Direct observation of valley-hybridization and universal symmetry of graphene with mesoscopic conductance fluctuations

TL;DR

This paper demonstrates how mesoscopic conductance fluctuations can be used to directly observe and manipulate valley quantum states in disordered graphene, revealing a universal symmetry class linked to its crystal structure.

Contribution

It introduces a method to tune and read valley quantum states in graphene through conductance fluctuation measurements, highlighting a universal symmetry class.

Findings

Conductance fluctuations are reduced by a factor of four when valley triplet states are gapped.

The results reveal a gate-tunable universal symmetry class in graphene.

Valley states can be directly observed and controlled via mesoscopic conductance measurements.

Abstract

In graphene, the valleys represent spin-like quantities and can act as a physical resource in valley-based electronics to novel quantum computation schemes. Here we demonstrate a direct route to tune and read the valley quantum states of disordered graphene by measuring the mesoscopic conductance fluctuations. We show that the conductance fluctuations in graphene at low temperatures are reduced by a factor of four when valley triplet states are gapped in the presence of short range potential scatterers at high carrier densities. We also show that this implies a gate tunable universal symmetry class which outlines a fundamental feature arising from graphene's unique crystal structure.