Between a metal and an insulator: the critical state of the Anderson transition

TL;DR

This paper experimentally investigates the critical point of the Anderson transition using a cold atomic gas, revealing scaling invariance and confirming theoretical predictions about wavepacket behavior at the transition.

Contribution

It provides the first experimental measurement of the critical wavefunction shape and scaling properties at the Anderson transition in a cold atom system.

Findings

Wavepacket dynamics at criticality show scaling invariance.

Momentum distribution matches self-consistent localization theory.

Experimental results confirm theoretical predictions.

Abstract

Using a three-frequency one-dimensional kicked rotor experimentally realized with a cold atomic gas, we study the transport properties at the critical point of the metal-insulator Anderson transition. We accurately measure the time-evolution of an initially localized wavepacket and show that it displays at the critical point a scaling invariance characteristic of this second-order phase transition. The shape of the momentum distribution at the critical point is found to be in excellent agreement with the analytical form deduced from self-consistent theory of localization.