Electrons in Fractal Geometries

Informations projet

FRACTAL

N° de convention de subvention: 865570

DOI

10.3030/865570

Projet clôturé

Date de signature de la CE 12 Decembre 2019

Date de début 1 Septembre 2020

Date de fin 28 Février 2026

Financé au titre de

• EXCELLENT SCIENCE - European Research Council (ERC)

Coût total

€ 2 718 750,00

Contribution de l’UE

€ 2 718 750,00

Coordonné par

UNIVERSITEIT UTRECHT
Netherlands

Periodic Reporting for period 3 - FRACTAL (Electrons in Fractal Geometries)

Période du rapport: 2023-09-01 au 2025-02-28

Résumé du contexte et des objectifs généraux du projet

The development of two-dimensional materials has enabled the discovery of new physical phenomena and led to the development of devices that are of crucial importance to our society. For example, we now base the definition of electrical resistance on the quantum Hall effect, a phenomenon exclusive to two dimensions. Similarly, the transistor that underpins every electronic device in use today relies on the manipulation of a two-dimensional electron gas. The realization that a material can have very different properties in two-dimensions compared to three-dimensions was a huge conceptual leap. In this project, a similar leap is taken: from integer (0,1,2,3) to non-integer, or fractional, dimensions. Specifically, we study (1) the properties of electrons in geometric fractals with dimension between 2 and 1. Fractals are objects that are self-similar on different length scales with two unique properties (i) a non-integer dimension and (ii) expansion symmetry but no periodicity. In addition, we aim to realize and experimentally characterize quasiparticles with fractional charge.

Travail effectué depuis le début du projet jusqu’à la fin de la période considérée dans le rapport et principaux résultats atteints jusqu’à présent

To engineer geometric fractals, and lattices with quasiparticles with fractional charge, the tip of a scanning tunneling microscope is used to position adsorbates with atomic scale precision. First, we developed a new platform to create artificial lattices, based on Cs atoms on InAs(111)A. This material system provides an energy resolution that is much superior that that of CO/Cu(111). We studied the manipulation mechanism in detail and built the first artificial lattices. Furthermore, in collaboration with the group of Prof. Allan (Leiden University and LMU Munich), we developed, tested, and implemented a new generation high-frequency preamplifier that can be used to measure shot-noise in a scanning tunneling microscope. Measuring shot-noise can provide direct access to the charge of (quasi)particles.

Progrès au-delà de l’état des connaissances et impact potentiel prévu (y compris l’impact socio-économique et les conséquences sociétales plus larges du projet jusqu’à présent)

Our new amplifier significantly outperforms previous generations and enables experiments that were previously impossible. We will use this amplifier to study a variety of systems, ranging from superconductors to artificial lattices that host quasiparticles with fractional charge.