arXiv subjects

Lorenzo Rosso

Publications and source records attributed to Lorenzo Rosso.

7 recordsLinked to original sources

arXiv2024

Loss induced collective mode in one-dimensional Bose gases

We show that two-body losses induce a collective excitation in a harmonically trapped one-dimensional Bose gas, even in the absence of a quench in the trap or any other external perturbation. Focusing on the dissipatively fermionized regime, we perform an exact mode expansion of the rapidity distribution function and characterize the emergence of the collective motion. We find clear coherent oscillations in the widths of the gas both in position and rapidity space as well as in the phase space quadrupole mode of the gas. We compare this motion to that of the well known breathing mode in the absence of losses and find that they differ in the motion of the density profile. We also discuss the role of losses in the collective motion of the gas following various other protocols, such as the removal of losses after a finite hold time, and when the harmonic trap is also quenched.

cond-mat.quant-gas↗

arXiv2024

Effects of atom losses on a one-dimensional lattice gas of hardcore bosons

Atom losses occur naturally during cold atoms experiments. Since this phenomenon is unavoidable, it is important to understand its effect on the remaining atoms. Here we study a gas of hard-core bosons on a lattice subject to $K$-body losses (where $K=1,2,3,\dots$ is the number of atoms lost in each loss event), and in particular we investigate the effect of losses on the rapidity distribution $ρ(k)$ of the atoms. Under the assumption that losses are weak enough so that the system relaxes between two loss events, we are able to determine the loss functional $F[ρ](k)$ encoding the loss process for $K$-body losses. We derive closed expressions for the cases of one- and two-body losses, and show their effects on the evolution of the total number of particles. Then we add a harmonic trapping potential and study the evolution of the position-dependent rapidity distribution of this system by solving numerically the evolution equation for one-, two- and three-body losses.

cond-mat.quant-gas↗

arXiv2023

A dynamical theory for one-dimensional fermions with strong two-body losses: universal non-Hermitian Zeno physics and spin-charge separation

We study an interacting one-dimensional gas of spin-1/2 fermions with two-body losses. The dynamical phase diagram that characterises the approach to the stationary state displays a wide quantum-Zeno region, identified by a peculiar behaviour of the lowest eigenvalues of the associated non-Hermitian Hamiltonian. We characterise the universal dynamics of this Zeno regime using an approximation scheme based on a effective decoupling of charge and spin degrees of freedom, where the latter effectively evolve in a non-Markovian way according to a non-Hermitian Heisenberg Hamiltonian. We present detailed results for the time evolution from initial states with one particle per site with either incoherent and antiferromagnetic spin order, showing how the two non-equilibrium evolutions build up drastically different charge correlations.

cond-mat.quant-gas↗

arXiv2022

Eightfold way to dark states in SU(3) cold gases with two-body losses

We study the quantum dynamics of a one-dimensional SU(3)-symmetric system of cold atoms in the presence of two-body losses. We exploit the representation theory of SU(3), the so-called eightfold way, as a scheme to organize the dark states of the dissipative dynamics in terms of generalized Dicke states and show how they are dynamically approached, both in the weakly- and and strongly-interacting and dissipative regimes. Our results are relevant for a wide class of alkaline-earth(-like) gases experiments, paving the way to the dissipative preparation and exploitation of generalized Dicke states.

cond-mat.quant-gas↗

arXiv2022

The one-dimensional Bose gas with strong two-body losses: the effect of the harmonic confinement

We study the dynamics of a one-dimensional Bose gas in presence of strong two-body losses. In this dissipative quantum Zeno regime, the gas fermionises and its dynamics can be described with a simple set of rate equations. Employing the local density approximation and a Boltzmann-like dynamical equation, the description is easily extended to take into account an external potential. We show that in the absence of confinement the population is depleted in an anomalous way and that the gas behaves as a low-temperature classical gas. The harmonic confinement accelerates the depopulation of the gas and introduces a novel decay regime, which we thoroughly characterise.

cond-mat.quant-gas↗

arXiv2021

One-dimensional spin-1/2 fermionic gases with two-body losses: weak dissipation and spin conservation

We present a theoretical analysis of the dynamics of a one-dimensional spin-1/2 fermionic gas subject to weak two-body losses. Our approach highlights the crucial role played by spin conservation in the determination of the full time evolution. We focus in particular on the dynamics of a gas that is initially prepared in a Dicke state with fully-symmetric spin wavefunction, in a band insulator, or in a Mott insulator. In the latter case, we investigate the emergence of a steady symmetry-resolved purification of the gas. Our results could help the modelisation and understanding of recent experiments with alkaline-earth(-like) gases like ytterbium or fermionic molecules.

cond-mat.quant-gas↗

arXiv2020

Dissipative flow equations

We generalize the theory of flow equations to open quantum systems focusing on Lindblad master equations. We introduce and discuss three different generators of the flow that transform a linear non-Hermitian operator into a diagonal one. We first test our dissipative flow equations on a generic matrix and on a physical problem with a driven-dissipative single fermionic mode. We then move to problems with many fermionic modes and discuss the interplay between coherent (disordered) dynamics and localized losses. Our method can also be applied to non-Hermitian Hamiltonians.

quant-ph↗