Ultrafast many-body interferometry of impurities coupled to a Fermi sea

TL;DR

This paper demonstrates ultrafast interferometry to observe real-time dynamics of impurities in a Fermi sea, revealing quasiparticle formation and quantum interference in a strongly interacting quantum system.

Contribution

It introduces ultrafast time-domain measurements of impurity dynamics in a Fermi sea, enabling real-time observation of many-body quantum evolution.

Findings

Real-time tracking of quasiparticle formation.

Observation of quantum interference between states.

Ultrafast control of strongly interacting quantum gases.

Abstract

The fastest possible collective response of a quantum many-body system is related to its excitations at the highest possible energy. In condensed-matter systems, the corresponding timescale is typically set by the Fermi energy. Taking advantage of fast and precise control of interactions between ultracold atoms, we report on the observation of ultrafast dynamics of impurities coupled to an atomic Fermi sea. Our interferometric measurements track the non-perturbative quantum evolution of a fermionic many-body system, revealing in real time the formation dynamics of quasiparticles and the quantum interference between attractive and repulsive states throughout the full depth of the Fermi sea. Ultrafast time-domain methods to manipulate and investigate strongly interacting quantum gases open up new windows on the dynamics of quantum matter under extreme non-equilibrium conditions.