Wigner molecules and hybrid qubits

It is demonstrated that exact diagonalization of the microscopic many-body Hamiltonian via systematic full configuration-interaction (FCI) calculations is able to predict the spectra as a function of detuning of three-electron hybrid qubits based on GaAs asymmetric double quantum dots (QDs). It is further shown that, as a result of strong inter-electron correlations, these spectroscopic patterns, including avoided crossings between states associated with different electron occupancies of the left and right wells, are inextricably related to the formation of Wigner molecules (WMs). These physical entities cannot be captured by the previously employed independent-particle or Hubbard-type theoretical modeling of the hybrid qubit. We report remarkable agreement with recent experimental results. Moreover, the present FCI methodology for multi-well QDs can be straightforwardly extended to treat Si/SiGe hybrid qubits, where the central role of WMs was recently experimentally confirmed as well.

Automated summary

The exact diagonalization of the microscopic many-body Hamiltonian using FCI calculations accurately predicts the spectra of three-electron hybrid qubits based on GaAs double quantum dots. These spectroscopic patterns are closely related to the formation of Wigner molecules due to strong inter-electron correlations. Previous theoretical models cannot capture these physical entities.