arXiv subjects

Morgan Berkane

Publications and source records attributed to Morgan Berkane.

6 recordsLinked to original sources

arXiv2026

Is the most random pattern random? Maximizing localization in a two-dimensional lattice with engineered disorder

We investigate localization in two models: a single particle in a two-dimensional square lattice described by the tight binding Hamiltonian, and a two-dimensional square qubit lattice. It is well-known that Anderson localization occurs under suitable conditions in which the system parameters are chosen randomly from some statistical distribution. We propose a situation in which the parameters, specifically the on-site energies, are carefully chosen in such a way that a localization-quantifying parameter is maximized. We demonstrate the optimization procedure with numerical calculations in which the engineered localization significantly exceeds the average localization caused by a random distribution of the on-site energies. We explore the relation between spatial patterns and localization efficiency. Furthermore, we use perturbation theory to gain insight into the localization mechanism and obtain an improved cost function for optimization calculations, leading to enhanced localization in both the single-particle and full Hilbert spaces. Although large-scale simulations for qubit lattices are computationally infeasible, we use small-system simulations to demonstrate that results obtained using the single-particle tight binding model can be adapted to identify optimal settings for qubit lattice systems to achieve maximum decoupling between the qubits, which can be valuable for optimizing the idle-state settings on a quantum processor.

quant-ph↗

arXiv2026

Thermodynamic state variables from a minimal set of quantum constituents

We show how the macroscopic state variables pressure, entropy and temperature of equilibrium thermodynamics can be consistently derived from the (quantum) chaotic spectral structure of one or two particles in two-dimensional domains. This provides a definition of work and heat from first principles, a microscopic underpinning of the first and second law of thermodynamics, and a transparent illustration of the ``eigenstate thermalization hypothesis''.

quant-ph↗

arXiv2025

Time-domain interferences as the source of electron-ion entanglement in Rabi-dressed photoemission

We investigate bipartite entanglement between a photoelectron and its parent ion when the latter undergoes Rabi oscillations, following the recent experiment of [Nandi et al. Science Advances 10, eado0668 (2024)]. Using numerical simulations on a model atom, we show that this entanglement results from ionization events occurring at different times, with the photoelectron leaving the ion in distinct superpositions of internal states due to the Rabi coupling. Our interpretation brings forward the possibility to access the purity of the photoion state from photoelectron spectra. Furthermore, we demonstrate a tomographic reconstruction of the dressed ionic state dynamics from the observable spectra.

physics.atom-ph↗

arXiv2024

Complete retrieval of attosecond photoelectron dynamics from partially-coherent states in entangled photoemission

We show that the complete photoemission dynamics in situations of electron-ion entanglement can be retrieved from photoelectron spectral measurements without information on the ion. To this end, we develop an energy-time analysis of the photoelectron's reduced density matrix based on first principles. We test and assess our approach with numerical simulations on a low dimensional model molecule in interaction with broadband composite pulses occulting the vibrational resolution. Our method is directly applicable to recent experimental schemes measuring the photoelectron reduced density matrices in atomic and molecular photoemission. Therefore, it opens a new window on the dynamics of decoherence and entanglement at the attosecond timescale.

physics.chem-ph↗

arXiv2024

Probing Wigner time delays with photoelectron interferometry: Anisotropic long-range imprint of the short-range centrifugal potential

We consider the two-photon ionization of Hydrogen-like atoms. We find an approximate expression of the long-range phase based on an asymptotic expansion of the continuum eigenfunctions within the Wentzel-Kramers-Brillouin approximation. Combined with commonly used perturbative approaches, the resulting analytic formalism can treat, at the same time, the two-photon propensity rules, the anisotropy in the continuum-continuum photoionization time delay and the soft-photon regime.

physics.atom-ph↗

arXiv2024

Anisotropic molecular photoemission dynamics: Interpreting and accounting for the nuclear motion

We investigate how vibration affects molecular photoemission dynamics, through simulations on two-dimension asymmetric model molecules including the electronic and nuclear motions in a fully correlated way. We show that a slight anisotropy in the electron-ion momentum sharing is sufficient to prevent one from unambigously characterizing the vibrationnaly averaged photoemission dynamics in terms of stereo Wigner delays. We further show that vibrational resolution can be retrieved in fixed-nuclei simulations, using effective molecular conformations that are specific to each vibrational channel. The optimal internuclear distances found empirically in 1-photon processes can be identified a priori using simple physical arguments. They also turn out to be efficient to simulate vibrationnally-resolved \rabbit measurements and to account for interchannel coherences in broadband 1-photon ionization.

physics.chem-ph↗