Measurement back-action in stacked graphene quantum dots

TL;DR

This study investigates how classical and quantum back-action from charge detectors influences electron transport in stacked graphene quantum dots, revealing unique effects due to graphene's properties and higher order quantum mechanisms.

Contribution

It demonstrates the first detailed experimental analysis of back-action effects in stacked graphene quantum dots, highlighting the role of strong capacitive coupling and quantum mechanical processes.

Findings

Finite bias induces current in unbiased dot due to capacitive coupling

Transport observed in classically forbidden regimes explained by quantum back-action

Unique features arise from graphene's properties and device architecture

Abstract

We present an electronic transport experiment in graphene where both classical and quantum mechanical charge detector back-action on a quantum dot are investigated. The device consists of two stacked graphene quantum dots separated by a thin layer of boron nitride. This device is fabricated by van der Waals stacking and is equipped with separate source and drain contacts to both dots. By applying a finite bias to one quantum dot, a current is induced in the other unbiased dot. We present an explanation of the observed measurement-induced current based on strong capacitive coupling and energy dependent tunneling barriers, breaking the spatial symmetry in the unbiased system. This is a special feature of graphene-based quantum devices. The experimental observation of transport in classically forbidden regimes is understood by considering higher order quantum mechanical back-action mechanisms.