# Ultrafast dynamic stark shift of an exciton-polariton condensate

## TL;DR

Researchers demonstrated ultrafast control of a semiconductor quantum condensate using the dynamic Stark effect, opening new possibilities for quantum and classical information technologies.

## Contribution

First observation of ultrafast dynamic Stark shift in an exciton-polariton condensate using femtosecond pulses.

## Key findings

- A transient blueshift in the condensate energy was induced using a Stark pulse.
- Distinct spectro-temporal oscillations in differential reflectance spectra revealed coherence buildup.
- The method enables non-invasive and ultrafast modulation of exciton-polariton condensates.

## Abstract

Time-dependent spatial modulation of a quantum condensate plays a key role in the investigation of the dynamics of collective coherent systems. Cold-atom condensates were already manipulated into forming solitons, vortices and optical lattices via the dynamic Stark effect. In the solid-state framework, semiconductor microcavity exciton-polaritons present an excellent platform for observing nonequilibrium condensate dynamics. Furthermore, the dynamic manipulation of exciton-polariton condensates offers numerous potential implementations in all-optical logic devices. We report the first observation of the energy modulation of an exciton-polariton condensate via the dynamic Stark effect. A Stark pulse is employed to induce a transient, coherence-preserving blueshift in the energy of the condensate of femtosecond-scale duration. A novel approach is presented for discerning the Stark effect in a condensate from the uncondensed case according to distinctive features in differential reflectance spectra, including spectro-temporal oscillations enabling to detect the buildup of coherence. The ultrafast and non-invasive modulation of the exciton-polariton condensate demonstrated here opens new research avenues of nonequilibrium physics of solid-state condensates as well as opportunities for polariton-based elements in both classical and quantum information technologies.

Ultrafast shaping of exciton-polariton condensates enables applications for classical and quantum logic devices and provides insights into the physics of nonequilibrium quantum condensates in solid-state. Here, the authors demonstrate ultrafast and reversible dynamic Stark modulation of a semiconductor exciton-polariton quantum condensate.