Correlations between Ground and Excited State Spectra of a Quantum Dot

TL;DR

This study investigates the relationship between ground and excited state spectra in quantum dots, revealing correlations and electron interaction effects through magnetoconductance measurements.

Contribution

It presents the first direct observation of correlations between excited and ground states in quantum dots for multiple electron additions, combining experimental data with a single-particle model.

Findings

Observed correlation between excited and ground states up to 4 electrons apart.

Detected electron-electron interaction effects as perturbations to the single-particle picture.

Identified magnetoconductance fluctuations as anticrossings indicating wavefunction exchange.

Abstract

We have studied the ground and excited state spectra of a semiconductor quantum dot for successive numbers of electron occupancy using linear and nonlinear magnetoconductance measurements. We present the first observation of direct correlation between the mth excited state of the N electron system and the ground state of the N+m electron system for m up to 4. Results are consistent with a non-spin-degenerate single particle picture of the filling of levels. Electron-electron interaction effects are also observed as a perturbation to this model. Magnetoconductance fluctuations of ground states are shown as anticrossings where wavefunction characteristics are exchanged between adjacent levels.