# Quantum Engineered Kondo Lattices

## TL;DR

This paper explores the quantum engineering of nanoscopic Kondo lattices, demonstrating how geometry influences their properties and revealing a new quantum phenomenon called the Kondo echo, advancing understanding of strongly correlated electron systems.

## Contribution

It introduces the concept of engineering Kondo droplets with tailored geometries to emulate heavy-fermion materials and uncovers the Kondo echo as a novel quantum signature.

## Key findings

- Geometry controls Kondo temperature in droplets.
- Coherent coupling approaches quantum-coherent Kondo lattice.
- Discovery of the Kondo echo as a probe of Kondo cloud correlations.

## Abstract

Recent advances in atomic manipulation techniques have provided a novel bottom-up approach to investigating the unconventional properties and complex phases of strongly correlated electron materials. By engineering artificial condensed matter systems containing tens to thousands of atoms with tailored electronic or magnetic properties, it has become possible to explore how quantum many-body effects---whose existence lies at the heart of strongly correlated materials---emerge as the size of a system is increased from the nanoscale to the mesoscale. Here we investigate both theoretically and experimentally the quantum engineering of nanoscopic Kondo lattices -- Kondo droplets -- that exemplify nanoscopic replicas of heavy-fermion materials. We demonstrate that by changing a droplet's real space geometry, it is possible to not only create coherently coupled Kondo droplets whose properties asymptotically approach those of a quantum-coherent Kondo lattice, but also to markedly increase or decrease the droplet's Kondo temperature. Furthermore we report on the discovery of a new quantum phenomenon -- the Kondo echo -- a signature of droplets containing Kondo holes functioning as direct probes of spatially extended, quantum-coherent Kondo cloud correlations.