Excited-state spectroscopy on a nearly-closed quantum dot via charge detection

TL;DR

This paper introduces a new charge detection method to measure the discrete energy spectrum of a nearly-closed quantum dot by analyzing charge dynamics induced by voltage pulses, enabling spectroscopic insights in the few-electron regime.

Contribution

A novel pulse-based charge detection technique for spectroscopic measurement of quantum dot energy levels in the weak coupling regime.

Findings

Successfully measured energy spectrum of a quantum dot in the few-electron regime.

Demonstrated charge detection method reveals energy levels via tunneling dynamics.

Applicable to nearly-closed quantum dots with weak lead coupling.

Abstract

We demonstrate a novel method for measuring the discrete energy spectrum of a quantum dot connected very weakly to a single lead. A train of voltage pulses applied to a metal gate induces tunneling of electrons between the quantum dot and a reservoir. The effective tunnel rate depends on the number and nature of the energy levels in the dot made accessible by the pulse. Measurement of the charge dynamics thus reveals the energy spectrum of the dot, as demonstrated for a dot in the few-electron regime.