arXiv subjects

T. Kottos

Publications and source records attributed to T. Kottos.

27 records · Page 2Linked to original sources

arXiv2007

Engineering fidelity echoes in Bose-Hubbard Hamiltonians

We analyze the fidelity decay for a system of interacting bosons described by a Bose-Hubbard Hamiltonian. We find echoes associated with "non-universal" structures that dominate the energy landscape of the perturbation operator. Despite their classical origin, these echoes persist deep into the quantum (perturbative) regime and can be described by an improved random matrix modeling. In the opposite limit of strong perturbations (and high enough energies), classical considerations reveal the importance of self-trapping phenomena in the echo efficiency.

cond-mat.other↗

arXiv2006

Bifurcations in Resonance Widths of an Open Bose-Hubbard Dimer

We investigate the structure of resonance widths of a Bose-Hubbard Dimer with intersite hopping amplitude $k$, which is coupled to continuum at one of the sites with strength $γ$. Using an effective non-Hermitian Hamiltonian formalism, we show that by varying the on-site interaction term $χ$ the resonances undergo consequent bifurcations. For $Λ=k/γ\geq 0.5$, the bifurcation points follow a scaling law ${\tilde χ}_n \equiv χ_n N/k = f_Λ(n-0.5/Λ)$, where $N$ is the number of bosons. For the function $f_Λ$ two different $Λ$ dependences are found around the minimum and the maximum bifurcation point.

cond-mat.other↗

arXiv2005

Wavepacket Dynamics, Quantum Reversibility and Random Matrix Theory

We introduce and analyze the physics of "driving reversal" experiments. These are prototype wavepacket dynamics scenarios probing quantum irreversibility. Unlike the mostly hypothetical "time reversal" concept, a "driving reversal" scenario can be realized in a laboratory experiment, and is relevant to the theory of quantum dissipation. We study both the energy spreading and the survival probability in such experiments. We also introduce and study the "compensation time" (time of maximum return) in such a scenario. Extensive effort is devoted to figuring out the capability of either Linear Response Theory (LRT) or Random Matrix Theory (RMT) in order to describe specific features of the time evolution. We explain that RMT modeling leads to a strong non-perturbative response effect that differs from the semiclassical behavior.

cond-mat.mes-hall↗

arXiv2001

Superballistic spreading of wave packets

We demonstrate for various systems that the variance of a wave packet $M(t)\propto t^ν$, can show a {\it superballistic} increase with $2<ν\le3$, for parametrically large time intervals. A model is constructed which explains this phenomenon and its predictions are verified numerically for various disordered and quasi-periodic systems.

cond-mat.dis-nn↗

arXiv1998

Finite-length Lyapunov exponents and conductance for quasi-1D disordered solids

The transfer matrix method is applied to finite quasi-1D disordered samples attached to perfect leads. The model is described by structured band matrices with random and regular entries. We investigate numerically the level spacing distribution for finite-length Lyapunov exponents as well as the conductance and its fluctuations for different channel numbers and sample sizes. A comparison is made with theoretical predictions and with numerical results recently obtained with the scattering matrix approach. The role of the coupling and finite size effects is also discussed.

cond-mat.dis-nn↗

arXiv1998

Finite-Size Corrections in Lyapunov Spectra for Band Random Matrices

The transfer matrix method is applied to quasi one-dimensional and one-dimensional disordered systems with long-range interactions, described by band random matrices. We investigate the convergence properties of the whole Lyapunov spectra of finite samples as a function of the bandwidth and of the sample length. Two different scaling laws are found at the maximal and minimal Lyapunov exponents.

cond-mat.dis-nn↗

arXiv1996

Evolution of wave packets in quasi-1D and 1D random media: diffusion versus localization

We study numerically the evolution of wavepackets in quasi one-dimensional random systems described by a tight-binding Hamiltonian with long-range random interactions. Results are presented for the scaling properties of the width of packets in three time regimes: ballistic, diffusive and localized. Particular attention is given to the fluctuations of packet widths in both the diffusive and localized regime. Scaling properties of the steady-state distribution are also analyzed and compared with theoretical expression borrowed from one-dimensional Anderson theory. Analogies and differences with the kicked rotator model and the one-dimensional localization are discussed.

cond-mat↗

arXiv1996

Transport properties of one-dimensional Kronig-Penney models with correlated disorder

Transport properties of one-dimensional Kronig-Penney models with binary correlated disorder are analyzed using an approach based on classical Hamiltonian maps. In this method, extended states correspond to bound trajectories in the phase space of a parametrically excited linear oscillator, while the on site-potential of the original model is transformed to an external force. We show that in this representation the two probe conductance takes a simple geometrical form in terms of evolution areas in phase-space. We also analyze the case of a general N-mer model.

cond-mat.dis-nn↗

arXiv1996

Scaling Properties of Localization Length in 1D Paired Correlated Binary Alloys of Finite Size

We study scaling properties of the localized eigenstates of the random dimer model in which pairs of local site energies are assigned at random in a one dimensional disordered tight-binding model. We use both the transfer matrix method and the direct diagonalization of the Hamiltonian in order to find how the localization length of a finite sample scales to the localization length of the infinite system. We derive the scaling law for the localization length and show it to be related to scaling behavior typical of uncorrelated Band Random Matrix, Anderson and Lloyd models.

cond-mat↗