Quantum quench of Kondo correlations in optical absorption

TL;DR

This paper reports the observation of Kondo correlations in optical absorption of a quantum dot, revealing a quantum quench and Anderson orthogonality catastrophe, with tunable exponents via magnetic field, opening new avenues in many-body quantum optics.

Contribution

It demonstrates the first optical measurement of Kondo correlations in a quantum dot and shows how a quantum quench affects many-body wavefunctions, with tunable parameters.

Findings

Observation of Kondo correlations in optical absorption.

Identification of Anderson orthogonality catastrophe signatures.

Tuning of power-law exponents with magnetic field.

Abstract

The interaction between a single confined spin and the spins of a Fermionic reservoir leads to one of the most spectacular phenomena of many body physics -- the Kondo effect. Here we report the observation of Kondo correlations in optical absorption measurements on a single semiconductor quantum dot tunnel-coupled to a degenerate electron gas. In stark contrast to transport experiments, absorption of a single photon leads to an abrupt change in the system Hamiltonian and a quantum quench of Kondo correlations. By inferring the characteristic power law exponents from the experimental absorption line-shapes, we find a unique signature of the quench in the form of an Anderson orthogonality catastrophe, originating from a vanishing overlap between the initial and final many-body wave-functions. We also show that the power-law exponents that determine the degree of orthogonality can be tuned by applying an external magnetic field which gradually turns the Kondo correlations off. Our experiments demonstrate that optical measurements on single artificial atoms offer new perspectives on many-body phenomena previously studied exclusively using transport spectroscopy. Moreover, they initiate a new paradigm for quantum optics where many-body physics influences electric field and intensity correlations.