# Sub-picosecond thermalization dynamics in condensation of strongly coupled lattice plasmons

## TL;DR

This study investigates sub-picosecond thermalization and condensation dynamics in strongly coupled lattice plasmon systems, revealing regimes of lasing, thermalization, and multimode condensation with control over ultrafast processes.

## Contribution

It demonstrates control and observation of thermalization and condensate formation at sub-picosecond timescales in plasmonic lattices with dye molecules.

## Key findings

- Identification of three regimes: lasing, thermalization, and multimode condensation.
- Condensation occurs when thermalization rate matches lattice size for short pump pulses.
- Achieved control over ultrafast thermalization and condensate formation.

## Abstract

Bosonic condensates offer exciting prospects for studies of non-equilibrium quantum dynamics. Understanding the dynamics is particularly challenging in the sub-picosecond timescales typical for room temperature luminous driven-dissipative condensates. Here we combine a lattice of plasmonic nanoparticles with dye molecule solution at the strong coupling regime, and pump the molecules optically. The emitted light reveals three distinct regimes: one-dimensional lasing, incomplete stimulated thermalization, and two-dimensional multimode condensation. The condensate is achieved by matching the thermalization rate with the lattice size and occurs only for pump pulse durations below a critical value. Our results give access to control and monitoring of thermalization processes and condensate formation at sub-picosecond timescale.