arXiv subjects

Alejandro S. Gómez

Publications and source records attributed to Alejandro S. Gómez.

4 recordsLinked to original sources

arXiv2026

Avalanches and Aging Driven by Parametric Amplification in Kerr Oscillator Networks

Gain, loss, and nonlinearity shape the phase-space landscape of driven-dissipative systems, such as Kerr parametric oscillator (KPO) networks realized in superconducting, nanomechanical, and photonic arrays. Networks of KPOs exploit the stationary states of this landscape for Ising machines, bosonic error-correcting codes, and sensing. Yet how transients reach these states from a given initial condition remains largely unexplored. Here we show that KPO networks with nonlinear couplings can develop avalanches in their transient dynamics: rapid cascades of amplification between modes reminiscent of the relaxation avalanches of glassy systems. The mechanism is that parametric gain first activates the modes whose detuning it can overcome, and their nonlinear frequency shifts then pull dormant modes into the gain window one at a time. Dormant modes keep decaying while they wait for their turn, so every activation starts from a smaller seed and the intervals between activations grow geometrically. The network thus ages: the longer it has evolved, the slower it changes, and activations accumulate only logarithmically in time. In a 20-mode network, each dwell lasts about twice as long as the previous one. While aging delays the approach to the stationary state, additive noise sets a floor on the seeds and unsticks the network, shortening the longest dwells first while the activation sequence survives to noise several orders of magnitude stronger.

cond-mat.stat-mech↗

arXiv2026

Multiple chiral Majorana states in proximitized magnetic topological insulator heterostructures

Achieving robust topological superconductivity with multiple Majorana channels is a key step for scalable topological quantum computing. To this end, we investigate magnetically doped three-dimensional topological insulator heterostructures proximitized by an s-wave superconductor within a fully three-dimensional extended Bernevig-Hughes-Zhang framework that explicitly accounts for vertical confinement. We show that magnetic exchange coupling, orbital mixing, and bulk band inversion cooperate to generate effective equal-spin p-wave pairing channels supporting multiple chiral Majorana modes. The number of Majorana channels is determined by the confined modes in the vertical direction and the high-Chern-number phases of the normal state, which allows us to derive an analytical criterion for the emergence of the multiple-Majorana topological superconducting phases. The chiral Majorana modes remain robust against strong disorder and moderate symmetry-breaking perturbations. We also demonstrate that a superconducting phase difference defining a vertical Josephson junction acts as a tunable parameter that controls the hybridization, minigap, and effective multiplicity of the low energy Majorana channels. Our results establish magnetic three-dimensional topological- insulator heterostructures as a promising platform for engineering multiple chiral Majorana modes.

cond-mat.mes-hall↗

arXiv2026

Quantum Dynamical Signatures of Topological Flow Transitions in Limit Cycle Phases

Quantum self-oscillatory phases are ubiquitous in driven-dissipative systems. Classically, each phase is defined by its flow pattern and how stationary sets organize phase space (e.g. fixed points and limit cycles), with transitions triggered by local bifurcations or global basin rearrangements. In the quantum regime, these reorganizations are often blurred by density-matrix averaging, and spectral indicators such as the Liouvillian gap can miss changes that unfold mainly in the transients. Here we introduce a topological graph invariant, the molecule, which captures the phase-space connectivity of fixed points and limit cycles. Transitions show up as discrete changes of this invariant, with each form marking a distinct quantum dynamical pattern (e.g. relaxation pathway). The molecule encodes the global topological constraints that govern how stationary sets and their basins can rearrange, clarifies when such rearrangements can affect the Liouvillian modes, and reveals additional transitions that remain hidden in the steady-state spectrum but stem from global changes of the flow topology. Our findings show that flow topology offers a clear and unified way to identify and classify dynamical phases beyond what Liouvillian spectra alone reveal.

cond-mat.mes-hall↗

arXiv2025

Monolayer transition metal dichalcogenides under finite-pulse polarized radiation

Recent advances in time-resolved angle-resolved photoemission spectroscopy have enabled access to ultrafast electron states and their spin dynamics in solids. Atomically thin transition metal dichalcogenides are paradigmatic two-dimensional materials where electron momentum and spin degrees of freedom are coupled, being suitable candidates for time-resolved spectroscopy studies. In this work, we present a thorough study of the electron dynamics when these materials are subject to an intense finite-pulse driving radiation. We extend the scope of the conventional Floquet engineering and rely of the so-called $t-t^{\prime}$ formalism to deal with driving fields described with two distinct time scales, namely the envelope amplitude timescale and the time period of the external field. The interplay between the finite-pulse timescales and the intrinsic properties of the electrons gives rise to transient valley polarization and dynamical modifications of band structures, revealed by the time-dependent circular dichroism of the sample.

cond-mat.mes-hall↗