Collective charge measurement in quantum dot chains: controlling barrier occupation and tunneling current

TL;DR

This paper studies how continuous quantum point contact measurements influence electron transport in a triple-quantum-dot system, revealing that structured measurement can enhance tunneling current and control barrier occupation.

Contribution

It demonstrates that global measurement schemes can significantly improve barrier occupation control and tunneling current in quantum dot chains, with optimal configurations identified.

Findings

Measurement improves barrier occupation and tunneling current.

Steady state becomes independent of Hamiltonian parameters under strong measurement.

Optimal measurement configuration maximizes steady-state current.

Abstract

We investigate nonequilibrium transport in a triple-quantum-dot (TQD) system, where the central dot acts as a discrete tunnel barrier, subject to continuous monitoring by a quantum point contact (QPC) that is capacitively coupled to all three dots with independently tunable strengths. We show that this global measurement scheme affects transport in a qualitatively distinct manner from single-site measurement. By engineering structured dephasing, measurement provides a significant improvement in the barrier occupation and tunneling current. In the strong-measurement limit, the steady state becomes independent of the underlying Hamiltonian parameters, and the barrier occupation can approach 1/2 for suitable measurement configurations. We identify an optimal measurement configuration that maximizes the steady-state current and show that near-optimal performance can be achieved with a simple central-dot readout scheme.