Talks

Density and pressure fluctuations in proliferating cell layers

Tissue growth is pivotal in embryonic development, tissue regeneration and disease progression. To ensure that tissue growth is properly controlled, cell growth and death is regulated by mechanical and biochemical feedback. However, cell proliferation is inherently stochastic. In this work, we introduce a new framework to model the feedback between stochastic tissue growth and regulation of proliferation. Using one-dimensional numerical simulations and theoretical analysis, we show that proliferating tissues show non-trivial statistical properties in the fluctuations of the density and pressure fields, including long-range correlations and different universality classes. These properties are controlled by the interplay between the statistical characteristics of the proliferation noise, the type of mechanical regulation, and the tissue size. Our results highlight new connections between non-equilibrium statistical mechanics and tissue dynamics, and provide insights into how small-scale non-equilibrium fluctuations impact the large-scale mechanical state of living tissues.

Quantum Dynamics Seminar: An Extended Rabi model for REMPI Spectroscopy

We investigate resonance-enhanced multiphoton ionization (REMPI) using an extended Rabi model incorporating dynamic Stark shifts, detuning, loss mechanisms and leakage induced complex (LIC) coupling. Our study focuses on the resulting population and phase dynamics, as well as the emergence and evolution of the Autler–Townes (AT) doublet structure in the photoelectron spectrum. The primary objective is to analyze the behavior of the AT doublet under variations in laser intensity, detuning, and pulse duration. To allow for analytical treatment, a flat-top pulse is employed - effectively reducing the problem to a time-independent form - to cater for the differing power-law dependence of the parameter functions on the pulse envelope. The analytical results are evaluated against numerical solutions of the time-dependent Schrödinger equation (TDSE). The model successfully captures key spectral features, including AT splitting, asymmetry, peak widths and multiplicity. These findings provide insight into the control of REMPI dynamics through pulse shaping, offering a framework for tailoring spectral structures in strong-field ionization.

Attractor reconstruction in attracting subspaces for robust reproduction of chaotic dynamics

Data-driven models of dynamical systems achieve time-series prediction and reproduction of a target chaotic system by reconstructing its attractor within their representation state space. This talk focuses on where in the representation space the attractor should be reconstructed. We present a method that reconstructs the attractor in an attracting low-dimensional subspace (slow submanifold), and show that it achieves robust reproduction of chaotic dynamics.

Slow dynamics, kinetic constraints and large deviations, from classical to quantum

Classical many-body systems that display slow collective relaxation (the typical example being glass formers) do so due to effective constraints in their dynamics, the simplest manifestation being kinetically constrained models. This approach highlights the relevance of rare events and of the properties of stochastic trajectories. I will review this perspective on slow dynamics, and describe what can be learnt by studying trajectory ensembles using the framework of large deviations. I will also discuss how this way of thinking can extend to quantum systems, highlighting the crossover of ideas and methods between classical and quantum non-equilibrium.

QUANT26 Colloquium

Colloquium

tba

TBA

TBA

Colloquium

tba

colcel26 Colloquium

TBA

TBA

TBA

TBA

Colloquium