, breathers, radiation (dispersive modes), and their mutual interactions. We here derive the TBA equations for the Toda chain directly from its inverse scattering transform. This results in solitonic modes interacting with radiation, extending the soliton gas picture. We provide numerical verification of our equations against well established TBA equations in terms of particle modes. We expect the same procedure should apply to KdV, and pure radiative models as defocusing NLS and Sinh-Gordon, while we discuss current limitations in other models such as focusing NLS (and Ablowitz-Ladik) and Sine-Gordon.

cond-mat.stat-mech↗

arXiv2026

Quasiparticle Diffusion for the Toda Fluid in Equilibrium

Many-body integrable systems can be understood as a gas of quasiparticles. They propagate ballistically and drive large-scale transport. However, with the exception of the hard rods system, no tools have been available to numerically track such quasiparticles. Focusing on the Toda fluid, whose integrability relies on the availability of a Lax pair, we present a numerical scheme to track quasiparticle trajectories as determined by the time-dependent eigenvectors of the Lax matrix. Simulating the Toda fluid in thermal equilibrium, this tracking scheme is used to numerical confirm Brownian motion of a quasiparticle. Simulated is also the motion of a tagged particle. Our numerical results for the diffusion constant matches with a novel TBA prediction. We believe our numerical scheme can be extended to other classical many-particle models possessing a Lax matrix.

cond-mat.stat-mech↗

arXiv2025

Revisiting the tensionless limit of pure-Ramond-Ramond AdS3/CFT2

We revisit the numerical solution of the mirror TBA equations for pure--Ramond-Ramond strings on $AdS_3\times S^3\times T^4$ in the tensionless limit. Our analysis uses the recently-proposed modification of the dressing factors which account for non-trivial exchange relations of the massless modes. At leading order in the tension, the dynamics is driven by the massless excitations associated to $T^4$ modes and their superpartners, but it is non-relativistic and interacting unlike what happens in the symmetric-product orbifold CFT of $T^4$.

hep-th↗

arXiv2025

Universal efficiency boost in prethermal quantum heat engines at negative temperature

Heat engines near the adiabatic limit typically assume a working medium at thermal equilibrium. However, quantum many-body systems often showcase conservation laws that hinder thermalization, leading to prethermalization in exotic stationary phases. This work explores whether prethermalization enhances or reduces engine efficiency. We investigate Otto cycles in quantum systems with varying numbers of conserved quantities. We find that additional conservation laws reduce efficiency at positive temperatures, but enhance it in regimes of negative temperatures. Our findings stem from general thermodynamic inequalities for infinitesimal cycles, and we provide evidence for integrable models undergoing finite cycles using the theoretical framework of Generalized Hydrodynamics. The relevance of our results for quantum simulators is also discussed.

quant-ph↗

arXiv2024

Particle Scattering and Fusion for the Ablowitz-Ladik Chain

The Ablowitz-Ladik chain is an integrable discretized version of the nonlinear Schrödinger equation. We report on a novel underlying Hamiltonian particle system with properties similar to the ones known for the classical Toda chain and Calogero fluid with $1/\sinh^2$ pair interaction. Boundary conditions are imposed such that, both in the distant past and future, particles have a constant velocity. We establish the many-particle scattering for the Ablowitz-Ladik chain and obtain properties known for generic integrable many-body systems. For a specific choice of the chain, real initial data remain real in the course of time. Then, asymptotically, particles move in pairs with a velocity-dependent size and scattering shifts are governed by the fusion rule.

cond-mat.stat-mech↗

arXiv2023

More on the tensionless limit of pure-Ramond-Ramond AdS3/CFT2

In a recent letter we presented the equations which describe tensionless limit of the excited-state spectrum for strings on $AdS_3\times S^3\times T^4$ supported by Ramond-Ramond flux, and their numerical solution. In this paper, we give a detailed account of the derivation of these equations from the mirror TBA equations proposed by Frolov and Sfondrini, discussing the contour-deformation trick which we used to obtain excited-state equations and the tensionless limit. We also comment at length on the algorithm for the numerical solution of the equations in the tensionless limit, and present a number of explicit numerical results, as well as comment on their interpretation.

hep-th↗

arXiv2023

The Tensionless Limit of Pure-Ramond-Ramond AdS3/CFT2

Despite impressive advances in the AdS3/CFT2 correspondence, the setup involving Ramond-Ramond backgrounds, which is related to the D1-D5 system of branes, remained relatively poorly understood. We use the Mirror TBA equations recently constructed by Frolov and Sfondrini to study the spectrum of pure Ramond-Ramond $AdS_3\times S^3\times T^4$ strings. We find that the leading-order contribution to the anomalous dimensions at small tension is due to the gapless worldsheet excitations, i.e. to the $T^4$ bosons and their superpartners, whose interactions are nontrivial.

hep-th↗